[Federal Register: July 10, 2008 (Volume 73, Number 133)]
[Rules and Regulations]
[Page 39789-39838]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr10jy08-18]
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Part II
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Final Rule To Amend the
Listing for the Preble's Meadow Jumping Mouse (Zapus hudsonius preblei)
To Specify Over What Portion of Its Range the Subspecies Is Threatened;
Final Rule
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FWS-R9-ES-2007-0003; 92220-1113-0000; C6]
RIN 1018-AV64
Endangered and Threatened Wildlife and Plants; Final Rule To
Amend the Listing for the Preble's Meadow Jumping Mouse (Zapus
hudsonius preblei) To Specify Over What Portion of Its Range the
Subspecies Is Threatened
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service/USFWS), under
the authority of the Endangered Species Act of 1973, as amended (Act),
amend the listing for the Preble's meadow jumping mouse (Zapus
hudsonius preblei) (Prebles) to specify over what portion of its range
the subspecies is threatened. Based on the best scientific and
commercial data available, we have determined that the Prebles is a
valid subspecies and should not be delisted based upon taxonomic
revision; the subspecies is not threatened throughout all of its range;
and the portion of the subspecies' current range located in Colorado
represents a significant portion of the current range where the
subspecies should retain its threatened status. This determination is
based on a thorough review of all available information, which
indicates that Prebles' populations in Wyoming are more widespread and
threats to the subspecies less severe than those known at the time of
listing, but that in Colorado the Prebles is likely to become
endangered within the foreseeable future.
DATES: This rule is effective August 11, 2008.
FOR FURTHER INFORMATION CONTACT: Susan Linner, Field Supervisor, U.S.
Fish and Wildlife Service, Colorado Field Office at 134 Union Blvd.,
Suite 670, Lakewood, CO 80228; telephone (303) 236-4773. Individuals
who are hearing-impaired or speech-impaired may call the Federal Relay
Service at 1-800-877-8339 for TTY assistance.
SUPPLEMENTARY INFORMATION:
General Information
Meadow jumping mice (Zapus hudsonius) are small rodents with long
tails, large hind feet, and long hind legs. Total length of an adult is
approximately 187 to 255 millimeters (7 to 10 inches), with the tail
comprising 108 to 155 millimeters (4 to 6 inches) of that length
(Krutzsch 1954, p. 420; Fitzgerald et al. 1994, p. 291).
Typical habitat for Prebles is comprised of well-developed riparian
vegetation with adjacent, relatively undisturbed grassland communities
and a nearby water source (Bakeman 1997, pp. 22-31). Prebles are
typically captured in areas with multi-storied cover with an understory
of grasses or forbs or a mixture thereof (Bakeman 1997, pp. 22-31;
Bakeman and Deans 1997, pp. 28-30; Meaney et al. 1997a, pp. 15-16;
Meaney et al. 1997b, pp. 47-48; Shenk and Eussen 1998, pp. 9-11; Schorr
2001, pp. 23-24). The shrub canopy is often willow (Salix spp.),
although other shrub species may occur (Shenk and Eussen 1998, pp. 9-
11). Trainor et al. (2007, pp. 471-472) found that high-use areas for
Prebles tended to be close to creeks and were positively associated
with the percentage of shrubs, grasses, and woody debris. Hydrologic
regimes that support Prebles' habitat range from large perennial rivers
such as the South Platte River to small drainages only 1 to 3 meters
(m) (3 to 10 feet (ft)) in width.
Meadow jumping mice are primarily nocturnal or crepuscular (active
during twilight), but also may be active during the day. The Prebles
uses uplands at least as far out as 100 m (330 ft) beyond the 100-year
floodplain (Shenk and Sivert 1999a, p. 11; Ryon 1999, p. 12; Schorr
2001, p. 14; Shenk 2004; USFWS 2003b, p. 26). While the Prebles'
dispersal capabilities are thought to be limited, in one instance a
Prebles was documented moving as far as 1.1 kilometers (km) (0.7 mile
(mi)) in 24 hours (Ryon 1999, p. 12). The Prebles typically enters
hibernation in September or October and emerges the following May
(Whitaker 1963, p. 5; Meaney et al. 2003).
For additional information on the biology of this subspecies, see
the May 13, 1998, final rule to list the Prebles as threatened (63 FR
26517) and the June 23, 2003, final rule designating critical habitat
(68 FR 37275).
Previous Federal Actions
We listed the Prebles as threatened under the Act on May 13, 1998
(63 FR 26517). On May 22, 2001 (66 FR 28125), we adopted a final
section 4(d) special rule for the Prebles that provides exemptions from
section 9 take prohibitions for certain rodent control activities,
ongoing agricultural activities, maintenance and replacement of
existing landscaping, and existing uses of water. On October 1, 2002
(67 FR 61531), we amended this rule to provide exemptions for certain
noxious weed control and ditch maintenance activities. The special
rule, as amended, was scheduled to end May 22, 2004, but was made
permanent on May 20, 2004 (69 FR 29101). On June 23, 2003, we
designated critical habitat for the Prebles in portions of Colorado and
Wyoming (68 FR 37275).
In June 2000, the Service established the Preble's Meadow Jumping
Mouse Recovery Team (Recovery Team) composed of scientists and
stakeholders. In June 2003, the Recovery Team provided their
recommendations to the Service in the form of a draft recovery plan.
The Service revised this technical working draft in November 2003. This
document (hereafter referred to as the Preliminary Draft Recovery Plan)
suggests the long-term protection of populations spread throughout the
current range of the subspecies in order to lessen or eliminate
threats. In particular, the documents suggest long-term protection of 1
large population (with June abundances of 2,500 or more individuals), 2
medium populations (with June abundances of 500-2,499 individuals), and
6 small populations (with evidence of occupancy; possibly 150 mice)
within the North Platte River basin; 2 large, 3 medium, and 18 small
populations within the South Platte River basin; and 1 large
population, and 6 small populations within the Arkansas River basin
(USFWS 2003b, pp. 19-23). Recovery planning efforts were halted in
December 2003 after new information became available questioning the
taxonomic validity of the subspecies. While the availability of the
Preliminary Draft Recovery Plan (USFWS 2003b) has not yet been
announced in the Federal Register, it represents the best scientific
information available to us concerning recovery needs of the Prebles.
On December 23, 2003, we received two nearly identical petitions,
from the State of Wyoming's Office of the Governor and Coloradans for
Water Conservation and Development, seeking to remove the Prebles from
the Federal List of Endangered and Threatened Wildlife (Freudenthal
2003; Sonnenberg 2003). The petitions maintained that the Prebles
should be delisted based on the taxonomic revision suggested by Ramey
et al. (2003) and new distribution, abundance, and trends data that
suggested the subspecies was no longer threatened or endangered
(Freudenthal 2003, p. 1; Sonnenberg 2003, p. 1).
On March 31, 2004, we published a notice announcing a 90-day
finding that the petitions presented substantial information indicating
that the
[[Page 39791]]
petitioned action may be warranted (69 FR 16944). On February 2, 2005,
we published a 12-month finding that the petitioned action was
warranted and a proposed rule to remove Prebles from the Federal List
of Endangered and Threatened Wildlife (70 FR 5404). This notice also
opened a 90-day public comment period. The proposed delisting was based
upon a taxonomic revision suggested by Ramey et al. (2004a (a revision
of Ramey et al. 2003)), which concluded that Prebles should be
synonymized with a neighboring subspecies (Ramey et al. 2004a, pp. 1,
13). Although this report remained unpublished and had received mixed
peer reviews, we concluded that a lack of distinct genetic and
morphologic differences suggested that Prebles was likely not a valid
subspecies of meadow jumping mouse (Zapus hudsonius). Considering the
weight that the findings of Ramey et al. (2004a) had in the proposed
delisting, verifying these results prior to making a final decision on
the proposal was a high priority of the Service (Williams 2004;
Morgenweck 2005). As such, we contracted with the U.S. Geological
Survey (USGS) to conduct additional genetic analysis of Prebles and
four neighboring subspecies of meadow jumping mice (USGS 2005, pp. 1-
4).
On January 25, 2006, the USGS released its report concluding that
the Prebles should not be synonymized with neighboring subspecies of
meadow jumping mice (King et al. 2006a, pp. 2, 29). On February 17,
2006, the Service extended the rulemaking process an additional 6
months as allowed under section 4(b)(6)(B)(i) of the Act (71 FR 8556).
This USGS study indicated that there was substantial disagreement
regarding the sufficiency or accuracy of the available data relevant to
the determination contained in our proposed rule. We reopened the
comment period for an additional 60 days and announced that we intended
to assemble a panel of experts to carefully review and assess the two
studies.
On March 30, 2006, we published a notice of availability of the
King et al. (2006a) and Ramey et al. (2005) data and extended the
comment period on the proposed delisting rule an additional 30 days (71
FR 16090). We then contracted with Sustainable Ecosystems Institute
(SEI) to organize a scientific review panel to analyze, assess, and
weigh the reasons why the data, findings, and conclusions of King et
al. differed from the data, findings, and conclusions of Ramey et al.
(as written in this sentence, and hereafter, ``Ramey et al.'' or ``King
et al.'' without a modifying date refers to the overall work of these
authors instead of a specific publication) (USFWS 2006, p. 14). On July
21, 2006, SEI delivered a final report to the Service (SEI 2006a).
On September 26, 2006, the State of Wyoming submitted a 60-day
notice of intent to sue over our failure to publish a final
determination on our 2005 proposed delisting rule within the timeframes
allowed by the Act. On January 24, 2007, the State of Wyoming filed a
petition for review with the court. On June 22, 2007, the Service and
the State of Wyoming reached a settlement agreement which required
that, by October 31, 2007, we submit to the Federal Register for
publication either (1) a withdrawal of our 2005 proposed delisting
regulation; or (2) a new proposed regulation considering the Prebles'
taxonomy and the subspecies' threatened status in light of all current
distribution, abundance, and trends data (State of Wyoming v. U.S.
Department of the Interior, No. 07CV025J (District of Wyoming 2007)).
On November 7, 2007, we published a revised proposed rule to amend the
listing of the Prebles to specify over what portion of its range the
subspecies is threatened and opened a 75-day public comment period (72
FR 62992). Under the settlement agreement with the State of Wyoming,
the Service agreed to submit a final determination on the revised
proposed rule to the Federal Register no later than June 30, 2008.
Public Comments Solicited
Comments on this rulemaking were accepted from February 2 to May 3,
2005 (70 FR 5404, February 2, 2005), from February 17 to April 18, 2006
(71 FR 8556, February 17, 2006; 71 FR 16090, March 30, 2006), and from
November 7, 2007 to January 22, 2008 (72 FR 62992, November 7, 2007).
Open houses and public hearings were held on December 10, 2007, in
Lakewood, Colorado, and on December 12, 2007, in Wheatland Wyoming (72
FR 62992, November 7, 2007). These opportunities to comment were
publicized via the Federal Register, press releases, public notices in
area newspapers, postings on our Web site, and direct contact with
Federal and State agencies, county governments, scientific
organizations, and other interested parties. In addition, the media
provided substantial coverage of the proposals. Comments could be hand
delivered to us, submitted to us via e-mail, mail, the Federal e-
Rulemaking Portal, fax, or provided during public hearing testimony.
Comments were submitted by a variety of parties including the
general public, business interests, environmental organizations, and
Federal, State, and local governments. We received 122 written, faxed,
or e-mailed comments during public comment periods (excluding peer
reviewers' comments discussed below). An additional eight comments were
provided during two public hearings. On March 24, 2006, the Service
received a Data Quality Act challenge on behalf of Coloradans for Water
Conservation and Development and the Colorado Farm Bureau. While this
challenge was handled separately from this rulemaking, all of the
relevant issues raised also were considered public comments and
considered in this final determination. All of the public comments
available prior to the July 2006 SEI panel were made available to the
panelists.
Peer Review
In accordance with our Interagency Policy for Peer Review in Act
Activities (59 FR 34270, July 1, 1994) and the Office of Management and
Budget's (OMB) Final Information Quality Bulletin for Peer Review (70
FR 2664, January 14, 2005), we sought the expert opinions of
appropriate and independent specialists regarding this rulemaking.
First, we contacted five reviewers with expertise in genetics,
systematics, and small mammals to review the taxonomic portions of this
document. Four of those solicited provided comments during one or more
of the comment periods (Gore 2008; Hoekstra 2005; Kelt 2005, 2006,
2008; Spencer 2005, 2006a, 2008). All of the peer reviews submitted
prior to the July 2006 SEI panel meeting were made available to the
expert panelists (Hoekstra 2005; Kelt 2005, 2006; Spencer 2005, 2006a).
Second, we contacted an additional five reviewers with expertise in
small-mammal biology, riparian-community ecology and status, population
dynamics and extinction risk, and/or development trends and land-use
conflicts to review the remainder of the 2007 revised proposal. All
five of these reviewers provided comments (Anderson 2008; Beauvais
2008; Buskirk 2008; Nupp 2008; Travis 2008).
Given the information now available, all of the experts who
commented on taxonomic portion of the rule were supportive of our
discussion, analysis, and/or conclusions. No reviewers expressed
significant concerns over our analysis of the Prebles' taxonomy.
Reviews that focused on the remainder of the 2007 revised proposed
rule were generally supportive of Service efforts, but provided
criticism
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and suggestions regarding various aspects of the revised proposed rule.
Six reviewers provided comments on whether evidence we presented in the
revised proposed rule sufficiently supported our removal of the Act's
protections for the Wyoming populations. Three reviewers supported our
proposal as being reasonable based on evidence presented. Two reviewers
questioned the proposal based largely on adequacy of existing knowledge
regarding Prebles' populations in Wyoming. One reviewer opposed the
proposal, calling it weakly supported. Two reviewers suggested that the
revised proposed rule should have made better use of geographic
information systems (GIS) to depict and analyze trapping efforts,
documented occurrence, appropriate habitat, and projected threats.
Reviewer opinions also varied on use of the Wyoming--Colorado State
line to delineate a significant portion of Prebles' range. While
reviewers generally considered a division based on the North Platte
River basin and the South Platte River basin more appropriate from an
ecological or mouse population perspective, three concluded that the
use of the State line was supported by the differing levels of threats
described. Two reviewers called for more detailed analysis of threats
as related to both sides of the State line. One reviewer discounted
significant differences in threats across the State line. Three
reviewers mentioned the administrative or practical convenience of
using the State line.
Summary of Public Comments
We reviewed all comments from peer reviewers and the public for
substantive issues and new information regarding this rulemaking.
Substantive comments received during the comment periods have been
addressed below or incorporated directly into this final rule. Comments
of a similar nature have been grouped together under subject headings
in a series of issues and responses.
Technical and Editorial Comments
Issue: Several technical and editorial comments were provided by
respondents. In addition, peer reviewers and other commenters provided
or suggested additional literature to consider in our final rule.
Response: We corrected inaccuracies in the revised proposed rule
wherever appropriate. We also edited portions of the text to make it
clearer. We reviewed and incorporated relevant additional literature
and information when appropriate. The list of literature cited in this
rule will be posted online (http://www.fws.gov/mountain-prairie/
species/mammals/preble/).
Defining a ``Listable Entity'' under section 4 of the Act.
Issue: We received numerous comments on taxonomic data quality and
quantity. Many questioned the amount of data necessary to make such
taxonomic determinations. Some commenters questioned the basis for the
initial listing of the subspecies. Other commenters discussed whether
the available data relied upon in our 2005 proposed rule was sufficient
or insufficient. Some commenters suggested we should employ the
precautionary principle when making a call on delisting. Other
commenters questioned our apparent reliance upon the peer reviewer
``majority vote'' as a justification for our 2005 proposed delisting.
Still other commenters noted or questioned evidence of political
interference in this rulemaking process.
Response: The Act requires that we base our determinations upon the
best scientific and commercial information available. As a result, we
evaluate all of the available information, its adequacy and
reliability, and determine what the weight of evidence suggests. This
final rule meets this standard. These issues and the available data are
discussed below in the sections titled: Taxonomy; Other Taxonomic
Information Available Prior to Listing; Taxonomic Information Solicited
After Listing; and Taxonomic Conclusions.
Issue: Many questioned the standards used to test what is a valid
subspecies. Some commenters suggested philosophical differences played
a role in shaping the hypothesis of each researcher and what each
researcher considered a valid subspecies. Other commenters suggested
that the Service is inconsistent in applying subspecies standards in
its section 4 determinations. Some commenters noted that there are no
quantitative standards in use by the scientific community or the
Service with which to objectively describe subspecies. Some commenters
suggested that acceptance by the scientific community is often nothing
more than opinion.
Response: As defined by the Act, a species includes any subspecies
of fish or wildlife or plant, and any distinct population segment (DPS)
of any species of vertebrate fish or wildlife which interbreeds when
mature. The Act does not further define subspecies. Service regulations
(50 CFR 424.11) state that ``In determining whether a particular taxon
or population is a species for the purposes of the Act, the Secretary
shall rely on standard taxonomic distinctions and the biological
expertise of the Department and the scientific community concerning the
relevant taxonomic group.'' This regulatory standard is consistent with
the Act's requirement that we make such determinations solely on the
basis of the best scientific and commercial data available. The Service
consistently applies this standard.
In this case, we determine that the best scientific and commercial
data available support the conclusion that the Prebles is a valid
subspecies. While philosophical differences among researchers may play
a role in what a particular researcher considers a biologically
meaningful difference, we conclude that the weight of evidence supports
the Prebles as a valid subspecies.
Specifically, the Prebles' geographic isolation from other
subspecies of meadow jumping mice (Krutzsch 1954, pp. 452-453; Long
1965, pp. 664-665; Beauvais 2001, p. 6; Beauvais 2004; SEI 2006a, p.
34) has resulted in the accretion of considerable genetic
differentiation (King et al. 2006b, pp. 4336-4348; SEI 2006a, pp. 41-
43). The available data suggest that the Prebles meets or exceeds
numerous, widely accepted subspecies definitions (Mayr and Ashlock
1991, pp. 43-45; Patten and Unitt 2002, pp. 26-34; SEI 2006a, p. 44).
In terms of quantitative standards, the 75 percent rule (Amadon
1949; Patten and Unitt 2002) is one of the only widely employed
quantitative subspecies definitions (Haig et al. 2006, pp. 1584-1594).
This definition suggests a subspecies is valid if 75 percent or more of
a population is separable from all (or > 99 percent of) members of the
overlapping population. As noted by SEI (2006a, p. 44), the Prebles
exceeds this quantitative standard.
Issue: We received numerous comments regarding the status of the
Prebles relative to the requirements of the Interagency Policy
Regarding the Recognition of Distinct Vertebrate Population Segments
Under the ESA (DPS policy) (61 FR 4722, February 7, 1996) including the
suggestion that the Prebles should or could be split into multiple DPSs
based on significant genetic differences observed between populations
north and south of Denver (Ramey et al. 2005, pp. 334-341; King et al.
2006a, pp. 28-29).
Response: The available data supports the taxonomic status of the
Prebles as a valid subspecies making most comments about potential
application of the DPS policy moot. We do not believe splitting the
subspecies into multiple DPSs would be prudent or beneficial
[[Page 39793]]
from a conservation perspective. In this case, we do not foresee any
significant benefit to recovering multiple DPSs instead of a single
listed entity.
Issue: Some commenters suggested that the Service's revised
proposed rule (72 FR 62992, November 7, 2007) displayed bias in our
presentation of the available information. Specifically, some
commenters suggested we highlighted flaws in reports questioning the
taxonomic validity of the Prebles, while not offering similar critiques
of information supporting the subspecies' taxonomic validity.
Response: To the maximum extent possible, we attempted to
objectively portray the available information regardless of the
position it articulated. All information was held to a similar level of
critical review. However, we have reviewed the final rule relative to
the specific objections and made minor revisions where appropriate.
Ramey et al. and King et al.
Issue: Some commenters suggested the Ramey et al. (2003, 2004a,
2004b, 2005) studies exhibited bias. Some commenters questioned whether
the studies could be relied upon because the studies were largely
funded by the State of Wyoming, one of the petitioners. Other
commenters noted that the conclusions strayed beyond genetics and
taxonomy into policy considerations.
Response: Ramey et al. (2004a, 2004b, 2005) were subjected to
extensive peer and public review, were reviewed and approved by a peer-
reviewed journal, and were reviewed by the SEI expert panel. All of
this information has been taken into consideration in this final
determination.
Issue: Some commenters suggested the King et al. (2006a, 2006b)
studies exhibited bias. It was suggested that Dr. King has a history of
designating unwarranted or questionable subspecies. Some commenters
questioned Dr. King's qualifications. Other commenters suggested that
USGS was inherently biased because the Service and USGS are sister
agencies under the Department of the Interior.
Response: King et al. (2006a, 2006b) were the subject of extensive
peer review and public review, were reviewed and approved by a peer-
reviewed journal, and were reviewed by the SEI expert panel. All of
this information has been taken into consideration in this final
determination.
We believe the USGS research team was well qualified to conduct the
analysis. For example, their previous work concerning Atlantic salmon
(Salmo salar) was upheld by a National Research Council (2002b, p. 4)
review. This validation provided us with confidence that these
researchers' expertise could meet our scientific needs. We do not
believe that USGS' research conclusions were biased by the fact that it
is a sister agency to the Service.
Issue: Some commenters questioned the critiques raised by peer
reviewers and the scientific community. Rebuttals were offered for each
criticism of Ramey et al. (2005) listed in the proposed rule. It was
suggested that we failed to explain that many of these issues were
relevant to the draft they evaluated (Ramey et al. 2004a, 2004b), but
resolved in the publication (Ramey et al. 2005). Finally, it was
suggested that many of these same issues plague the King et al. (2006b)
report.
Response: We have revised this section (see the Taxonomic
Information Solicited After Listing section below) so as to clearly
explain that many of the issues raised by peer reviewers of Ramey et
al. (2004a, 2004b) were rectified in the 2005 publication (Ramey et al.
2005). Each of these critiques was carefully considered. All of the
issues remaining in this section of this final rule continue to remain
relevant and may have contributed, at least in part, to the conclusions
of Ramey et al. (2005).
For example, while the comment defended the use of museum
specimens, we remain concerned that Ramey et al.'s (2004a, 2004b, 2005)
reliance upon museum specimens may have contributed to contamination of
numerous key samples. As noted by Douglas (2004), the quality of DNA
extracted from museum specimens is often inferior, fragmented, and low
quantity. As a result, amplification can be difficult and cross-
contamination with other high-quality DNA can occur. Ramey et al.
(2004a, p. 6) confirmed ``some DNA extracts, most notably those of
older museum specimens (prior to 1980), did not amplify well or at
all.'' King et al. (2006b, pp. 4355-4357) demonstrated that numerous
key DNA sequences were not repeatable. Most importantly, SEI (2006a,
pp. 21-30) confirmed evidence of contamination of key Ramey et al.
samples after reviewing the original supporting data. While other
explanations are possible (King et al. 2006, p. 4345; Ramey et al.
2007, p. 3519), we have concluded that the Ramey et al. (2005) data
demonstrates sufficient evidence of contamination to warrant inclusion
on this list of concerns.
Similarly, results can be meaningfully altered if a museum
specimen's tag (marking locality and subspecies) is incorrect. This
appears to be the case with museum specimens KU115895, KU115896, and
KU115897 (Anderson & Jones 1971 as cited in King et al. 2006b, p.
4357). That said, museum specimens remain a valuable resource in
providing specimens from a large geographic area and often allow a
study to be executed in relatively short time. As recommended by the
literature, proper precautions are required (Cooper and Poinar 2000).
Most of the other critiques of Ramey et al. centered on study
design and the thoroughness of the evaluation. We continue to list
these issues because each of these factors may have influenced the
study's results and conclusions. We also have tried to clarify when a
similar issue may have influenced the results and conclusions of King
et al. The relative importance of many of these issues is discussed in
the SEI report (SEI 2006, pp. 20-43).
Issue: Numerous commenters suggested that the sampling regime was a
critical difference between the two studies (Ramey et al. 2004a, 2004b,
2005; King et al. 2006a, 2006b). Several commenters suggested that
Crandall and Marshall (2006) represented the best scientific and
commercial information available in that their report combined the
Ramey et al. (2005) and King et al. (2006a) data into a single,
comprehensive analysis.
Response: We think that an ideal sampling strategy, with unlimited
resources, would sample many individuals from many populations across
the range of all 12 recognized meadow jumping mouse subspecies.
Instead, Ramey et al. sampled a few individuals from many sites, while
King et al. sampled many individuals from a few sites. Each approach
has its strengths and weaknesses.
The Ramey et al. approach likely captures variation across the
range of the subspecies (Ramey et al. 2005, p. 332), but may
underestimate the level of within-population variation, inflate within-
subspecies variance, and potentially lower the between-subspecies
differentiation (King et al. 2006b, p. 4346). The King et al.
population-oriented approach likely denotes the diversity within a
population (King et al. 2006b, p. 4346), but may not capture variance
along past or present contact zones between the subspecies (SEI 2006a,
pp. 31-43) and may predispose the results to an exaggeration of genetic
distances among subspecies (Ramey et al. 2007, p. 3519). We considered
each of these potential sources of bias in our evaluation of the
available data. Overall, we concluded that sampling played only a minor
role
[[Page 39794]]
in shaping differences between the two studies. Instead, we believe
apparent contamination among a number of key samples was likely the
primary reason the Ramey et al. (2005) and King et al. (2006b) mtDNA
data differed. While Crandall and Marshall (2006) employed a hybrid
approach reevaluating both the Ramey et al. and King et al. mtDNA
sequences, this unpublished study has a number of important weaknesses
(see Spencer 2006b) including the inclusion of these same questionable
samples. As Crandall and Marshall (2006, p. 5) put it, ``much is
dependent on these few samples.'' We have concluded that inclusion of
these apparently contaminated samples makes the mtDNA results and
conclusions of Ramey et al. (2005) and Crandall and Marshall (2006)
unreliable.
Issue: Several commenters suggested that even if the apparently
contaminated samples are removed from the analysis, the data still
supports the conclusions of Ramey et al. (2005).
Response: No data or analysis were presented to support the
assertion that Ramey et al.'s key conclusions would not differ if the
suspect samples were removed. Ramey et al. (2007, p. 3520) state that
``With the samples in question excluded, analysis of molecular variance
results just exceed our threshold, but the Prebles is still not even
close to being reciprocally monophyletic.'' This suggests the mtDNA
results would satisfy Ramey et al.'s (2005, p. 332) a priori mtDNA
hypothesis for a valid subspecies where there was greater molecular
variance among than within subspecies. Overall, we feel the available
data is compelling in its support of the validity of this taxon.
Issue: A few commenters suggested that Ramey et al. set up
subspecies standards in advance of data collection, while King et al.
relied upon post-hoc interpretations of the data.
Response: Our evaluation of Ramey et al. (2003, p. 4; 2004a, p. 4;
2005, pp. 331-334), USGS (2005, p. 3) and King et al. (2006a, p. 5;
2006b, p. 4332) revealed that both research teams developed their
hypotheses in advance of data collection which they consistently
applied throughout the process.
Issue: A few commenters questioned whether hybridization between
the Prebles and the western jumping mouse could have impacted each
study's results.
Response: Genetic distance between the Prebles and the western
jumping mouse is significant (King et al. 2006b, p. 4341), and the
available genetic studies experienced no difficulty differentiating
between the two species (Riggs et al. 1997, pp. 6-11; Ramey et al.
2005, p. 332; King et al. 2006b, p. 4341). Wunder and Harrington (1996,
section 6.0) also ruled out hybridization based on a small sampling of
random amplification of polymorphic DNA (RAPD) (an amplification of
random segments of DNA with single primer of arbitrary nucleotide
sequence). Based upon the best scientific and commercial information
available, we do not believe hybridization is occurring between these
two distinct species.
Issue: Several commenters suggested King et al. examined too much
data. Specifically, it was suggested that the statistically significant
differences observed by King et al. were the result of the large number
of microsatellite loci (the specific position of a gene or other
chromosomal marker) examined and not reflective of any meaningful
biological difference.
Response: We find no support for the position that significant
differences detected by King et al. were an artifact of an excessively
large sample size. The Ramey et al. and King et al. microsatellite
results do not appear dependent upon the number of loci examined (5 and
21 loci, respectively) as both data sets support a statistically
significant independent cluster that corresponds to the Prebles
(Crandall and Marshall 2006, pp. 26-27; SEI 2006a, p. 43). This, in
combination with other available data, supports continued recognition
of the subspecies as a valid taxon.
Information Quality and Peer Review for Taxonomy
Issue: Numerous commenters suggested we should not rely upon
unpublished literature that has not been subjected to a scientific
journal's peer review process. They felt that using Ramey et al. or
King et al. violated the Data Quality Act (44 U.S.C. 3516 et seq.) and
Service policy. Several commenters thought we should reopen the comment
period once these documents were accepted for publication or published.
Response: The Act requires that our actions be based upon the best
scientific and commercial information available. Occasionally, relevant
scientific and commercial information is not, or has not yet been,
published. In these cases, peer review may assist us in our evaluation
of the available science. At this point, most of the key literature
relevant to the subspecies' taxonomy has been subjected to extensive
peer review, reviewed and published by peer-reviewed journals, and
reviewed by the SEI expert panel. Additionally, the public has had an
opportunity to review and comment on all of the relevant literature (70
FR 5404, February 2, 2005; 71 FR 8556, February 17, 2006; 71 FR 16090,
March 30, 2006; 72 FR 62992, November 7, 2007). Finally, we have
conducted numerous peer reviews of our regulatory proposals (70 FR
5404, February 2, 2005; 71 FR 8556, February 17, 2006; 71 FR 16090,
March 30, 2006; 72 FR 62992, November 7, 2007) in compliance with the
Interagency Cooperative Policy for Peer Review in Act Activities (59 FR
34270, July 1, 1994) and the Office of Management and Budget's ``Final
Information Quality Bulletin for Peer Review'' (Office of Management
and Budget 2004). We have evaluated all of the available information,
its adequacy and reliability, and determined what the weight of
evidence suggests. Given the above, we feel we have exceeded all
Federal requirements for information quality and peer review.
Issue: Several commenters questioned the independence,
impartiality, political motivation, and appropriate expertise of select
local peer reviewers. Some commenters questioned the independence and
impartiality of the Colorado Division of Wildlife (CDOW) in soliciting
these peer reviews.
Response: The CDOW solicited and received nine peer reviews of
Ramey et al. (2004a) from regional scientists with a variety of
expertise relevant to the questions at hand. These reviews were
transmitted to us on April 24, 2004. We believe that the CDOW acted
independently and impartially in selecting qualified reviewers of the
subject study. During the summer of 2004, we solicited reviews from
seven additional scientists selected for expertise in genetics and
systematics. Reviewers were targeted from a wide variety of areas to
geographically balance the CDOW review. Collectively, this diverse
group of experts provided a balanced and objective review. To maintain
consistency, we later contacted the same 16 experts to peer review
Ramey et al. (2004b) and King et al. (2006a). It should be noted that
some reviewers declined to participate in subsequent rounds of review
(Ramey et al. 2004b; King et al. 2006a) because of these accusations of
bias.
Issue: Some commenters questioned why the Service asked non-
geneticists to review King et al. (2006a).
Response: As noted above, we solicited peer reviews of King et al.
(2006a) from the same 16 reviewers asked to review Ramey et al. (2004a,
2004b). While we recognized this group included some non-geneticists,
we felt consistency among reviewers was critical. We note that most of
the non-
[[Page 39795]]
geneticists voluntarily declined to participate in the review of King
et al. (2006a). The one exception, Armstrong (2006), is a respected
academic with considerable expertise on the Prebles. His review was
useful.
Expert Panel
Issue: Several commenters questioned the Service's decision to
organize a scientific panel to review the available information on the
species' taxonomic and conservation status.
Response: Recognizing the controversial nature of this
determination, the Service decided not to organize and convene an
expert panel ourselves. Instead, we contracted with an independent
organization to assemble and manage the scientific review panel.
Issue: Numerous parties had issue with the SEI expert panel. Some
commenters opined that the SEI panel was tainted because the
composition of the panel and the time allotted to participants was
altered to favor a particular outcome. Some commenters questioned the
objectivity and qualifications of SEI and the panelists.
Response: We stand by the process used in the SEI review panel.
Following an open and competitive bid process, SEI was selected as the
contractor in June 2006. Once selected, SEI ran all aspects of this
process within the bounds of the contract. The selection and retention
of panelists as well as the agenda was entirely within SEI's purview.
SEI also determined that the public could attend. In addition, Drs.
Ramey, Crandall, and King addressed the panel in person. Other
scientists participated over the phone. Questions from the audience
were also presented for the panel's consideration. The panel also had
access to published literature, unpublished reports, third-party
critiques, public comments, and other materials suggested by interested
parties (SEI 2006a, pp. 48-55). Overall, we think that the process was
fair, open, and unbiased.
Furthermore, we believe SEI and the panelists were well qualified
to conduct the contracted review. SEI regularly conducts such
scientific reviews including panels on northern spotted owl, pallid
sturgeon, and Everglades restoration (see: http://www.sei.org/). The
panelists' qualifications are well established. As illustrated in
appendix 1 of the SEI (2006a, pp. 56-82) report, each panelist has an
extensive background in the genetic and systematic issues relevant to
the Prebles' review.
Issue: Some commenters suggested that the SEI report went beyond
the original scope of their contract. Specifically, commenters
suggested the SEI report should have abstained from offering reviewers'
taxonomic conclusions.
Response: We contracted with SEI to analyze, assess, and weigh the
reasons why the data, findings, and conclusions of the two studies
differed (USFWS 2006, p. 14). Incorporation of the panelists' taxonomic
conclusions was a natural outgrowth of the contract's stated purpose.
The final report fully satisfied SEI's contractual obligations.
Availability of Taxonomic Information
Issue: Several commenters raised a concern that we relied on a
paper (King et al. in review) for this rulemaking that we did not
possess and thus was not available for public review during the comment
period. Since this report was not available, some commenters requested
an extension of the comment period.
Response: The revised proposed rule referenced a document by USGS
cited as ``King et al. (in review).'' This article was not the primary
jumping mouse study by King et al. The primary study and its supporting
data were released to the public in early 2006 (King et al. 2006a; 71
FR 8556, February 17, 2006; 71 FR 16090, March 30, 2006) and published
in Molecular Ecology in late 2006 (King et al. 2006b).
Instead, King et al. (in review) was a comment article that
Molecular Ecology intended to publish in the News and Views section of
the journal, in response to Ramey et al. (2007) (another comment
article). These comment articles were cited once in the revised
proposed rule in a sentence that read: ``Other evaluations of the
available literature and data include Ramey et al. (in press), King et
al. (in review), Crandall and Marshall (2006), Spencer (2006b), and
Cronin (2007).'' This sentence cited King et al. (in review), among
other documents, to inform the public we were aware of its existence.
However, our determination that the Prebles is a valid subspecies did
not use or rely on this document.
The comment was correct that we did not have this document in our
files. By citing the document as ``in review,'' we intended to convey
that the document had been drafted and submitted for publication, but
not yet accepted as it was still undergoing peer review. The USGS
typically does not release documents unless they have been accepted for
publication or otherwise peer reviewed. As the peer review process for
this document remains incomplete, the article is solely in the
possession of USGS and the reviewing journal.
Given the context of this citation and its inconsequentiality to
our determination, we do not think that this document was critical to
the public's review or understanding of our proposal. Therefore, we did
not grant an extension of the comment period.
Distribution, Status, Population Size, and Population Trends
Issue: Some commenters contended that our 2005, 12-month finding
and proposed rule should have evaluated the distribution, abundance,
trends, and threats information from the delisting petitions.
Response: On February 2, 2005, we issued a 12-month finding on a
petition to delist the Prebles and proposed to remove the mouse from
the Federal list of endangered and threatened species (70 FR 5404,
February 2, 2005). The basis for the proposed action was that the
Prebles was ``likely not a valid subspecies of meadow jumping mouse.''
It was not necessary or appropriate to consider distribution,
abundance, trends, or threats until it was determined that the Prebles
qualified as a listable entity under the Act. Once we determined that
the Prebles was a valid subspecies, we considered all relevant
information on Prebles' distribution, abundance, trends, and threats in
our revised proposed rule (72 FR 62992, November 7, 2007) and in this
final rule.
Issue: Some commenters suggested that Figure 1 could have been more
clear or more informative. Specific suggestions put forth were to:
Include more detail; depict all jumping mouse captures noting the
species; and provide a better explanation of the data depicted in the
key and text. One reviewer commented that the database from which
Figure 1 was derived should be available to the public.
Response: Figure 1 was too busy and difficult to read in the
Federal Register. As a result, we have split this graphic
representation of occupancy into a Wyoming (Figure 1) and a Colorado
figure (Figure 2). We also revised the corresponding text. This final
rule more clearly depicts known Prebles' distribution and results of
other trapping efforts. The supporting data (Service 2008) is available
upon request.
Issue: Reviewers commented that distribution of available habitat
and threats to the Prebles could be mapped, quantified, and better
visualized through use of GIS. One reviewer suggested that we clearly
map all threats or confirm that project constraints make these measures
impractical.
[[Page 39796]]
Response: The Service has mapped potential Prebles' habitat (67 FR
47154, July 17, 2002; 68 FR 37276, June 23, 2003), as has the Wyoming
Natural Diversity Database (WNDD) (Beauvais 2001, 2004), the CDOW, and
some Colorado counties. The Center for the West produced a series of
GIS maps predicting growth through 2040 for the west including the
Colorado Front Range and Wyoming (Travis et al. 2005, pp. 2-7). These
models represent a good approximation of projected development
pressures. We also worked with the CDOW to examine protection status of
designated critical habitat units and other selected areas supporting
the Prebles. These results are summarized in the 5-factor analysis
below.
Issue: We received numerous comments on data quality and quantity
relative to the subspecies' status. Many noted limited available
information or data on historical and current range, current abundance,
population trends, threats, and ecological relationships. Some
commenters suggested this illustrated the weakness of our original
listing and, therefore, suggested we should delist range-wide. Other
commenters suggested a change in listing status in any portion of the
subspecies' range should be precluded until better data is available.
Response: The Act requires our determinations be based upon the
best scientific and commercial information available. As a result, we
evaluate all of the available information, its adequacy and
reliability, and determine what the weight of evidence suggests. This
final rule meets this standard.
Issue: One reviewer suggested that we quantify relative abundance
of the Prebles and compare abundance estimates to habitat features to
better define quality habitat. This reviewer thought we could estimate
relative abundance by calculating and comparing Prebles captured per
trap night (number of traps employed times number of nights of
trapping) for all trapping efforts throughout Prebles' range.
Response: Where we have abundance information, we present it in
this final rule. Data available is not adequate to quantify and compare
the relative abundance of the Prebles across its range with any
reasonable degree of confidence (i.e., much of the trapping was on
small sites and over short periods with inconsistent timing and
conditions).
Issue: One commenter claimed our analysis is flawed because the
Prebles cannot be differentiated from the western jumping mouse.
Response: Genetic markers are effective in differentiating meadow
jumping mice and western jumping mice (Riggs et al. 1997, pp. 2-8;
Ramey et al. 2005, pp. 344-346; King et al. 2006b, pp. 4341, 4344).
Additionally, Discriminant Function Analysis (DFA) (analysis of cranial
measurements and an anterior medial toothfold characteristic) appears
to be a reliable technique for differentiating the two species (Conner
and Shenk 2003a). We acknowledge that, for a number of historical and
recent capture sites, mice were tentatively identified in the field
based on capture location, size, and external features, but definitive
identification to species was never attempted. In many of these cases,
genetic samples were not obtained nor were voucher specimens taken;
therefore, the specimen's species identity remains inconclusive. As
noted below, positive identification to species is only an issue in
areas of overlapping range (i.e., high-elevation sites in Colorado and
most of Wyoming). We have addressed potential shortcomings for species
identification in our analysis, and we have reviewed and modified the
text for added clarity.
Issue: Several commenters noted that Prebles are now known from
more drainages and a greater number of sites than at the time of
listing. These commenters suggested this was evidence that Prebles'
populations are secure. One commenter requested that we state the
specific number of sites where the Prebles is known to occur.
Response: We have acknowledged an increase in our knowledge of
distribution of Prebles, especially in the Wyoming portion of its
range. We have summarized areas of known or potential occurrence by
river basin, drainage (8-digit USGS hydrologic units), and river or
stream. We also have emphasized instances where confirmed captures have
extended our knowledge of Prebles' range and occurrence. We think that
the number of individual capture sites is less meaningful.
Documentation of multiple capture sites within portions of drainages or
along streams where Prebles' populations occur is largely a function of
trapping effort. When multiple sites are within close proximity of each
other, counting each occurrence instead of a single population
exaggerates abundance. Further, as one peer reviewer correctly
cautioned, trends cannot be established from the number of documented
sites alone, and that an increase in documented sites resulting from
increased trapping efforts could mask a decreasing population trend.
Issue: One commenter stated that the Prebles' range has not
declined significantly. This commenter suggested the subspecies is now
known to be present in virtually all historically documented locations
except those in the greater Denver area.
Response: The subspecies' declines within Colorado are fully
explained in Factor A below. This analysis includes the apparent
extirpation of the subspecies from approximately 420 km (260 mi) in and
downstream of areas with concentrated human development. In terms of
historically documented locations (i.e., sites from which we have
specimens prior to 1980), we are aware of 17 such sites in Colorado. Of
these, only one of these sites is currently thought to support the
Prebles. The majority of historical records of Prebles in Colorado come
from what is now widely known as the Front Range urban corridor, which
extends well beyond the Denver area. In Wyoming, with the possible
exception of Cheyenne, the Prebles is likely present at the few sites
where it was historically documented.
Issue: One commenter concluded that the high number of section 7
consultations conducted in Colorado as compared to Wyoming was evidence
of ``expansive range and increasing populations'' in Colorado.
Response: A more reasonable explanation for the number of section 7
consultations is that human development is expanding into areas of
Prebles' occurrence. In Wyoming, far less development is occurring in
areas where the Prebles is present.
Issue: Some commenters questioned how we established that over 80
percent of trapping efforts in Colorado since listing have failed to
capture Prebles. They questioned whether western jumping mice were
included in the results and questioned the expertise of the trappers
conducting the studies. Some commenters requested comparative trapping
success rates from Wyoming trapping.
Response: From 1998 to 2007, 27 percent of 1,350 data points
associated with trapping efforts targeting Prebles in Colorado have
resulted in captures of jumping mice (USFWS 2008). When we controlled
for repeated trapping at single sites, such as established research
sites, jumping mouse capture rates drop to less than 20 percent. Even
this estimate may be high as some of these jumping mice were likely
western jumping mice, particularly those from high-elevation trapping
efforts.
From 1998 to 2007, 74 percent of 219 data points associated with
trapping efforts in Wyoming have resulted in captures of jumping mice
(USFWS
[[Page 39797]]
2008). The overlapping range of Prebles and western jumping mouse in
Wyoming must be considered when comparing Preble's capture success
between the two States. Based on individual mice confirmed to species,
it is likely that more of the successful trapping efforts in Wyoming
captured only western jumping mice. Of positive jumping mouse capture
sites, 29 percent of the sites included only Prebles, 55 percent of the
sites included only western jumping mice, 5 percent of the sites had
both species present, and specimens from 11 percent of the successful
sites were never positively identified to species.
All jumping mouse trapping efforts since listing have been carried
out by researchers holding Service and State permits. While experience
of individual biologists may vary, we believe all individuals permitted
to trap Prebles are qualified to conduct such surveys.
Foreseeable Future
Issue: One commenter stated that foreseeable future as defined in
the revised proposed rule was too short, citing climate change
projections to 100 years and Service HCPs issued for 50 years.
Response: The term foreseeable future is not defined by the Act or
in the implementing regulations at 50 CFR part 424. Merriam-Webster's
Law Dictionary (1996) defines ``foreseeable'' as such as that which
reasonably can or should be anticipated such that a person of ordinary
prudence would expect it to occur or exist under the circumstances
(Merriam-Webster's Dictionary of Law 1996; Western Watershed Project v.
Foss (D. Idaho 2005; CV 04-168-MHW). Determination of foreseeable
future is typically based on the timeframe over which the best
available scientific data allows us to reasonably assess the threats
and the species' response to those threats, and is supported by
species-specific factors, including the species' life history
characteristics (e.g., generation time) and population dynamics. From a
scientific perspective, it would be inappropriate to set foreseeable
future timeframes so short that natural variability in the ecosystem of
the species, short-term population dynamics, or the expression of life
history traits of the species through generational-scale variation in
reproductive success or recruitment cannot be accounted for in the
longer-term examination of factors impacting the species. Typically,
threats tend to operate through their effects on survival and
productivity over multiple generations, with one to two generations
being insufficient to separate natural variability from directional
effects of threats. Whenever possible, we will determine the
``foreseeable future'' based on a detailed assessment of threats and
species-specific biological information.
For the Prebles, we defined foreseeable future based upon a threat-
projection timeframe because future development intensity and patterns
are likely to be the single greatest factor contributing to the
subspecies' future conservation status. The foreseeable future for the
Prebles, based on the currently available data, extends to
approximately 2040. While it is likely human population growth and
development projections could be extrapolated out into the more distant
future, growth and development projections beyond this point are of
increasingly lower value as uncertainty escalates. However, we agree
that not all threat factors are necessarily foreseeable over the same
time horizon and that for some threat factors a longer time horizon may
be appropriate. Thus, this rule considers the range of climatic
conditions predicted by the Intergovernmental Panel on Climate Change
(IPCC) for the 21st century. While climate projections routinely go out
past this 2040 time horizon (IPCC 2007, p. 7), climate change
forecasts, like human development projections, become less certain as
they are extended into the future (Hall 2008; Meyers 2008). The IPCC
acknowledged this uncertainty in their most recent report when they
stated that projections beyond the next two decades depend on specific
emission scenarios (IPCC 2007, p. 7). The duration of section 10
permits, issued in support of approved Habitat Conservation Plans, have
no bearing on what is foreseeable for this subspecies.
Impacts From Increased Human Population and Development
Issue: Some commenters stated that local extirpations of Prebles in
the Front Range urban corridor cannot be used to speculate about future
threats in other portions of its range. They suggested that development
threats are localized and do not affect most Prebles' populations.
Response: While threats do vary across the range of the subspecies,
we believe that the rule adequately captures and presents the severity
of the issue across all portions of the subspecies' range. The direct
and indirect effects of human development have resulted in substantial
habitat alteration across large parts of the Colorado range. While
habitat alteration has been most severe in the expanding Front Range
urban corridor, projected future human growth will substantially extend
this area of impact. Additional threats exist outside of areas of
intense human development. For example, linear projects such as roads
and pipelines may impact multiple counties and can affect rural habitat
as well as that in urbanizing areas, and potential impacts from
overgrazing are more likely to affect Prebles' habitat in rural areas
than in areas of high residential density.
Issue: Some commenters suggested that population growth forecasts
can be unreliable. They pointed to the current housing slump and
suggest that population growth within the Prebles' range will be less
than predicted. One commenter stated that the Center for the American
West models' depiction of development patterns in the future have
limited utility since they assume that all private land is technically
buildable and available for development.
Response: Any future predictions include a degree of uncertainty.
That said, we consider projections and related models to be the best
information available on this subject. Economic downturns, that are
relatively short-lived, are unlikely to significantly alter long-term
forecasts.
The Center for the American West models (Travis et al. 2005, pp. 2-
7) predict development patterns on a sub-regional basis. The fate of
individual parcels could be determined by a number of factors not
addressed by the models, and the model developers have noted that the
projections should not be applied to individual properties. We have
cited these models in evaluating threats related to likely patterns of
future human growth, not the presumed fate of individual properties. We
have expanded our discussion of the models and their use in the text.
Issue: One reviewer noted that while human development in Wyoming
is likely to be far less than in Colorado, Wyoming does not ``lack''
development and much of it will be in rural areas. A few commenters
addressed current and modeled future human population growth in Wyoming
centered near Cheyenne. One reviewer questioned whether the absence of
the Prebles in Cheyenne area was the result of development. Another
reviewer concluded that projected growth in the Cheyenne area would not
result in impacts to the Prebles because it would not overlap areas
known to support the subspecies.
Response: We acknowledge that human development is likely to occur
in portions of Wyoming now supporting the Prebles. However, we believe
that expansion of human presence and
[[Page 39798]]
related threats will be localized and relatively minor, and will not
threaten the continued persistence of the Prebles in those areas.
Known occurrence records suggest that the Prebles is not common or
widely present in the South Platte River basin in Wyoming. The cause of
this rarity is unknown. The continued existence of the Prebles in the
Cheyenne area also is unknown. Sites of recent confirmation of the
Prebles in the South Platte River basin of Wyoming have been well
upstream from Cheyenne. Development could impact Prebles' populations
in the Cheyenne area, should they exist. However, the long-term
viability of populations in these drainages is more likely to depend on
persistence in upstream portions of the drainages rather than the
Cheyenne area.
Issue: Some commenters predicted that secondary impacts associated
with human development in Colorado would impact Prebles' habitat in
southern Wyoming. Particular issues raised included vacation homes,
human recreational activities, water resource development and storage,
and aggregate mining.
Response: As human populations in Colorado, particularly northern
Colorado, continue to grow, secondary impacts may spill over into
southeastern Wyoming. Regarding vacation homes, the Center for the West
models of human population growth take into account urban, suburban,
ex-urban, and rural development (http://www.centerwest.org/futures/
west/2040.html; http://www.centerwest.org/futures/archive/development/
development_wy.html). These projections suggest ex-urban development
could link Cheyenne and Fort Collins by mid-century, but indicate
little development in the documented range of the Prebles in Wyoming.
While some development will undoubtedly occur, we do not have data to
indicate meaningful impacts are likely anywhere in the Wyoming portion
of the subspecies' range, except around Cheyenne where the subspecies
has not been recently documented to occur.
While increasing population may result in increased recreation, new
water development, or additional aggregate mining, we are not aware of
any specific proposals that would increase the effects of these types
of activities on Prebles' populations. These issues are evaluated
further in our 5-Factor analysis below.
Impacts From Agriculture
Issue: Some commenters stated that grazing is not a significant
threat, as evidenced by the special 4(d) rule allowing continued
agricultural activities. One commenter stated that chronic violations
of grazing regulations on public grazing lands impact Prebles' habitat.
One commenter provided a Bureau of Land Management (BLM) (2004) report
on public range in Wyoming, to demonstrate that range improvements have
occurred over time. The report stated that range conditions have
improved over time; efforts are under way to stop invasive weeds; and
wildlife populations have increased.
Response: Our special rule provides exemption from take
prohibitions under section 9 of the Act for certain land uses including
continued agriculture. While overgrazing can and does impact Prebles'
habitat, and in some cases can be a threat, the 4(d) rule (66 FR 28125,
May 22, 2001; 67 FR 61531, October 1, 2002; 69 FR 29101, May 20, 2004)
was instituted to acknowledge that those ongoing agricultural
operations maintaining habitat that supports the Prebles are an asset
to conservation and recovery. Through this special rule, we anticipated
increased opportunity to partner with agricultural interests toward
conservation of the Prebles.
While we are aware of instances where operators have violated
provisions of their grazing permits, we have concluded that this is not
a widespread threat within the Prebles' range. We solicited and
received data and information on livestock grazing from the U.S. Forest
Service (USFS) regarding three National Forests that support Prebles'
populations. Allotment inspection records or monitoring reports were
received from the Laramie Ranger District, Medicine Bow National Forest
in Wyoming (Florich 2008); the Canyon Lakes Ranger District, Arapahoe
National Forest (Hodges 2008); and the South Park Ranger District, Pike
National Forest (Branch 2008). While the records include instances of
non-compliance and note grazing impacts to habitat, more often they
reflect livestock grazing conducted in accordance with grazing plans
that are consistent with maintenance of Prebles' habitat. Federal
agencies, including the USFS and BLM, work cooperatively with the
Service to fulfill their responsibilities under the Act. For example,
we recently coordinated with the USFS regarding permittee non-
compliance issues on the Arapahoe National Forest's Greyrock allotment.
In that area, riparian habitat along the North Fork, Cache La Poudre
River is recovering following remedial measures to counteract
overgrazing.
We reviewed BLM (2004). While not specific to the Prebles' range,
we are encouraged by its conclusions that conditions on BLM grazing
lands in Wyoming are improving.
Issue: One commenter stated that the Service inappropriately cited
the Taylor (1999) trapping study as evidence of Prebles' compatibility
with grazing. This comment indicated that: The properties on which the
trapping was conducted are not representative of most grazing
operations; the report documents grazing impacts on riparian habitat;
and Prebles' populations may have decreased since this study because of
drought.
Response: The study at issue is by far the most extensive effort
conducted on private lands in Wyoming. Jumping mice were captured at 18
of 21 survey sites representing diverse habitat conditions. Genetic
testing confirmed Prebles at 11 sites, western jumping mice at 3 sites,
both species at 3 sites, and one site was never identified to species
(it is also worth noting that although many sites had multiple
captures, not all specimens were preserved for species identification).
Capture sites included both ideal habitat, such as riparian habitat or
sub-irrigated hayfields, and sites where grazing or other factors had
impacted habitat quality. While Prebles' habitat and populations are
likely affected by periodic droughts, results of this trapping effort
demonstrate a broad, long-term ability of the subspecies to coexist
with traditional agricultural operations in Wyoming.
Issue: Some commenters recommended that we explore additional
threats to the Prebles in Wyoming from agricultural conversion to
biofuels.
Response: As discussed in the revised proposed rule, the conversion
of native habitat to row crops has become increasingly rare in both
Colorado and Wyoming (U.S. Department of Agriculture 2000, Tables 2, 3,
& 9). This trend likely reflects that riparian habitats (and other
areas) that could be feasibly converted to crop production have already
been converted. Although pressures to increase agricultural production
may result from the demand to produce biofuels, we are not aware of
information that indicates this would result in meaningful decreases in
the Prebles' riparian habitat in Wyoming. We explored whether former
cropland removed from production through the Conservation Reserve
Program (CRP) is now being returned to production and concluded that
this scenario is likely to
[[Page 39799]]
have a negligible impact on the Prebles and its habitat. The issue is
further discussed in Factor A below.
Other Potential Threat Factors
Issue: One commenter noted that if the Prebles was delisted,
forestry operations including thinning and prescribed burns could be a
significant threat.
Response: The role of fire, a natural part of the ecosystem, is
discussed under Factor E below. Thinning of trees increases sunlight at
ground level and prescribed burns release nutrients, both of which can
promote increased vegetative growth at ground level. While these forest
management activities can result in adverse impacts to Prebles'
habitat, the impacts are generally temporary and offset by long-term
benefits. In general, we conclude that management designed to improve
forest health or prevent catastrophic fire will contribute to the long-
term conservation of the Prebles and its habitat.
Issue: Some commenters highlighted threats that occur range-wide
including: Lack of adequate regulatory mechanisms in the absence of the
Act's protections; invasive weeds; hydrologic changes brought on by
climate change; and catastrophic fire. We also received some comments
supporting our conclusion that only minor threats occur in Wyoming, but
substantial threats related to human development occur in Colorado.
Response: This rule summarizes the magnitude, immediacy, and
likelihood of foreseeable threats in both States and as well as at the
county or drainage level where supporting data are available. While
some threats are relatively similar across portions of the two States,
these non-development-related threats are not substantial factors
driving the subspecies' conservation status. We believe small,
fragmented populations are likely at greatest risk from these secondary
threat factors. Across most of the subspecies' Colorado range,
development actions will increasingly cause populations to become small
and fragmented, thus, susceptible to these factors. The available data
suggest that few Wyoming Prebles' populations suffer from small
population size and fragmentation, and no foreseeable threats are
likely to substantially increase this inherent vulnerability. Thus,
despite a continued risk from some potential threats in both Wyoming
and Colorado, these factors are not likely to threaten or endanger the
subspecies in all of its range.
Issue: Some commenters recommended that we explore additional
threats to the Prebles in Wyoming from energy development, especially
coalbed methane and natural gas.
Response: Information on coalbed methane targets in Wyoming (Jones
and DeBruin 1990, p. 10) indicates that coalfields and the range of the
Prebles have little overlap in Wyoming. Furthermore, the coalfields
that are nearest the subspecies' range are believed to have low coalbed
methane development potential (DeBruin 2004, p. 6). Similarly, only a
small portion of the Wyoming range of the Prebles may overlap with oil
and gas producing formations (e.g., cretaceous and early tertiary
rocks). A much larger portion of the subspecies' range overlaps with
exposed undifferentiated precambian rocks or other non oil and gas
producing formations (DeBruin 2002). Based on the limited potential for
development of these resources within the Wyoming range of Prebles, we
conclude that these activities (directly or indirectly) would not
meaningfully affect the conservation status of the Prebles in Wyoming
now or in the foreseeable future.
Issue: Some commenters believe there is a lack of understanding
regarding the relationship between the two jumping mouse species in all
Wyoming drainages.
Response: We do know that the Prebles and the western jumping mouse
coexist in multiple drainages in both Wyoming and Colorado. In absence
of evidence to the contrary, we conclude that this coexistence is not a
recent occurrence. Because information is lacking as to whether, or to
what degree, populations of Prebles and western jumping mice impact one
another, we cannot conclude that western jumping mouse presence is a
threat to the Prebles. However, further research may be valuable to
identify the relationship between the two species where they co-occur.
Issue: We received several comments on the potential threat to the
Prebles from climate change. These commenters suggested that we had not
given sufficient attention to future threats caused or compounded by
climate change; that it could affect future demand and competition for
water resources and influence water resource development; and that a
warming climate could cause shifts in the subspecies' range and
increase the importance of high-latitude, high-altitude Prebles'
populations in Wyoming to the subspecies' survival. In contrast, we
received a comment that future precipitation changes were too uncertain
to be used in an analysis of future threats.
Response: According to the IPCC (2007, p. 2) ``warming of the
climate system is unequivocal, as it is now evident from observations
of increases in global air and ocean temperatures, widespread melting
of snow and ice, and rising global average sea level.'' In general, a
trend of warming in the mountains of western North America is expected
to decrease snowpack, hasten spring runoff, and reduce summer flows
(IPCC 2007, p. 11). While this change could affect the Prebles and its
habitat, to date, a negative impact has not been documented. A
significant degree of uncertainty exists as to how projected climate
changes, alone and in concert with other threats, will affect the
Prebles over the foreseeable future. This issue is discussion in
greater detail in Factor E below.
Issue: One reviewer noted that our analysis struggles to weigh
cumulative effects, and that threats to the Prebles were likely larger
than a simple account of individual effects.
Response: In the biological sense, cumulative effects include
effects of stressors imposed by more than one mechanism, that when
taken together can have different or more dramatic effects than those
recognized from any one alone. In the context of threats to the
Prebles, a combination of identifiable threats may have more impact
than what would be expected for each individually. Cumulative effects
are difficult to predict. Based on the best information available, we
have considered the potential for cumulative effects of threats in our
analysis. In many instances, we cite that small or fragmented
populations may be more vulnerable to specific threats; this outcome
also is likely the case with regard to vulnerability to cumulative
effects.
Issue: One commenter cited a report by Cryan (2004) that indicates
that habitat for meadow jumping mice is increasing in the West.
Response: Cryan (2004, p. 7) reviewed and synthesized existing
information on meadow jumping mice in the northern Great Plains (North
Dakota, South Dakota, Nebraska, Montana, and Wyoming). While he
attributed a likely increase in meadow jumping mouse habitat in the
western parts of the Great Plains to westward expansion of riparian
forests and mixed-grass prairie, this assertion was not specific to the
range of the Prebles nor do we see this habitat trend occurring within
the subspecies' range.
Existing Protections
Issue: Several commenters stated that we failed to properly
consider Federal,
[[Page 39800]]
State, and local efforts to conserve the Prebles. One commenter thought
that we did not differentiate between Federal and other lands in terms
of future development threats. Some commenters suggested that States
and counties will continue to protect the Prebles regardless of
delisting. One commenter stated that extensive local regulations
prohibit development in riparian habitat. Other commenters suggested
that conservation measures by State and local governments are
widespread and that lands set aside as open space or under conservation
easements protect Prebles' habitat. The CDOW (Nesler 2008) commented
that our recognition of ongoing efforts in Colorado is incomplete. The
CDOW provided an estimate that, as of spring 2007, 45 percent of
occupied Prebles' habitat in Colorado was protected in public lands,
land trusts, or through conservation easements.
Response: Both the revised proposed rule and this final rule
considered the differential level of threat facing Prebles' populations
and their habitat on Federal and other lands. In general, private lands
face the greatest threat from direct development pressures. However,
Federal and other public lands are not immune from development threats.
Roads, trails, recreational facilities including campgrounds, and other
human development is likely to affect habitat present on public lands.
Indirect effects of upstream development also can meaningfully impact
Prebles' populations on protected lands.
Effectiveness of local regulations in maintaining naturally
functioning riparian corridors varies greatly depending on how these
apparently flexible regulations are implemented. While certain local
regulations are designed to conserve wetlands or floodplains on private
lands, their effectiveness in conserving Prebles is uncertain. It is
also unlikely they would effectively control land uses (grazing,
mowing, cutting, and burning) that may affect the hydrology,
vegetation, and hibernacula sites on which the Prebles depends.
Importantly, most local regulations are flexible and provide little
assurance. It is not clear what level of interest in Prebles'
conservation would continue following delisting.
We have worked with the CDOW to further understand, document, map,
and analyze the lands in public ownership in Colorado. This rule
appropriately weighs existing and likely future conservation efforts.
All of these factors are discussed below in Factor D and considered in
the Conclusion of the 5-Factor Analysis.
Issue: Some commenters stated that there is no proof that existing
HCPs are working to protect the Prebles.
Response: HCPs developed for the Prebles are designed to support
its conservation and recovery. Permit conditions and monitoring
requirements help insure that conservation benefits ensue. Some
individual HCPs are complete and have met their planned objectives
while other HCPs are in the implementation or monitoring phase.
Issue: One commenter stated that the CWA is the ``cornerstone of
surface water quality protection,'' and requires mitigation of all
wetland and riparian habitats impacted. Thus, security of the Prebles'
habitat is assured under the CWA.
Response: The primary purpose of the CWA is to protect water
quality. To achieve this goal, the CWA seeks to avoid and minimize
impacts to jurisdictional wetlands. Human impacts to many habitats
utilized by the Prebles (including riparian and floodplain habitats
outside of jurisdictional wetlands, and adjacent upland habitats) are
not directly addressed by the CWA.
Issue: Some commenters suggested that we had not followed section
4(b)(1)(A) of the Act and our Policy for Evaluation of Conservation
Efforts (PECE Policy) (68 FR 15100, March 28, 2003) when addressing
beneficial measures to conserve the Prebles.
Response: Section 4(b)(1)(A) of the Act requires that we make
listing determinations solely on the basis of the best scientific and
commercial data available after conducting a review of the species'
status and after taking into account those efforts being made by State
and local governments. This rulemaking meets this standard, including
consideration of efforts being made by State and local governments.
The PECE policy was developed to ensure consistent and adequate
evaluation of current and future conservation efforts when considering
species for addition to the Federal list of endangered and threatened
species. This policy does not apply to delisting determinations.
Nevertheless, we have appropriately weighed existing and likely future
conservation efforts. This evaluation, included in Factor D below,
considered Federal, State, and local regulations; land ownership, use,
and management; and relevant programs and initiatives of conservation
significance to the Prebles.
Issue: Several commenters suggested the subspecies was threatened
in Wyoming by a lack of adequate regulatory mechanisms.
Response: Under the Act, listing can be justified in cases where
the entity suffers from the inadequacy of existing regulatory
mechanisms. In order to meet this standard, the lack of adequate
protections, typically in combination with other threat factors, must
result in the species being in danger of extinction throughout all or a
significant portion of its range (i.e., endangered) or likely to become
an endangered species within the foreseeable future throughout all or a
significant portion of its range (i.e., threatened). The Wyoming
population of Preble's do not appear, at present or within the
foreseeable future, dependent upon regulatory mechanisms to maintain
their conservation status. As such, the lack of regulatory mechanisms
does not appear to threaten or endanger this portion of the range and,
thus, the Act's protections are not warranted in Wyoming because of
inadequate regulatory mechanisms.
Prebles Status Under the Act, Service Conclusions, and Our Use of
Significant Portion of Range
Issue: One commenter suggested that we would be in violation of the
Interagency Policy Regarding the Role of the State Agencies in Act
Activities and Executive Order 13352 if we failed to delist the
Prebles, since both the States of Wyoming and Colorado supported
delisting.
Response: Neither the Interagency Policy Regarding the Role of the
State Agencies in Act Activities (59 FR 34275, July 1, 1994) nor
Executive Order 13352 (69 FR 52989, August 30, 2004) delegates Act
listing decisions to the States. Such delegation would violate the Act.
Instead, the Interagency Policy Regarding the Role of the State
Agencies in Act Activities requires that we solicit and utilize the
expertise of and information possessed by State agencies. Similarly,
Executive Order 13352 promotes cooperative conservation, with an
emphasis on appropriate inclusion of local participation in Federal
decision making, in accordance with their representative agency
missions, policies, and regulations. We have worked, and will continue
to work cooperatively in seeking and utilizing all relevant information
in possession of both the Wyoming Game and Fish Department (WGFD) and
the CDOW as required for decisions made under section 4 of the Act.
Thus, we have met or exceeded the requirements of the Interagency
Policy Regarding the Role of the State Agencies in Act Activities and
Executive Order No. 13352.
Issue: Several commenters suggested that the Service should delist
the Prebles because of the economic impact of the listing or the
expense of conservation efforts relative to the
[[Page 39801]]
conservation benefits realized. Some commenters suggested that the
Final Listing Priority Guidance for Fiscal Year 2000 (Listing Priority
Guidance) (57 FR 57114, October 22, 1999) requires that we focus our
efforts on listing actions that provide the greatest conservation
benefits.
Response: Any determination on whether a species is threatened or
endangered must be based solely on the basis of the species
conservation status using the best scientific and commercial
information available. Spending on a species or economic impacts cannot
be considered in such a determination.
The Final Listing Priority Guidance for Fiscal Year 2000 (57 FR
57114, October 22, 1999) does not apply to this rulemaking. The Listing
Priority Guidance provides guidance for assigning relative priorities
to listing actions conducted by the Service's Listing Program under
section 4 of the Act. The guidance clearly articulates that delisting
activities are not part of the listing program. Delisting activities
have been undertaken by the Service's Recovery Program since fiscal
year 1999.
Issue: One commenter was concerned that the revised proposed rule
was inconsistent with Prebles' status as classified by the WNDD.
Response: The WNDD (2003, p. A-12) lists the Prebles among 1 of 35
mammal species or subspecies of concern in Wyoming (specific ranking
and ranking criteria available at: http://uwadmnweb.uwyo.edu/wyndd/SOC/
2003_WYNDD_Soc.pdf). In making our determination we considered the
best scientific and commercial information available including
information available from the WNDD. However, our evaluation and
determination of status under the Act is not dictated by the WNDD
classification of the Prebles.
Issue: Several commenters stated that the 2007 Department of the
Interior Solicitor's opinion (U.S. Department of the Interior 2007) was
an incorrect interpretation of the Act. These commenters argued that we
have authority to list or delist only whole species, subspecies, and
DPSs--in other words, if we find a species to be in danger of
extinction in only a significant portion of its range, we must list it
and apply all of the protections of the Act to its entire range, even
to portions of the range that are not at risk. These commenters opined
that the ``partial-listing'' approach represents a dramatic departure
from thirty years of listing practice.
In particular, some commenters suggested the Prebles should be
protected rangewide because it is threatened over a significant portion
of its range. They suggested ``partial-listings'' would lead to a
limitless series of petitions and lawsuits over the status of taxa in
portions of their ranges.
Others suggested the subspecies should be delisted throughout its
entire range, unless the threats are so severe in the Colorado portion
of the range that it puts the subspecies' ``future * * * in doubt.''
This commenter suggested the Service's new listing approach
inappropriately allows ``partial-listings'' when the loss of a portion
of range results in a decrease, no matter how small, in the ability to
conserve a species, subspecies, or DPS.
Response: We agree with the interpretation of the Act set forth in
the Solicitor's opinion, and disagree with these comments for the
reasons given in that opinion. It is true that the Act only allows the
listing and delisting of species, subspecies, or DPSs. As such, this
action lists the Preble's because the subspecies is likely to become
endangered within the foreseeable future in a significant portion of
its range. However, once we determine listing is appropriate, section
4(c) of the Act requires we ``specify with respect to each such species
over what portion of its range it is threatened.'' In this case, we are
specifying that the subspecies is threatened in Colorado. Thus, the
protections of the Act are only necessary and shall only apply in the
Colorado portion of its range.
The interpretation of the Act advocated by these commenters fails
to give sufficient consideration to the import of section 4(c), is
inconsistent with legislative history of the Act that strongly supports
the view that Congress intended to give the Secretary broad discretion
to tailor the protections of the Act with the needs of the species, and
would lead to absurd results.
Moreover, even before the 2007 Solicitors opinion, we have applied
differential levels of protections for species facing differential
levels of threats in different parts of their range. For example, in
1978, the gray wolf (Canis lupus) was protected as endangered in the
lower-48 States, except in Minnesota, where it was protected as
threatened (a lower level of protection is often provided to threatened
species than to endangered species) (43 FR 9607, March 9, 1978). Nor is
the listing determination for Prebles the only listing determination
applying the Solicitor's opinion. In our 2008 Gunnison prairie dog 12-
month finding (73 FR 6660, February 5, 2008), we determined that the
Gunnison's prairie dog does not warrant the Act's protections
throughout its range, but that the significant portion of the species'
range located in central and south-central Colorado and north-central
New Mexico does warrant protection under the Act.
According to the Solicitor's opinion, we have broad discretion in
defining what portion of a range is ``significant,'' but this
discretion is not unlimited. Specifically, we may not define
``significant'' to require that a species is endangered only if the
threats faced by a species in a portion of its range are so severe as
to threaten the viability of the species as a whole. The suggestion by
one of the commenters that a portion of the range of a species can be
significant only if its loss would put the ``future [of the species] in
doubt'' rests on a single quote from hearing testimony on a bill that
was a precursor to the Act. If by the future of the species being in
doubt the commenter means that the threat to the portion of the range
must threaten the entire species, such an interpretation would read the
``significant portion or its range'' language from the Act. Unlike the
Solicitor's opinion, the commenter did not address this issue, or the
relevant case law.
For this determination, we used an analysis similar to that we have
used in other recent listing determinations: A portion of a species'
range is significant if it is part of the current range of the species
and it contributes substantially to the representation, resiliency, or
redundancy of the species. The contribution must be at a level such
that its loss would result in a decrease in the ability to conserve the
species. In other words, in considering significance, the Service asks
whether the loss of this portion likely would eventually move the
species toward extinction, but not to the point where the species
should be listed as threatened or endangered throughout all of its
range.
To determine if a portion of the species' range contributes
substantially to the resiliency of the species, the Service considered
in this instance: (1) To what extent does this portion of the range
contribute to the total of large blocks of high-quality habitat? (2) To
what extent do the population size and characteristics within this
portion of the range contribute to the ability of the species to
recover from periodic disturbances? (3) To what extent does this
portion of the range act as a refugium of the species? (4) To what
extent does this portion contain an important concentration of habitats
necessary for certain life history functions?
To determine if a portion of the species' range contributes
substantially
[[Page 39802]]
to the redundancy of the species, the Service considered in this
instance: (5) To what extent does this portion of the range contribute
to the total [gross area] range of the species? (6) To what extent does
this portion of the range contribute to the total population of the
species? (7) To what extent does this portion of the range contribute
to the total suitable habitat? (8) To what extent does this portion of
the range contribute to the geographical distribution of the species?
To determine if a portion of the species' range contributes
substantially to the representation of the species, the Service
considered in this instance: (9) To what extent does this portion of
the range contribute to the genetic diversity of the species? (10) To
what extent does this portion of the range contribute to the
morphological/physiological diversity of the species? (11) To what
extent does this portion of the range contribute to the behavioral
diversity of the species? (12) To what extent does this portion of the
range contribute to the diversity of ecological settings in which the
species is found?
These questions provide for a relative ranking (high, medium, and
low) of the level of the portion's contribution to the listable
entity's (species, subspecies or DPSs) representation, resiliency, or
redundancy. Because the questions may not be independent of each other
or equivalent in value, it is inappropriate to ``sum'' the high,
medium, and low rankings across questions or arrive at a total
``score.'' Rather, the questions are tools to identify those factors
that are important in considering a portion's contribution to
resiliency, redundancy, and representation, and whether it is
significant. The Service then reviews the results and the
justifications to decide whether the portion contributes substantially
to the representation, redundancy and resiliency of the listable entity
(species, subspecies or DPS). In general, if the contribution to the
representation, resiliency, or redundancy of all the questions is low,
the portion likely does not contribute substantially to representation,
resiliency, or redundancy; if the contribution to the representation,
resiliency, or redundancy of most or multiple questions are high, the
portion likely contributes substantially to representation, resiliency,
or redundancy.
Issue: Several commenters suggested the ``partial-listing''
approach allowed by the Solicitor's opinion undoes the effect of the
1978 DPS amendments to the Act.
Response: We do not believe this approach undoes the 1978
amendments to the Act, instead it compliments the 1978 amendments. A
DPS of a vertebrate species which interbreeds when mature is considered
and treated as a species (i.e., a listable entity) under the Act. A
significant portion of the range is a portion of the range of the
listed entity (whether a full species, subspecies, or DPS of a
vertebrate) that contributes meaningfully to the conservation of the
species. Therefore, we may apply the protections of the Act in a
significant portion of a DPS. In addition, we may apply the protections
of the Act in a significant portion of a species or subspecies of non-
vertebrate.
According to our DPS policy (61 FR 4722, February 7, 1996), a DPS
must be discrete and must be significant to the taxon to which it
belongs (species or subspecies) as a whole. The term ``significant'' in
the Act's definitions of endangered and threatened species should not
be considered entirely equivalent to the ``significance'' element of
the DPS policy. We recognize, however, that many of the attributes
(described below) we have identified as important for evaluating
whether a portion of a species' range is significant are similar to the
attributes identified in the DPS policy as being appropriate for
evaluating the significance of a potential DPS. There is no requirement
that a significant portion of the range be discrete, but similar to
DPSs, a significant portion of the range must be significant. As
explained in detail previously, the significance of a significant
portion of the range is based on an evaluation of its contribution to
the conservation of the listable entity being considered. The DPS
policy lists four possible factors to consider when determining
significance, but does not limit consideration of significance to only
those four factors. The considerations we made in this instance for
determining whether a portion is significant encompass and expand on
some of the concepts in the DPS policy.
Issue: One commenter suggested we use a 4(d) rule to reduce
regulatory restrictions in more secure portions of its range instead of
this ``partial-listing'' approach.
Response: Special rules under section 4(d) of the Act apply only
where the protections of the Act are in place. Thus, once we determined
the subspecies was not threatened in the Wyoming portion of its range,
use of section 4(d) was no longer an option for Prebles populations in
Wyoming. While a 4(d) rule allows us to tailor the Act's taking
provisions as necessary and advisable to provide for the conservation
of the species, the approach utilized here also eliminates the need for
critical habitat and consultation under section 7 of the Act. We
believe this approach is more consistent with the intention of Congress
as expressed in the legislative history concerning the phrase
``significant portion of its range.''
Issue: Some commenters questioned our analysis and conclusion
regarding the status of the Prebles in Wyoming as compared to our
analysis and conclusion regarding Colorado. They stated that, like
Colorado, the Wyoming portion of the range is necessary for resiliency,
redundancy, and representation of the Prebles, and that loss of
populations in Wyoming would result in a decrease in our ability to
conserve the Prebles. Some commenters stated that Preble's populations
in Wyoming should be protected because, even with the protections of
the Act, the subspecies continues to decline in Colorado. These
commenters suggested Wyoming Preble's populations will likely be
essential to conserving the subspecies.
Response: The Wyoming portion of its range is necessary for
resiliency, redundancy, and representation of the Prebles. The basis
for amending the listing of the Prebles in the Wyoming portion of its
range is not the lack of significance of Wyoming populations to the
survival of the subspecies, but rather that Wyoming populations appear
secure into the foreseeable future without protections of the Act.
Overall, in the absence of the Act's protective measures, we believe
the subspecies will likely remain secure and well distributed across
Wyoming into the foreseeable future. We have concluded that the lack of
present or threatened impacts to the Prebles in these areas indicates
that this subspecies is neither in danger of extinction, nor likely to
become endangered within the foreseeable future, throughout all of its
range. Thus, the Prebles does not merit continued listing as threatened
throughout all of its range. In Colorado, where we have determined the
Prebles remains threatened, the Act will provide for the subspecies'
protection and, with the assistance of our partners, eventual recovery.
Issue: Some commenters suggested a ``partial delisting'' would not
improve the conservation status of the subspecies and would treat
different communities inequitably with regards to the level of
protection required and costs associated with them over different
geographic areas.
Response: We believe this approach allows for a more surgical
application of the Act, as envisioned by Congress when it wrote the
``significant portion of its range'' language. The Act does not
[[Page 39803]]
allow us to consider in this listing decision whether there would be
higher costs in Colorado than in Wyoming. On the whole, we believe this
targeted approach provides for the necessary and appropriate needs of
the species, while avoiding unnecessary regulatory burdens.
Issue: Two reviewers suggested that our proposal, which would
result in the removal of the Act's protections for the Prebles in
Wyoming, but not in the Colorado portion of its range, may limit human
activities in Colorado and thereby encourage the transfer of those same
activities and impacts to the Prebles' habitats in Wyoming.
Response: We have concluded that this outcome is unlikely. For
example, we cannot envision prohibitions of the Act limiting
residential development in Colorado to the extent that development
options in Wyoming are pursued that would otherwise not be pursued.
Much more likely, human development activities planned in Colorado that
could adversely impact the Prebles would be modified. Prebles'
occurrence is largely limited to riparian corridors and adjacent
uplands that make up a small portion of the Colorado Front Range. Most
activities that could prove harmful to the subspecies and its habitat
can be feasibly modified to avoid impacts, or adverse effects can be
addressed through section 7 consultations or HCPs. If relocation of
projects occurs, in most cases we think that viable project
alternatives are likely to be near the originally proposed site.
Issue: A few commenters stated that a change in listing status
could preclude further investigation, monitoring, and assessing of the
Prebles in Wyoming. Other commenters argued that we did not explain how
maintenance of populations in Wyoming would be assured without
monitoring. Some commented that a 5-year monitoring plan should be
developed to monitor State and county commitments to conserve the
Prebles and its habitat. One suggested a ``special rule'' be developed
to assure such monitoring.
Response: As discussed previously, according to 50 CFR 424.11(d) of
our regulations, we may delist a species if the best available
scientific and commercial data indicate that the species is neither
endangered nor threatened for the following reasons: (1) The species is
extinct; (2) the species has recovered and is no longer endangered or
threatened; and/or (3) the original scientific data used at the time
the species was classified were in error. Section 4(g)(1) of the Act
requires us to monitor a species for at least 5 years after it is
delisted based on recovery. In this case, we are amending the status of
the Prebles based on new information that was not available at the time
of listing. Of the three options laid out in 50 CFR 424.11(d) of our
regulations and identified above, we have determined that this case
most appropriately falls under option (3) the original scientific data
used at the time the species was classified were in error. The Act does
not require us to monitor a species in such cases. However, we intend
to work with the State and other interested parties in Wyoming to
continue monitoring efforts for the subspecies.
The State of Wyoming has committed to conducting ongoing monitoring
efforts for the Prebles and to ensuring its long-term viability
(Freudenthal 2008). The State has expressed an interest in working with
the Service in developing monitoring protocols. The State is working
with the WNDD to determine relative connectivity of Prebles'
populations in Wyoming. In addition, the WNDD (Griscom et al. 2007) is
engaged in a 5-year to 7-year study with the USFS to inventory and
monitor Prebles' populations, correlate populations with habitat
conditions, and measure effects of fire and livestock grazing.
Issue: Several commenters stated that any delisting rule for the
Prebles must provide evidence that the subspecies has met the recovery
criteria cited in the Preliminary Draft Recovery Plan.
Response: Because this action is based upon error (i.e., ``the
original scientific data used at the time the species was classified
were in error'') and not recovery, satisfying the Preliminary Draft
Recovery Plan is not necessary. Additionally, recovery plans are not
regulatory documents and are instead intended to provide guidance to
the Service, States, and other partners on methods of minimizing
threats to listed species and on criteria that may be used to determine
when recovery is achieved. In short, recovery of a species is a dynamic
process requiring adaptive management that may, or may not, fully
follow the guidance provided in a recovery plan. Finally, the
Preliminary Draft Recovery Plan is a draft and has not been approved by
either the Service or the Recovery Team.
That said, we believe that our determinations regarding the
conservation status of Prebles in Wyoming and Colorado are largely
consistent with the recovery concepts described in the Preliminary
Draft Recovery Plan. In Wyoming, the Preliminary Draft Recovery Plan
focuses on maintaining 1 large population and 2 medium populations. The
availability of large, connected areas of suitable habitat with
confirmed Prebles occurrence records suggests these populations
currently exist (USFWS 2003b, pp. iv, 29; Beauvais 2004; USFWS 2008).
Because these populations face no meaningful threats over the
foreseeable future, we believe these populations will be maintained
well into the foreseeable future. Thus, the protections of the Act are
no longer necessary or appropriate in this portion of range. The same
is not true for Prebles' populations in Colorado where the protections
of the Act remain necessary.
Issue: One commenter questioned our conclusions and stated that
there was no indication that habitat conditions for the Prebles have
improved since the time of listing and that the same threats persist.
Response: Our determination that the Prebles should remain listed
in the Colorado portion of its range recognizes the continuation of the
main threats identified at the time of listing. Our determination
regarding Prebles populations in Wyoming is based on expanded knowledge
of populations present and subsequent evaluation of foreseeable threats
in relation to areas supporting these populations.
Issue: One commenter noted that, based on extrapolated estimates of
the Prebles per mile and extent of apparently occupied habitat, more
Prebles exist in Colorado than are needed for recovery as proposed in
the Preliminary Draft Recovery Plan.
Response: Extrapolation of Prebles' numbers based on limited
distribution and population data must be made with caution. Habitat
varies greatly across the known range of the subspecies and the actual
extent of occupied habitat is largely unknown. In addition, the
Preliminary Draft Recovery Plan does not emphasize total numbers of
Prebles throughout the subspecies' range, but rather the documentation
of existing populations of specified size and distribution,
establishing stability of these populations over time, and the
elimination of threats. We cannot, based on the best available
information, conclude that Prebles' populations in Colorado meet these
criteria or warrant removal of the protections of the Act.
Use of State Line To Delimit the Colorado Significant Portion of Range
Issue: Some commenters questioned the use of the State line to
delineate the Colorado significant portion of range. They were
concerned that the State border does not represent a biological divide
between Prebles' populations. Furthermore, they contend that southern
Wyoming and northern Colorado are ecologically similar, as are
[[Page 39804]]
the dominant agricultural land uses. Some suggested the use of the
State line to delineate the Colorado significant portion of range
appeared to be a political compromise. Some commenters suggested that
we should study Prebles' interactions across the State line. One
reviewer questioned whether a metapopulation or source-sink structure
existed with populations in one State, dependent on populations in the
other. Other commenters stated that management practicality favors use
of the State line. One respondent commented that landowners are used to
and better understand regulations based on governmental lines (rather
than watershed lines) and that regulation based on State or county
lines best corresponds to local zoning and development-related
permitting.
Response: The State line is not a strict ecological divide.
However, this rule incorporates this geopolitical boundary because it
appropriately divides differential threats to the north and south. As
such, it is relevant biologically to the subspecies' status.
Furthermore, the available data suggests use of the State line will
not split any Prebles' populations into federally protected and
unprotected segments. Prebles' populations in the Upper Lodgepole,
Upper Laramie, Crow Creek, and Lone Tree Creek drainages are not known
in Colorado, and Prebles' populations in the Cache La Poudre drainage
are not known to occur in Wyoming. While such populations may exist, we
see little potential for Prebles' populations in any drainage to have a
significant component in the immediate area of the Wyoming-Colorado
State line. Based on known dispersal abilities of the Prebles and
proximity of known populations in Wyoming and Colorado, interaction
across the State line is not known or likely to occur. Even if such
interactions exist, they are likely infrequent or unimportant to
populations on either side. Further, if such dependency exists, we do
not anticipate it would be disrupted by the action in this final rule.
Threats north of the border that would disrupt any metapopulation
dynamic are minimal, while populations in Colorado remain protected.
As we have described, there also is a practical consideration
supporting use of the State line to delineate the significant portion
of range where the Act's protections are still necessary.
Issue: One commenter thought that political boundaries may be
supportable in the assessment of listing status in cases where State
regulations vary, but noted that there are no such differences between
Wyoming and Colorado.
Response: Differential protection under State regulations could
render a State line an important boundary of differing threats. In this
case, we have concluded that levels of threats differ largely because
of differing levels of projected human population growth. Rationale for
using the State line is the same (i.e., differential threats) though
the reason for the threats differs.
Modification of the Boundaries for the Colorado Significant Portion of
Range
Issue: We received numerous comments regarding our delineations of
the southern, eastern, and western boundaries of the Colorado
significant portion of range. Some supported the boundaries as
proposed. One feared that altering the proposed lines of protection
could detract from recovery activities. Another commenter suggested
that boundaries were adequately delineated, and that block clearances
and site exclusions are viable regulatory options to address concerns
at sites within the significant portion of range where the Prebles was
not likely present. One commenter stated that attempts to fine tune
boundaries by drainages or counties were inappropriate and supported
the proposed latitude-longitude boundaries. This commenter concluded
that ``simplest is best.'' In contrast, we also received comments that
we should remove areas where appropriate habitat for Prebles was not
present.
Response: We have considered these comments and continue to
conclude that a broad delineation of the Colorado significant portion
of range is appropriate. Such a delineation is likely to encompass all
Prebles' populations, maximizing conservation potential within
Colorado. Fine-scale delineation of habitat is more akin to a critical
habitat designation and not appropriate for a significant portion of
the range designation of where the Act's protections apply. Elimination
of all non-habitat would require determinations of habitat suitability
for each individual stream reach creating an unwieldy task.
Furthermore, only listing the subspecies in these stream reaches would
require lengthy legal descriptions of all habitat boundaries including
possible UTM delineations (a standardized coordinate system based on
the metric system and a division of the earth into sixty 6-degree-wide
zones). This would be difficult for the public, other Federal agencies,
State agencies, local governments and other interested parties to
interpret and implement.
We also considered an intermediate approach. This approach would
apply the Act's protections to all riparian areas and their associated
wetlands, their 100-year floodplain and an additional 100 m (330 ft)
within the portion of Colorado west of 103 degrees 40 minutes West,
north of 38 degrees 30 minutes North, and east of 105 degrees 50
minutes West. One difficulty with this approach is that 100-year flood
plains have not been designated by Federal Emergency Management Agency
throughout the range of the subspecies. Because these designations have
not been defined across the range, the actual table at 50 CFR 17.11
would require lengthy legal descriptions including possible UTM
delineations. Alternatively, we considered applying the Act's
protections to all riparian areas and their associated wetlands plus a
defined buffer (such as 1,000 m (3,300 ft)) within the portion of
Colorado west of 103 degrees 40 minutes West, north of 38 degrees 30
minutes North, and east of 105 degrees 50 minutes West. This approach
would likely be inaccurate as actual utilized habitat varies across
streams and within streams based on topography of that particular
reach. An additional complication with this approach is defining
``riparian areas and their associated wetlands.'' Generally, these
terms lack a regulatory definition. Perhaps the closest regulatory
definition is Clean Water Act's (CWA) area of authority described as
``navigable waters of the United States.'' Unfortunately, many areas
utilized by Prebles fall outside these jurisdictional wetlands. As
such, the actual table at 50 CFR 17.11 would again require lengthy
legal descriptions including possible UTM delineations. As such, we
believe these intermediate approaches would also be difficult for the
public, other Federal agencies, State agencies, local governments and
other interested parties to interpret and implement.
Instead, we will continue to determine potential for habitat at a
particular site to support the Prebles on a case-by-case basis. All
block clearances and site exclusions will continue to be subject to
individual review, amendment, and expansion/contraction as more
information becomes available on Prebles' presence.
Issue: Some commenters opined that Prebles' populations in
particular drainages, counties, or stream reaches in Colorado should be
removed from protection under the Act based on considerations similar
to those we cited for removing protections in Wyoming. One commenter
suggested that all areas where threats were less severe should be
excluded from protections in Colorado. The State of Wyoming suggested
that we remove protections of the Act for
[[Page 39805]]
Prebles' populations in Lone Tree-Owl, Crow Creek, and Upper Laramie
drainages in Colorado.
Response: We have considered these comments and continue to
conclude that existing Prebles' populations in Colorado represent a
single significant portion of range that should not be further
subdivided. While we also considered splitting the subspecies into
significant portions of the range based on river basins (i.e., only
removing the Act's protections in the North Platte River basin), we
concluded that this would be more difficult to administer with little
conservation benefit to the subspecies.
Given expected development patterns in the Colorado portions of
these drainages, we do not believe the available data support Wyoming's
proposal to remove the Act's protections for Prebles' populations in
Lone Tree-Owl, Crow Creek, and Upper Laramie drainages in Colorado.
While we recognize that information is currently lacking to confirm the
presence of existing Prebles' populations in the Colorado portion of
Lone Tree-Owl and Crow Creek drainages, we believe that, based on the
availability of suitable habitat (Pague and Granau 2000, pp. 2-3, 5-3,
7-3), portions of these drainages may be occupied.
Issue: One reviewer suggested that we extend the limits of the
Colorado significant portion of range protection further east to
include lower basins and the confluence of occupied rivers and streams.
This reviewer thought that such protection might be critical to habitat
connectivity and dispersal.
Response: In cases where lower portions of drainages and basins are
thought to be outside of the current range of the Prebles, we doubt
that dispersal via these routes would occur as suitable habitat no
longer exists and is not viewed as likely recoverable. Therefore, we do
not see any reason to extend protection to these areas that are
unlikely to support the subspecies. Connectivity among populations in
separate drainages may be occurring overland where drainages have
closely adjacent headwater streams or by way of water conveyance
ditches.
Other Issues
Issue: One commenter suggested that our final rule should address
Prebles' status in Wyoming by June 30, 2008, consistent with our
settlement agreement with the State of Wyoming, but allow for
additional time to consider status of the Prebles in Colorado.
Response: Our revised proposed rule addressed the status of the
Prebles throughout its range. It would be inconsistent with our draft
guidance on the application of a significant portion of range analysis
and settlement agreement to delay our final determination for any part
of the Prebles' range. Status of the Prebles in Colorado will be
further evaluated during future 5-year reviews.
Issue: Several commenters requested that the final rule clarify how
the removal of the Act's protections in Wyoming impacts existing HCPs
and previous section 7 consultations including mitigation, monitoring,
and reporting requirements.
Response: No HCPs are in effect in Wyoming so this portion of the
issue is moot. Previous commitments made through the section 7 process
with respect to an action area in Wyoming will no longer be binding as
of the effective date of this listing determination; however,
coordination with lead Federal agencies should be pursued to
substantiate their jurisdiction over other aspects of previously
approved projects. For example, commitments specific to the Prebles and
to conservation of wetlands and adjacent buffers under CWA permits may
overlap.
Issue: Some commenters questioned how the proposed action might
impact section 9 take prohibitions and the section 7 consultation
process, including jeopardy determinations.
Response: The prohibitions under section 9 of the Act and
requirements under section 7 of the Act apply to the portion of the
subspecies' range where it remains threatened. Our jeopardy analysis
will be conducted on the significant portion of range which remains
listed (i.e., Colorado), rather than the subspecies' range as a whole.
The question we will ask with regard to the jeopardy analysis is,
``does the proposed action appreciably reduce the likelihood of
survival and recovery of the species within the significant portion of
range where the prohibitions of the Act apply?''
Taxonomy
The Prebles is a member of the family Dipodidae (jumping mice)
(Wilson and Reeder 1993, p. 499), which contains four extant genera.
Two of these, Zapus (jumping mice) and Napaeozapus (woodland jumping
mice), are found in North America (Hall 1981, p. 841; Wilson and Ruff
1999, pp. 665-667).
In his 1899 study of North American jumping mice, Edward A. Preble
concluded the Zapus genus consisted of 10 species (Preble 1899, pp. 13-
41). According to Preble (1899, pp. 14-21), Z. hudsonius (the meadow
jumping mouse) included five subspecies. Preble (1899, pp. 20-21)
classified all specimens of the meadow jumping mouse from North Dakota,
Montana, South Dakota, Wyoming, Nebraska, Colorado, and Missouri as a
single subspecies, Z. h. campestris. Cockrum and Baker (1950, pp. 1-4)
later designated specimens from Nebraska, Kansas, and Missouri as a
separate subspecies, Z. h. pallidus.
Krutzsch (1954, pp. 352-355) revised the taxonomy of the Zapus
genus after studying morphological characteristics of 3,600 specimens.
This revision reduced the number of species within this genus from 10
to 3, including Z. hudsonius (the meadow jumping mouse), Z. princeps
(the western jumping mouse), and Z. trinotatus (the Pacific jumping
mouse). According to Krutzsch (1954, pp. 385-453), the meadow jumping
mouse included 11 subspecies.
Krutzsch (1954, pp. 452-453) described and named the subspecies
Prebles (Zapus hudsonius preblei) based on geographic separation and
morphological (physical form and structure of an organism) differences.
Krutzsch (1954, pp. 452-453) discussed the presence of physical habitat
barriers and the lack of known intergradation (merging gradually
through a continuous series of intermediate forms or populations)
between the Prebles, known only from eastern Colorado and southeastern
Wyoming, and other identified subspecies of meadow jumping mice ranging
to the east and north. Additionally, Krutzsch (1954, pp. 452-453)
examined the morphometric characteristics of 4 adult and 7 non-adult
specimens. Krutzsch (1954, pp. 452-453) reported 7 distinguishing
traits, but only published quantitative results (9 measurements) on two
of these traits (n=3) (Krutzsch 1954, p. 465). Acknowledging the small
number of samples upon which his conclusion was based, Krutzsch (1954,
p. 453) nonetheless concluded that the differences between Prebles and
neighboring meadow jumping mice was considerable and enough to warrant
a subspecific designation.
In Krutzsch's analysis, subspecies neighboring Prebles included
Zapus hudsonius campestris in northeastern Wyoming, southwestern South
Dakota, and southeastern Montana; Z. h. intermedius in North Dakota,
and northwestern, central, and eastern South Dakota; and Z. h. pallidus
(Cockrum and Baker 1950) in Nebraska, Kansas, and Missouri (Krutzsch
1954, pp. 441-442, 447-452). In 1981, Hafner et al. (1981, p. 501)
identified Z. h. luteus from Arizona and New Mexico as another
neighboring subspecies of meadow
[[Page 39806]]
jumping mouse. This population had previously been assumed a subspecies
of western jumping mouse (Krutzsch 1954, pp. 406-407; Hall and Kelson
1959, pp. 774-776; Jones 1981, p. iv). Among recognized subspecies,
Krutzsch (1954, p. 452) found that Prebles most closely resembled Z. h.
campestris from northeastern Wyoming, but documented differences in
coloration and skull characteristics.
Krutzsch's description (1954), as modified by Hafner et al. (1981,
p. 501), with 12 subspecies of meadow jumping mice, has been generally
accepted by most small mammal taxonomists for the past half-century
(Hall and Kelson 1959, pp. 771-774; Long 1965, pp. 664-665; Armstrong
1972, pp. 248-249; Whitaker 1972, pp. 1-2; Hall 1981, pp. 841-844;
Jones et al. 1983, pp. 238-239; Clark and Stromberg 1987, p. 184;
Wilson and Reeder 1993, p. 499; Hafner et al. 1998, pp. 120-121; Wilson
and Ruff 1999, pp. 666-667).
Other Taxonomic Information Available Prior to Listing
As part of a doctoral dissertation, Jones (1981, pp. 4-29, 229-303,
386-394, 472) analyzed the morphology of 9,900 specimens within the
Zapus genus from across North America, including 39 Prebles' specimens.
Jones' dissertation (1981, p. 144) concluded that the Pacific jumping
mouse was not a valid taxon and suggested reducing the number of
species in the genus to two (the western jumping mouse and the meadow
jumping mouse). At the subspecific level, Jones (1981, pp. V, 303)
concluded that no population of meadow jumping mouse was sufficiently
isolated or distinct to warrant subspecific status. Regarding the
Prebles, Jones (1981, pp. 288-289) wrote that ``No named subspecies is
geographically restricted by a barrier, with the possible exception of
Z. h. preblei [Preble's meadow jumping mouse]'' which ``appears to be
isolated,'' but that ``no characteristics indicate that these
populations have evolved into a separate taxon.'' Jones' taxonomic
conclusions regarding the Prebles are difficult to evaluate as he did
not compare the Prebles to Z. h. campestris, the closest neighboring
subspecies, nor did he conduct statistical tests of morphological
differences between the Prebles and any other subspecies. This
dissertation was approved by Jones' doctoral committee and the Indiana
State University's School of Graduate Studies in 1981 (Jones 1981, p.
ii). Jones' (1981) findings were not published in a peer-reviewed
journal and were not incorporated into the formal jumping mouse
taxonomy.
Prior to listing, the CDOW contracted for a genetic analysis of the
Prebles (Riggs et al. 1997). Riggs et al. (1997, p. 1) examined 433
base-pairs in 1 region of the mitochondrial deoxyribonucleic acid
(mtDNA) (maternally inherited genetic material) across 5 subspecies of
meadow jumping mouse (92 specimens). This study concluded that the
Prebles' specimens formed a homogenous group recognizably distinct from
other nearby populations of meadow jumping mice (Riggs et al. 1997, p.
12). At the request of the Service, Hafner (1997, p. 3) reviewed the
Riggs study, inspected Riggs' original sequence data, and agreed with
its conclusions. The supporting data for this report remain privately
held (Ramey et al. 2003, p. 3). The Riggs et al. (1997) results were
not published in a peer-reviewed journal. Prior to listing, this study
was the only available information concerning the genetic uniqueness of
the Prebles relative to neighboring subspecies.
Our original listing determined that Krutzsch's (1954) revision of
the meadow jumping mouse species, including the description of the
Prebles, was widely supported by the scientific community as indicated
by the available published literature (63 FR 26517, May 13, 1998). Our
1998 determination weighed the information in unpublished reports, such
as Jones (1981), and public comments on the rule and found that they
did not contain enough scientifically compelling information to suggest
that revising the existing taxonomy was appropriate (63 FR 26517, May
13, 1998). Our 1998 conclusion was consistent with Service regulations
that require us to rely on standard taxonomic distinctions and the
biological expertise of the Department and the scientific community
concerning the relevant taxonomic group (50 CFR 424.11).
Taxonomic Information Solicited After Listing
In 2003, the Service, the State of Wyoming, and the Denver Museum
of Nature and Science funded a study to resolve ongoing taxonomic
questions about the relationship between the Prebles and neighboring
mouse taxa (USFWS 2003a, pp. 1-2). In December 2003, we received a
draft report from the Denver Museum of Nature and Science examining the
uniqueness of the Prebles relative to other nearby subspecies of meadow
jumping mice (Ramey et al. 2003). In 2004, the Service and other
partner agencies provided additional funding to expand the scope of the
original study (USFWS 2004). In August 2005, an expanded version of
this original report was published in the journal Animal Conservation
(Ramey et al. 2005). This publication included an examination of
morphometric differences, mtDNA, and microsatellite DNA (a short,
noncoding DNA sequence, usually two to five base-pairs, that is
repeated many times within the genome of an organism). Ramey et al.
(2005, pp. 339-341) also examined the literature for evidence of
ecological exchangeability among subspecies (a test of whether
individuals can be moved between populations and can occupy the same
ecological niche).
Ramey et al.'s morphometric analysis tested 9 skull measurements of
40 Prebles, 40 Zapus hudsonius campestris, and 37 Z. h. intermedius
specimens (Ramey et al. 2005, p. 331). Their results did not support
Krutzsch's (1954, p. 452) original description of the Prebles as
``averaging smaller in most cranial measurements'' (Ramey et al. 2005,
p. 334). Ramey et al. (2005, p. 334) found that only one cranial
measurement was significantly smaller, while two cranial measurements
were significantly larger.
Ramey et al. examined 346 base-pairs in 1 region of the mtDNA
across 5 subspecies of meadow jumping mice (205 specimens) (Ramey et
al. 2005, pp. 331-332, 335). Ramey et al. (2005, p. 335, 338) found low
levels of difference between the Prebles and neighboring subspecies.
The subspecies failed Ramey et al.'s tests of uniqueness in that the
subspecies did not show greater molecular variance among than within
subspecies or did not demonstrate nearly complete reciprocal monophyly
with respect to other subspecies. The data demonstrated that all of the
mtDNA haplotypes (alternate forms of a particular DNA sequence or gene)
found in the Prebles also were found in Zapus hudsonius campestris. The
mtDNA data demonstrated evidence of recent gene flow between the
Prebles and neighboring subspecies (Ramey et al. 2005, p. 338).
Ramey et al. (2005, pp. 333-334, 338) analyzed 5 microsatellite
loci across 5 subspecies of meadow jumping mice (195 specimens). The
subspecies failed Ramey et al.'s tests of uniqueness in that the
subspecies did not show greater molecular variance between than within
subspecies and that multiple private alleles were not at a higher
frequency than shared alleles at the majority of loci (Ramey et al.
2005, p. 333). Ramey et al. (2005, p. 340) concluded that these results
were consistent with their morphometric and mtDNA results.
Finally, a review of the literature found no published evidence of
adaptive or ecological differences
[[Page 39807]]
between Prebles and other subspecies of jumping mouse. Ramey et al.
(2005, pp. 339-341) conclude that the lack of morphological difference
supported the proposition of no adaptive or ecological difference.
Based on hypothesis testing using four lines of evidence--
morphometrics, mtDNA, microsatellites, and a lack of recognized
adaptive differences--Ramey et al. (2005, p. 340) concluded that
Prebles and Zapus hudsonius intermedius should be synonymized with Z.
h. campestris.
Prior to publication of Ramey et al. (2005) in Animal Conservation,
the CDOW and the Service solicited 16 peer reviews of the 2004 draft
report provided to the Service (Ramey et al. 2004a). Fourteen of these
reviewers provided comments (Armstrong 2004; Ashley 2004; Bradley 2004;
Conner 2004; Crandall 2004; Douglas 2004; Hafner 2004; Meaney 2004;
Mitton 2004; Oyler-McCance 2004; Riddle 2004; Sites 2004; Waits 2004;
White 2004). In 2005, the Service approached the same 16 experts to
review Ramey et al. 2004b (an expansion of Ramey et al. 2004a). Eleven
of these reviewers provided comments (Ashley 2005; Baker and Larsen
2005; Bradley 2005; Crandall 2005; Douglas 2005; Hafner 2005; Maldonado
2005; Mitton 2005; Oyler-McCance 2005; Waits 2005; White 2005). In
2006, some of these reviewers provided comments on Ramey et al. (2005)
as part of their review of King et al. (2006a). Krutzsch (2004) also
reviewed Ramey et al. (2004a). In August 2006, Animal Conservation
published two critiques of Ramey et al. (2005) (Martin 2006; Vignieri
et al. 2006) and two responses (Crandall 2006b; Ramey et al. 2006a).
Many of the reviewers generally supported the findings of Ramey et
al. (Baker and Larsen 2005; Bradley 2004, 2005; Crandall 2004, 2005;
Hafner 2004; Krutzsch 2004; Maldonado 2005; Meaney 2004; Mitton 2004,
2005; Riddle 2004; Sites 2004; Waits 2004, 2005). However, the
reviewers raised a number of important issues. Because these experts
reviewed the unpublished reports (Ramey et al. 2004a, 2004b), many of
the criticisms were addressed prior to publication in Animal
Conservation (Ramey et al. 2005). For example, reviewers recommended
that the study be augmented to include microsatellite data; this
information was added to the published version (Ramey et al. 2005).
Some of the most significant unresolved issues identified included:
(1) Reliance upon museum specimens which can be prone to
contamination (Douglas 2004, 2005, 2006; Hafner 2006; Maldonado 2005);
(2) The reliability of, and failure to validate, specimens' museum
identification tag (Ashley 2005; Douglas 2004, 2005; Hafner 2004;
Oyler-McCance 2004, 2005, 2006);
(3) The sampling regime and its impact on the analysis (Ashley
2006; Crandall 2006a; Douglas 2006; Hafner 2006; Maldonado 2005, 2006;
Oyler-McCance 2004, 2006);
(4) Reliance upon a small portion (346 base-pairs) of mtDNA (Ashley
2004, 2005; Baker and Larsen 2005; Crandall 2004, 2005, 2006a; Douglas
2004, 2005, 2006; Hafner 2005, 2006; Maldonado 2005; Oyler-McCance
2004, 2005, 2006; Riddle 2004; Sites 2004; Waits 2004, 2005);
(5) The small number of microsatellite DNA loci examined (five)
(Crandall 2006a; Oyler-McCance 2006; Hafner 2006; Vignieri et al. 2006,
p. 241);
(6) The statistical tests employed (Crandall 2004; Douglas 2004,
2005; Hafner 2006; Maldonado 2005; Mitton 2005; Oyler-McCance 2005,
2006);
(7) The criteria used and factors considered to test taxonomic
validity as well as alternative interpretations of the data (Ashley
2004; Conner 2004; Douglas 2004, 2005, 2006; Hafner 2005, 2006; Oyler-
McCance 2004, 2005; Vignieri et al. 2006, pp. 241-242; White 2004);
(8) Whether the western jumping mouse was an appropriate outgroup
(a closely related group that is used as a rooting point of a
phylogenetic tree) (Douglas 2004);
(9) Failure to measure all of the morphological traits examined by
Krutzsch (1954) (Vignieri et al. 2006, p. 238); and
(10) An inadequate evaluation of ecological exchangeability and
habitat differences among subspecies (Ashley 2004; Conner 2004; Douglas
2004; Meaney 2004; Mitton 2004; Oyler-McCance 2004, 2005; Sites 2004;
Vignieri et al. 2006, p. 238; Waits 2004, 2005). Collectively, these
critiques indicated that delisting based on the conclusions of Ramey et
al. alone might be premature.
Because the proposed rule to delist the Prebles relied solely upon
an unpublished report (Ramey et al. 2004a) that had received mixed peer
reviews (see above), verifying these results was a high priority of the
Service (Morgenweck 2005; Williams 2004). Thus, in 2006, the Service
contracted with USGS to conduct an independent genetic analysis of
several meadow jumping mouse subspecies (USGS 2005, pp. 1-4). The USGS
study concluded that the Prebles should not be synonymized with
neighboring subspecies (King et al. 2006a, pp. 2, 29). An expanded
version of this report was published in the journal Molecular Ecology
(King et al. 2006b). This study included an examination of
microsatellite DNA, 2 regions of mtDNA, and 15 specimens critical to
the conclusions of Ramey et al. (2005).
King et al.'s (2006b, p. 4336) microsatellite analysis examined
approximately 4 times the number of microsatellite loci (21) and more
than 1.75 times more specimens (348 specimens) than Ramey et al. (2005)
across the same 5 subspecies of meadow jumping mice. King et al.
(2006b, p. 4337) concluded that their microsatellite data demonstrated
a strong pattern of genetic differentiation between the Prebles and
neighboring subspecies. King et al. (2006b, pp. 4336-4341) also
reported that multiple statistical tests of the microsatellite data
verified this differentiation.
In their evaluation of mtDNA, King et al. (2006b, p. 4341) examined
approximately 4 times the number of base-pairs across 2 regions (374
control region and 1,006 cytochrome-B region base-pairs) and more than
1.5 times more specimens (320 specimens for the control region analysis
and 348 for the cytochrome-B analysis) than Ramey et al. (2005) across
the same 5 subspecies of meadow jumping mice. King et al. (2006b, p.
4341) concluded that these data suggested strong, significant genetic
differentiation among the five subspecies of meadow jumping mice
surveyed.
Additionally, their mtDNA results indicated that the Prebles did
not share haplotypes with any neighboring subspecies (King et al.
2006b, p. 4341). Such haplotype sharing contributed to Ramey et al.'s
(2004a, pp. 1, 9; 2005, p. 335) conclusion that the Prebles was not
unique and that the Prebles was a less genetically variable population
of Zapus hudsonius campestris. Because of these conflicting results,
King et al. (2006b, pp. 4355-4357) reexamined 15 specimens from the
University of Kansas Museum collection that were key in Ramey et al.'s
determination that neighboring subspecies shared haplotypes. King et
al. (2006b, p. 4357) could not duplicate the mtDNA sequences reported
by Ramey et al. for these specimens. If these specimens were removed
from the analysis, neither study would illustrate haplotype sharing
between the Prebles and neighboring subspecies. King et al. (2006b, p.
4357) concluded that ``these findings have identified the presence of a
systemic error in the control region data reported by Ramey et al.
(2005)'' and ``calls into question all of the results of Ramey et al.
(2005) based on the
[[Page 39808]]
mtDNA genome and prevents analysis of the combined data.'' King et al.
(2006, p. 4357) noted that possible reasons for the difference in
sequences included contamination, mislabeling of samples, or other
procedural incongruity. Ramey et al. (2007, pp. 3519-3520) proposed a
number of alternative explanations for these contradictory results
including nuclear paralogs (copies of mtDNA sequence that have been
incorporated into the nuclear genome and are now pseudogenes, that is,
they are no longer functional), heteroplasmy (the existence of more
than one mitochondrial type in the cells of an individual), different
amplification primers and conditions, and template quality.
Overall, King et al. (2006b, p. 19) concluded that considerable
genetic differentiation occurred among all five subspecies and found no
evidence to support the proposal to synonymize the Prebles, Zapus
hudsonius campestris, and Z. h. intermedius.
Prior to its release, King et al. (2006a) underwent an internal
peer review per USGS policy (USGS 2003, pp. 3, 6, 12, 28-33). In an
effort to provide consistent, comparable reviews, we solicited peer
reviews from the same 16 reviewers asked to review Ramey et al. (2004a,
2004b). Nine of the experts provided comments (Armstrong 2006; Ashley
2006; Bradley 2006; Crandall 2006a; Douglas 2006; Hafner 2006;
Maldonado 2006; Oyler-McCance 2006; Riddle 2006). Ramey et al. (2006b,
2007) also critiqued King et al. (2006a, 2006b).
Most of the reviewers supported the findings of King et al.
(Armstrong 2006; Ashley 2006; Douglas 2006; Hafner 2006; Maldonado
2006; Oyler-McCance 2006; Riddle 2006). These reviews offered a number
of issues and possible explanations why the results differed from Ramey
et al. Because reviewers were asked to review the unpublished report
(King et al. 2006a), some of the issues were addressed in the Molecular
Ecology publication (King et al. 2006b). For example, numerous reviews
suggested expanding the geographic range of the study by adding a
Prebles' population in Wyoming; this issue was addressed in the
published version (King et al. 2006b). Similarly, the publication
incorporated the suggestion to retest the museum specimens Ramey et al.
(2005) identified as having shared haplotypes for signs of cross
contamination. Some of the other issues raised included:
(1) The sampling regime and its impact on the analysis (Armstrong
2006; Ashley 2006; Crandall 2006a; Douglas 2006; Oyler-McCance 2006;
Ramey et al. 2007, p. 3519; Riddle 2006);
(2) Failure to evaluate morphometrics and ecological
exchangeability (Crandall 2006a);
(3) Reliance upon a small portion of control region mtDNA (Riddle
2006);
(4) The number of loci examined (i.e., too many), the programs used
to analyze the data, and the resulting sensitivity in detecting
difference (Crandall 2006a; Ramey et al. 2006b; Ramey et al. 2007, p.
3519);
(5) a specimen collection methodology which could cause
contamination (Ramey et al. 2007, p. 3519);
(6) The statistical tests employed (Crandall 2006a; Douglas 2006;
Maldonado 2006; Riddle 2006); and
(7) The criteria used and factors considered to test taxonomic
validity and alternative interpretations of the data (Bradley 2006;
Crandall 2006a).
Given the discrepancies between the Ramey et al. and King et al.
reports, we contracted for a scientific review to analyze, assess, and
weigh the reasons why the data, findings, and conclusions of the two
studies differed (USFWS 2006, p. 14). Following an open and competitive
bid process, we selected SEI as the contractor (USFWS 2006).
SEI assembled a panel of experts with the necessary scientific
expertise in genetics and systematics (SEI 2006a, pp. 7, 56-82). The
panelists reviewed, discussed, and evaluated all of the literature
relevant to this issue including published literature, unpublished
reports, third-party critiques, public comments, and other materials
suggested by interested parties (SEI 2006a, pp. 48-55). Additionally,
the panel examined and reanalyzed the raw data (SEI 2006a, pp. 8, 21)
used by Ramey et al. and King et al., including the mtDNA data,
microsatellite DNA data, and original sequence chromatograms (automated
DNA sequence data output recordings) (SEI 2006a, pp. 8, 23). The
scientific review panel was open to the public and allowed for
interactions among panel members, Dr. King, Dr. Ramey, other
scientists, and the public.
In July 2006, SEI delivered a report outlining its conclusions to
the Service (SEI 2006a). Although the panelists were not obligated to
reach a consensus, they did not disagree on any substantive or
stylistic issues (SEI 2006a, p. 9). Thus, the report represented the
consensus of all three panelists, as well as the individual opinions of
each panelist. The panel organized its evaluation into four sections
corresponding with the different types of scientific evaluations
performed, including morphology, ecological exchangeability, mtDNA, and
microsatellite DNA. The panel's findings with regard to each are
summarized briefly below. The full report is available for review at
http://www.fws.gov/mountain-prairie/species/mammals/preble/Prebles_
SEI_report.pdf.
Morphology: The panel found that all seven of the morphological
characters examined by Krutzsch (1954, pp. 452-453) should have been
reexamined in order to support Ramey et al.'s proposed taxonomic
revision. The panel also concluded that the type specimen (the original
specimen from which the description of a new species is made) of each
taxon should have been included in the analysis. The panel's conclusion
was that an insufficient test of the morphological definition of the
Prebles had been conducted to support the synonymy of the Prebles with
other subspecies (SEI 2006a, p. 41).
Ecological Exchangeability: The panel concluded that no persuasive
evidence was presented regarding ecological exchangeability, and that
the ecological exchangeability of the subspecies remains unknown (SEI
2006a, p. 41).
MtDNA: The panel noted that data provided by Ramey et al. (2005)
and King et al. (2006b) differed in geographic sampling strategy,
amount of sequence data examined, aspects of the analysis, and quality
(SEI 2006a, p. 41). All of these could help explain why the two studies
came to differing conclusions. However, the panel noted that the most
significant difference between the two studies in terms of mtDNA was
whether the Prebles shared any mtDNA haplotypes with other subspecies
of meadow jumping mice. Upon review of the raw data, the panel found
evidence of contamination within some of the key sequences reported by
Ramey et al. and that the supporting data for the samples in question
was of poor quality and/or quantity (SEI 2006a, pp. 23-32). The panel
concluded that no reliable evidence existed of any haplotype sharing
between the Prebles and neighboring subspecies (SEI 2006a, p. 42). The
panel determined that if the conflicting mtDNA sequences were removed
from consideration, the two studies' mtDNA data would largely agree
(SEI 2006a, p. 32). The panel also suggested that because the western
jumping mouse and the meadow jumping mouse are distantly related,
western jumping mouse may perform poorly as an outgroup, leading to
poor resolution of relationships among meadow jumping mouse subspecies.
While both Ramey et al. and King et al. used western jumping mice as
their outgroup, an unrooted analysis lacking these genetic points of
reference showed
[[Page 39809]]
clearer phylogenetic structuring between the subspecies (SEI 2006a, p.
42).
Microsatellite DNA: The panel found that the two microsatellite
datasets contain similar information. The panel pointed out that both
the Ramey et al. (2005) and King et al. (2006b) microsatellite data, as
well as Crandall and Marshall's (2006) reanalysis of these data,
strongly support a statistically significant independent cluster that
corresponds to the Prebles, providing support for a distinct subspecies
(SEI 2006a, pp. 42-43). The panel indicated that while the
microsatellite data alone did not make a strong case for evolutionary
significance, in concert with the mtDNA data (discussed above), the two
datasets corroborate the distinctness of the Prebles (SEI 2006a, p.
43).
The panel's overall conclusion was that the available data are
broadly consistent with the current taxonomic status of the Prebles as
a valid subspecies and that no evidence was presented that critically
challenged its status (SEI 2006a, p. 4). In August 2006, Ramey et al.
(2006c) submitted a statement to the Service disputing the approach and
conclusions of the SEI report. Some of the most significant issues
raised included: (1) Objection to the deference given to Krutzsch
(1954); (2) disagreement with the suggestion that all seven
morphometric characters examined by Krutzsch (1954) and the type
specimen should be reexamined; (3) dispute with the assertion that
Ramey et al.'s (2005) evaluation of ecological significance was
inadequate; (4) the contention that the Prebles and neighboring
subspecies remain weakly genetically differentiated; and (5) SEI's
failure to develop objective standards for testing the validity of
suspect subspecies. No new data or analyses were presented in this
statement, and the panel previously considered most of these
contentions (Ramey et al. 2003, 2004a, 2004b, 2005, 2006a, 2006b; SEI
2006a, 2006b, 2006c). Other evaluations of the available literature and
data include Ramey et al. (2007), Crandall and Marshall (2006), Spencer
(2006b), and Cronin (2007).
Taxonomic Conclusions
When listed in 1998, the Prebles was widely recognized as a valid
subspecies by the scientific community (Hall and Kelson 1959, pp. 771-
774; Long 1965, pp. 664-665; Armstrong 1972, pp. 248-249; Whitaker
1972, pp. 1-2; Hall 1981, pp. 841-844; Jones et al. 1983, pp. 238-239;
Clark and Stromberg 1987, p. 184; Wilson and Reeder 1993, p. 499;
Hafner et al. 1998, pp. 120-121; Wilson and Ruff 1999, pp. 666-667). At
the time of listing, Krutzsch (1954) represented the best available
information on the taxonomy of the Prebles (63 FR 26517, May 13, 1998).
Our 1998 conclusion was consistent with Service regulations that
require us to rely on standard taxonomic distinctions and the
biological expertise of the Department and the scientific community
concerning the relevant taxonomic group (50 CFR 424.11). However, when
the best available science indicates that the generally accepted
taxonomy may be in error, the Service must rely on the best available
science (Center for Biological Diversity, et al., v. Robert Lohn, et
al., 296 F. Supp. 2d. 1223 W.D. Wash. 2003). Such considerations led to
our February 2, 2005, proposal to delist the Prebles based upon
information that questioned the subspecies' taxonomic validity (70 FR
5404).
We now determine that the best scientific and commercial data
available support the conclusion that the Prebles is a valid
subspecies. Specifically, the Prebles' geographic isolation from other
subspecies of meadow jumping mice (Krutzsch 1954, pp. 452-453; Long
1965, pp. 664-665; Beauvais 2001, p. 6; Beauvais 2004; SEI 2006a, p.
34) has resulted in the accretion of considerable genetic
differentiation (King et al. 2006b, pp. 4336-4348; SEI 2006a, pp. 41-
43). The available data suggest that the Prebles meets or exceeds
numerous, widely accepted subspecies definitions (Mayr and Ashlock
1991, pp. 43-45; Patten and Unitt 2002, pp. 26-34; SEI 2006a, p. 44).
In reaching this conclusion, we have not used a presumption that we
must rely on the established taxonomy in the absence of conclusive data
to the contrary (see SEI report at p. 39). After a review of all
available information, we have determined that the taxonomic revision
for the Prebles suggested in our proposed delisting rule (70 FR 5404,
February 2, 2005) is no longer appropriate.
Historical Range and Recently Documented Distribution
Generally, the Prebles' range includes portions of the North
Platte, the South Platte, and the Arkansas river basins (Long 1965, p.
665; Armstrong 1972, pp. 248-249; Clark and Stromberg 1987, p. 184;
Fitzgerald et al. 1994, p. 293; Clippinger 2002, p. 20).
At the time of listing, we described the historical range in
Wyoming as including five counties (Albany, Laramie, Platte, Goshen,
and Converse), but cited only two sites with recent reports of jumping
mice likely to be the Prebles. We cited a study by Compton and Hugie
(1993, p. 6) suggesting the subspecies might be extirpated in Wyoming
and comments by the WGFD that the Prebles had likely been extirpated
from most or all of its historical range in Wyoming (Wichers 1997).
At the time of listing, we assumed that most of the subspecies'
current range was in Colorado. Within Colorado, the final listing rule
described a presumed historical range including portions of 10 counties
(Adams, Arapahoe, Boulder, Denver, Douglas, El Paso, Elbert, Jefferson,
Larimer, and Weld) and cited recent documentation of the subspecies in
7 of these 10 counties (Boulder, Douglas, El Paso, Elbert, Jefferson,
Larimer, and Weld).
Since we listed the Prebles in 1998, our knowledge about
distribution of the subspecies has grown substantially. Numerous
trapping surveys conducted during the last 9 years in Wyoming and
Colorado have documented the subspecies' presence or likely absence at
locations of suitable habitat. While many recent trapping efforts have
been at locations with no record of historical surveys, most have been
within the presumed historical range of the Prebles or in adjacent
drainages where habitat and elevation appeared suitable. Thus, the
recent increase in sites of Prebles' occurrence likely represents an
improvement in our understanding of the subspecies' range as a result
of increased trapping effort rather than any actual expansion of the
range of the Prebles.
In Wyoming, recent captures and confirmed identification have
expanded our knowledge of the distribution of the Prebles to include
over two dozen new plains, foothills, and montane sites, including
presence west of the Laramie Mountains in the North Platte River basin
and in the Upper Laramie River drainage in Albany County (Taylor 1999;
USFWS 2008). Post-listing activities have identified many additional
sites occupied by the subspecies. Since listing, trapping efforts in
Wyoming targeting Prebles have captured jumping mice at 72 percent of
sites (124 of 173 sites) (USFWS 2008). Of positive jumping mouse
capture sites, 29 percent of the sites included only Prebles, 55
percent of the sites included only western jumping mice, 5 percent of
the sites had both species present, and specimens from 11 percent of
the successful sites were never positively identified to species. These
data also reveal that the Prebles occurs in four of the five counties
that we described as the likely historical range at the time of listing
including Albany, Laramie, Platte, and
[[Page 39810]]
Converse counties. While generalized range maps (Long 1965, p. 665,
Armstrong 1972, pp. 248-249, Clark and Stromberg 1987, p. 184) depicted
Prebles' range extending east into Goshen County, we have no evidence
that the subspecies was ever present there.
At the time of listing, we discussed how increased trapping efforts
in Colorado had recently documented distribution in Elbert, Larimer,
and Weld counties. We also suggested other sites where trapping should
occur to determine if Prebles were present. Additional trapping since
listing has expanded the documented distribution of the Prebles in
Colorado to include: (1) Additional foothill and montane sites along
the Front Range in Larimer, Boulder, Jefferson, and Douglas counties;
(2) previously untrapped rural prairie and foothill streams in southern
Douglas County and adjacent portions of Elbert County; and (3)
additional prairie and foothill streams in northwestern El Paso County.
Although we have identified some additional sites occupied by the
Prebles, since listing over 80 percent of Colorado trapping efforts
targeting Prebles have failed to capture jumping mice (as illustrated
in Figure 2 below) (USFWS 2008). In 2007, 2 of 31 trapping efforts
targeting new sites in Colorado resulted in captures of jumping mice.
These negative trapping results suggest that the subspecies is rare or
extirpated from many portions of the subspecies' historical range in
Colorado. Areas where the subspecies is presumed extirpated are
discussed in the Factor A discussion below.
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The Prebles has now been recently documented in portions of Albany,
Laramie, Platte, and Converse counties in Wyoming; and in portions of
Boulder,
[[Page 39813]]
Douglas, El Paso, Elbert, Jefferson, Larimer, and Weld counties in
Colorado (Figures 1 and 2). The North Platte River at Douglas, Wyoming,
marks the northernmost confirmed location for the Prebles. Specimens
from Colorado Springs, Colorado, mark the southernmost documented
location of the Prebles.
The Prebles is generally found at elevations between 1,420 m (4,650
ft) and 2,300 m (7,600 ft). At the lower end of this elevation
gradient, the semi-arid climate of southeastern Wyoming and eastern
Colorado limits the extent of riparian corridors and restricts the
range of the Prebles (Beauvais 2001, p. 3). The Prebles is likely an
Ice Age relict; once the glaciers receded from the Front Range of
Colorado and the foothills of Wyoming and the climate became drier, the
Prebles was confined to riparian systems where moisture was more
plentiful (Fitzgerald et al. 1994, p. 1994; Smith et al. 2004, p. 293).
The eastern boundary for the subspecies is likely defined by the dry
shortgrass prairie, which may present a barrier to eastward expansion
(Beauvais 2001, p. 3). In Wyoming, the Prebles has not been found east
of Cheyenne, Laramie County (Beauvais 2001, p. 3). Habitat modeling and
trapping suggest the subspecies does not occur in Wyoming's Goshen,
Niobrara, and eastern Laramie counties (Keinath 2001, p. 7). In
Colorado, the Prebles has not been found on the extreme eastern plains
(Clippinger 2002, pp. 20-21).
At the higher elevations, discerning the status of the Prebles is
complicated by the overlap in the ranges of the Prebles and the western
jumping mouse (Long 1965, pp. 665-666; Clark and Stromberg 1987, pp.
184-187; Schorr 1999, p. 3; Bohon et al. 2005; Schorr et al. 2007, p.
5). Field differentiation between the Prebles and the western jumping
mouse is difficult (Conner and Shenk 2003a, p. 1456). Generally, the
western jumping mouse occurs in the montane and subalpine zones and the
Prebles occurs lower, in the plains and foothills (Smith et al. 2004,
p. 10). Using this information as a guide, many jumping mice were
trapped and released without being conclusively identified as either a
Prebles or a western jumping mouse. Western jumping mice have been
verified at elevations well below the upper elevation limit of the
Prebles (Smith et al. 2004, p. 11), leading to difficulty in making
assumptions regarding identification based on elevation. Drainages
where overlapping ranges have been verified include: The Glendo
Reservoir, Lower Laramie, Upper Laramie, and Horse Creek drainages in
Wyoming (Conner and Shenk 2003b, pp. 26-27, 34-37; Meaney 2003; King
2006a; King 2006b; King et al. 2006b, pp. 4351-4353); and the Cache La
Poudre, Big Thompson, and Upper South Platte River drainages in
Colorado (Bohon et al. 2005; King 2005; King 2006a; King et al. 2006b,
pp. 4351-4353; Schorr et al. 2007).
Size, external morphology, dentition, skull measurements, and
genetic analysis can all be used to differentiate meadow jumping mice
from western jumping mice (Krutzsch 1954, pp. 351-384; Klingenger 1963,
p. 252; Riggs et al. 1997, pp. 6-11; Conner and Shenk 2003a; Ramey et
al. 2005, p. 332; King et al. 2006b, p. 4341). The following
description of the Prebles' current distribution and status emphasizes
locations where individual mice have been positively identified through
genetic analysis or DFA (Conner and Shenk 2003a). Information regarding
individual mice and capture locations can be found in Riggs et al.
(1997, pp. 7-11, A1-A4), Conner and Shenk (2003b, pp. 31-35), and King
et al. (2006b, pp. 4351-4353). Positive identification of individual
mice is most important in areas where both the Prebles and the western
jumping mouse occur. Overlap appears to occur in most of Wyoming's
occupied drainages (as described further below). In Colorado, with few
exceptions, jumping mice positively identified below 2,050 m (6,700 ft)
have been Prebles. Between 2,050 m (6,700 ft) and 2,320 m (7,600 ft) in
Colorado, Prebles and western jumping mice are known to have an
overlapping distribution in the Cache La Poudre, Big Thompson, and
Upper South Platte River drainages.
Below is a summary of recent (since 1980) trapping data by drainage
(as defined by 8-digit USGS hydrologic units), within both Wyoming
(e.g., the North and South Platte River basins) and Colorado (e.g., the
South Platte River and Arkansas River basins). Although trapping data
is important because it absolutely confirms the occurrence of jumping
mice at particular locations, trapping data is only one of several
lines of evidence we use to estimate the actual range of the
subspecies. Records have been compiled by the Service (2008) in
coordination with the WNDD, State of Wyoming, and CDOW. Figure 1 above
illustrates all recently confirmed Prebles' capture locations in
Wyoming. Figure 2 above illustrates all recent Prebles' capture
locations in Colorado. Given wide areas of overlapping range in
Wyoming, we require all Wyoming specimens to be confirmed as Prebles in
order to be considered in our discussion below (and in Figure 1). In
Colorado, jumping mice are considered Prebles in our discussion below
(and in Figure 2) when identification is confirmed or, if they occur in
areas below 2,050 m (6,700 ft), where western jumping mice have not
been documented.
North Platte River Basin, Wyoming--In the North Platte River basin,
occurrence of the Prebles has been confirmed in four Wyoming counties
(Converse, Platte, Albany, and Laramie) as reported by drainage below.
The Middle North Platte drainage represents the northern extent of
the reported Prebles' historic range. Jones (1981) examined one
Prebles' specimen from within this drainage, trapped at Boxelder Creek,
Converse County. Recent trapping surveys have been quite limited and
generally at high elevations. Although several other recent jumping
mice have been trapped in this drainage, these specimens have not been
confirmed as Prebles.
In the Glendo Reservoir drainage, the Prebles is known from several
locations, including along the North Platte River at Douglas (King
2006b), and Cottonwood Creek and its tributaries (Meaney 2003; King
2006a; King 2006b; King et al. 2006b, pp. 4351-4353). While the western
jumping mouse also has been confirmed from the Glendo Reservoir
drainage, trapping records to date suggest that the Prebles is more
common.
In the Lower Laramie drainage, the Prebles has been confirmed from
the Laramie River and its tributaries, including the North Laramie
River, and Sturgeon, Wyman, Rabbit, and Luman creeks; as well as
several locations along Chugwater Creek and its tributaries (King
2006b; King et al. 2006b, pp. 4351-4353). Both Prebles and western
jumping mice occur in the Sybille Creek, Friend Creek and the Friend
Park areas (Conner and Shenk 2003b, pp. 26-27, 34-37; King 2006a; King
2006b; King et al. 2006b, pp. 4351-4353). The Lower Laramie drainage
appears to support coexisting Prebles and western jumping mice in
multiple locations.
In the Horse Creek drainage, the Prebles has been widely documented
west of Interstate Highway 25 (I-25) and at one site east of I-25. The
majority of these recent captures have been made in Bear Creek and its
tributaries, and in headwaters of Horse Creek and its tributaries. Both
Prebles and western jumping mice inhabit multiple sites on both creeks
(Conner and Shenk 2003b, pp. 26-27, 34-37; Meaney 2003; King 2006b;
King et al. 2006b, pp. 4351-4353).
In the Upper Laramie drainage, the Prebles has been confirmed at
Hutton
[[Page 39814]]
Lake National Wildlife Refuge (NWR) and from a site north of Laramie
(Meaney 2003). Other specimens at these same sites have been confirmed
as western jumping mice (Meaney 2003; King 2006a). Therefore, it
appears likely that both Prebles and western jumping mice are present
at multiple sites in this drainage. Based on positive identification of
the Prebles from the sites mentioned above, Smith et al. (2004, p. 12)
suggested the range of the Prebles may extend into the Upper Laramie
River, Little Laramie River, Rock Creek, and possibly the Medicine Bow
River. Documented occurrence of Prebles' populations in these areas
would represent a significant extension of the known range of the
subspecies in Wyoming.
South Platte River Basin, Wyoming--Within the Wyoming portion of
the South Platte River basin, Prebles have been confirmed present,
albeit possibly in low numbers, within two drainages in Laramie and
Albany Counties.
In the Upper Lodgepole drainage, jumping mice have been found from
several locations at and upstream of Highway 211. While at least one
Prebles has been confirmed (Riggs et al. 1997, pp. 7-11, A1-A4), most
of the captured mice have been identified as western jumping mice
(Meaney 2003; King 2006a). Therefore, while this drainage supports the
Prebles, its distribution may be limited.
Although historically reported from Cheyenne (Krutszch 1954),
presumably from the Crow Creek drainage, Prebles' occurrence in this
drainage remains uncertain. Specimens from Warren Air Force Base were
assumed to be Prebles based on the elevation of 1,900 m (6,150 ft), but
subsequent analyses identified only western jumping mice (Riggs et al.
1997, pp. 7-11, A1-A4; Conner and Shenk 2003b, pp. 26-27, 34-37; King
2006a). The only recent confirmed Prebles occurrence in this drainage
comes from the South Crow Creek Reservoir area (Meaney 2003).
Additional efforts have only verified western jumping mice from Middle
Crow Creek, the South Fork of Middle Crow Creek, and South Crow Creek
Reservoir (Meaney 2003; King 2006a). No jumping mice have been reported
downstream of Cheyenne.
The Lone Tree Creek drainage was previously assumed to be inhabited
by the Prebles. However, DFA analysis of existing museum specimens
(Conner and Shenk 2003b, pp. 26-27, 34-37) and genetic analysis of
specimens obtained from trapping efforts (Riggs et al. 1997, pp. 7-11,
A1-A4; King 2006a), have only confirmed the presence of western jumping
mice in this drainage.
South Platte River Basin, Colorado--Prebles has been recently
documented within the South Platte River basin in seven counties:
Larimer, Weld, Boulder, Jefferson, Douglas, Elbert, and El Paso. From
the Wyoming State line south through the Denver area, little recent
documentation of the Prebles exists from sites east of the foothills
where most of the subspecies' historical records occur. This area
largely corresponds to the Front Range urban corridor, an area
experiencing continued human population growth and development
(Clippenger 2002, pp. 22-26; Colorado Demography Office 2007). At
higher elevation plains and foothills sites south of the Denver area,
the Prebles has been documented at a number of locations where riparian
habitats are still largely intact. With rare exception, all jumping
mouse records verified below 2,050 m (6,700 ft) in the South Platte
River drainage of Colorado have been Prebles.
In the Cache La Poudre River drainage, jumping mice have been
documented on sites upstream of Fort Collins, Larimer County, at
elevations consistent with known Prebles' distribution. These sites
include the main stem Cache La Poudre River and its tributaries,
including Young Gulch and Stove Prairie Creek, and the North Fork Cache
La Poudre River and its tributaries, including Stonewall, Rabbit, and
Lone Pine Creeks. Shenk and Eussen (1999, pp. 11-12) cautioned that
both Prebles and western jumping mice were likely present in some of
these areas. Subsequent genetic analysis confirmed both the Prebles and
the western jumping mouse in Cherokee Park at 2,260 m. (7,480 ft) (King
2005, 2006b), but only Prebles have been confirmed from lower
elevations, including Rabbit and Lone Pine Creeks, the Livermore
Mountain area, and the North Fork of the Cache La Poudre River (Riggs
et al. 1997, pp. 7-11, A1-A4; King et al. 2006b, pp. 4351-4353).
Despite a number of trapping efforts, no jumping mice have been
recently documented within the Fort Collins area of Larimer County or
downstream on the Cache La Poudre River to its confluence with the
South Platte River at Greeley, Weld County (USFWS 2008).
Within the Big Thompson drainage, the Prebles has been documented
in foothills sites along Buckhorn Creek and certain of its tributaries,
and on Dry Creek, in Larimer County. Three tributaries of Buckhorn
Creek up to 2,240 m (7,360 ft) had Prebles; however, both Prebles and
western jumping mice were confirmed from the Lakey Canyon site at 2,170
m (7,120 ft), and a mouse from the North Fork of the Big Thompson River
at 2,170 m (7,120 ft) was confirmed as a western jumping mouse (King
2006a). Despite a number of trapping efforts, the Prebles has not been
documented on the Big Thompson and Little Thompson Rivers through the
Front Range urban corridor, but has been found on both rivers east of
I-25, in Weld County.
In the Saint Vrain drainage, the Prebles has been documented along
the Saint Vrain River and its tributaries, and water conveyance ditches
upstream of the town of Hygiene, on two tributaries of Boulder Creek
west of the City of Boulder, and along South Boulder Creek, all in
Boulder County; and on upper reaches of Coal and Rock Creeks, Jefferson
County. On Rocky Flats NWR, Jefferson County, the Prebles has been
documented on Rock Creek, as well on nearby Walnut and Woman Creeks
within the Middle South Platte-Cherry Creek drainage. Several of these
locations include mice confirmed as Prebles (Riggs et al. 1997, pp. 7-
11, A1-A4; Conner and Shenk 2003b, pp. 26-27, 34-37). Prebles'
occurrence has not been documented along eastern parts of the drainage,
the Saint Vrain River from Hygiene, Boulder County, downstream to its
confluence with the South Platte River, along Boulder Creek from the
City of Boulder east to its confluence with the Saint Vrain River, or
downstream of Rocky Flats NWR on Walnut, Woman, or Dry creeks.
In the Clear Creek drainage, the Prebles has been verified in the
foothills on Ralston Creek (Riggs et al. 1997, pp. 7-11, A1-A4), and
unidentified jumping mice have been captured on two tributaries of
Clear Creek at elevations consistent with Prebles' occurrence (below
2,300 m (7,600 ft)). No jumping mice have been captured on either creek
downstream through the urban corridor to the South Platte River.
In the Upper South Platte drainage, the Prebles has been documented
immediately upstream of Chatfield Reservoir on the South Platte River,
and also well upstream on the South Platte River and its tributaries in
Jefferson and Douglas Counties to near the Teller County-Douglas County
line. The USFS provided a summary of Prebles' trapping efforts at 15
sites in the Upper South Platte drainage in the Pike National Forest
(Bohon et al. 2005). Based on examination of voucher specimens, Prebles
were confirmed at six sites up to 2,300 m (7,600 ft) and western
jumping mice were confirmed from six sites, the lowest of which, at
2,030 m (6,660 ft), was lower than five Prebles' sites (Bohon et al.
2005). Schorr et al. (2007) also summarized co-occurrence of the
Prebles and the
[[Page 39815]]
western jumping mouse in the same area. Also in the Upper South Platte
drainage, the Prebles has been widely documented upstream of Chatfield
Reservoir on Plum Creek, including occurrences on East Plum Creek, West
Plum Creek, and various tributaries, all in Douglas County (Riggs et
al. 1997, pp. 7-11, A1-A4; Conner and Shenk 2003b, pp. 26-27, 34-37;
King et al. 2006b, pp. 4351-4353). Western jumping mice have also been
confirmed in this drainage at 1,800 m (5,900 ft) and 1,950 m (6,400 ft)
(Conner and Shenk 2003b, pp. 26-27, 34-37). An estimated 64 km (40 mi)
of streams are occupied by the Prebles throughout the Plum Creek
watershed (Pague and Schuerman 1998, p. 5). On the downstream portion
of this drainage, below Chatfield Reservoir, there is no recent
documentation of Prebles' presence on the South Platte River through
Denver.
In the Middle South Platte-Cherry Creek drainage, Prebles have been
found on Cherry Creek and its tributaries from approximately the
Arapahoe County--Douglas County line, upstream to the headwaters of
East and West Cherry Creeks near the Palmer Divide in El Paso County.
Also within the Middle South Platte-Cherry Creek drainage, limited
trapping efforts have documented the Prebles on Running Creek and a
tributary, Hay Creek, in Elbert County. Based on limited genetic
analysis and DFA, western jumping mice have not been confirmed from
this drainage. The Prebles has not been documented downstream along
Cherry Creek through Arapahoe County and Denver to the South Platte
River. Because of numerous negative trapping efforts and loss of
contiguous suitable habitat from development, we no longer consider the
greater Denver area (including most of Denver County and portions of
Adams, Arapahoe, Boulder, Broomfield, Douglas, and Jefferson Counties)
to be occupied. On the South Platte River downstream from the Denver
area, a single Prebles was recently captured from near the South Platte
River in Milliken, Weld County, not far from the confluence of the Big
Thompson River and South Platte River (Savage and Savage 2001).
Northwest of Denver and widely separated from other captures in this
drainage, Prebles has been documented on Walnut and Women Creeks at
Rocky Flats NWR.
Farther east, Prebles has been recorded on Kiowa Creek, Elbert
County. Additional trapping in suitable habitat in Elbert County would
be useful to document whether the Prebles is present along significant
reaches of the Middle South Platte-Cherry Creek and Kiowa Creek
drainages, and on the Bijou Creek drainage, Elbert County, where it has
not yet been documented. The only trapping effort to date in the Bijou
Creek drainage was an unsuccessful effort in apparently suitable
habitat in Arapahoe County.
Arkansas River Basin, Colorado--In the Arkansas River basin,
current occurrence of the Prebles is limited largely to the Fountain
Creek drainage and specifically to Monument Creek and its tributaries
north of Colorado Springs. Genetic analysis and DFA have thus far
confirmed no western jumping mice from within the Prebles' range in
this drainage (Conner and Shenk 2003b, pp. 26-27, 34-37; King et al.
2006b, pp. 4351-4353). The Prebles has been well studied at the U.S.
Air Force Academy (Academy) on Monument Creek and its tributaries, and
has been documented farther upstream on Monument Creek and on
tributaries to the east and north toward the Palmer Divide. Numerous
Prebles' captures on streams in northwestern El Paso County are the
result of extensive trapping that has taken place in conjunction with
proposed development projects. Downstream of the Academy, numerous
surveys indicate that the Prebles has little likelihood of occurrence
along Monument Creek through the downtown portions of Colorado Springs.
Similarly, extensive trapping with negative results suggests that the
Prebles is now extirpated from Cottonwood Creek and its tributaries.
In the Chico Creek drainage, jumping mice (assumed to be Prebles as
explained above) have been documented on the upper reaches of Black
Squirrel Creek and on a tributary, both in El Paso County. Limited
trapping efforts in potential Prebles' habitat farther to the east in
the Chico Creek drainage and in the Big Sandy Creek drainage have not
documented Prebles' occurrence. Downstream, to the east and south,
these drainages appear to have little habitat suitable for the Prebles.
Within the Arkansas River basin south of the documented Prebles'
locations, jumping mice have not been documented within southern El
Paso, Pueblo, and Fremont counties, despite targeted trapping efforts
(Bunn et al. 1995; Werner 2003).
In conclusion, according to the existing trapping records, the
Prebles appears to be widespread in the North Platte River basin where
trapping efforts confirm the subspecies' distribution across at least
four drainages. The Prebles appears scarce within the Wyoming portion
of the South Platte River basin, where trapping efforts to date provide
few confirmed occurrences of the subspecies and suggest that the
western jumping mouse is much more widespread. Within the Colorado
portion of the South Platte River Basin, the Prebles has little
likelihood of occurrence in portions of some drainages that coincide
with the Front Range development corridor (areas around I-25 from Fort
Collins south through the Denver metropolitan area); is more widespread
in foothills and some montane areas within these same drainages; and is
generally present in rural portions of drainages south of Denver. In
the Arkansas River basin in Colorado, Prebles' distribution appears
very limited, with confirmed occurrence largely in upper Monument Creek
and some headwater tributaries.
Data limitations do not allow us to equate documented distribution
with range. For example, the Prebles has been documented in two places
approximately 19 km (12 mi) apart along Kiowa Creek in Elbert County,
and it is reasonably likely to occur both between these sites and
further downstream in the drainage, but no trapping has occurred to
confirm or deny this assertion. Similarly, on Trout Creek a Prebles was
documented in Douglas County near the Teller County line, and it is
reasonable to assume the subspecies also may occur in Teller County.
Given these data limitations, ``range'' is defined in the Conclusion of
the 5-Factor Analysis section of this rule below.
Abundance
Studies designed to estimate populations of the Prebles have
occurred on only a few sites. As a result, no reliable regional,
Statewide, or rangewide population estimates for the Prebles have been
developed. Population density and trends are not well known in Wyoming
(WGFD 2005, p. 36). There are a few population estimates but little
trend information for Prebles' populations in Colorado. In addition,
because jumping mouse populations in a given area vary significantly
from year to year (Quimby 1951, pp. 91-93; Whitaker 1972, p. 4), short-
term studies may not accurately characterize abundance. In an ongoing
trapping study, population highs of 24 and 69 Prebles per site were
estimated for 2 control sites in 1999; subsequent trapping in 2002,
during regional drought conditions, found no Prebles present at either
site (Bakeman 2006, p. 11). Meaney et al. (2003, p. 620) estimated
Prebles' populations on study sites over 4 years, noted absence of the
Prebles at certain sites during some seasons, and suggested that 10 or
more years of study might be necessary to
[[Page 39816]]
assess the full extent of population variation.
White and Shenk (2000, p. 9) summarized abundance estimates from
nine sites in Colorado during 1998 and 1999 (Meaney et al. 2000;
Kaiser-Hill 2000; Ensight Technical Services 1999, 2000, 2001; Shenk
and Sivert 1999b; Schorr 2001). Since Prebles are found in linear
riparian communities, abundances were estimated in number of
individuals per km (or mi) of riparian corridor. Estimates of linear
abundance ranged widely, from 4 to 67 mice/km (6 to 107 mice/mi) with a
mean of 33 +/- 5 mice/km (53 +/- 8 mice/mi) (White and Shenk 2000, p.
9). The subsequent addition of new sites and 2 more years of data
(2000-2001) provided a range of 2 to 67 mice/km (3 to 107 mice/mi) and
a mean of 27 +/- 4 mice/km (44 +/- 6 mice/mi) (Shenk 2004).
The above estimates, coupled with sufficient knowledge of occupied
stream miles, may provide a rough indicator of Prebles' numbers within
a stream reach or drainage. The Recovery Team used the above estimate
(Shenk 2004) to approximate stream miles required to support varying
sized populations of the Prebles (USFWS 2003b, p. 25). Hayward (2002)
cautioned that reliance on an average number of mice per length of
stream to predict population sizes would result in the overestimation
of actual population size for about half of all sites. Of additional
concern in any assessment of Prebles' population size is the potential
for including western jumping mice in the estimate (Bohon et al. 2005;
Schorr et al. 2007, p. 4). This issue is of particular importance in
areas where both Prebles and western jumping mice are known to occur,
including most sites in Wyoming and higher elevation Colorado sites.
The Prebles' population estimates above do not include estimates
for riparian corridors along mountain streams or any sites in Wyoming.
In Pike National Forest, Colorado, site inspection of many streams
previously mapped as Prebles' habitat revealed poorly developed or
intermittent riparian vegetation surrounded by sparse uplands dominated
by pine forest (Bohon et al. 2005). Poor trapping success even in
apparently suitable habitat suggested low population densities in Pike
National Forest compared to those at lower elevations (Bohon et al.
2005; Hansen 2006, p. 168). In studies targeting the Prebles at higher
elevation riparian sites in Douglas, Jefferson, and Teller counties,
Schorr et al. (2007, p. 4) reported a 0.6 percent capture rate of
jumping mice over 19,500 trap nights. In Albany County, Wyoming,
Griscom et al. (2007) reported jumping mouse capture rates of 0.5
percent on the Douglas Ranger District and 1.3 percent on the Laramie
Ranger District of Medicine Bow National Forest (over 3,200 trap nights
in each district). Because coexistence of the Prebles and the western
jumping mouse was likely in both studies, the capture rate of the
Prebles was probably significantly lower. In comparable trapping effort
in high-quality habitat at lower elevations, Schorr (2001, p. 18)
reported a 3.5 percent capture rate of Prebles over 14,700 trap nights
at the Academy, and Meaney et al. (2003, p. 616) reported a 3.4 percent
capture rate of Prebles over 21,174 trap nights along South Boulder
Creek, Boulder County. While we think that more research is needed
before definitive conclusions can be drawn regarding Prebles' abundance
and security along montane streams and headwaters, it appears that
these reaches support a lower density of mice than plains and foothill
sites.
Population Trends
Without comprehensive population estimates for the subspecies, the
only basis for trend assessment is presence or absence surveys in
historically documented sites (Smith et al. 2004, p. 29). This
presence/absence information paints a very different picture for
Wyoming compared to Colorado.
In Wyoming, we now have much more information regarding Prebles'
distribution than we had at time of listing, when we knew of only two
occupied sites. Much of what we noted in the listing to be historical
range of the Prebles in Wyoming has now been definitively found to
support the subspecies. But, while many jumping mice have been
confirmed as Prebles in the North Platte River basin, trapping records
to date suggest the subspecies is uncommon in the South Platte River
basin, with only western jumping mice confirmed present at several
locations within presumed Prebles' range.
In Colorado, historical trapping records establish that the Prebles
was present in a range that included major plains streams from the base
of the Colorado Front Range east to at least Greeley, Weld County
(Armstrong 1972, p. 249; Fitzgerald et al. 1994, p. 293; Clippenger
2002, p. 18). Recent trapping efforts have documented that the Prebles
is rare or absent from these same areas today (Ryon 1996, p. 2;
Clippinger 2002, p. 22; USFWS 2008). This pattern is especially
apparent along prairie riparian corridors directly or indirectly
impacted by human development. This issue is discussed further in
Factor A below.
Summary of Factors Affecting the Subspecies
Section 4 of the Act and its implementing regulations (50 CFR part
424) set forth the procedures for listing, reclassifying, or removing
species from listed status. ``Species'' is defined by the Act as
including any species or subspecies of fish or wildlife or plants, and
any distinct vertebrate population segment of fish or wildlife that
interbreeds when mature (16 U.S.C. 1532(16)). Once the ``species'' is
determined we then evaluate whether that species may be endangered or
threatened because of one or more of the five factors described in
section 4(a)(1) of the Act. We must consider these same five factors in
delisting determinations. Under 50 CFR 424.11(d), we may remove the
protections of the Act if the best available scientific and commercial
data substantiate that the species is neither endangered nor threatened
for the following reasons: (1) The species is extinct; (2) the species
has recovered and is no longer endangered or threatened; or (3) the
original scientific data used at the time the species was classified
were in error. Data error applies when subsequent investigations show
that the best scientific or commercial data available when the species
was listed, or the interpretation of such data, were in error.
We may delist a species for any of the above reasons only if such
data substantiate that the species is neither endangered nor
threatened. Determining whether a species meets these definitions
requires consideration of the same five categories of threats specified
in section 4(a)(1) of the Act. For species that are already protected
as endangered or threatened, this analysis of threats is an evaluation
of both the threats currently facing the species and the threats that
are reasonably likely to affect the species in the foreseeable future
following removal of the Act's protections.
Under section 3 of the Act, a species is ``endangered'' if it is in
danger of extinction throughout all or a ``significant portion of its
range'' and is ``threatened'' if it is likely to become endangered
within the foreseeable future throughout all or a ``significant portion
of its range.'' The word ``range'' in the phrase ``significant portion
of its range'' refers to the range in which the species currently
exists. Range is discussed further in the Conclusion of the 5-Factor
Analysis section of this proposal below. For the purpose of this
analysis, we evaluate whether the currently listed subspecies should be
considered threatened or endangered.
[[Page 39817]]
Then, we consider whether there are any portions of the subspecies'
range in danger of extinction or likely to become endangered within the
foreseeable future.
Foreseeable future is determined by the Service on a case-by-case
basis, taking into account a variety of species-specific factors such
as lifespan, genetics, breeding behavior, demography, threat-projection
timeframes, and environmental variability. For the purposes of this
proposal, we define foreseeable future based upon a threat-projection
timeframe because future development intensity and patterns are likely
to be the single greatest factor contributing to the subspecies' future
conservation status. As described in more detail below, human-
population-growth projections extend out to 2035 in Colorado and 2036
in Wyoming. Similarly, water requirements are estimated through 2030 in
Colorado and 2035 in Wyoming. A Center for the West model predicting
future land-use patterns projects development changes within the range
of the Prebles through 2040. Such projections frame our analysis as
they help us understand what factors can reasonably be anticipated to
meaningfully affect the subspecies' future conservation status. In our
view, the foreseeable future for this subspecies, based on the
currently available data, extends to approximately 2040. While it is
likely some of the above estimates could be extrapolated out into the
more distant future, development projections beyond this point are of
increasingly lower value as uncertainty escalates. We also believe that
not all threat factors are necessarily foreseeable over the same time
horizon. When reliable data is available, we consider a longer time
horizon.
The following analysis examines all five factors currently
affecting, or that are likely to affect, the Prebles within the
foreseeable future.
A. The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
Introduction--Decline in the extent and quality of Prebles' habitat
is the primary factor threatening the subspecies (Bakeman 1997, p. 78;
Hafner et al. 1998, p. 122; Pague and Grunau 2000). In our 1998 final
rule to list Prebles as threatened (63 FR 26517, May 13, 1998), we
stated that Colorado east of the Front Range and adjacent areas of
southeastern Wyoming had changed, over time, from predominantly prairie
habitat intermixed with perennial and intermittent streams, and
associated riparian habitats, to an agricultural and increasingly urban
setting.
In our listing decision, we determined that Prebles' populations
had experienced a decline and faced continued threats linked to
widespread loss and fragmentation of the subspecies' required riparian
habitat from human land uses including--urban, suburban, and
recreational development; highway and bridge construction; water
development; instream changes associated with increased runoff and
flood control efforts; aggregate (sand and gravel) mining; and
overgrazing (63 FR 26517, May 13, 1998). These human land-use
activities affect the Prebles by directly destroying its protective
cover, nests, food resources, and hibernation sites; disrupting
behavior; or acting as a barrier to movement. We noted that such
impacts reduced, altered, fragmented, and isolated habitat to the point
where Prebles' populations may no longer persist. We also noted that
patterns of capture suggested that Prebles' populations fluctuate
greatly over time at occupied sites, raising questions regarding
security of currently documented populations that are isolated and
affected by human development.
Historical records in Colorado (pre-1980) illustrate areas of
Prebles' occupancy along the Front Range within both foothill and
prairie riparian corridors (Armstrong 1972, p. 249; Fitzgerald et al.
1994, p. 293). Between 1980 and 2005, the human population of Colorado
counties within the Prebles' range increased by nearly 60 percent, from
1.7 million to 2.7 million (Colorado Demography Office 2007). As
explained further below, the apparent absence of the Prebles in areas
of substantial development, where trapping had previously confirmed the
subspecies' presence, supports the conclusion that human land uses
adversely affect Prebles' populations.
Ryon (1996) evaluated the condition of eight historical Prebles'
capture sites in six Colorado counties based on vegetation structure,
dominant plant species, and trapping results. Ryon reported no Prebles'
captures at any of the seven sites trapped (one site no longer
contained suitable habitat) (1996, p. 25). In addition, he reported
that the historical sites contained fewer native species in plant
communities and were lacking the multi-strata vegetation structure he
observed at sites where trapping had recently confirmed Prebles'
presence (Ryon 1996, p. 30). Investigations into land-use changes at
the historical sites suggested that most had been directly altered in
terms of habitat or had been influenced by habitat fragmentation (Ryon
1996, p. 30). Clippinger (2002, pp. 14-29) mapped and compared past
(through 1972) and current (post-1972) distribution records of the
Prebles in central Colorado and southeastern Wyoming based on museum
specimens, published accounts, and unpublished reports. Clippinger
reported that his distribution maps illustrated a loss of Prebles'
populations in expanding urban and suburban areas, especially around
Cheyenne, Denver, and Colorado Springs, and in general along the
eastern extent of historical range (Clippinger 2002, p. 22). Note that
Clippinger's reference to historical range is based on the few existing
records (through 1972) documenting Prebles' occurrence. These records
are focused around what is now the I-25 urban corridor and based upon
our current knowledge of the subspecies do not truly represent the
likely extent of the historical range of the subspecies. The apparent
loss of historically occupied sites (those 17 sites where the
subspecies was documented to occur prior to 1980) provides insight into
human development impacts on Prebles' habitat. Only 1 of 17 of these
documented historical sites of Prebles' occurrence in Colorado (Bear
Creek, Boulder County) is thought to currently support the Prebles.
Prebles' populations have little likelihood of occurrence along
large portions of major river and stream reaches within the subspecies'
historical described range in Colorado including:
The Cache La Poudre River within Fort Collins and
downstream to its confluence with the South Platte River at Greeley, 60
km (37 mi);
The Big Thompson River and Little Thompson River through
the Front Range urban corridor east to I-25, approximately 50 km (32
mi);
The Saint Vrain River from Hygiene to its confluence with
the South Platte River, 35 km (22 mi);
Boulder Creek from Boulder east to its confluence with the
Saint Vrain River, approximately 35 km (22 mi);
Walnut, Woman, and Dry Creeks downstream from Rocky Flats
NWR to the confluence of Dry Creek and beyond to the South Platte
River, 40 km (25 mi);
Ralston Creek and Clear Creek through the urban corridor
to the South Platte River, approximately 40 km (25 mi);
The South Platte River downstream of Chatfield Reservoir
through Denver to Brighton, 60 km (38 mi);
The South Platte River downstream from Brighton to
Greeley, approximately 55 km (34 mi) (one recent capture described
above);
[[Page 39818]]
Cherry Creek from the Arapahoe County-Douglas County line
downstream through Denver to the South Platte River, 30 km (19 mi); and
Monument Creek downstream from its confluence with
Cottonwood Creek through Colorado Springs, approximately 15 km (9 mi).
In total, Prebles populations appear to have little likelihood of
occurrence along 420 km (260 mi) of major river and stream reaches in
and downstream of areas with concentrated human development. However,
despite apparent downstream extirpations, many of these same streams
continue to support Prebles populations in their upstream reaches or
tributaries.
Historical losses relative to ongoing threats are relevant in
predicting whether the subspecies is likely to become endangered in all
or a significant portion of its current range within the foreseeable
future. It appears unlikely that the Prebles can be returned to the
historical localities within the Front Range urban corridor; however,
we find that the subspecies' apparent local extirpation from areas of
human development provides useful perspective about the potential
impacts of future development within the remaining range of the
Prebles. If the protections of the Act were removed, we expect these
threat factors, discussed in more detail below, would continue to
affect the subspecies in large portions of its current range into the
foreseeable future.
For the purposes of this final rule, we reviewed and considered the
best available information regarding threats within the range of the
Prebles, including Ryon (1996), Bakeman (1997), Shenk (1998), Pague and
Granau (2000), Clippinger (2002), and Service (2003b). We summarize
these accounts below.
Following listing, The Nature Conservancy, under a contract with
the Colorado Division of Natural Resources, formed a Prebles Meadow
Jumping Mouse Science Team (Pague 1998). With guidance from the Science
Team and following numerous meetings with scientists and stakeholders,
Pague and Grunau (2000) developed a conservation planning handbook that
addressed each of seven Colorado counties containing Prebles
populations. The document identified key issues that stress the Prebles
for all presumed threat factors operating in known or suspected
Prebles' habitat, and assigned a qualitative risk assessment level to
each of the identified issues. The work of Pague and Granau (2000)
continues to provide important, science-based insight into threats to,
and potential conservation strategies for, the Prebles in Colorado on a
county-by-county basis. Habitat-related ``issues'' identified as high
or very high priority in one or more counties included habitat
conversion through housing, commercial, and industrial construction;
travel corridor (i.e., roadway) construction; travel corridor
maintenance; fragmentation of habitat and corridors; hydrological flow
impairment; habitat conversion to a reservoir; bank stabilization; high
impact livestock management; rock and sand extraction; invasive weeds;
and catastrophic fire (Pague and Granau 2000, pp. 1-15, 2-12, 3-13, 4-
14, 5-14, 6-15, 7-14). Pague (2007) provided observations updating the
2000 report. No comparable document exists for the four Wyoming
counties where the subspecies occurs.
The Prebles is listed as a ``threatened'' species in Colorado by
the CDOW. Colorado's Comprehensive Wildlife Conservation Strategy lists
the meadow jumping mouse (including both the Prebles and Zapus
hudsonius luteus, which occurs in extreme south-central Colorado) as a
``Species of Greatest Conservation Need,'' citing threats to habitat
and range including habitat conversion (due to housing, urban, and
exurban development) and habitat degradation (due to altered native
vegetation and altered hydrological regime) (CDOW 2006, p. 102).
The WGFD does not list the meadow jumping mouse (including both the
Prebles and Zapus hudsonius campestris, which occurs in northeastern
Wyoming) among their list of ``mammalian species of special concern.''
The WGFD classifies the meadow jumping mouse as NSS5, indicating that
it is widely distributed, population status suspected to be stable, and
habitat not restricted (Freudenthal 2008). In contrast, the Wyoming
Comprehensive Wildlife Plan (WCWP) lists the meadow jumping mouse as a
``Species of Greatest Conservation Need'' (WGFD 2005, p. 10).
Fruedenthal (2008) noted that this listing is applied to numerous
species and that it reflects relative lack of data regarding these
species.
The WCWP identifies ecoregions in the State and provides a summary
of ``mean habitat quality'' scores for each ecological system (or
habitat) within the ecoregion (WGFD 2005, pp. 19-25). Within the three
Wyoming ecoregions that include Prebles' range (Central Shortgrass
Prairie, Northern Great Plains Steppe, and Southern Rocky Mountains),
the two ecological systems most likely to support the Prebles (Rocky
Mountain Lower Montane Foothill Riparian and Shrubland, Western Great
Plains Riparian/Western Great Plains Floodplain) ranked in the lowest
20 percent in mean habitat quality relative to the State's other
ecosystems (WGFD 2005, pp. 19-25). Among threats to habitat in these
ecoregions are invasive plants, residential development radiating from
the Cheyenne area, and recreation in the Southern Rocky Mountain region
(WGFD 2005, pp. 53, 55, 56).
The direct impacts of development on the Prebles and its habitat
have likely slowed since our 1998 listing because of protection
afforded to the Prebles and its critical habitat rangewide under the
Act. One indication of continuing adverse impacts to the Prebles and
its habitat is the number of formal consultations performed to date
under section 7 of the Act and the number of section 10 permits issued
to date in conjunction with approved Habitat Conservation Plans (HCPs).
Section 7 of the Act requires Federal agencies to consult with the
Service to ensure that their actions do not jeopardize the continued
existence of the subspecies or cause destruction or an adverse
modification of critical habitat. Thus far, the section 7 process has
been successful in preventing Federal actions from jeopardizing the
continued existence of the subspecies or resulting in the destruction
or adverse modification of critical habitat.
Section 10(a)(1)(B) of the Act authorizes the Service to issue
permits for non-Federal actions that result in the incidental taking of
listed wildlife. Incidental take permit applications must be supported
by an HCP that identifies conservation measures that the permittee
agrees to implement for the species to avoid, minimize, and mitigate
the impacts of the requested incidental take.
As of June 2008, we have conducted 130 formal section 7
consultations (113 in Colorado, 17 in Wyoming) and issued 19 HCP-
related incidental take permits (all in Colorado) for projects
affecting the Prebles. We have authorized take for actions that did not
result in jeopardy but nevertheless may result in permanent impacts to
over 340 ha (840 ac) of Prebles' habitat, and temporary impacts to more
than twice that amount of habitat. These projects have incorporated
conservation measures or mitigation to avoid or minimize adverse
impacts to the Prebles.
However, even with the protections afforded to the subspecies under
section 7, we have concluded that habitat overall has continued to
decline in quality and quantity, especially in Colorado. In the absence
of listing, projects in Prebles' habitat would go
[[Page 39819]]
forward with reduced Federal oversight. Other Federal, as well as State
and local regulatory mechanisms, that may provide protection for the
Prebles and its habitat are evaluated under Factor D below.
Residential and Commercial Development--Clippinger (2002) assessed
the impacts of residential development on the Prebles. He analyzed
Colorado land-cover data compared to positive and negative trapping
results for the Prebles in a GIS analysis and concluded that the
likelihood of successful trapping of Prebles was reduced by either low-
or high-density residential developments when the developments were
within 210 m (690 ft) of the trapping sites (Clippinger 2002, pp. iv,
94). Clippinger (2002, p. iv) noted that the Prebles can be a useful
indicator of environmental integrity in riparian areas and associated
upland areas in the Colorado Piedmont. These data suggest that nearby
development increases the risk of local extirpation of Prebles from
occupied sites.
Theobald et al. (1997) emphasized both housing density and spatial
patterns in evaluating effects of residential development on wildlife
habitat. They concluded that while clustered development can decrease
habitat disturbance (Theobold et al. 1997, p. 34), much of the Rocky
Mountain West is experiencing what has been termed ``rural sprawl''
where rural areas are growing at a faster rate than urban areas
(Theobold et al. 2001, p. 4). In Colorado, residential demand and State
law encourage developers to design subdivisions with lots of at least
14 ha (35 ac) each with one house, to avoid detailed county subdivision
regulations (Riebsame et al. 1996, p. 420). The Larimer County Master
Plan (Larimer County Planning Division 1997) cites a trend toward
residential properties with relatively large lots, which leads to
scattered development and more agricultural land taken out of
production. Where public and private lands are intermingled, private
land ownership typically follows valley bottoms (Theobald et al. 2001,
p. 5), thus rural development is likely to disproportionately affect
valley-bottom riparian areas (Riebsame et al. 1996, p. 402), the
favored habitat of the Prebles. Beyond direct impact to habitat, when
ranches are subdivided, subsequent residential construction and
associated disturbance can result in the disruption of wildlife
movement along stream corridors (Riebsame et al. 1996, p. 402). Rural
development disproportionately occurs around edges of undisturbed
public lands and affects the conservation value of the undisturbed
public lands (Hansen et al. 2005, p. 1900).
Human development often causes subtle effects on riparian habitat
as well. Indirect effects of human settlement have resulted in declines
in native trees and shrubs, greater canopy closure, and a more open
understory with reduced ground cover within riparian habitat (Miller et
al. 2003, p. 1055). An open understory does not favor the Prebles,
which prefers dense ground cover of grasses and shrubs and is less
likely to use open areas where predation risks are assumed to be higher
(Trainor et al. 2007, pp. 472-476; Clippinger 2002, pp. 69, 72).
Fragmentation is another indirect impact of development occurring
in proximity to Prebles' habitat. The Prebles is closely associated
with narrow riparian systems that represent a small percentage of the
landscape within the subspecies' range. Fragmentation of these linear
habitats limits the extent and size of Prebles' populations. As
populations become fragmented and isolated, it becomes more difficult
for them to persist (Caughley and Gunn 1996, pp. 165-189). Major risks
associated with small populations include--demographic stochasticity
(an increased risk of decline in small populations due to variability
in population growth rates arising from random differences among
individuals in survival and reproduction within a season);
environmental stochasticity (an increased risk of decline in small
populations due to variation in birth and death rates from one season
to the next in response to weather, disease, competition, predation, or
other factors external to the population); and loss of genetic
variation (a reduction in the amount of diversity retained within
populations and an increased chance that deleterious recessive alleles
may be expressed; the loss of diversity can limit a population's
ability to respond adaptively to future environmental changes)
(Caughley and Gunn 1996, pp. 165-189). These issues are discussed in
greater detail in Factor E below. The Recovery Team determined that
small, fragmented units of habitat will not be as successful in
supporting the Prebles in the long term as larger areas of contiguous
habitat (USFWS 2003b, p. 21). On a landscape scale, maintenance of
dispersal corridors linking patches of Prebles' habitat may be critical
to the subspecies' conservation (Shenk 1998, p. 21).
One indicator of the level of development pressure since listing is
the number of development-related section 7 consultations and HCPs
completed by the Service. Of the 127 formal consultations and 19 HCPs
completed in Colorado, 19 section 7 consultations and 10 HCPs were
specifically for residential and commercial developments with direct
adverse effects to the Prebles or its habitat. Approved projects
allowed for adverse impacts (permanent or temporary) in excess of 210
ha (520 ac) of Prebles' habitat. While conservation measures or
mitigation in various forms have been incorporated into all permitted
projects, implementation of these habitat restoration and enhancement
measures has been hampered by factors such as drought or flooding.
Recent development pressure has been most concentrated south of Denver,
Colorado, in Douglas and El Paso counties; eight section 7
consultations and three HCPs have occurred in the Middle South Platte-
Cherry Creek drainage, all south of Denver, and eight section 7
consultations and four HCPs have occurred in the Fountain Creek
drainage. We also have worked with other Federal agencies and a
substantial number of landowners and developers to avoid adverse
impacts to Prebles' habitat, thus avoiding formal consultation or the
need for HCPs. Additional planned residential and commercial
development projects that would adversely affect Prebles' habitat in
Colorado are continually being reviewed by the Service. Since listing,
protections afforded under the Act have slowed, but not eliminated, the
loss of Prebles' habitat due to residential and commercial development
in Colorado. We conclude that in the absence of the protections under
the Act, Prebles' habitat in Colorado and the populations it supports
would be lost at a greatly increased rate from residential and
commercial development.
Continued rapid development is expected along Colorado's Front
Range as the human population continues to grow. The State of Colorado
expects the population of counties supporting the Prebles to increase
by an additional 1.5 million people from 2005 to 2035 (an increase of
69 percent), including: 100,000 in Boulder County; 284,000 in Douglas
County; 43,000 in Elbert County; 371,000 in El Paso County; 154,000 in
Jefferson County; 203,000 in Larimer County; and 326,000 in Weld County
(Colorado Demography Office 2008). These expected increases support
Pague and Grunau's (2000) conclusion that habitat conversion is a very
high priority issue to the Prebles in Larimer, Weld, and El Paso
counties, and a high
[[Page 39820]]
priority issue for the remaining counties supporting the Prebles in
Colorado.
In contrast to the situation in Colorado, no formal section 7
consultations or HCPs have been sought for residential or commercial
development in Wyoming. This reduced level of consultations reflects
the general lack of development pressure within Prebles' habitat. This
relative lack of development pressure is predicted to continue into the
foreseeable future as described below.
Wyoming estimates that the population of the counties supporting
the Prebles will increase by about 11,000 people from 2005 to 2020,
including: An increase of 800 in Albany County; an increase of 1,500 in
Converse County; an increase of 9,100 in Laramie County; and a decrease
of 400 in Platte County (Wyoming Department of Administration and
Information 2007). Commercially available estimates suggest counties
supporting the Prebles will increase by about 18,400 people from 2006
through 2036, including: A decline of 3,700 in Albany County; an
increase of 3,500 in Converse County; an increase of 18,300 in Laramie
County; and an increase of 300 in Platte County (Economy.com 2007 as
provided by Lui 2007).
While population growth rates provide valuable insight into
development pressures, they may not provide a complete picture. For
example, human population increases in Cheyenne, Fort Collins, Greeley,
Longmont, the immediate Denver metropolitan area, and much of Colorado
Springs are likely to have little direct impact on the Prebles because
the subspecies appears to have little likelihood of occurrence within
and downstream from these cities. Conversely, substantial human
population increases in the Laramie Foothills of Larimer County,
Colorado, or southern portions of Douglas County, Colorado, are likely
to have a high impact to the Prebles. In Wyoming, given the small
projected increases in the human population, we expect rural
development will continue to have only small, localized impacts.
Modeling exercises also can provide some insights into future land-
use development patterns. While these models have weaknesses, such as
an inability to accurately predict economic upturns or downturns,
uncertainty regarding investments in infrastructure that might drive
development (such as roads, airports, or water projects), and an
inability to predict open-space acquisitions or conservation easements,
we nevertheless think that such models are useful in adding to our
understanding of likely development patterns. For example, in 2005, the
Center for the West produced a series of maps predicting growth through
2040 for the West including the Colorado Front Range and Wyoming
(Travis et al. 2005, pp. 2-7). The projections for the Colorado Front
Range (available at: http://www.centerwest.org/futures/frtrng/
2040.html) illustrate significant increases in urban/suburban, low-
density suburban, and exurban land uses across virtually all private
lands within the Colorado portion of the Prebles' range. These
projections depict that only small isolated patches of Prebles' habitat
in public ownership, including headwater areas in Federal ownership,
would avoid the direct impacts of residential and associated commercial
development. In his review of the revised proposed rule, Travis (2008)
noted that while land-use modeling and projections retain uncertainties
and are not at a resolution useful for assessing habitat patterns, both
the empirical record and the projections show development filling gaps
along the Colorado Front Range. Although similar maps for Wyoming are
older (http://www.centerwest.org/futures/archive/development/
development_wy.html) or less refined (http://www.centerwest.org/
futures/west/2040.html), they suggest only limited increases in
development, primarily around Cheyenne. Travis (2008) called the
difference between land development trends in the Colorado Front Range
and those in Wyoming ``logical and real.''
Based upon known impacts to the Prebles associated with current
development pressures and best available projections for future
development (as described above and in relation to Factor D below), we
conclude that residential and commercial development constitutes a
substantial threat to the Prebles in Colorado, now and into the
foreseeable future. In Wyoming, residential and commercial development
is likely to be limited with only small, localized impacts to the
Prebles expected. While more significant development is projected in
the vicinity of Cheyenne, recent trapping efforts have not confirmed
presence of Prebles in this area.
Transportation, Recreation, and Other Rights-of-Way Through
Habitat--At the time of listing, the Service concluded that roads,
trails, or other linear development through the Prebles' riparian
habitat could act as partial or complete barriers to dispersal (63 FR
26517, May 13, 1998). These forms of development have continued to
affect and fragment Prebles' habitat. Since listing, the Service has
conducted 40 formal consultations under section 7 of the Act for road
or bridge projects (33 in Colorado and 7 in Wyoming) resulting in
permitted impacts to approximately 50 ha (125 ac) of Prebles' habitat.
In addition, a formal 2005 programmatic section 7 consultation with the
Federal Highway Administration for the Wyoming Statewide Transportation
Improvement Program could result in 19 future highway projects with
impacts to 42 ha (104 ac) of Prebles' habitat. Under the Douglas County
(Colorado) Regional HCP for the Prebles, completed in May 2006, 67
approved road and bridge construction projects by Douglas County, and
the cities of Parker and Castle Rock, may affect up to 122 ha (302 ac)
of Prebles' habitat over a 10-year period.
One of the largest road projects is the improvement to I-25 in El
Paso County, Colorado. The proposed construction will affect 10 of the
eastern tributaries of Monument Creek thought to support the Prebles
(Bakeman and Meaney 2001, p. 21). Impacts to the Prebles include
habitat fragmentation and modification, change in population size, and
behavioral impacts (Bakeman and Meaney 2001, pp. 18-20). While measures
to avoid, minimize, and mitigate impacts were identified, the project
will have significant cumulative effects on Prebles in the Monument
Creek drainage, especially east of I-25 (Bakeman and Meaney 2001, pp.
i, ii, 22-27).
With an increased human population, a high level of road
construction and maintenance projects will occur; in the absence of the
Act's protective measures, impacts to the Prebles and its habitat would
likely be substantial. While the Act rarely stops such projects, it
does promote measures to avoid, minimize, or compensate for impacts to
the subspecies and helps control the level of negative impacts to the
Prebles and its habitat. Pague and Grunau (2000) considered ``travel
corridor construction'' to be a high-priority issue to Prebles'
populations in Weld, Douglas, Elbert, and El Paso counties in Colorado.
Human-caused impacts associated with recreation include backcountry
roads, trails, and campgrounds, which are often located along streams
and near water (WGFD 2005, p. 56). Recreational trail systems are
frequently located within riparian corridors (Meaney et al. 2002, p.
116). The development of trail systems can affect the Prebles by
modifying its habitat, nesting sites, and food resources in both
riparian and upland areas. Use of these trails by
[[Page 39821]]
humans or pets can alter wildlife activity and feeding patterns
(Theobold et al. 1997, p. 26). Meaney et al. (2002, pp. 131-132)
suggest fewer Prebles were found on sites with trails than on sites
without trails. While temporal and spatial variation in Prebles'
numbers resulted in low precision of population estimates and weak
statistical support for a negative trail effect, the authors considered
the magnitude of the potential effect sufficient to encourage careful
management and additional research (Meaney et al. 2002, pp. 115, 131-
132). Since the listing of the Prebles in 1998, a dozen recreational
trail projects with proposed impacts to Prebles' habitat in Larimer,
Boulder, Douglas, and El Paso counties, Colorado, have been addressed
through section 7 consultations or HCPs. None have been addressed
through section 7 in Wyoming. An additional 24 trail projects have been
permitted under the Douglas County Regional HCP. As human populations
continue to increase (as discussed above), we anticipate increased
demand for recreational development in public open space and on
conservation properties. Without protections afforded by the Act,
Prebles' populations on properties free from residential and commercial
development threats will still be subject to widespread threats from
future recreational development and increased human use.
Many utility lines (sewer, water, gas, communication, and electric
lines, and municipal water ditches) cross Prebles' habitat. Current and
future utility rights-of-way through these habitats will cause habitat
destruction and fragmentation from periodic maintenance and new
construction. Since the listing of the Prebles, 20 utilities projects
adversely affecting the Prebles and its habitat have been evaluated
through section 7 consultations (16 in Colorado, 4 in Wyoming). In
addition, an approved HCP with Denver Water permits impacts to 34 ha
(84 ac) of Prebles' habitat at multiple sites in Colorado. While often
more costly than trenching, avoidance measures such as directional
drilling under riparian crossings can reduce or avoid impacts to the
Prebles. If the Prebles were to be delisted, we do not anticipate that
project operators would voluntarily directionally drill to avoid
Prebles' habitat.
Overall, we conclude that threats related to transportation,
recreation, and other rights-of-way through habitat are directly
related to human population pressures. Thus, we expect these issues
will have substantial impacts to Prebles' populations in Colorado, but
less impacts to Prebles' populations in Wyoming.
Hydrologic Changes--Establishment and maintenance of riparian plant
communities are dependent on the interactions between surface-water
dynamics, groundwater, and river-channel processes (Gregory et al.
1991, pp. 542-545). Changes in hydrology can alter the channel
structure, riparian vegetation, and valley-floor landforms (Gregory et
al. 1991, pp. 541-542; Busch and Scott 1995, p. 287). Thus, changes in
the timing and abundance of water can be detrimental to the persistence
of the Prebles in these riparian habitats due to resultant changes in
vegetation (Bakeman 1997, p. 79). Changes in hydrology may occur in
many ways, but two of the more prevalent are the excessively high and
excessively low runoff cycles in watersheds with increased areas of
paved or hardened surfaces, and disruption of natural flow regimes
downstream of dams, diversions, and alluvial wells (Booth and Jackson
1997, pp. 3-5; Katz et al. 2005, pp. 1019-1020).
Urbanization can dramatically increase frequency and magnitude of
flooding while decreasing base flows (the portion of stream flow that
is not surface runoff and results from seepage of water from the ground
into a channel slowly over time; base flow is the primary source of
running water in a stream during dry weather) (Booth and Jackson 1997,
pp. 8-10; National Research Council 2002a, pp. 182-186). Infiltration
of precipitation is greatly reduced by increases in impervious
surfaces. The magnitude of peak flows increases in urban areas as water
runs off as direct overland flow. Increased peak flows can exceed the
capacity of natural channels to transport flows, trigger increased
erosion, and degrade habitat (Booth and Jackson 1997, pp. 3-5). Changes
in hydrology associated with urbanization can result in channel
downcutting, lowering of the water table in the riparian zone, and
creation of a ``hydrologic drought,'' which in turn alters vegetation,
soil, and microbial processes (Groffman et al. 2003, p. 317).
Meanwhile, reduced infiltration results in reduced groundwater
recharge, reduced groundwater contributions to stream flow, and,
ultimately, reduced base flows during dry seasons (National Research
Council 2002a, p. 182; Groffman et al. 2003, p. 317). Established
methods of mitigating downstream impacts of urban development, such as
detention basins, have only limited effectiveness; downstream impacts
are probably inevitable without limiting the extent of watershed
development (Booth and Jackson 1997, p. 17).
In response to altered hydrology, stormwater-management, flood-
control, and erosion-control efforts occur along many streams within
the former and current range of the Prebles. The methods used include
channelization; construction of detention basins, outfall structures,
drop structures, riprap banks, impervious cement channels; and other
structural stabilization. Structural stabilization methods designed to
manage runoff and control erosion can increase the rate of stream flow,
shorten channel length, narrow riparian areas, destroy riparian
vegetation, and prevent or prolong the time required for vegetation
reestablishment (Booth and Jackson 1997, p. 4). These impacts may
affect plant composition, soil structure, and physiography of riparian
systems to the point where habitat supporting the Prebles is so altered
that populations can no longer persist. Pague and Grunau (2000)
considered ``bank stabilization'' to be a high-priority issue for the
Prebles in Weld and El Paso counties. Since the listing of the Prebles,
22 stormwater management, stream stabilization, or outfall structure
projects with impact to Prebles' habitat have been addressed through
formal section 7 consultations in Colorado; none have occurred in
Wyoming.
The Prebles' apparent absence downstream from most areas of
extensive urbanization (including Cheyenne, Wyoming, and Fort Collins,
Longmont, Boulder, Golden, Denver, Parker, and Colorado Springs,
Colorado) may be attributable to such changes in hydrology described
above. Corn et al. (1995, p. 14) and Schorr (2001, p. 30) expressed
concern over the integrity of protected riparian habitats on Monument
Creek and its tributaries through the Academy because of development
activities upstream. In 2007, all eastern tributaries of Monument Creek
on the Academy experienced adverse impacts to occupied Prebles' habitat
due to erosive head cutting, channel degradation, and impacts to
vegetation that were attributable to regional stormwater management,
and commercial and residential development (Mihlbachler 2007).
In Colorado, degraded riparian habitats have been restored, in part
as mitigation for adverse impacts to the Prebles. Work to restore
Prebles' habitat through a 0.86 km (0.54 mi) urban stream reach of East
Plum Creek, Douglas County appears to have increased vegetation cover
and Prebles' use (Bakeman 2006, pp. 4, 8). The effort
[[Page 39822]]
has restored connectivity of upstream and downstream riparian habitat
though this previously degraded urban stream reach. Similarly, recent
projects on Cherry Creek, Douglas County, have restored groundwater
levels and downcut channels in or near Prebles' habitat by employing
rock or sheet pile drop structures.
If we were to delist the Prebles, we believe that runoff-related
impacts to riparian habitats within and downstream of development would
likely increase in areas of high development, such as along Colorado's
Front Range urban corridor, and that restoration of impacted riparian
systems would be somewhat less likely to occur.
At the time of listing, we stated that the Prebles depended on
vegetative habitat that was in turn dependent on physical factors
including surface flows and groundwater. Water development and
management in its various forms alters vegetation composition and
structure, riparian hydrology, and flood-plain geomorphology directly,
as well as through alterations to habitat located downstream; these
alterations often, but not always, have adverse impacts to the Prebles
(63 FR 26517 May 13, 1998). The creation of irrigation reservoirs at
the expense of native wetlands is a factor that negatively affected
Prebles' populations over the previous century (Fitzgerald et al. 1994,
p. 293). Reservoirs with barren shorelines can create barriers to
Prebles' movement and fragment populations along stream corridors.
Current and future reservoir construction is necessary to respond
to municipal water needs. By 2030, municipal and industrial demand for
water in Colorado will increase 60 percent, by 578 million cubic meters
(m\3\) (469,000 acre-feet (af)) yearly in the South Platte River
drainage and by 41 percent, 133 million m\3\ (108,000 af) yearly in the
Arkansas River drainage (Colorado Water Conservation Board 2004). Even
under the most optimistic scenarios, the Colorado Water Conservation
Board (2004, p. 13-17) estimated a shortfall relative to municipal and
industrial demands of 111 million m\3\ (90,000 af) of water in the
South Platte drainage and 22 million (m\3\) (18,000 af) in the Arkansas
drainage by 2030. The expanded storage and transport of water that will
be needed to address these demands has the potential to significantly
impact Prebles' habitat. Pague and Grunau (2000) considered
hydrological impacts (water quality, flow regime, and groundwater) to
be a high-priority issue to the Prebles in all Colorado counties
supporting populations.
Since the listing of the Prebles, we have conducted two section 7
consultations for new reservoirs in Colorado, the Reuter-Hess Reservoir
in Douglas County and the Pinewood Springs Reservoir in Larimer County.
Through these consultations, 7 ha (17 ac) of impacts to Prebles'
habitat were authorized. Three water projects currently proposed will,
if developed, significantly affect Prebles' habitat including--the
proposed expansions of existing Halligan and Seaman Reservoirs in the
Cache La Poudre drainage, Larimer County, Colorado, and storage
reallocation at Chatfield Reservoir, in the Upper South Platte
drainage, Jefferson and Douglas counties, Colorado. Options being
considered at Halligan Reservoir could inundate up to 4.0 km (2.5 mi)
of Prebles' habitat and affect the Prebles' critical habitat at the
site of the proposed dam. At Seaman Reservoir, the currently favored
option would inundate about 4.0 km (2.5 mi) of Prebles' critical
habitat. Options being investigated at Chatfield Reservoir have
generated a preliminary estimate that up to 130 ha (330 ac) of existing
Prebles' habitat, including almost 28 ha (70 ac) of critical habitat,
would be inundated. These and other water projects also will result in
alteration of flows that could further affect Prebles' habitat.
In Wyoming, estimates of projected water use in the Platte River
Basin through 2035, range from a 38 million m\3\ (31,000 af) decrease
to a 90 million m\3\ (73,000 af) increase (Wyoming Water Development
Commission 2006, p. 10). No significant reservoir projects are
currently planned within Prebles' habitat in Wyoming. While the Platte
River Plan identifies ``upper Laramie River storage'' as a future
storage opportunity (Wyoming Water Development Commission 2006, p. 31),
potential impacts to Prebles are uncertain based on limited knowledge
of the subspecies' occurrence in the drainage and uncertainty regarding
the location of any future water projects.
Beyond direct effects to the Prebles and its habitat through
construction or inundation, changes in flows related to water
diversion, storage, and use also affect riparian habitats downstream in
a variety of ways. In the foreseeable future, a number of changes in
amount and timing of diversions, water uses, and return flows will
affect many streams supporting the Prebles. The cumulative impacts of
such changes to specific Prebles' populations, both adverse and
potentially beneficial, are difficult to predict. As flows are captured
or diverted, or as groundwater supplies are depleted through wells,
natural flow patterns are changed, and more xeric plant communities may
replace the riparian vegetation. Sediment transport is disrupted by on-
stream reservoirs. Loss of sediment encourages channel downcutting,
which in turn affect groundwater levels (Katz et al. 2005, p. 1020).
The resulting conversion of habitats from moist or mesic, shrub-
dominated systems to drier grass- or forb-dominated systems make the
area less suitable for the Prebles.
Given the projected future demands for water, we conclude that
major water development projects affecting the Prebles in Colorado
would likely occur regardless of whether the subspecies remains listed.
Measures to minimize and compensate for impacts specific to the Prebles
and its habitat are less likely to be incorporated into project plans
if the subspecies were to be delisted. Fewer and smaller projects are
likely to occur in Wyoming, creating a negligible threat.
Aggregate Mining--At the time of listing, we cited alluvial
aggregate mining as a threat to the Prebles. Aggregate mining is
focused on floodplains, where these mineral resources most commonly
occur, and specifically on the same gravel deposits that may provide
important hibernation sites (63 FR 26517, May 13, 1998). Alluvial
aggregate mining continues to be a threat to the Prebles in Colorado.
Alluvial aggregate extraction may produce long-term changes to Prebles'
habitat by removing (often permanently) shrub and herbaceous
vegetation, and by altering hydrology. Often, mined pits are
constructed with impervious liners and converted to water reservoirs
after aggregate is removed. This conversion precludes restoration of
riparian shoreline vegetation and alters adjacent groundwater flow.
Since listing, we have conducted formal consultation under section
7 of the Act regarding impacts to the Prebles at two aggregate mines in
Colorado. We have worked with project proponents to avoid impacts at
others. At Rocky Flats NWR, private aggregate mining activities could
affect Prebles' habitat directly or through alteration of hydrology
along Rock Creek. While aggregate mining continues to affect
floodplains in the Colorado Front Range, many project sites are along
downstream reaches of larger streams and rivers where Prebles'
populations now appear absent. Pague and Grunau (2000) considered
``rock and sand extraction'' to be a high-priority issue in Weld,
Jefferson, and Douglas counties. While some stream channels within the
range of the Prebles, in Wyoming have historically been mined for
aggregate,
[[Page 39823]]
including the Laramie River at Laramie and Lodgepole and Crow creeks at
Cheyenne, mining is not widespread (Wyoming State Geological Survey
(WSGS) 2008).
Since construction aggregates are so low in value relative to their
weight, transportation costs require that aggregate sources be located
as close to the point of use as possible (WSGS 2008). Therefore,
threats related to aggregate mining are likely to be more intense in
areas in close proximity to human development. Thus, we expect this
issue will have greater impact on Prebles' populations in Colorado.
Given the high cost of transporting aggregate, increased development in
Colorado will not cause a significant increase in aggregate mining in
Wyoming. To the extent that aggregate mining will occur in Wyoming, it
is likely to continue to be in close proximity to development such as
the expanding urban centers of Laramie and Cheyenne.
Oil and Gas--As a result of public comments we received, we also
investigated whether oil and gas exploration and extraction poses a
threat to the Prebles. A large portion of the subspecies' Wyoming range
overlaps with exposed undifferentiated precambian rocks or other
formations with low potential for of oil and gas development (DeBruin
2002). A GIS analysis of oil and gas potential (Anderson 1990) relative
to the subspecies likely range (Beauvais 2004) indicates that
approximately 79 percent of the Prebles range in Wyoming occurs in
areas with low oil and gas potential. This analysis indicates that less
than 1 percent of the Prebles range in Wyoming occurs in areas with
high oil and gas potential, while approximately 20 percent overlap with
areas of moderate oil and gas potential. Even within these moderate and
high potential areas, only one oil and gas field occurs (DeBruin 2002).
In addition, coalfields and the range of the Prebles have little
overlap in Wyoming (DeBruin 2004, p. 2) indicating a minimal risk of
Prebles habitat being altered for coal production. In Colorado, many
new wells are being drilled on the plains within or to the east of the
Front Range urban corridor (mostly in Weld County). Few Prebles exist
in areas of current oil and gas production exploration and production.
In addition, wells are usually located in upland areas away from
riparian habitats supporting Prebles' populations. Based on the limited
potential for development of these resources within the range of
Prebles, we conclude that these activities (directly or indirectly)
will not meaningfully affect the conservation status of the Prebles
throughout its range now or in the foreseeable future.
Agriculture--At the time of listing we cited conclusions by Compton
and Hugie (1993a; 1993b) that human activities, including conversion of
grasslands to farms and livestock grazing, had adversely impacted
Prebles. They concluded that development of irrigated farmland had a
negative impact on Prebles' habitat, and that any habitat creation it
produced was minimal (Compton and Hugie 1993a; Compton and Hugie
1993b). In general, negative trapping results suggest that the Prebles
does not occur in areas cultivated for row crops. Historically, the
rapid rate of native habitat conversion to row crops likely had a
significant adverse impact on the Prebles. Because conversion of native
habitat to row crops has become increasingly rare in both Colorado and
Wyoming (U.S. Department of Agriculture 2000, Tables 2, 3, & 9), such
conversions are unlikely to present a similar threat in the future in
any portion of the subspecies' range.
Although pressures to increase agricultural production may result
from the demand to produce biofuels, we are not aware of information
that suggests this would result in meaningful decreases in the Prebles'
riparian habitat in Colorado or Wyoming. We conclude that in the
absence of protections afforded by the Act, only a little of the
subspecies' habitat is at risk from agricultural conversion. In
Wyoming, where such a scenario in Prebles' habitat appears more likely
than in Colorado, we explored whether former cropland removed from
production for conservation purposes is now being returned to
production. For example, through the CRP, farmers and ranchers enroll
eligible agricultural land in 10- to 15-year contracts and plant
appropriate cover such as grasses and trees in crop fields and along
streams. The plantings help prevent soil and nutrients from running
into regional waterways and affecting water quality. The long-term
vegetative cover also improves wildlife habitat and soil quality.
Wildlife habitat provided through the CRP can be at risk when CRP
contracts expire and lands are returned to agricultural production.
In Wyoming counties within the range of the Prebles, the percent of
cropland enrolled in the CRP program ranges from 0 to 26 percent. CRP
contracts that will eventually expire for Wyoming counties within the
range of the subspecies include: 1,736 ha (4,286 ac) currently enrolled
in Converse County; 38,164 ha (94,234 ac) currently enrolled in Laramie
County; and 23,612 ha (58,301 ac) currently enrolled in Platte County
(Farm Service Agency 2008). In Albany County, there are 5,910 hectares
(ha) (14,594 acres (ac)) identified by the U.S. Department of
Agriculture as ``cropland'' and none of this cropland is currently
enrolled in the CRP (Farm Service Agency 2008). While some landowners
may not choose to renew their contracts given current and expected
demand for biofuel raw materials, these counties have not witnessed a
meaningful decline in enrollment since the biofuels boom began. From
2004 to 2007, enrollment: declined 74 ha (183 ac) in Converse County;
increased 778 ha (1,922 ac) in Laramie County; declined 186 ha (460 ac)
in Platte County; and did not change in Albany County (Farm Service
Agency 2008). These data suggest changes in enrollment are likely to
have a negligible impact on the Prebles and its habitat.
The Prebles uses native grass and alfalfa hayfields that are in or
adjacent to suitable riparian habitat. This juxtaposition is often the
case, since hay production requires large amounts of water. Mowing of
hay may directly kill or injure Prebles, reduce food supply (since many
plants will not mature to produce seed), and remove cover. Late season
mowing may be especially problematic, because Prebles are approaching
hibernation and their nutritional needs are high (Clippinger 2002, p.
72). Additionally, hay production may preclude growth of willows and
other shrubs that are important as hibernation habitat for the Prebles.
Hayfields often are irrigated through ditch systems. The Prebles uses
overgrown water conveyance ditches and pond edges, and may use
agricultural ditches as dispersal routes (Meaney et al. 2003, pp. 612-
613). Ditch maintenance activities may kill individual Prebles and
periodically alter their habitat. Existing special regulations at 50
CFR 17.40(1) exempt certain ditch maintenance operations from take
prohibitions of the Act in recognition that habitat the ditches provide
is dependent on the ditches retaining their function. Prebles'
populations have persisted in areas hayed for many years (Taylor 1999).
Haying operations that allow dense riparian vegetation to remain in
place are likely compatible with persistence of Prebles' populations.
Impacts to riparian habitat from livestock are well documented in
the scientific literature (Kauffman and Krueger 1984, pp. 431-435;
Armour et al. 1991, pp. 7-11; Fleischner 1994, pp. 629-638; Belsky et
al. 1999, pp. 419-431; Freilich et al. 2003, pp. 759-765). Livestock
have damaged 80 percent of
[[Page 39824]]
stream and riparian ecosystems in the western United States (Belsky et
al. 1999, p 419.). Adverse impacts of grazing include changes to stream
channels (downcutting, trampling of banks, increased erosion), flows
(increased flow and velocity, decreased late-season flow), the water
table (lowering of the water table), and vegetation (loss to grazing,
trampling, and through altered hydrology) (Kauffman and Krueger 1984,
pp. 432-435).
Impacts from cattle grazing to other jumping mice have been
documented by Frey (2005), Giuliano and Homyack (2004), and Medin and
Clary (1989). Ryon (1996, p. 3) cited livestock grazing as a
contributor to the lack of structural habitat diversity he observed on
historical Prebles' sites in Colorado. On a working ranch in Douglas
County, Colorado, Prebles were detected within cattle exclosures, but
not on grazed areas. Previous trapping had documented Prebles upstream
and downstream, but not on the ranch (Ensight Technical Services 2004,
p. 9). On private lands in Douglas County, Colorado, Pague and
Schuerman (1998, pp. 4-5) observed a swift rate of residential land
development and significant fragmentation of habitat, but noted that in
some cases accompanying secession of grazing had allowed recovery of
degraded riparian habitats.
In Colorado, City of Boulder lands endured intensive grazing,
farming, or haying regimes until they became part of the Boulder Open
Space system. Grazing and haying, used as land management tools,
continue on Boulder Open Space sites currently supporting the Prebles.
In their study of small mammals on Boulder Open Space, Meaney et al.
(2002, p. 133) found no adverse effects of managed grazing on abundance
of individual small mammal species or on species diversity.
There is no doubt that cattle can greatly affect vegetation,
especially in times of drought; grazing practices that assure
maintenance of riparian shrub cover may be a key consideration in
maintaining Prebles' populations (Ensight Technical Services 2004, p.
9). Recent drought, in combination with grazing, may have had an
increased effect on Prebles' habitat.
Overgrazing threats are not limited to large livestock producing
operations. On subdivided ranch properties, often termed
``ranchettes,'' horses and other livestock can heavily affect the small
tracts within which they are fenced (Pague and Grunau 2000, p. 1-14).
In Colorado, many large ranch properties are being subdivided into
ranchettes. We have concluded that this represents a widespread threat
to significant areas of Colorado, where an increase in rural
development is forecast in the foreseeable future. Pague and Grunau
(2000) considered ``high impact livestock grazing'' to be a high-
priority issue for the Prebles in Larimer, Weld, Elbert, and El Paso
counties in Colorado, largely due to the projected increase in such
ranchettes. Based on human growth projections, subdivision of ranches
is expected to be minimal in portions of Wyoming where the Prebles
exists.
In Wyoming, where large-scale commercial ranching is more prevalent
in the Prebles' range than in Colorado, overgrazing is thought to occur
sporadically across the landscape, most obviously where cattle
congregate in riparian areas in winter and spring. Grazing has occurred
within Prebles' habitat for many decades, and populations of Prebles
have been documented on sites with a long history of grazing. For
example, jumping mice were trapped at 18 of 21 sites on True Ranches
properties (mice from 14 of these sites have since been confirmed as
Prebles (King et al. 2006b, pp. 4351-4353)), primarily within sub-
irrigated hay meadows that have been subjected to livestock grazing and
hay production for approximately 100 years (Taylor 1999, p. 5).
At the time of listing we addressed overgrazing by livestock. We
stated that it may cause significant impacts to Prebles' habitat, but
that timing and intensity of grazing were probably important in
maintaining habitat and that maintenance of woody vegetative cover
could be key (63 FR 26517, May 13, 1998). Overgrazing was thought to
have eliminated the Prebles from much of its former Wyoming range
(Clark and Stromberg 1987, p. 185; Compton and Hugie 1993b, p. 4).
Trapping efforts since listing have greatly expanded our understanding
of the subspecies' range in Wyoming, showing that our assertions that
grazing eliminated the Prebles from these areas were incorrect.
As suggested by Bakeman (1997, p. 79) and Pague and Grunau (2000,
p. 1-17), and as supported by the examples above, grazing is compatible
with Prebles when timing and intensity are appropriately managed. We
now believe that agricultural operations that have maintained habitat
supportive of Prebles' populations are consistent with conservation and
recovery of the subspecies. In recognition of this, in 2001 we adopted
special regulations at 50 CFR 17.40(1) which exempted existing
agricultural activities, including grazing, plowing, seeding,
cultivating, minor drainage, burning, mowing, and harvesting, from the
prohibitions of the Act. The exemption does not apply to new
agricultural activities or to those that expand the footprint or
intensity of the activity. We established the exemption to provide a
positive incentive for agricultural interests to participate in
voluntary conservation activities and to support surveys and studies
designed to determine status, distribution, and ecology of Prebles,
which in turn could lead to more effective recovery efforts.
The number of cattle in counties currently known to support the
Prebles, in Wyoming totaled 270,000 head in 2006 (National Agriculture
Statistics Service 2007). Cattle numbers appear stable in Albany,
Converse, and Laramie counties, but higher than the average for the
last 20 years in Platte County. Cattle numbers in Colorado counties
supporting the Prebles totaled 666,000 head in 2006; 550,000 of these
cattle were in Weld County (National Agriculture Statistics Service
2007). Excluding Weld, all of these Colorado counties have shown a
marked downward trend in cattle numbers over the past 20 years,
reflecting human development on former agricultural lands (National
Agriculture Statistics Service 2007).
Overall, we expect traditional grazing operations to continue in
Wyoming. Such operations have generally proven compatible with
maintenance of Prebles' populations, suggesting timing and intensity
have generally been managed appropriately. This management has taken
place without oversight of the Act as allowed in the special
regulations at 50 CFR 17.40(1). We have no reason to conclude that the
management of these ranches will change in an adverse way over the
foreseeable future.
Summary--Within Colorado, human land uses within the Prebles' range
have destroyed, degraded, and fragmented habitat and continue to do so.
While protections of the Act have avoided, minimized, and helped to
compensate for direct human land-use impacts to occupied Prebles'
habitat, direct and secondary impacts to riparian habitats have likely
diminished the areas that are capable of sustaining Prebles'
populations. Given the projected future growth rates in Colorado, and
absent protections associated with Federal activities and listing under
the Act, we have concluded that threats posed by human development
activities discussed above would rise dramatically following delisting.
Most Colorado Prebles' sites documented since listing are subject to
the same level of threats discussed above for the Colorado
[[Page 39825]]
portion of the range in general. Documentation of these new sites does
not change our conclusion as to the current and future conservation
status of the subspecies in this portion of its range. Regulatory
mechanisms that could help reduce such negative impacts, while
currently limited, are discussed under Factor D below.
In Wyoming, the Prebles appears to be much more widely distributed
than previously assumed, while current and future threats to habitat
and range appear limited. At the time of listing, the Prebles was not
known to exist in the North Platte River basin and known from only two
sites in Wyoming's portion of the South Platte River basin (63 FR
26517). Since listing, additional distributional data has verified that
the subspecies is widespread in the North Platte River basin with
demonstrated occupancy in 4 drainages and at least 15 rivers or
streams; we also believe the subspecies also may occur in multiple
rivers or streams in a fifth North Platte drainage (the Middle North
Platte). An improved understanding of the subspecies' distribution
suggests that historical agricultural activities, such as grazing and
haying, have had a minimal impact on the subspecies to date. In short,
continuation of these long-standing activities appears supportive of
existing Prebles' populations. We have no indication these agricultural
practices are likely to change in the foreseeable future in ways that
would affect the subspecies' long-term conservation status. A low
projected human population growth rate is predicted for the four
Wyoming counties occupied by the Prebles, suggesting that few
development-related threats are likely in this portion of the
subspecies' range into the foreseeable future. In short, the best
scientific and commercial information suggests that impacts to the
Wyoming portion of the subspecies' range are likely to be minor with
only small and localized effects. Therefore, we conclude that present
or threatened destruction, modification, or curtailment of the Prebles'
habitat and range in Wyoming do not suggest that the subspecies
requires listing in this portion of its range in order to sustain it
for the foreseeable future.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
The Prebles is not collected for commercial or recreational reasons
and we have no information to indicate that the subspecies would be
once it is delisted. Some collection of specimens occurs for scientific
and educational purposes and these activities will continue to be
permitted under existing state regulations in both Colorado and Wyoming
once the subspecies is delisted. Although we are aware that
unintentional mortalities have resulted from capture and handling of
Prebles by permitted researchers, the level of take associated with
this activity does not rise to the level that would affect populations
of the subspecies, nor is it likely to do so once we remove the
protections of the Act. Furthermore, we have no information to indicate
that collection for scientific or educational reasons is it likely to
become, a significant threat to the subspecies, even if the protections
afforded the subspecies under Colorado and Wyoming state laws were
removed (see our discussion below of Factor D).
C. Disease or Predation
At the time of listing, we had no evidence of disease causing
significant impacts to the Prebles (63 FR 26517, May 13, 1998). No
further evidence exists that any parasite or disease has caused a
significant impact to populations. While plague relationships for most
North American rodents are poorly understood, plague may interact
synergistically with other natural and human-induced disturbances,
increasing risk of local extirpation and rangewide extinction (Biggins
and Kosoy 2001, p. 913). Plague has not been documented in the Prebles.
However, Pague and Grunau (2000, p. 1-19) considered disease to be a
potentially high-priority issue for the Prebles. They cited unknown
resistance of the Prebles to plague and other diseases, and noted that
small populations could be especially vulnerable to effects of an
epizootic. Should disease materialize into a substantive issue, we
believe populations in Colorado would be at higher risk because
development pressures in this portion of the range are more likely to
result in small, fragmented, and unsustainable populations.
At the time of listing, we addressed potential predators of the
Prebles whose densities could increase in the suburban or rural
environment, including striped skunk (Mephitis mephitis), raccoon
(Procyon lotor), and the domestic cat (Felis catus) (63 FR 26517, May
13, 1998). Increased impacts of native and exotic predators that
accompany rural development can affect species viability (Hansen et al.
2005, p. 1899). We noted opinions that free-ranging domestic cats and
feral cats locally presented a problem to Prebles' populations. Where
predator populations are increased through human land uses, they may
contribute to the loss or decrease of Prebles. Generally, we have found
proponents of new residential developments near Prebles' habitat to be
receptive to prohibitions on free-ranging cats and dogs (Canis
domesticus) when negotiating minimization measures through section 7 of
the Act. However, enforcement is often through covenants administered
by homeowners' associations, with uncertain success. If the Prebles
were to be delisted and Federal protection under the Act discontinued,
similar covenants on new development in and near Prebles' habitat would
be less likely, and existing covenants may not be as strictly enforced.
Beyond previously known or anticipated predators of jumping mice,
introduction of non-native bullfrogs (Rana catesbiana) in Colorado has
resulted in predation on Prebles (Trainor 2004, p. 58). However, we
have no information to suggest that predation from bullfrogs has
affected Prebles' populations.
While many uncertainties remain regarding disease and predation, we
believe the best available scientific and commercial data suggest that
disease is most likely to only be a factor in small and fragmented
populations, and that increases in predation will likely only
contribute to the reduction, fragmentation, and loss of Prebles'
populations when such populations are exposed to increased human
presence. As noted above, increased human presence is expected to be a
significant issue in Colorado and of minimal concern in Wyoming. Thus,
we expect these issues have the potential to meaningfully affect
Prebles' populations in developing areas of Colorado, but comparable
impacts in Wyoming are not expected.
D. The Inadequacy of Existing Regulatory Mechanisms
This factor considers the regulatory mechanisms that would remain
in place in the absence of the Act's protective measures. Current and
likely future protections are considered. In areas where the
protections of the Act are removed, the Service has no assurances that
previous conservation commitments made under sections 7 or 10 of the
Act will remain in place.
At the time of listing, we cited the lack or ineffectiveness of
laws and regulations protecting the Prebles and its habitat (63 FR
26517, May 13, 1998). Protective measures discussed below include
Federal, State, and local protections.
Federal Protections--Existing Federal laws, such as the CWA (33
U.S.C. 1251 et seq.), Federal Power Act (16 U.S.C.
[[Page 39826]]
791a et seq.), Fish and Wildlife Coordination Act (16 U.S.C. 661 et
seq.), National Forest Management Act (16 U.S.C. 1600 et seq.), Federal
Land Policy and Management Act (43 U.S.C. 1701 et seq.), Food Security
Act (16 U.S.C. 3801 et seq.), and National Environmental Policy Act (42
U.S.C. 4321 et seq.), provide limited protection for non-listed
species.
Section 404 of the CWA generally requires avoidance and
minimization (when practicable), and mitigation of adverse impacts to
jurisdictional wetlands and waters of the United States associated with
filling. Human impacts to jurisdictional wetlands may be permitted when
alternatives that would avoid wetlands are found not to be practicable.
Section 404 of the CWA does not apply to non-jurisdictional waters or
wetlands. In these cases, activities affecting these waters or wetlands
would not require Federal permits under section 404 of the CWA. More
importantly, section 404 of the CWA provides no comparable safeguards
for non-jurisdictional riparian and upland areas used by the Prebles.
The CWA, section 303, establishes the water quality standards and
Total Maximum Daily Load (TMDL) programs. Water quality standards are
set by States, Territories, and Tribes. They identify the uses for each
waterbody, for example, drinking water supply, contact recreation
(swimming), and aquatic life support (fishing), and the scientific
criteria to support that use. A TMDL is a calculation of the maximum
amount of a pollutant that a waterbody can receive and still meet water
quality standards, and an allocation of that amount to the pollutant's
sources. Colorado and Wyoming are required under section 305(b) of the
CWA to complete an assessment of their surface waters. From this
assessment a CWA 303(d) list of impaired water bodies is developed.
These are waters that are not currently meeting their designated uses
because of impairments to the waters.
The EPA encourages communities, watershed organizations, and local,
state, tribal, and federal environmental agencies develop and implement
watershed plans to meet water quality standards and protect water
resources. These plans can include measures that will help protect
riparian areas and may in some cases provide benefits to the Preble's
Meadow Jumping Mouse. For example, in Wyoming the Crow Creek Watershed
Plan coordinated by the Laramie County Conservation District, includes
recommendations to protect riparian habitat because of the benefits for
water quality (the plan is available at http://www.lccdnet.org/
waterquality/watershed%20plan/FinalPlan.pdf). While these efforts to
improve water quality have the potential to improve or protect riparian
habitat, the measures are typically not mandatory and such watershed
planning efforts do not encompass the range of the subspecies. Thus,
the CWA provides only limited protection of habitats utilized by the
Prebles and is not capable of substantially reducing threats to
individual Prebles' populations or to the subspecies as a whole.
On lands administered by the USFS and BLM, the current status of
the Prebles as threatened invokes management priorities in accordance
with protections of the Act. If delisted, these protections would no
longer apply. However, Federal land-management agencies, through their
regulations, policies, and management plans, work to ensure long-term
conservation of all wildlife species of concern. Of the three National
Forests supporting Prebles' populations, the Medicine Bow-Routt
National Forest has a forest management plan that includes standards
and guidelines specific to conservation of the Prebles. The Arapahoe-
Roosevelt National Forest and the Pike-San Isabel National Forest have
forest plans that predate the listing of the Prebles (Warren 2007). If
delisted, the Prebles would likely be considered a subspecies
warranting conservation concern by Federal land-holding agencies and,
as such, retain some continued degree of conservation priority.
On military installations, the Sikes Act Improvement Act of 1997
(16 U.S.C. 670a et seq.) requires each facility that includes land and
water suitable for the conservation and management of natural resources
to complete an Integrated Natural Resources Management Plan (INRMP).
This plan must integrate implementation of the military mission of the
installation with stewardship of the natural resources found there. In
both Colorado and Wyoming, this process has provided the opportunity to
consider the potential impacts of military actions on the Prebles.
The Academy in El Paso County, Colorado, has an INRMP in place, a
conservation and management plan, and a programmatic consultation under
section 7 of the Act, which provide guidance for Air Force management
decisions for certain activities that may affect the subspecies.
Research on the Prebles is ongoing at the Academy; the conservation and
management plan is designed to be updated as new information is
collected. Warren Air Force Base in Laramie County, Wyoming, has an
INRMP and a conservation and management plan. However, the base may
only support the western jumping mouse. Both plans are designed to be
in place for 5 years. The emphasis given to conservation of the Prebles
in these plans may decline in the future if the subspecies were to be
delisted.
The presence of Prebles has been documented at two of the Service's
NWRs. We manage the Rocky Flats NWR, near Boulder, Colorado, in a
manner consistent with conservation of the Prebles. This management is
unlikely to change if the Prebles were to be delisted.
More recently, a single Prebles as well as western jumping mice
have been confirmed from Hutton Lake NWR near Laramie, Wyoming. Because
the subspecies was only recently documented on Hutton Lake NWR, the
subspecies' needs were previously not explicitly addressed in
management documents. While past management was primarily waterfowl
oriented, refuge management plans have been developed to address the
needs of the Prebles (Kelly 2008).
Service-approved HCPs and their incidental take permits contain
management measures and protections for identified areas that protect,
restore, and enhance the value of these lands as habitat for the
Prebles. These measures, which include explicit standards to avoid,
minimize, and mitigate any impacts to the covered (sub)species and its
habitat, are designed to ensure that the biological value of covered
habitat for the Prebles is maintained, expanded, or improved. Large
regional HCPs expand upon the basic requirements set forth in section
10(a)(1)(B) of the Act and reflect a voluntary, cooperative approach to
large-scale habitat and (sub)species conservation planning. The primary
goal of such HCPs is to provide for the protection and management of
habitat essential for the conservation of the (sub)species while
directing development to other areas. In any HCP, permittees may
terminate their participation in the agreement and abandon the take
authorization set forth in the permit.
To date, we have approved 19 single-species HCPs for the Prebles,
all in Colorado. Eighteen of the associated permits allow approximately
280 ha (700 ac) of permanent or temporary impact to Prebles' habitat,
and preserve or enhance habitat to offset impacts. The largest of
these, the approved HCP for Douglas County and the Towns of Castle Rock
and Parker, allows impacts of up
[[Page 39827]]
to 170 ha (430 ac), in exchange for the acquisition of 24 km (15 mi) of
stream (455 ha (1,132 ac) of habitat) acquired and preserved for the
long-term benefit of the Prebles.
The remaining HCP, issued in January 2006, is the Livermore Area
HCP in Larimer County. The planning area for this HCP includes a large
portion of Larimer County, approximately 1,940 square km (750 square
mi), including a Prebles' ``conservation zone'' estimated at
approximately 324 km (201 mi) of stream and 8,570 ha (21,320 ac). The
HCP cites protection of 114 km (71 mi) of stream, mostly on CDOW lands;
however, it is not clear what proportion of these areas support
Prebles. Local landowners and public agencies holding land within the
boundaries of this HCP may opt for coverage under the HCP and receive
take permits for activities consistent with the HCP. The Livermore Area
HCP is designed to support current land uses, including ranching and
farming. However, inclusion of landowners is optional, and they may
choose to pursue land uses inconsistent with those specified in the
HCP. Thus far, we have issued no individual permits under this HCP.
Of the two regional HCPs in development, the El Paso County effort
is proceeding slowly and the Boulder County effort appears to be on
hold. It is unlikely that these conservation plans would be completed
or implemented if the Prebles did not remain listed under the Act.
State Protections--Under the nongame provisions of the CDOW
Regulations (Chapter 10, Article IV) the Prebles currently may only be
taken legally by permitted personnel for educational, scientific, or
rehabilitation purposes. This regulation would remain in effect if the
Prebles was delisted under the Act. In Wyoming, continued
classification of the meadow jumping mouse as a ``nongame species''
under section 11 of Chapter 52 (Nongame Wildlife) of the Wyoming Game
and Fish Commission regulations would protect the Prebles from takings
and sales by allowing the issuance of permits only for the purpose of
scientific collection. As mentioned previously in our discussion under
Factor B, overutilization for commercial, recreational, scientific, or
educational purposes is not now, nor is it likely to become, a
significant threat to the subspecies, even if the protections afforded
the subspecies under Colorado and Wyoming laws were removed.
Numerous State lands (CDOW and WFGD lands, State Park lands, State
Land Board lands) and mitigation properties (such as those of the
Colorado Department of Transportation) would continue to provide a
measure of protection for the Prebles should it be delisted. While some
of these conservation properties may have management specifically
designed to preserve and enhance Prebles' habitat, others are managed
more generally for wildlife habitat, for human recreation, or for
multiple uses.
State programs have been available to help preserve the Prebles
through the acquisition, preservation, and management of its habitat.
These include the Great Outdoors Colorado Trust Fund and the Species
Conservation Trust Fund. In comments to the Service, then Colorado
Department of Natural Resources Commissioner, Russell George, stated
that State and local initiatives could provide for conservation of the
Prebles, independent of Federal oversight. He listed nearly 40
conservation projects in 5 Front Range Colorado counties where the
Prebles ``may be present'' (George 2004). The conservation value of
many of these projects is uncertain since most were developed without
specific regard to the Prebles' distribution and its conservation.
Local Protections--At the time of listing, we pointed out that
while a myriad of regional or local regulations, incentive programs,
and open-space programs existed, especially in Colorado, few
specifically protected the Prebles or its habitat from inadvertent or
intentional adverse impacts (63 FR 26517, May 13, 1998). Many local
regulations create a process of site-plan review that ``considers'' or
``encourages'' conservation of wildlife, wetlands, and other natural
habitats, but have no mandatory measures requiring avoidance or
mitigation of impacts. Effectiveness of local regulations in
maintaining naturally functioning riparian corridors varies greatly
depending on how these apparently flexible regulations are implemented.
Following listing under the Act, development and other projects in and
near Prebles' habitat have received increased scrutiny from local
jurisdictions, often in coordination with Service authorities. Open-
space acquisitions and easements also have taken the presence of the
Prebles into account. It is not clear what level of interest in
Prebles' conservation would continue following delisting. Local
governments would likely relax review procedures for projects in known
or suspected Prebles' habitat. Beyond the direct impact to Prebles'
habitat, secondary impacts of development (including increased
recreational use, altered flow regimes and groundwater levels, and
increase in domestic predators) are unlikely to be adequately
addressed. While certain local regulations are designed to conserve
wetlands or floodplains on private lands, it is unlikely they would
effectively control land uses (grazing, mowing, cutting, and burning)
that may affect the hydrology, vegetation, and hibernacula sites on
which the Prebles depends. The adequacy of such protective measures is
more important within Colorado than Wyoming given the intense
development pressures in the Colorado counties where the Prebles
occurs.
Douglas County, Colorado, owns 14 properties that encompass 24 km
(15 mi) of stream and associated riparian habitats potentially
beneficial to the Prebles (Matthews 2004). Of Douglas County streams on
non-Federal property within the county-mapped Riparian Conservation
Zone, 105 km (65 mi), or 23 percent, are under some form of permanent
protection (Matthews 2004), including 77 km (48 miles) on Plum Creek
and its tributaries and 25 km (16 mi) on Cherry Creek and its
tributaries (Matthews 2008). However, occurrence of the Prebles on many
of these properties has not been extensively documented. For example,
while there are 23.4 km (14.5 mi) of mapped riparian corridors on the
large Greenland Ranch conservation property, the presence of the
Prebles has been documented at only two sites. Future conservation
efforts to augment protected areas and to link protection over large
expanses of connected streams in Douglas County could contribute
greatly to maintaining secure Prebles' populations in the Upper South
Platte and Middle South Platte-Cherry Creek drainages. If the Prebles
was delisted, management priorities on protected lands and direction of
future conservation efforts would likely change. In order to ensure
long-term management for the Prebles, the Preliminary Draft Recovery
Plan suggests the Service and our partners develop and implement long-
term management plans and cooperative agreements prior to delisting
(USFWS 2003b, pp. iv, 33, 39, 47-47, 51-52).
Larimer County has acquired or secured easements to considerable
lands, including some properties under the Laramie Foothills Project,
in partnership with The Nature Conservancy, the City of Fort Collins,
and the Legacy Land Trust. While conservation efforts have increased,
especially in the Livermore Valley, residential development remains the
largest threat to the Prebles in the county (Pague 2007). The extent to
[[Page 39828]]
which Prebles' populations are supported by these properties, the fate
of remaining private lands in the North Fork, Cache La Poudre River and
its tributaries, and the ability to link conservation lands and
traditional agricultural lands supporting the Prebles along stream
reaches are key to protecting the potentially large Prebles' population
thought to exist in this area.
The City of Boulder, Boulder County, and Jefferson County have
extensive lands protected under their open-space programs. While the
extent of known Prebles' occurrences in these counties is limited
compared to that documented in Larimer and Douglas counties, known
populations exist on open space protected from residential and
commercial development.
Overall, the CDOW examined land ownership of over 58,000 ha
(143,000 ac) in Colorado they considered occupied by the Prebles and
concluded 45 percent of the area was ``protected'' (i.e., in public
ownership, land trust, or conservation easement) (Nesler 2008).
Occupancy of land was calculated based on proximity to documented
meadow jumping mouse capture locations. Captures are the result of
trapping surveys, which may disproportionately target public lands
easily trapped for research purposes or proposed development sites
trapped for Act compliance purposes. Thus, the 45 percent statistic may
not reflect the actual proportion of suitable habitat that is
protected. Still it suggests some meaningful progress toward recovery
of the subspecies in this portion of its range.
At the request of the Service, the CDOW conducted a similar
evaluation for specific areas we consider of high importance to
Prebles' conservation in Colorado. These included designated Prebles'
critical habitat units and additional units of proposed critical
habitat where the proposed units were excluded from the final
designation due to ongoing conservation efforts (HCPs in development in
Boulder, Douglas, and El Paso counties). While our proposal and
designation of critical habitat units focused on lands in public
ownership, which may bias the results, examination of these areas
provides some perspective into potential protections in place in
Colorado.
Across nine total units, lands in public ownership, land trusts, or
conservation easements comprised approximately 51 percent of these
areas (Kindler 2008). Percentage of lands in these categories varied
greatly from unit to unit as follows:
45 percent of critical habitat unit SP4, which encompasses
approximately 141.8 km (88.1 mi) of streams within the North Fork of
the Cache La Poudre River watershed;
96 percent of critical habitat unit SP5, which encompasses
approximately 82.4 km (51.2 mi) of streams within the Cache La Poudre
River watershed;
64 percent of critical habitat unit SP6, which encompasses
approximately 69.2 km (43.0 mi) of streams within the Buckhorn Creek
watershed;
64 percent of proposed critical habitat unit SP8, which
encompasses approximately 11.8 km (7.3 mi) of streams within the South
Boulder Creek watershed;
13 percent of critical habitat unit SP10, which
encompasses approximately 12.9 km (8.0 mi) of streams within the
Ralston Creek watershed;
45 percent of the proposed critical habitat unit SP11,
which encompasses approximately 32.1 km (19.9 mi) of streams within the
Cherry Creek watershed;
31 percent of the proposed critical habitat unit SP12,
which encompasses approximately 146.6 km (91.1 mi) of streams within
the Plum Creek watershed; and
5 percent of the proposed critical habitat unit A1, which
encompasses approximately 56.3 km (35.0 mi) of streams within the
Monument Creek watershed.
Units SP4, SP12 and A1 correspond to the three large Prebles'
populations in Colorado called for in the Preliminary Draft Recovery
Plan. Units SP4 and SP12 demonstrate 45 percent and 31 percent in
protected land use categories, respectively. The 5 percent protected in
unit A1 underestimates the actual percent of this large population
protected as the proposed critical habitat unit excluded the Air Force
Academy. The Preliminary Draft Recovery Plan calls for documentation of
these Prebles' populations, maintenance of habitat connectivity over
long expanses of streams, and the elimination of future threats within
these drainages. While the above percentages of lands in protected
ownership categories is encouraging, existing protections do not
fulfill Preliminary Draft Recovery Plan objectives, nor do they assure
the future well-being of these Prebles' populations.
As discussed above, fragmentation of Prebles' habitat and resulting
impacts on the future security of Prebles' populations is a significant
concern. Even in drainages where lands in public ownership or private
properties dedicated to conservation are relatively extensive,
development of intervening private lands is likely to fragment habitat
and may impact Prebles' populations. As of this writing, we have not
obtained data on fragmentation within the above areas.
Many of the public ownership areas are high-elevation, montane
headwater habitats. As discussed previously, such areas may have less
suitable habitat that supports lower density Prebles' populations than
at plains and foothill sites. Additionally, within Colorado, it appears
that as elevation increases there is an increased occurrence of the
western jumping mouse. Thus, in order to rely upon the contribution
that these high elevation areas provide to the long-term security of
the Prebles, positive identification to species and localized
demographic data would be required.
Finally, public ownership may not preclude properties from human
development, other land uses, or management priorities incompatible
with the well-being of the Prebles. Those lands that are protected and
managed in a manner that is compatible with the needs of the Prebles
may be subject to secondary impacts from activities off site. Most
prominent among these secondary impacts are those resulting from
changes in flow regimes. Recent evidence suggests secondary impacts
from development of private land upstream from the Academy (proposed
unit A1) threaten the integrity of habitat present and the Prebles'
population it supports.
In Wyoming, as would be expected in areas where development
pressures are substantially less, the regional and local regulations
affecting Prebles habitat appear to be less extensive than in the
Colorado portion of its range. Currently Albany, Laramie, and Platte
Counties in Wyoming have zoning regulations including the regulation of
subdivision development (Reid in litt.). These and other local
protections provide some protection of water resources and floodplains
and reduce soil erosion. Overall, local protections in the Wyoming
portion of the Prebles range appear minimal.
Reinitiated recovery planning efforts will work to further define
recovery needs and coordinate progress toward these goals with State,
other Federal, and local entities. While the above statistics suggest
additional recovery efforts are required, the potential for protecting
existing Prebles' populations and recovering the subspecies in Colorado
appears high. While fewer protections are in place in Wyoming,
substantially reduced threat levels (see Factor A discussion) indicates
that comparable protections are not necessary in this portion of the
subspecies' range.
[[Page 39829]]
Summary--In the absence of the Act's protective measures, Federal
conservation efforts for the Prebles would be largely limited to
Federal properties, where the subspecies may be maintained as a
priority subspecies and conserved through existing or future management
plans.
While State regulations in both Colorado and Wyoming would regulate
purposeful killing of Prebles; as noted in Factors B and D above, we do
not view this as a significant concern driving the subspecies' long-
term conservation status. If delisted, State and local regulations
would do little to conserve the Prebles or its habitat on private
lands. Public land holdings, conservation easements, and other
conservation efforts, past and future, could support the Prebles on
specific sites.
In Colorado, the extent and pattern of conservation efforts in
relation to Prebles' distribution, and the appropriate management of
Prebles' habitat, would largely dictate the long-term viability of
Prebles' populations.
At this time, no large populations and few medium populations, as
described in the Preliminary Draft Recovery Plan, are known to exist in
Colorado on contiguous stream reaches that are secure from development.
Management plans that specifically address threats to the Prebles are
few, and management priorities would likely change if we were to delist
the subspecies. Much of the intervening private lands would likely be
subject to development within the foreseeable future (this issue is
described in more detail in Factor A above). If we were to delist the
subspecies, given current and projected levels of protections, we
believe that most Prebles' populations in Colorado would not be secure
into the foreseeable future.
In Wyoming, the best available scientific and commercial
information indicates that at least one large population (in the Lower
Laramie drainage) and two medium populations (in the Glendo and Horse
Creek drainages) occur along contiguous stream reaches that are secure
from development as recommended in the Preliminary Draft Recovery Plan
(USFWS 2003b, pp. 19, 22). While regulatory measures in Wyoming do not
guarantee protection of these populations, such assurances are not
needed because threats to the Prebles and the subspecies' habitat are
limited for the foreseeable future (see Factor A discussion).
E. Other Natural or Manmade Factors Affecting the Subspecies' Continued
Existence
At the time of listing, we judged this subspecies susceptible to a
number of other factors, including impact from naturally-occurring
events including flooding, invasive weeds and weed control programs,
pesticides and herbicides, and secondary impacts associated with human-
caused development (63 FR 26517, May 13, 1998). For most of these
factors, we have little more information than we had at the time of
listing. Additional concerns that were not considered at the time of
listing include the potential for competition between the Prebles and
the western jumping mouse, and future effects of changing climate on
the Prebles, including its potential to heighten threats from fire and
drought.
Flooding and fire are natural components of the Wyoming and
Colorado foothills and plains, and Prebles' habitat naturally waxes and
wanes with these events. While these natural events may affect Prebles'
populations by killing individuals and by destroying riparian and
adjacent upland habitat on which they depend, the effects to vegetation
are often temporary. Normal flooding and fire events also may help
maintain the vegetative communities that provide suitable habitat for
the Prebles. An increase in impervious surfaces and denuding of
vegetation caused by human activity can result in increased frequency
and severity of flood events and prevent the re-establishment of
favored riparian communities. While an extreme flood event has
potential to eliminate an entire Prebles' population in an affected
stream reach, it would be less likely to eliminate a population over an
entire drainage where Prebles' occurrence extends to side tributaries
and headwaters.
Periodic fire may be of value in maintaining riparian,
transitional, and upland vegetation within Prebles' habitat. In a
review of the effects of grassland fires on small mammals, Kaufman et
al. (1990) found a positive effect of fire on meadow jumping mice in
one study and no effect on the species in another study. Fire may
regenerate decadent willow (Salix sp.) stands along streams and
encourage higher stem densities considered more favorable to the
Prebles.
Long periods of fire suppression result in fuel buildup, especially
in forested areas, and can result in catastrophic fires that alter
habitat dramatically, change the structure and composition of the
vegetative communities, and potentially affect large numbers of Prebles
or multiple populations. Following more intense fires, precipitation in
a burned area may degrade Prebles' habitat by causing greater levels of
flooding, erosion, and sedimentation along creeks. As habitat
redevelops, it will likely be reoccupied by the Prebles, assuming that
there are occupied, connected stream reaches where Prebles' populations
have continued to persist.
An example of catastrophic fire in Prebles' habitat occurred in
2002. The Hayman and Schoonover fires in Jefferson and Douglas
counties, Colorado, encompassed over 3,000 ha (7,500 ac) of potential
Prebles' habitat, or approximately 20 percent of the potential habitat
within the boundaries of Pike National Forest (Elson 2003).
Approximately 342 ha (844 ac) of proposed critical habitat were burned.
While riparian habitat that was lightly burned was expected to recover
relatively quickly, increases in erosion and sedimentation downstream
have been severe, and may continue to affect Prebles' habitat for many
years. Because of severe fire-related impacts, we withdrew from the
final critical habitat designation for the Prebles (68 FR 37275, June
23, 2003) a portion of Gunbarrel Creek that we had proposed as critical
habitat for the subspecies before the Hayman fire. Even prior to the
Hayman and Schoonover fires, Pague and Granau (2000), in their
consideration of Prebles conservation in Colorado, considered
catastrophic fire to be a high-priority issue for Douglas County.
Fire has the potential to affect the Prebles' populations both
directly and indirectly. The intensity, extent, and location of any
fire event will likely dictate the nature and severity of the impact to
the Prebles. Catastrophic fire events are, by their nature, rare, but
have the potential over the foreseeable future to impact any existing
foothill and montane Prebles' population.
Drought is another issue that can have a significant negative
effect on the Prebles. Drought lowers stream flows and the adjacent
water table, in turn impacting riparian habitat on which the subspecies
is dependent. Drought may exacerbate adverse impact of cattle grazing
on Prebles habitat. Frey (2005, p.62) found that drought had a major
influence on the status and distribution of Zapus hudsonius luteus in
New Mexico. In 2002, a year with regional drought conditions, Bakeman
(2006, p. 11) failed to capture Prebles at two sites where he had
previously documented substantial populations. While Prebles
populations have coexisted with
[[Page 39830]]
periodic drought, significant increases in frequency or severity of
drought could impact the persistence of Prebles. This is likely to be a
more significant factor for small and fragmented populations, while
large populations with substantial tracts of suitable habitat will be
better protected.
Invasive, noxious plants can encroach upon a landscape, displace
native plant species, form monocultures of vegetation, and may
negatively affect food and cover for the Prebles. The control of
noxious weeds may entail large-scale removal of vegetation and
mechanical mowing operations, which also may affect the Prebles. The
tolerance of the Prebles for invasive plant species remains poorly
understood. Leafy spurge (Euphorbia esula) may form a monoculture,
displacing native vegetation and thus reducing available habitat
(Selleck et al. 1962; Pague and Grunau 2000, p. 1-18). Nonnative
species including tamarisk (Tamarix ramosissima) and Russian olive
(Elaeagnus angustifolia) may adversely affect the Prebles (Garber 1995,
p. 16; Pague and Grunau 2000, p. 1-18). Existing special regulations at
50 CFR 17.40(1) exempt take incidental to noxious weed control. We
instituted this exemption to recognize that control of noxious weeds is
likely to produce long-term benefits to native vegetation supportive of
the Prebles.
It remains unknown to what extent point and non-point source
pollution (sewage outfalls, spills, urban or agricultural runoff) that
degrades water quality in potential habitat may affect the abundance or
survival of the Prebles. From an examination of their kidney structure,
it is not clear whether Prebles require drinking water from open water
sources, or may obtain water through dew and their foods (Wunder 1998).
Likewise, it is unknown whether pesticides and herbicides, commonly
used for agricultural and household purposes within the range of the
Prebles, pose a threat to Prebles directly, or through their food
supply, including possible bioaccumulation.
Human-caused development creates a range of additional potential
impacts (through human presence, noise, increased lighting, introduced
animals, and the degradation of air and water quality) that could alter
Prebles' behavior, increase the levels of stress, and ultimately
contribute to loss of vigor or death of individuals, and extirpation of
populations. Introduced animals associated with human development may
displace, prey upon, or compete with the Prebles. Feral cats and house
mice were common in and adjacent to historical capture sites where
Prebles were no longer found (Ryon 1996, p. 26). While no cause-and-
effect relationship was documented, the Prebles were 13 times less
likely to be present at sites where house mice were found (Clippinger
2002, p. 104). We have an incomplete understanding of the mechanisms by
which the breadth of human-caused development impacts Prebles'
populations. However, the absence of Prebles' populations in portions
of Colorado drainages where riparian habitat appears relatively
favorable but human encroachment is pervasive suggests a potential
cause-and-effect relationship. Cumulative impacts from a variety of
factors in addition to habitat loss may contribute to local
extirpations.
Colorado's Comprehensive Wildlife Conservation Strategy lists
``scarcity'' as a threat to meadow jumping mice that may lead to
inbreeding depression (CDOW 2006, p. 102). Small populations can be
threatened by stochastic, or random, changes in a wild population's
demography or genetics (Brussard and Gilpin 1989, pp. 37-48; Caughley
and Gunn 1996, pp. 165-189). A stochastic demographic change in small
populations, such as a skewed age or sex ratio (for example, a loss of
adult females), can negatively affect reproduction and increase the
chance of extirpation. Isolation of populations may disrupt gene flow
and create unpredictable genetic effects that could impact Prebles'
persistence in a given area. While the susceptibility of the Prebles to
such events has not been researched, the documented tendency for
Prebles' numbers to vary widely over time heightens concern for small
and isolated populations. Within populations, periodic lows in numbers
of Prebles present more accurately reflect potential vulnerability than
typical or average numbers present. Although many trapping efforts have
targeted Prebles in small, isolated reaches of habitat, few have
documented presence. As noted above, we have determined that
populations in Colorado would be at higher risk over the foreseeable
future because development pressures in this portion of the range are
more likely to result in small, fragmented, and unsustainable
populations.
The relative ranges, abundance, and relationship between the
Prebles and the western jumping mouse are not yet clearly understood,
especially in Wyoming. Recent confirmation of extensive range overlap
in Wyoming and the apparent predominance of the western jumping mouse
in some southern Wyoming drainages with few or no recent records of
Prebles, provide reason for concern. It is unknown whether western
jumping mice are actively competing with Prebles, affecting Prebles'
population size, and possibly limiting distribution, or if this
distribution pattern is unrelated to their interaction. Additional
study of this issue would be desirable. Although questions remain, we
do not have information to indicate that presence of the western
jumping mouse constitutes a threat to the Prebles.
Climate change is another issue of potential concern. According to
the IPCC (2007, p. 2), ``Warming of the climate system is unequivocal,
as is now evident from observations of increases in global average air
and ocean temperatures, widespread melting of snow and ice, and rising
global average sea level.'' Average Northern Hemisphere temperatures
during the second half of the 20th century were very likely higher than
during any other 50-year period in the last 500 years and likely the
highest in at least the past 1,300 years (IPCC 2007, p. 2). It is very
likely that over the past 50 years: cold days, cold nights, and frosts
have become less frequent over most land areas, and hot days and hot
nights have become more frequent (IPCC 2007, p. 2). It is likely that:
Heat waves have become more frequent over most land areas, and the
frequency of heavy precipitation events has increased over most areas
(IPCC 2007, p. 2). It is difficult to ascertain what impact these
changes have had on the subspecies.
The IPCC (2007, p. 7) predicts that changes in the global climate
system during the 21st century are very likely to be larger than those
observed during the 20th century. For the next two decades, a warming
of about 0.2 [deg]C (0.4 [deg]F) per decade is projected (IPCC 2007, p.
7). Afterward, temperature projections increasingly depend on specific
emission scenarios (IPCC 2007, p. 7). Various emissions scenarios
suggest that by the end of the 21st century, average global
temperatures are expected to increase 0.6 to 4.0 [deg]C (1.1 to 7.2
[deg]F) with the greatest warming expected over land (IPCC 2007, pp. 7-
9). Localized projections suggest the West may experience among the
greatest temperature increase of any area in the lower 48 States (IPCC
2007, p. 9). The IPCC says it is very likely that hot extremes, heat
waves, and heavy precipitation will increase in frequency (IPCC 2007,
p. 8). There also is high confidence that many semi-arid areas like the
western United States will suffer a decrease in water resources due to
climate change (IPCC 2007, p. 8).
While these global and regional projections are the most accurate
use of
[[Page 39831]]
the available models, we also attempted to obtain more localized
predictions. Specifically, we submitted an information request for
climate change projections specific to the range of the subspecies to
the National Center for Atmospheric Research via their Regional
Climate-Change Projections Multi-Model Ensembles program. As of this
writing, we have not received a response.
Potential impacts to the Prebles from predicted future climate
changes are somewhat uncertain. A trend of warming in the mountains of
western North America is expected to decrease snowpack, hasten spring
runoff, and reduce summer flows (IPCC 2007, p. 11). Stream-flow
reductions or seasonal changes in flow due to climate change will
probably cause a greater disruption in those watersheds with a high
level of human development (Hurd et al. 1999, p. 1402). The three major
river basins that support the Prebles have heightened vulnerability to
the effects of climate change due to the degree of human development
(particularly in Colorado), natural variability in stream flow, ratio
of precipitation lost to evapotranspiration, and groundwater depletion
(Hurd et al. 1999, p. 1404). Conflicts between human needs for water
and maintenance of existing wetland and riparian habitats could be
heightened. While fewer cold days and nights could result in increased
vegetative yield in colder environments, increased summer heat may
increase the frequency and intensity of wildfires, and areas affected
by drought may increase (IPCC 2007, p. 13). Overall, it appears
reasonable to assume that Prebles will be affected negatively by
climate change, and that changes in stream flows and resultant effects
on riparian habitats may be a key factor. Adverse impacts seem more
likely in those drainages where human demand for water resources is
greatest; however, we lack sufficient certainty to predict more
specifically how climate change will affect Prebles' populations.
While many uncertainties remain regarding other natural or manmade
factors, we believe the best available scientific and commercial data
are insufficient to indicate that these factors are a threat to the
long-term conservation status of the Prebles. To the extent that
meaningful impacts are possible, small and fragmented mouse populations
are likely to be more vulnerable.
Conclusion of the 5-Factor Analysis
As required by the Act, we considered the five potential threat
factors to assess whether the Prebles is threatened or endangered
throughout all or a significant portion of its range. When considering
the listing status of a species, the first step in the analysis is to
determine whether the species is in danger of extinction throughout all
of its range. If this is the case, then we list the species in its
entirety. For instance, if the threats to a species are directly acting
on only a portion of its range, but they are at such a large scale that
they place the entire species in danger of extinction, we would list
the entire species.
Destruction and modification of habitat and the resulting
curtailment of range is the most significant factor affecting the
future conservation status of the subspecies. Within Wyoming, new
distributional data and a better understanding of threats has altered
our perception of the subspecies' status in this portion of its range.
At the time of listing, the Prebles was not known to exist in the North
Platte River basin and known from only two sites in Wyoming's portion
of the South Platte River basin (63 FR 26517). Since listing,
additional distributional data has verified that the subspecies is
widespread in the North Platte River basin with demonstrated occupancy
in 4 drainages (Glendo Reservoir, Lower Laramie, Horse Creek, and Upper
Laramie) and at least 15 rivers or streams (North Platte River,
Cottonwood Creek, Cottonwood Creek tributaries, North Laramie River,
Sturgeon Creek, Wyman Creek, Rabbit Creek, Luman Creek, Chugwater
Creek, Chugwater Creek tributaries, Sybille Creek, Friend Creek, Friend
Park area, Bear Creek, Bear Creek tributaries, Horse Creek, and Horse
Creek tributaries). Based on habitat availability, apparent historic
occupancy (Jones 1981, p. 469), recent untested Zapus captures (some of
which may be Prebles), and proximity to the confirmed Prebles in
Douglas, Wyoming, we believe the subspecies also may occur along
multiple rivers or streams in a fifth North Platte drainage (the Middle
North Platte). Trapping efforts to date suggest that the subspecies may
remain limited in number and distribution within the Wyoming portion of
the South Platte River basin.
While abundance information is limited, the existence of large,
connected areas of suitable habitat with confirmed Prebles occurrence
records (USFWS 2003b, pp. iv, 29; Beauvais 2004; USFWS 2008) suggests
that Wyoming supports one large population (with a June abundance of
greater than 2,500 adults) and two medium-sized populations (with a
June abundance of more than 500 adults). In the absence of significant
threats, these large and medium populations are believed large enough
to be self-sustaining. Furthermore, Wyoming's large and medium
populations are distributed across three different drainages (including
the Chugwater Creek portion of the Lower Laramie drainage, the Horse
Creek portion of the Horse drainage, and the Cottonwood Creek portion
of the Glendo Reservoir drainage), distributing risk from any one
catastrophic or stochastic event.
An improved understanding of the subspecies' distribution,
including the subspecies' continued occurrence in grazed portions of
Wyoming, suggests that historical agricultural activities, such as
grazing and haying, have had a minimal impact on the subspecies to date
(as discussed in greater detail in Factor A above). In short,
continuation of these long-standing activities appears supportive of
existing Prebles' populations. We have no indication these agricultural
practices are likely to change in the foreseeable future in ways that
would affect the subspecies' long-term conservation status. A low
projected human population growth rate is predicted for the four
Wyoming counties occupied by the Prebles, suggesting that few
development-related threats are likely in this portion of the
subspecies' range into the foreseeable future.
Other factors considered included: overutilization, disease,
predation, fire, flooding, drought, invasive weeds, weed control
programs, pesticides, herbicides, non-point source pollution, secondary
impacts associated with human development, scarcity, the potential for
competition between the Prebles and the western jumping mouse, and the
future effects of climate change. Although questions remain regarding
some of these factors, we do not have sufficient information to
indicate that any of these factors, individually or cumulatively, are a
threat to the subspecies' long-term conservation status in this portion
of its range. To the extent that meaningful impacts are possible, these
factors are likely to be most significant to small and fragmented
populations. In Wyoming, we expect these factors will continue to have
only small, localized impacts on the subspecies.
Threats to the Colorado portion of range (discussed in more detail
below), indicate that, in the absence of the Act's protections, most of
the Colorado Prebles' populations will face a high risk of extirpation
within the foreseeable future. While properties in public ownership
provide some meaningful protections across portions of Colorado
[[Page 39832]]
(particularly in high-elevation and headwater areas), these areas are
not adequate to provide for the subspecies' long-term well-being in
Colorado in the absence of the Act's protections.
Based on a better understanding of distribution and threats, we
find that the available data do not support the conclusion that the
Prebles is likely to become endangered in the foreseeable future
throughout ``all'' of its range. Overall, in the absence of the Act's
protective measures, we believe the subspecies will likely remain
secure and well distributed across Wyoming into the foreseeable future.
Distributional data has verified that the subspecies is more widespread
in the North Platte River basin of Wyoming than previously known, and
we are not aware of any threats that are likely to have significant
effects on the long-term conservation status of populations of Prebles
in this portion of its range. We expect threats to the Wyoming portion
of the subspecies' range to be minor with only small and localized
effects. We believe North Platte populations are sufficiently large and
widely distributed to withstand these impacts. We conclude that the
lack of present or threatened impacts to the Prebles in these areas
indicates that this subspecies is neither in danger of extinction, nor
likely to become endangered within the foreseeable future, throughout
all of its range. Thus, the Prebles does not merit continued listing as
threatened throughout all of its range.
Having determined that the Prebles does not meet the definition of
threatened or endangered in all of its range, we must next consider
whether there are any significant portions of the subspecies' range
that are in danger of extinction or are likely to become endangered in
the foreseeable future. On March 16, 2007, a formal opinion was issued
by the Solicitor of the Department of the Interior, ``The Meaning of
`In Danger of Extinction Throughout All or a Significant Portion of Its
Range' '' (U.S. Department of the Interior 2007). We have summarized
our interpretation of that opinion and the underlying statutory
language below. A portion of a species' range is significant if it is
part of the current range of the species and is important to the
conservation of the species because it contributes meaningfully to the
representation, resiliency, or redundancy of the species. The
contribution must be at a level such that its loss would result in a
decrease in the ability to conserve the species.
The first step in determining whether a species is threatened or
endangered in a significant portion of its range is to identify any
portions of the range of the species that warrant further
consideration. The range of a species can theoretically be divided into
portions in an infinite number of ways. However, there is no purpose to
analyzing portions of the range that are not reasonably likely to be
both significant and either threatened or endangered. To identify those
portions that warrant further consideration, we determine whether there
is substantial information indicating that (1) the portions may be
significant, and (2) the species may be in danger of extinction there
or likely to become so within the foreseeable future. In practice, a
key part of this analysis is whether the threats are geographically
concentrated in some way. If the threats to the species are essentially
uniform throughout its range, no portion is likely to warrant further
consideration. Moreover, if any concentration of threats applies only
to portions of the range that are unimportant to the conservation of
the species, such portions will not warrant further consideration.
If we identify any portions that warrant further consideration, we
then determine whether in fact the species is threatened or endangered
in any significant portion of its range. Depending on the biology of
the species, its range, and the threats it faces, it may be more
efficient for the Service to address the significance question first,
or the status question first. Thus, if the Service determines that a
portion of the range is not significant, the Service need not determine
whether the species is threatened or endangered there; if the Service
determines that the species is not threatened or endangered in a
portion of its range, the Service need not determine if that portion is
significant.
The terms ``resiliency,'' ``redundancy,'' and ``representation''
are intended to be indicators of the conservation value of portions of
the range. Resiliency of a species allows the species to recover from
periodic disturbances. A species will likely be more resilient if large
populations exist in high-quality habitat that is distributed
throughout the range of the species in such a way as to capture the
environmental variability found within the range of the species. It is
likely that the larger size of a population will help contribute to the
viability of the species overall. Thus, a portion of the range of a
species may make a meaningful contribution to the resiliency of the
species if the area is relatively large and contains particularly high-
quality habitat or if its location or characteristics make it less
susceptible to certain threats than other portions of the range. When
evaluating whether or how a portion of the range contributes to
resiliency of the species, it may help to evaluate the historical value
of the portion and how frequently the portion is used by the species.
In addition, the portion may contribute to resiliency for other
reasons; for instance, it may contain an important concentration of
certain types of habitat that are necessary for the species to carry
out its life-history functions, such as breeding, feeding, migration,
dispersal, or wintering.
Redundancy of populations may be needed to provide a margin of
safety for the species to withstand catastrophic events. This concept
does not mean that any portion that provides redundancy is per se a
significant portion of the range of a species. The idea is to conserve
enough areas of the range such that random perturbations in the system
act on only a few populations. Therefore, we must examine each area
based on whether that area provides an increment of redundancy that is
important to the conservation of the species.
Adequate representation ensures that the subspecies' adaptive
capabilities are conserved. Specifically, we should evaluate a portion
to see how it contributes to the genetic diversity of the species. The
loss of genetically based diversity may substantially reduce the
ability of the species to respond and adapt to future environmental
changes. A peripheral population may contribute meaningfully to
representation if there is evidence that it provides genetic diversity
due to its location on the margin of the species' habitat requirements.
Based on the discussion in our 5-factor threats analysis above, we
readily identified the Colorado portion of the current range of the
Prebles as warranting further consideration to determine if it is a
significant portion of the range that is threatened or endangered. Even
with the new information confirming the extent of the range in Wyoming,
the range in Colorado still constitutes a substantial portion of the
current range, and the threats are largely concentrated in that
portion.
We considered the question of how to define the portion of the
current range that we would consider further. We concluded that it was
appropriate to consider all of the current range in Colorado as a
single portion of the range for the purpose of this analysis. We have
determined that the Wyoming/Colorado State line is an appropriate
delineation for separating the populations in the two States because
the respective threats to the subspecies appear to be
[[Page 39833]]
significantly different in the two States. Furthermore, Prebles'
populations in the Upper Lodgepole, Upper Laramie, Crow Creek, and Lone
Tree Creek drainages are not known in Colorado, and Prebles'
populations in the Cache La Poudre drainage are not known to occur in
Wyoming. While our survey data is limited, this suggests use of the
State line is unlikely to split any Prebles' populations into
federally-protected and unprotected segments.
While we also considered splitting the subspecies into significant
portions of the range based on river basins (i.e., only removing
protections in the drainages of the North Platte River basin), it is
unlikely the split between the North Platte and South Platte River
basins are an appreciably more meaningful biological divide. The
available information suggests that: Prebles populations are known from
the headwater portions of both the Upper Lodgepole drainage within the
South Platte River basin and the Horse Creek drainage within the North
Platte River basin; suitable habitat from these drainages come within a
few hundred meters of each other; and the habitat in this area, while
not ideal for traversing, lacks an obvious physical barrier. This
apparent proximity and lack of barriers suggest occasional crossing may
occur. This contrasts with the areas on either side of the State line
where apparently unoccupied and unsuitable habitat predominates.
Furthermore, we believe using basins to divide the significant portion
of range would be more difficult to administer. Thus, given that there
does not appear to be any additional biological benefit to the
subspecies and our assertion that the respective threats to the Prebles
appear to be significantly different in the two States, we have
determined that the State line represents the appropriate northern
boundary for the Colorado significant portion of range.
Within Colorado, threats to the Prebles are comparable between the
South Platte River basin and Arkansas River basin. Similarly, threats
to the Prebles are comparable north and south of Denver. Because both
of these possible partitions have a comparable status, further division
of the subspecies' range between these two portions of its range in
Colorado is, at present, unnecessary.
Another possibility we considered was whether smaller units might
be appropriate. For example, we considered each individual drainage or
each individual county. Given the best scientific and commercial
information available, we concluded that such subdivisions would not
result in units that would each meaningfully contribute to the
representation, resiliency, or redundancy of the subspecies at a level
such that its loss would result in a decrease in the ability to
conserve the subspecies. In our view, only when drainages or counties
are aggregated are they significant per the above definition. The most
logical aggregation of drainages is basins, which are already
considered above. The most logical aggregation of counties within
Colorado is a north and south of Denver split, which also is already
considered above. Therefore, further division of the subspecies' range
within Colorado is either not appropriate or unnecessary.
To determine whether the Prebles is threatened in any significant
portion of its range, we first consider how the concepts of resiliency,
representation, and redundancy apply to the conservation of this
particular subspecies. The Colorado portion of the range meaningfully
affects resiliency in that it encompasses a high percentage of the
entire range's large blocks of high quality habitat, and contributes to
the species' long-term viability by allowing it to recover from
disturbance and respond resiliently to environmental change. Similarly,
presumed sizable populations within this portion of range are
sufficiently robust to make a high contribution to the ability of the
subspecies to recover from periodic disturbance. The Preliminary Draft
Recovery Plan accounts for resiliency by calling for the long-term
protection of a number of large and medium populations. The Recovery
Team estimated that large and medium populations would require a
network of 72 to 126 km (45 to 78 mi) and 14 to 26 km (9 to 16 mi),
respectively, of connected streams (mainstem plus tributaries) whose
hydrology supports riparian vegetation and provides Prebles' habitat
(USFWS 2003b, p. 25). The Colorado portion of the range meaningfully
affects resiliency in that it includes three of the four large
populations and three of the five medium populations called for in the
Preliminary Draft Recovery Plan (USFWS 2003b, p. 22). These
recommendations may have slightly overestimated Colorado's contribution
to resiliency as the Preliminary Draft Recovery Plan assumed no
occupancy in the Upper Laramie drainage (which appears to be occupied
and may support sizable populations) and the Middle North Platte-Casper
(which may be occupied, although current occupancy has not been
confirmed). Even if one assumes additional sizable populations in these
Wyoming drainages, the Colorado portion of the subspecies' range offers
a high level of contribution to the subspecies' resiliency.
The Colorado portion of the range meaningfully affects redundancy
in that it appears to make: a high level of contribution to the total
range of the subspecies; a high level of contribution to the total
population of the subspecies; a medium to high level of contribution to
the total suitable habitat; and a high level of contribution to the
geographic distribution of the subspecies. Specifically, the Colorado
portion of range includes all or substantial portions of 13 of the 19
drainages comprising the current range of the Prebles (9 of which have
confirmed occupancy in Colorado). Furthermore, this portion of range
includes 2 of the 3 river basins within the subspecies' range (all of
the Arkansas River basin and the vast majority of the South Platte
River basin) amounting to approximately half of the subspecies'
potential suitable habitat. While Colorado totaled about 65 percent of
the proposed critical habitat by river-mile and total acreage (67 FR
47154, July 17, 2002), this estimate may have overestimated Colorado's
share of suitable habitat as recent data suggests a more widespread
distribution across the North Platte River basin in Wyoming. Still,
Colorado populations of Prebles are a major contributor to the total
population of the subspecies and loss of the subspecies across this
portion of the range would result in a substantial gap in the range of
the subspecies. Collectively, this confirms that the Colorado portion
of the subspecies' range offers a high level of contribution to the
subspecies' redundancy.
Finally, the Colorado portion of the range meaningfully affects
representation in that it makes a high level of contribution to the
genetic diversity of the subspecies. The available data demonstrate
that Colorado populations demonstrate genetic material substantially
unique with significant differences among populations north and south
of Denver. Specifically, 3 of the 4 known mtDNA control region
haplotypes are limited to Colorado populations with 2 of the 4 known
mtDNA control region haplotypes only occurring south of Denver (King et
al. 2006b, p. 4358). Within the mtDNA cytochrome b region, 17 of 21
haplotypes are limited to Colorado populations, with 9 of the 21
haplotypes only occurring south of Denver (King et al. 2006b, p. 4359).
Microsatellite DNA data also demonstrates significant divergence
[[Page 39834]]
within the subspecies north and south of Denver. Again, the above
estimates may slightly overestimate Colorado's share of the subspecies'
genetic diversity and divergence as King et al. (2006b, p. 4333) only
analyzed 28 Wyoming specimens. Still, this confirms that the Colorado
portion of the subspecies' range offers a high level of contribution to
the subspecies' representation.
We conclude that the loss of the Prebles within Colorado would
result in a decrease in the ability to conserve the subspecies. We have
determined that, based on its importance to the conservation of the
subspecies and because it contributes meaningfully to Prebles'
representation, resiliency, or redundancy, the Colorado portion of the
range constitutes a significant portion of the subspecies' range as
described in the Act.
If we identify any portions as significant, we then determine
whether in fact the species is threatened or endangered in this
significant portion of its range. Within Colorado, riparian habitat has
been severely modified or destroyed by human activities. With current
and projected human population increases and commensurate increases in
urban and rural development, road construction, and water use, the
ongoing loss and modification of riparian habitat will continue in much
of the Prebles' Colorado range. Even with the protections of the Act,
development in Colorado has continued to affect Prebles' habitat, both
directly and indirectly. The best currently available information
suggests that at least half of the Prebles' current range in Colorado
is on private land with potential for future development. In the
absence of the Act's protections, most of this habitat could be lost or
degraded within the foreseeable future. While appreciable lands in
Colorado supporting the Prebles are controlled by Federal or State
agencies, or have been set aside as open space by local governments,
many of these areas also are likely to experience some habitat
degradation in the absence of the Act's protections. Some of these
areas will experience negative indirect effects from upstream
development. Where conservation properties are not extensive, the
Prebles' populations are likely to become small, fragmented, and
unsustainable. Additional recovery efforts are required to establish
and protect extensive contiguous conservation properties in Colorado.
Besides ``present or threatened destruction, modification, or
curtailment of its habitat or range,'' a variety of other factors were
considered including: overutilization, disease, predation, fire,
flooding, drought, invasive weeds, weed control programs, pesticides,
herbicides, non-point source pollution, secondary impacts associated
with human development, scarcity, the potential for competition between
the Prebles and the western jumping mouse, and the future effects of
climate change. In general, we do not have conclusive information to
indicate that these factors are, individually, a threat to the
subspecies' long-term conservation status. To the extent that
meaningful impacts are possible, these factors are likely to be most
significant to smaller and more fragmented populations. Thus, we expect
these issues could be meaningful as cumulative impacts in the Colorado
portion of subspecies' range where development pressures are likely to
substantially reduce and fragment populations.
Our improved understanding of the subspecies' range in Colorado
does not change our conclusion as to the Prebles' status in this
portion of the subspecies' range. As noted above, new data have
expanded the confirmed distribution of the Prebles to include
additional sites in Boulder, Douglas, El Paso, Jefferson, and Larimer
counties. Most of the newly discovered sites are subject to the same
level of threats discussed above. Thus, recently documented sites in
Colorado do not meaningfully alter the future conservation status of
the subspecies in this portion of its range.
Determining whether a significant portion of range is threatened or
endangered requires a consideration of the magnitude and immediacy of
threats. Growth patterns suggest continuous development radiating out
from urban/suburban centers across nearly all non-protected portions of
the subspecies' range within the foreseeable future. Prebles'
populations closest to these urban/suburban centers will be subject to
high-magnitude, imminent threats that would, in the absence of the
Act's protections, extirpate populations in the near future. At
present, none of Colorado's presumed large or medium populations
currently face such high magnitude, imminent threats. This suggests
this significant portion of range is not in danger of extinction (i.e.,
not currently endangered).
Prebles' populations further from these urban/suburban centers face
gradually escalating threats over the foreseeable future as
development's footprint expands into important suitable and occupied
Prebles habitat. In the absence of the Act's protections, within the
foreseeable future, most Prebles' populations will be faced with a high
risk of extirpation. The available information suggests that the Cache
La Poudre system may be the only drainage approaching sufficient
quantity and quality of protected habitat to provide for the
subspecies' long-term conservation needs. Thus, based on the best
scientific and commercial information available, we find that, in the
absence of the Act's protections, the Prebles is likely to become
endangered within the foreseeable future throughout the Colorado
portion of its range (i.e., currently threatened). That said, we
believe, with continued protection and additional strategic recovery
efforts, recovery will eventually be achieved in the Colorado portion
of the subspecies' range.
In conclusion, the best scientific and commercial data suggest that
the Prebles is not likely to become endangered in the foreseeable
future throughout all of its range. We base this conclusion primarily
on a lack of present or threatened impacts to the Prebles or its
habitat in Wyoming. However, based on the magnitude of development
threats and other pressures to the populations throughout the Colorado
portion of the range, and the lack of effective regulatory mechanisms
in the absence of the Act's protective measures, we conclude that the
significant portion of the subspecies' range within Colorado continues
to meet the definition of threatened under the Act, and should remain
listed. Therefore, we are amending the listing for the Prebles to
specify that the subspecies is threatened in only the Colorado portion
of its range.
Determining the Boundary of the Significant Portion of the Range
In determining the boundaries of the significant portion of its
range where the subspecies is threatened, we may consider factors such
as whether there is a biological basis (e.g., population groupings,
genetic differences, or differences in ecological setting) or
differences in threats due to regulatory basis (e.g., international or
State boundaries where the threats might be different on either side of
the boundary) for dividing the range into finer portions and whether
extinction risk is spread evenly across the range of the subspecies.
Significant portion of range boundaries may consist of geographical
features, constructed features (e.g., roads), or administrative
boundaries at any scale when biological factors are the basis for
defining the significant portion of range.
If we determine a subspecies is threatened in a specified
significant portion of range, the boundaries used to
[[Page 39835]]
legally define the extent of a significant portion of range are
identified. We used here the following principles to determine the
boundaries:
(1) Boundaries enclose and define the area where threats are
sufficient to result in a determination that a portion of a subspecies'
range is significant, and is endangered or threatened.
(2) Boundaries clearly define the portion of the range that is
specified as threatened or endangered, and may consist of geographical
or administrative features or a combination of both.
(3) Boundaries do not circumscribe the current distribution of the
subspecies so tightly that opportunities for recovery are foreclosed.
The scale of the boundaries is determined case-by-case to be
appropriate to the size of the portion of the subspecies' range, and
the availability of unambiguous geographic or administrative
boundaries. As previously stated the range of the subspecies is the
general area in which the subspecies can be found, including migratory
corridors, seasonal habitats, and habitats used on a regular, though
not necessarily seasonal, basis.
The scale at which one defines the range of a particular species is
fact and context dependant. In other words, whether one defines the
range at a relatively coarse or fine scale depends on the life history
of the species at issue, the data available, and the purpose for which
one is considering range.
The Prebles is secretive, almost never observed without trapping,
and relatively rare even where present. Confirmed occupancy is based
almost entirely on intensive trapping efforts, requiring hundreds of
trap nights. Prebles are able to move miles along stream corridors over
their lifetime (Schorr 2003), typically utilizing riparian (river)
corridors. Although the subspecies commonly uses riparian vegetation
immediately adjacent to a stream, other features that provide habitat
for the subspecies include seasonal streams (Bakeman 1997), low moist
areas and dry gulches (Shenk 2004), agricultural ditches (Meaney et al.
2003), and wet meadows and seeps near streams (Ryon 1996). Given
records of confirmed presence and patterns of existing riparian
habitat, we can draw inferences as to what we would consider occupied
drainages or portions of these drainages.
To date, aside from some earlier work from the CDOW and the
Colorado Natural Heritage Program, the objective of most trapping
surveys has not been to document the limits of occupied habitat in
Colorado. While much of the Prebles' distribution is on private lands,
most trapping surveys on private lands have been conducted by
consultants, based on anticipated development of the property by
landowners. This has resulted in far more trapping on private lands
within the expanding development corridor than on private lands in
rural lands where no development is planned. Therefore, we have less
assurance of current presence or potential absence of the Prebles in
areas further removed from the Front Range development corridor.
Trapping can only confirm presence, not prove absence. At some
sites, researchers have seen dramatic changes in estimated populations
from season-to-season and year-to-year (Meaney et al. 2002, p. 122;
Bakeman 2006, p. 4). A single trapping effort in any presumed occupied
site could be unsuccessful if it corresponded to times when few or no
mice are likely to be present. Prebles may move in and out of areas
(individuals have been shown to move miles along stream corridors over
their lifetime). In areas within the range of the subspecies, multiple
trap efforts in a drainage or portions of a drainage are needed to
provide strong evidence that Prebles are likely absent. Again, in many
areas outside the Front Range development corridor trapping has been
more limited; in some areas where presence has not been confirmed by
trapping we do not believe trapping data is determinative of the
Prebles' absence at particular sites, much less whole drainages or
portions thereof.
As with other determinations under the Act, we do not define the
current range on the basis of conclusive evidence; rather, we use the
best available data. The purpose of defining range (and hence the
significant portion of the range) is to set the boundaries of the
protections of the Act. Therefore, defining the boundaries too narrowly
may lead to the failure to protect some Prebles. On the other hand,
drawing the boundaries relatively expansively will not lead to
unnecessary expense on the part of the Service or the public because,
as described in detail below, existing guidance on block clearance
zones will remain in place. Therefore, in the context of describing the
current range for the purpose of defining the scope of the listing for
the Prebles, we have determined that it is appropriate to use a
relatively coarse scale to capture all of the areas where the best
available data, presented below, suggests the Prebles is likely to
occur. As noted above, boundaries are not to circumscribe the current
distribution of the subspecies so tightly that opportunities for
recovery are foreclosed.
The Preliminary Draft Recovery Plan suggests maintaining at least
one recovery population within each drainage (to provide resiliency,
representation, and redundancy) within the existing range of the
subspecies. The Preliminary Draft Recovery Plan, which represents the
best available science, identifies thirteen drainages in Colorado that
comprise the area significant to the conservation of the subspecies
including Big Sandy, Big Thompson, Bijou, Cache La Poudre, Chico, Clear
Creek, Crow Creek, Fountain Creek, Kiowa, Lone Tree-Owl, Middle South
Platte-Cherry Creek, Saint Vrain, and Upper South Platte (as
illustrated in Figure 3). Based on the assessments of habitat by the
Recovery Team, the Preliminary Draft Recovery Plan includes these
drainages as representing the current range of the subspecies on the
presumption that suitable habitat and at least a small population
occurs in each. An intent of the Preliminary Draft Recovery Plan is to
preserve populations throughout the existing range to maximize the
preservation of the remaining genetic diversity that may be present.
While we recognize that information is currently lacking to confirm the
presence of existing Prebles' populations in some of these drainages,
we believe that, based on the availability of suitable habitat (Pague
and Granau 2000, pp. 2-3, 5-3, 7-3), portions of these drainages may be
occupied.
For convenience in distinguishing this boundary on-the-ground we
employ latitude and longitude coordinates. We have concluded that the
latitude and longitude boundaries below provide an appropriate
delineation for the significant portion of the Prebles' range in
Colorado. These boundaries are inclusive of all areas likely to support
Prebles' populations in Colorado. As a result, all records confirming
Prebles' occurrence in Colorado are captured within these boundaries.
We think that it is highly unlikely that there will be discovery of
currently existing Prebles' populations outside these boundaries in
Colorado. Therefore, we conclude that removing protections outside
these boundaries in Colorado would be of little biological consequence.
Thus, based on best available data, we have identified the portion of
Colorado west of 103 degrees 40 minutes West, north of 38 degrees 30
minutes North, and east of 105 degrees 50 minutes West as the
significant portion of the range of the subspecies (illustrated in
Figure 3).
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[GRAPHIC] [TIFF OMITTED] TR10JY08.002
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[[Page 39837]]
Eastern Boundary (103 Degrees, 40 Minutes West)
This boundary is inclusive of all areas within the current Prebles'
survey guidelines (east to a north-south line through Fort Morgan,
Morgan County) (USFWS 2004), and also includes the eastern (downstream)
extent of the Big Sandy drainage (designated in the Preliminary Draft
Recovery Plan).
Southern Boundary (38 Degrees, 30 Minutes North)
This boundary is inclusive of all areas within the current survey
guidelines (south including all of El Paso County) and also includes
the majority of the Fountain Creek and Chico Creek drainages
(designated in the Preliminary Draft Recovery Plan). Habitat in the
southern portion of El Paso County is limited. The small portions of
the Fountain and Chico drainages that fall outside the boundary are
outside of the current survey guidelines and believed not to support
the Prebles.
Western Boundary (105 Degrees 50 Minutes West)
This boundary is inclusive of elevations up to and beyond 2,316 m
(7,600 ft) in the Cache La Poudre River, Clear Creek and Upper South
Platte drainages and all portions of the Big Thompson and St. Vrain
drainages. As such, it includes all high-elevation areas where we
believe that the Prebles is likely to occur.
Administrative Processes
As part of our management of the subspecies on-the-ground within
this significant portion of range area, the Service will continue to
use block clearance zones to eliminate unnecessary processes (e.g.,
compliance with section 7 of the Act) while protecting the listed
entity. In designating a block clearance zone, the Service eliminates
the need for individuals or agencies to coordinate with the Service
prior to conducting activities at locations within the Prebles' range
when the area affected by the action is wholly contained within the
designated block clearance zone. The establishment of these block
clearance zones is based on the likely absence of the subspecies within
the area, and little likelihood that any of the area would be of
importance to the recovery of the subspecies. Block clearance zones
have been approved for the Denver metropolitan area (including most of
Denver County and portions of Adams, Arapahoe, Boulder, Broomfield,
Douglas, and Jefferson counties) and along Monument, Cottonwood, and
Sand creeks in the Colorado Springs area. While this substantially
reduces the regulatory burden, should an individual Prebles be found in
a block-cleared area, it would be fully protected under the Act. In
addition, outside of the block clearance zone, but within the
significant portion of range, we would continue to identify, on a
project-by-project basis, whether surveys for the Prebles are needed
based on whether suitable habitat is present within the action area of
the project and results of recent trapping surveys nearby.
We considered excluding block clearance zones from the listing as
outside the current range of the subspecies, but we have concluded that
approach would be impractical and ill-advised. For example, Prebles'
block clearance zones expand on a near annual basis. If a revision to
the Code of Federal Regulations was required to achieve this revision,
the process would require annual proposed and final rules. This
approach would be both unwieldy from a workload perspective and result
in an unnecessary delay in reducing our regulatory oversight as this
process typically takes a year to complete. Furthermore, the listing
backlog (i.e., a shortfall of funds that preclude the listing of
species that are warranted-but-precluded from threatened or endangered
status and the designation of critical habitat) would preclude
relisting areas even if future information suggests the area was
removed prematurely (unless emergency listing was deemed appropriate).
This double standard as well as the difficult and time-consuming nature
of the process suggests this approach is not realistic, not desirable,
and inappropriate. As we have in the past, the Service will consider
modification of the current block-clearance zones, or the addition of
new zones, when the available data demonstrate such an action is
appropriate.
Effects of the Rule
This action amends the listing for the Prebles by specifying that
the subspecies is threatened in the Colorado portion of its range. The
prohibitions and conservation measures provided by the Act,
particularly through sections 7 and 9, no longer apply to this
subspecies in Wyoming. Federal agencies are no longer required to
consult with us to ensure that any action they authorize, fund, or
carry out in Wyoming would not likely jeopardize the continued
existence of the subspecies or result in destruction of or adversely
modify critical habitat in Wyoming. However, to the extent an activity
in Wyoming would adversely affect the subspecies or critical habitat
within its range listed in Colorado, consultation under section 7 would
still be required. The take exemptions of the 4(d) special rule are no
longer necessary and, therefore, no longer apply in Wyoming (May 22,
2001, 66 FR 28125; October 1, 2002, 67 FR 61531; May 20, 2004, 69 FR
29101). This action eliminates critical habitat (June 23, 2003, 68 FR
37275) in Wyoming.
Paperwork Reduction Act
This rule does not contain any new collections of information that
require approval by the Office of Management and Budget (OMB) under the
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.). This rule
will not impose recordkeeping or reporting requirements on State or
local governments, individuals, businesses, or organizations. An agency
may not conduct or sponsor, and a person is not required to respond to,
a collection of information unless it displays a currently valid OMB
control number.
National Environmental Policy Act
The Service has determined that Environmental Assessments and
Environmental Impact Statements, as defined under the authority of the
National Environmental Policy Act of 1969, need not be prepared in
connection with regulations adopted pursuant to section 4(a) of the
Act. A notice outlining the Service's reasons for this determination
was published in the Federal Register on October 25, 1983 (48 FR
49244).
References
A complete list of all references cited herein is available upon
request from the Colorado Field Office (see ADDRESSES).
Author
The primary authors of this document are staff located at the
Colorado Field Office (see ADDRESSES).
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
record keeping requirements, Transportation.
Regulation Promulgation
0
Accordingly, we amend part 17, subchapter B of chapter I, title 50 of
the Code of Federal Regulations, as set forth below.
PART 17--[AMENDED]
0
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.
4201-4245; Pub. L. 99-625, 100 Stat. 3500; unless otherwise noted.
[[Page 39838]]
0
2. Amend Sec. 17.11(h) by revising the entry for ``Mouse, Preble's
meadow jumping'' under ``MAMMALS'' in the List of Endangered and
Threatened Wildlife to read as follows:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Vertebrate
-------------------------------------------------------- population where Critical Special
Historic range endangered or Status When listed habitat rules
Common name Scientific name threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mammals
* * * * * * *
Mouse, Preble's meadow jumping... Zapus hudsonius U.S.A. (CO, WY)..... U.S.A., north- T 636 17.95(a) 17.40(l)
preblei. central CO (that
portion of
Colorado west of
103 degrees 40
minutes West,
north of 38
degrees 30 minutes
North, and east of
105 degrees 50
minutes West).
* * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
0
3. Amend Sec. 17.40(l) as follows:
0
a. By revising paragraph (l)(2)(vi)(E) to read as set forth below; and
0
b. By revising paragraph (l)(4) to read as set forth below.
Sec. 17.40 Special rules--mammals.
* * * * *
(l) * * *
(2) * * *
(vi) * * *
(E) Any future revisions to the authorities listed in paragraphs
(l)(2)(vi)(A) through (D) of this section that apply to the herbicides
proposed for use within the species' range as specified in the fourth
column of the table in Sec. 17.11(h).
* * * * *
(4) Where does this rule apply? The take exemptions provided by
this rule are applicable within the significant portion of the range of
the Preble's meadow jumping mouse as specified in the fourth column of
the table in Sec. 17.11(h).
* * * * *
Sec. 17.95 [Amended]
0
4. In Sec. 17.95(a), amend the entry for ``Preble's Meadow Jumping
Mouse (Zapus hudsonius preblei)'' by removing paragraphs (4) through
(7), and by redesignating paragraphs (8) through (13) as (4) through
(9), respectively.
Dated: June 26, 2008.
H. Dale Hall,
Director, U.S. Fish and Wildlife Service.
[FR Doc. E8-15141 Filed 7-9-08; 8:45 am]
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