[Federal Register: December 3, 2009 (Volume 74, Number 231)]
[Proposed Rules]
[Page 63343-63366]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr03de09-14]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FWS-R6-ES-2008-0111] [MO 92210 50083 B2]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition to List the Black-tailed Prairie Dog as Threatened or
Endangered
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of a 12-month petition finding.
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[[Page 63344]]
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce our
12-month finding on a petition to list the black-tailed prairie dog
(Cynomys ludovicianus) as threatened or endangered under the Endangered
Species Act of 1973, as amended (Act). After review of all available
scientific and commercial information, we find that listing the black-
tailed prairie dog as either threatened or endangered is not warranted
at this time. However, we ask the public to continue to submit to us
any new information that becomes available concerning the status of, or
threats to, the black-tailed prairie dog or its habitat at any time.
This information will help us to monitor and conserve the species.
DATES: The finding announced in this document was made on December 3,
2009.
ADDRESSES: This finding is available on the Internet at http://
www.regulations.gov. Supporting documentation we used in preparing this
finding is available for public inspection, by appointment, during
normal business hours at the U.S. Fish and Wildlife Service, South
Dakota Ecological Services Office, 420 South Garfield Avenue, Suite
400, Pierre, SD 57501; telephone (605) 224-8693. Please submit any new
information, materials, comments or questions concerning this finding
to the above street address.
FOR FURTHER INFORMATION CONTACT: Pete Gober, Field Supervisor, U.S.
Fish and Wildlife Service, South Dakota Ecological Services Office (see
ADDRESSES section). If you use a telecommunications device for the deaf
(TDD), call the Federal Information Relay Service (FIRS) at 800-877-
8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Endangered Species Act of 1973, as
amended (Act) (16 U.S.C. 1531 et seq.), requires that for any petition
to revise the Federal Lists of Endangered and Threatened Wildlife and
Plants that contains substantial scientific and commercial information
indicating that listing the species may be warranted, we make a finding
within 12 months of the date of receipt of the petition. In this
finding, we will determine that the petitioned action is: (a) not
warranted, (b) warranted, or (c) warranted but the immediate proposal
of a regulation implementing the petitioned action is precluded by
other pending proposals to determine whether species are threatened or
endangered, and expeditious progress is being made to add or remove
qualified species from the Federal Lists of Endangered and Threatened
Wildlife and Plants. Such 12-month findings must be published in the
Federal Register.
Previous Federal Actions
We received a petition dated October 21, 1994, from the
Biodiversity Legal Foundation and Jon C. Sharps, to classify the black-
tailed prairie dog as a Category 2 candidate species. Category 2
includes taxa for which information in our possession indicates that a
proposed listing rule was possibly appropriate, but for which
sufficient data on biological vulnerability and threats were not
available to support a proposed rule. We reviewed the petition and on
May 5, 1995, we concluded that the black-tailed prairie dog did not
warrant Category 2 candidate status.
On July 31, 1998, we received a petition from the National Wildlife
Federation dated July 30, 1998, to list the black-tailed prairie dog as
threatened throughout its range. On August 26, 1998, we received
another petition to list the black-tailed prairie dog as threatened
throughout its range from the Biodiversity Legal Foundation, Predator
Project, and Jon C. Sharps. We accepted this second request as
supplemental information to the National Wildlife Federation petition.
On February 4, 2000, we announced a 12-month finding that issuing a
proposed rule to list the black-tailed prairie dog was warranted but
precluded by other higher priority actions (65 FR 5476), and the
species was included in the list of candidate species. Two candidate
assessments and resubmitted petition findings for the black-tailed
prairie dog were completed on October 30, 2001 (66 FR 54303), and June
13, 2002 (67 FR 40657). On August 18, 2004, we completed a resubmitted
petition finding for the black-tailed prairie dog (69 FR 51217)
concluding that listing the species was not warranted, and the species
was removed from the candidate list. This removal was the result of new
information regarding the amount of occupied habitat present throughout
the species' range and a reevaluation of potential threats. Estimates
from the 2004 finding were more accurate than those available during
the earlier assessments and indicated nearly 3 times more occupied
habitat was present than we originally believed. We concluded that the
trends in the amount of occupied habitat did not support listing the
species.
On February 7, 2007, Forest Guardians and others filed a complaint
challenging the decision to remove the black-tailed prairie dog from
the candidate list. On August 6, 2007, we received a formal petition
dated August 1, 2007, from Forest Guardians (now WildEarth Guardians),
Biodiversity Conservation Alliance, Center for Native Ecosystems, and
Rocky Mountain Animal Defense, requesting that we list the black-tailed
prairie dog throughout its historical range in Arizona, Colorado,
Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South
Dakota, Texas, and Wyoming and in Canada and Mexico. The petitioners
requested that, if the Service believes that Cynomys ludovicianus
arizonensis is a distinct subspecies or population segment, we list it
as threatened or endangered throughout its historical range. The
petitioners also requested that the Service designate critical habitat
for the species.
The petition clearly identified itself as a petition and included
the requisite identification information as required in 50 CFR
424.14(a). We acknowledged receipt of the petition in a letter on
August 24, 2007, and indicated that emergency listing of the black-
tailed prairie dog was not warranted. We also explained that we would
not be able to address their petition until fiscal year 2009, due to
existing court orders and settlement agreements for other listing
actions. However, in fiscal year 2008, funding became available, and we
began work on this petition finding. The plaintiffs withdrew their
February 7, 2007, complaint on October 9, 2007.
On March 13, 2008, WildEarth Guardians filed a complaint for
failure to complete a 90-day finding on their August 1, 2007, petition.
On July 1, 2008, a stipulated settlement and order was signed, in which
we agreed to submit a 90-day finding to the Federal Register by
November 30, 2008, and deliver a 12-month finding to the Federal
Register by November 30, 2009. We published a 90-day finding for the
black-tailed prairie dog in the Federal Register on December 2, 2008
(73 FR 73211). Today's notice constitutes the 12-month finding on the
August 1, 2007, petition to list the black-tailed prairie dog as
threatened or endangered.
Species Information
The black-tailed prairie dog is a member of the Sciuridae family,
which includes squirrels, chipmunks, marmots, and several species of
prairie dogs. Prairie dogs constitute the genus Cynomys. Taxonomists
currently recognize five species of prairie dogs belonging to two
subgenera, all in North America (Hoogland 2006a, pp. 8-9). The white-
tailed subgenus, Leucocrossuromys, includes Utah (C. parvidens), white-
tailed (C. leucurus), and Gunnison's prairie dogs (C. gunnisoni)
(Hoogland 2006a, pp. 8-9).
[[Page 63345]]
The black-tailed subgenus, Cynomys, consists of Mexican (C. mexicanus)
and black-tailed prairie dogs (Hoogland 2006a, pp. 8-9). Generally, the
black-tailed prairie dog occurs east of the other four species in less
xeric (dry) habitat (Hall and Kelson 1959, p. 365).
The Utah and Mexican prairie dogs are currently listed as
threatened (49 FR 22330, May 29, 1984) and endangered (35 FR 8491, June
2, 1970), respectively. The Gunnison's prairie dog is currently a
candidate species within the montane portion of its range (73 FR 6660,
February 5, 2008). The Service is considering whether listing is
warranted for the white-tailed prairie dog through a formal status
review which is due to be submitted to the Federal Register by June 1,
2010, under a court-approved settlement agreement.
Research on the evolutionary divergence of the various taxa and
populations of Cynomys indicates that the black-tailed prairie dog
should be considered a monotypic species (a taxonomic group without
lower level subdivisions) (Pizzimenti 1975, p. 64). Based on this
information, we determined that the black-tailed prairie dog is a valid
taxonomic species and a listable entity under the Act.
We also investigated the petitioners' request that we list the
subspecies Cynomys ludovicianus arizonensis if we found it to be a
distinct subspecies. The best available information indicates that C.
l. arizonensis is not a distinct subspecies (Pizzimenti 1975, p. 64).
Pizzimenti (1975, p. 64) researched the evolutionary divergence of the
various taxa and populations of Cynomys and concluded that the black-
tailed prairie dog should be considered a single monotypic species and
that further subspecific differentiation was not supported due to the
similarity of characteristics between purported subspecies. Later
research on the genetic variability within and among populations of
black-tailed prairie dogs in New Mexico also concluded that subspecies
classification could not be supported (Chesser 1983, p. 326).
Therefore, based on currently available information, we conclude that
there are no distinct subspecies of black-tailed prairie dog.
The black-tailed prairie dog is a burrowing, colonial mammal that
is brown in color (Hoogland 2006a, pp. 8-9). Black-tailed prairie dogs
are approximately 12 inches (in) (30 centimeters (cm)) in length and
weigh 1 to 3 pounds (lbs) (500 to 1,500 grams (g)) (Hoogland 2006a, pp.
8-9). Key characteristics distinguish the black-tailed prairie dog from
other prairie dog species:
(1) It has a longer (2 to 3 in (7-10 cm)) tail that is black-
tipped;
(2) It is generally non-hibernating, except possibly in the
northern and southern extremes of its range (Tuckwell and Everest 2009,
p. 1; Truett et al. 2007, p. 10); and
(3) It lives at lower elevations (2,300-7,200 feet (ft) (700-2,200
meters (m))) (Hoogland 2006a, pp. 8-9). Overlap of the geographic
ranges of the five species is minimal; consequently, species usually
can be identified by locality (Hall and Kelson 1959, p. 365; Hoogland
2006a, pp. 8-9).
The black-tailed prairie dog is typically found in level or gently
sloping short- and mixed-grass rangeland, primarily east of the Rocky
Mountains (Koford 1958, p. 8). The species is an herbivore, consuming
short-grasses such as buffalograss (Buchloe dactyloides) and blue grama
(Bouteloua gracilis) as well as several forb species (Koford 1958, p.
6). Prairie dogs also clip taller forage, without consuming it, to
enhance their detection of predators (Hoogland 2006a, p. 15). Numerous
species prey on the prairie dog including badger (Taxidea taxus),
coyote (Canis latrans), black-footed ferret (Mustela nigripes), golden
eagle (Aquila chrysaetos), and many other species of raptor (Hoogland
1995, pp. 14-15).
Several biological factors determine the reproductive potential of
the black-tailed prairie dog. Females live 4 to 5 years, usually do not
breed until their second year, and produce a single litter with an
average of three pups annually (Hoogland 2001, p. 917; Hoogland 2006b,
p. 29). Therefore, one female may produce zero to 15 young in its
lifetime. While the species is not prolific in comparison to many other
rodents, it is capable of rapid population increases after population
reductions (Collins et al. 1984, p. 360; Pauli 2005, p. 17; Reeve and
Vosburgh 2006, p. 144).
The colonial nature of prairie dogs, especially the black-tailed
prairie dog, is a noteworthy characteristic of the species (Miller et
al. 1996, p. 20). Historically, black-tailed prairie dogs generally
occurred in large complexes, containing multiple colonies that often
contained thousands of individuals. These complexes covered hundreds or
thousands of acres (ac), and extended for miles (Lantz 1903, p. 2671;
Bailey 1905, p. 90; Bailey 1932, p. 122; Ceballos et al. 1993, p. 109).
Currently, most colonies and complexes are much smaller.
Colonial behavior offers an advantageous defense mechanism by
aiding in the detection of predators and by deterring predators through
mobbing behavior (Hoogland 1995, pp. 3-6). Colonial behavior also
increases reproductive success through cooperative rearing of juveniles
and aids parasite removal via shared grooming (Hoogland 1995, pp. 3-6).
However, colonial behavior can increase the disadvantageous
transmission of disease (Olsen 1981, p. 236; Biggins and Kosoy 2001, p.
911; Antolin et al. 2002, p. 122). Plague is a disease that was
introduced to North America and can spread from prairie dog to prairie
dog through social behaviors such as grooming that transfers fleas
carrying the disease. The disease can also be transmitted by pneumonic
(airborne) or septicemic (blood) routes (see Threats Analysis, Factor
C).
An estimated 2.4 million ac (1 million hectares (ha)) of occupied
habitat exists in a constantly shifting mosaic throughout an estimated
283 million ac (115 million ha) of suitable habitat that occurs across
a range of approximately 440 million ac (178 million ha). Historically,
unsuitable habitat included wetlands, lands with steep slopes, lands
with shallow or sandy soils, and wooded areas. More recently, tilled
croplands and urban areas have also been considered to be only
marginally suitable. Black-tailed prairie dog colonies may expand or
contract from year to year (Koford 1958, p. 12). Whether a colony
expands or contracts depends on a combination of several factors such
as climate, poisoning, disease, and shooting. Prairie dogs may also
disperse over considerably long distances and establish new colonies.
Dispersal distances up to 6 miles (mi) (10 kilometers (km)) over a
period of a few weeks have been documented (Knowles 1985, p. 37).
Dispersal can maintain genetic diversity or restore it following plague
epizootics (Trudeau et al. 2004, p. 206).
The black-tailed prairie dog is considered a keystone species; that
is, it is an indicator of diverse species composition within an
ecosystem, and key to the persistence of that ecosystem (Kotliar et al.
1999, pp.183, 185). The black-footed ferret, swift fox (Vulpes velox),
golden eagle, and ferruginous hawk (Buteo regalis) use prairie dogs as
a food source. The mountain plover (Charadrius montanus) and burrowing
owl (Athene cunicularia) use habitat (burrows) created by prairie dogs
(Kotliar et al. 1999, pp. 181-182). The most obligatory species of this
group is the black-footed ferret, which has a clearly documented
dependence on the prairie dog (Linder et al. 1972, pp. 23-24; Kotliar
et al. 2006, pp. 55-57). Numerous other species share habitat
[[Page 63346]]
with prairie dogs, and rely on them to varying degrees (Kotliar et al.
2006, pp. 54-55).
Species Range
The historical range of the black-tailed prairie dog included
portions of 11 States (Arizona, Colorado, Kansas, Montana, Nebraska,
New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and Wyoming),
Canada, and Mexico (Hall and Kelson 1959, p. 365). This corresponds
approximately with the Great Plains Physiographic Province, a zone of
about 400 miles wide extending eastward from the Rocky Mountains.
Approximately 395 million ac (160 million ha) of potential habitat are
estimated to have existed across a range of approximately 440 million
ac (178 million ha) (Black-footed Ferret Recovery Foundation (BFFRF)
1999, p. 4; Ernst 2008, p. 2). The species currently exists in the same
11 States, Canada, and Mexico, from extreme south-central Canada to
northeastern Mexico and from approximately the 98\th\ meridian west to
the Rocky Mountains. This very roughly corresponds to the western
halves of North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, and
Texas and the eastern halves of Montana, Wyoming, Colorado, and New
Mexico. The species was largely extirpated from Arizona before 1940
(Arizona Game and Fish Department 1988, p. 22), and later described as
extinct in that State (Cockrum 1960, p. 76). However, in 2008, the
species was reintroduced into a small portion of its historical range
in Arizona via translocations from wild populations in New Mexico (Van
Pelt 2009, p. 41). Range contractions have occurred in the southwestern
portion of the species' range in Arizona, New Mexico, and Texas through
conversion of grasslands to desert shrub (Weltzin et al. 1997, pp. 758-
760; Pidgeon et al. 2001, p. 1773). In the eastern portion of the
species' range in Kansas, Nebraska, Oklahoma, South Dakota, and Texas,
range contractions are largely due to habitat destruction as a result
of cropland development (BFFRF 1999, p. 1).
Population Estimates
Most estimates of black-tailed prairie dog populations are based on
estimates of the amount of occupied habitat (Facka et al. 2008, p.
360), not numbers of individual animals. Biggins et al. (2006 p. 94)
evaluated several methodologies for estimating prairie dog populations
and concluded that counting actual numbers of prairie dogs is feasible
only for small areas. Determining the actual population of a colony
requires marking all colony residents. This method is reasonable for
only a small number (less than five) of small colonies (each with less
than 200 residents) because of the difficulty and impracticality of
catching and marking all residents (Biggins et al. 2006, p. 102).
Estimates of occupied habitat remain the best measure of estimating
prairie dog abundance over a larger area. The actual number of prairie
dogs present depends upon the density of animals in that locality.
Density of prairie dogs varies depending on the season, ecological
region, and climatic conditions, but typically ranges from 2 to 18
individuals per ac (5 to 45 per ha) in early spring, before the
emergence of young-of-the year (King 1955, p. 46; Koford 1958, pp. 10-
11; Hoogland 1995, p. 98; Fagerstone and Ramey 1996, p. 85). Prairie
dog occupied habitat may expand locally during drought, with a
concurrent decline in density, due to the extended foraging area needed
to obtain food. Density can also vary spatially and temporally due to
poisoning, plague, and recreational shooting as discussed in later
sections.
A more accurate large-scale estimate of occupied habitat can be
derived by applying a correction factor for percent occupancy (the
percent of habitat with burrows currently occupied by black-tailed
prairie dogs) to an initial estimate. We can estimate percent occupancy
via an on-site inspection of a portion of a survey area to confirm the
presence of prairie dogs. This is particularly important in colonies
that have been impacted by plague or poisoning. In these instances
burrows remain but prairie dogs are absent. This unoccupied habitat
should not be included in estimations of occupied habitat. We believe
that occupied habitat is a reasonable measure to use in evaluating the
persistence of the species inasmuch as comparisons involve millions of
acres (hectares) and several-fold more millions of individual prairie
dogs, whose numbers may fluctuate between and within years.
We have relied on the best available estimates of occupied habitat
from States, land managers, researchers, or other sources to evaluate
distribution, abundance, and trends of prairie dog populations. Recent
trends of prairie dog populations are an appropriate surrogate for
evaluating the status of the species.
Numerous estimates of black-tailed prairie dog occupied habitat are
available, spanning a time period from 1903 to the present. In Table 1,
we summarize historical estimates, estimates from a 1961 range wide
survey, and the most recent available estimates. The 1961 estimates
came from a Bureau of Sport Fisheries and Wildlife (BSFW) range wide
survey that followed large-scale poisoning efforts and represent a low
point in occupied habitat. Other estimates are from a variety of
agencies and individuals as cited in Table 1. Additional estimates
derived between 1961 and the most recent available estimates are also
available in the Service's 2000 12-month finding and in the 2004
species assessment that removed the black-tailed prairie dog from the
candidate list (Service 2000, p. 98; Service 2004, p. 7).
Some of these intermediate estimates are derived from field
efforts, others are based on censuses by phone or mail, and the
remainder are a result of desktop extrapolations. Desktop
extrapolations used known estimates of occupied habitat that existed
for portions of a state to derive a Statewide estimate for occupied
habitat. These studies provide intermediate estimates of occupied
habitat and additional information regarding trends.
Table 1. Occupied Habitat Estimates for the Black-tailed Prairie Dog
----------------------------------------------------------------------------------------------------------------
Historical ac 1961 (BSFW) ac Most Recent ac Year of Most
State or Country (ha)\A\ (ha)\A\ (ha) Recent Survey
----------------------------------------------------------------------------------------------------------------
Arizona 650,000 (263,000) 0 8 (3)\3\ 2008
\1\
1,396,000
(565,000) \2\.
----------------------------------------------------------------------------------------------------------------
Colorado 3,000,000 96,000 788,657 (319,158) 2006
(1,214,000) \4\ (39,000).......... \6\
5,445,000
(2,204,000) \2\.
7,000,000
(2,833,000) \5\.
----------------------------------------------------------------------------------------------------------------
[[Page 63347]]
Kansas 2,000,000 50,000 173,593 2006
(809,000) \7\ (20,000).......... (70,251)\3\
2,500,000
(1,012,000) \5\.
7,503,000
(3,036,000) \2\.
----------------------------------------------------------------------------------------------------------------
Montana 1,471,000 28,000 193,862 2008
(595,000) \8\ (11,000).......... (78,453)\9\
6,000,000
(2,428,000) \5\.
10,667,000
(4,317,000) \2\.
----------------------------------------------------------------------------------------------------------------
Nebraska 6,000,000 30,000 136,991 2003
(2,428,000) \5\ (12,000).......... (55,438)\10\
9,021,000
(3,651,000) \2\.
----------------------------------------------------------------------------------------------------------------
New Mexico 6,640,000 17,000 40,000 2003
(2,687,000) \11\ (7,000)........... (16,187)\12\
8,950,000
(3,622,000) \2\.
----------------------------------------------------------------------------------------------------------------
North Dakota 2,000,000 20,000 22,597 (9,145)\13\ 2006
(809,000) \5\ (8,000)...........
2,201,000
(891,000) \2\.
----------------------------------------------------------------------------------------------------------------
Oklahoma 950,000 (384,000) 15,000 57,677 (23,341)\3\ 2002
\5\ (6,000)...........
4,625,000
(1,872,000) \2\.
----------------------------------------------------------------------------------------------------------------
South Dakota 1,757,000 33,000 630,849 2006
(711,000) \14\ (13,000).......... (255,296)\15\
6,411,000
(2,594,000) \2\.
----------------------------------------------------------------------------------------------------------------
Texas 16,703,000 26,000 115,000 2006
(6,759,000) \2\ (11,000).......... (46,539)\3\
57,600,000
(23,310,000) \16\.
----------------------------------------------------------------------------------------------------------------
Wyoming 5,786,000 49,000 229,607 2006
(2,342,000) \2\ (20,000).......... (92,919)\17\
16,000,000
(6,475,000) \5\.
----------------------------------------------------------------------------------------------------------------
U.S. Total 78,708,000 364,000 2,388,841 ..................
(31,852,000) \2\ (147,000)......... (966,730)
102,583,000
(41,514,000).
(non-BFFRF
citations) \B\.
----------------------------------------------------------------------------------------------------------------
Canada 2,000 (1,000) \5\ 4,485 (1,815)\3\ 2007
----------------------------------------------------------------------------------------------------------------
Mexico 1,384,000 36,561 (14,796)\3\ 2006
(560,000) \18\
----------------------------------------------------------------------------------------------------------------
Range wide Total 80,094,000- 2,429,887 ..................
103,969,000 (983,340) \1\
(32,413,000-
42,075,000).
----------------------------------------------------------------------------------------------------------------
\A\ Estimates rounded to the nearest thousand.
\B\ Low U.S. total estimate derived from the total of all BFFRF\2\ estimates (a single methodology described
below) for each State. High total estimates were derived by adding all other estimates; in States with more
than one other historical estimate (CO, KS, MT) the average was used.
\1\ Van Pelt 1998
\2\ BFFRF 1999
\3\ Koch 2009
\4\ Clark 1989
\5\ Knowles 1998
\6\ Odell et al. 2008
\7\ Lantz 1903
\8\ Flath and Ibach 2009
\9\ Hanauska-Brown 2009
\10\ Amack and Ibach 2009
\11\ Bailey 1932
\12\ Johnson et al. 2004
\13\ Knowles 2007
\14\ Linder et al. 1972
\15\ Vonk 2009
\16\ Bailey 1905
\17\ Grenier et al. 2007a
\18\ Ceballos et al. 1993
Historical estimates of black-tailed prairie dog occupied habitat
for a particular State are often quite variable. This is likely due to
the imprecise survey methodologies used to derive early estimates.
Additionally, some historical estimates were made after land conversion
and poisoning had been initiated. If the average historical estimates
(not including estimates from BFFRF 1999) in Table 1 for each State,
Canada, and Mexico are summed, the range wide historical estimate of
occupied habitat is approximately 104 million ac (42 million ha).
The Black-footed Ferret Recovery Foundation (BFFRF) (1999, p. 4)
addressed this variability in historical estimates by evaluating U.S.
Geological Survey land use and land cover data throughout the range of
the black-tailed prairie dog. The BFFRF assumed that suitable land
cover types such as grassland and agricultural land were potential
habitat for the species historically. Other land cover types such as
forests, rocky areas, wetlands, and lands with excessive slopes were
not considered. Whicker and Detling (1988, p. 778) estimated that
black-tailed
[[Page 63348]]
prairie dogs occupied at least 20 percent of short- and mixed-grass
prairies historically. BFFRF applied this 20 percent historical
occupancy rate to its estimate of potential habitat to derive an
estimate of approximately 79 million ac (32 million ha) of historically
occupied habitat in the United States.
A reasonable range wide estimate of historically occupied habitat
for the black-tailed prairie dog that considers all historical
estimates from Table 1 is approximately 80 to104 million ac (32 to 42
million ha).
In 1961, the BSFW, a predecessor agency of the Service, tabulated
habitat estimates on a county-by-county basis throughout the range of
all prairie dog species in the United States (BSFW 1961, p. 1). These
estimates were completed by District Agents for BSFW who were familiar
with remaining extant prairie dog populations. The survey was completed
in response to concerns from within the agency regarding possible
adverse impacts to prairie dogs following large-scale poisoning (Oakes
2000, p. 167). These data provide an estimate for a single point in
time when prairie dogs were reduced to very low numbers following a
half century of intensive, coordinated government poisoning efforts.
The petitioners questioned the use of the BSFW (1961) survey due to
its brevity and the fact that it represented an extreme low point in
black-tailed prairie dog occupied habitat. However, this survey has
been cited in other seminal documents, including Leopold (1964, p. 38)
and Cain et al. (1972, Appendix VIII). These latter two documents
resulted in substantial changes in predator and rodent control policies
in the United States, including a ban of Compound 1080, a highly toxic
poison once widely used to control prairie dogs and other mammalian
species. We agree that the early 1960s likely represented an extreme
low in occupied habitat, but believe that the BSFW (1961) estimates of
occupied habitat for the species are useful for trend analyses and
represent the best available information for that time period.
The most recent Statewide estimates vary in survey date from 2002
to 2008 and include all black-tailed prairie dog occupied habitat known
in a given State. The most current range wide estimate is approximately
2.4 million ac (1 million ha) including Canada and Mexico. Trends for
occupied habitat in the United States appear to be increasing from the
low point of 364,000 ac (147,000 ha) in 1961. Statewide trends for the
same period (1961 - present) range from nearly stable in North Dakota
to an approximately 19-fold increase in South Dakota. The status in
Arizona is currently indeterminate due to the recent reintroduction.
We recognize that different methodologies were used at different
times and in different locales for the various occupied habitat
estimates. However, we believe that these estimates are the best
available information and are comparable for the purpose of determining
general population trends. Methods for determining occupied habitat
have improved in recent years with the advent of tools such as aerial
survey, satellite imagery, and Geographic Information Systems (GIS).
Consequently, estimates that use these tools can be expected to be more
accurate. Ground-truthing a percentage of the land surveyed to
determine the percent of habitat occupied adds additional confidence to
any large-scale estimate. States continue to refine their
methodologies. A workshop is being planned in 2010 by the Western
Association of Fish and Wildlife Agencies to further evaluate current
survey methodologies for accuracy, statistical validity, cost, and
other considerations. More detailed information regarding survey
methodology, distribution, abundance, and trends for each State is
provided as follows.
Arizona
Survey methodology - The most recent survey by the Arizona Game and
Fish Department in 2008 consisted of ground mapping, including ground-
truthing (Van Pelt 2009, p. 41). The small amount of occupied habitat
enabled a detailed survey effort with ground-truthing throughout and a
high degree of confidence in the estimate.
Distribution - Historically, black-tailed prairie dog occupied
habitat existed in extreme southeastern Arizona (Hall and Kelson 1959,
p. 365). The species was extirpated from the State by approximately
1940 (Arizona Game and Fish Dept. 1988, p. 22). In October 2008, the
species was reintroduced on Las Cienegas National Conservation Area
(Voyles 2009, pp. 1-2).
Abundance - Historically approximately 650,000 ac (263,000 ha) (Van
Pelt 1998, p. 1) to 1,396,000 ac (565,000 ha) (BFFRF 1999, p. 4) of
black-tailed prairie dog occupied habitat existed in Arizona. The most
recent survey was conducted in 2008 (Van Pelt 2009, p. 41) and percent
occupancy was 100 percent. The most recent estimate is 8 ac (3 ha) of
occupied habitat, following an October 2008 reintroduction on Las
Cienegas National Conservation Area (Koch 2009, p. 7). The next survey
is scheduled for 2009 (Van Pelt 2009, p. 41).
Trends - Arizona contains approximately 1 percent of the potential
habitat (Ernst 2008, p. 2) and less than 1 percent of currently
occupied habitat in the United States. In 1961, no black-tailed prairie
dog occupied habitat was found in Arizona (BSFW 1961, p. 1). Currently
8 ac (3 ha) are estimated to occur (Koch 2009, p. 7). The recent date
of reintroduction does not allow for any interpretation of trends.
However, reintroduction of the species after approximately 70 years of
absence in the State is notable.
Colorado
Survey methodology - The most recent survey by the Colorado
Division of Wildlife (CDOW) in 2006 consisted of aerial line-intercept
surveys. The observers in airplanes fly line-intercepts and record the
flight path and length of lines flown above black-tailed prairie dog
colonies, then estimate the cumulative area of colonies from the
percentage of the flight path intercepted by prairie dog colonies. CDOW
attempted to ground-truth 10 percent of recorded colony intercepts
(dependent upon landowner permission) (Odell et al. 2008, p. 1312).
Improvements were made in previous survey methods, and results were
published in the Journal of Wildlife Management (Odell et al. 2008, p.
1312). However, petitioners and other parties expressed concerns that
this study overestimated the amount of occupied habitat in Colorado
(Knowles 2009, pp. 1-2; McCain 2009, p. 2; Miller 2009, pp. 1-3;
Proctor 2009, p. 2; Reading 2009, pp. 1-9; Sidle 2009a, p. 1). Specific
concerns included the method of designating active and inactive
colonies, the absence of density evaluation in determination of
occupancy, differences in occupancy levels compared to surrounding
states, and the likelihood of this methodology being adopted by other
states without further refinement.
Estimates derived from large-scale surveys, such as those conducted
at a Statewide level, are not as accurate as smaller-scale, more
intensive surveys that can include ground-truthing of 100 percent of
the habitat. This level of effort is not feasible in large surveys.
Nearly all States, including Colorado, dedicate considerable resources
to conducting surveys and refining their methodologies, which
contribute to improved estimates in future surveys. The CDOW added
ground-truthing to their most recent survey, which further refined
their estimate of black-tailed
[[Page 63349]]
prairie dog occupied habitat. We consider the estimate provided by
Odell et al. (2008, p. 1311) to constitute the best available
information for Colorado.
Distribution - Historically, black-tailed prairie dog occupied
habitat existed in the eastern half of Colorado, east of the Front
Range mountains (Hall and Kelson 1959, p. 365). Currently, distribution
appears to be scattered in remnant populations throughout at least 75
percent of the historical range (Van Pelt 2009, p. 14).
Abundance - Historically, approximately 3,000,000 ac (1,214,000 ha)
(Clark 1989, p. 17) to 7,000,000 ac (2,833,000 ha) (Knowles 1998, p.
12) of black-tailed prairie dog occupied habitat existed in Colorado.
CDOW completed the most recent survey in 2006 (Van Pelt 2009, p.14).
Percent occupancy was 88 percent (Odell et al. 2008, p. 1311). Adjusted
to account for 88 percent occupancy, the most recent estimate of
occupied habitat is 788,657 ac (319,158 ha) (Odell et al. 2008, p.
1311). The next survey is scheduled for 2011 (Van Pelt 2009, p. 14).
Trends - Colorado contains approximately 8 percent of the potential
habitat (Ernst 2008, p. 2) and approximately 33 percent of currently
occupied habitat in the United States. In 1961, Colorado contained an
estimated 96,000 ac (39,000 ha) of black-tailed prairie dog occupied
habitat (BSFW 1961, p. 1). Currently, 788,657 ac (319,158 ha) of
occupied habitat are estimated to occur in the state (Odell et al.
2008, p. 1311). This amount represents an apparent eight-fold increase
in occupied habitat since 1961.
Kansas
Survey methodology - The Kansas Department of Wildlife and Parks
conducted the most recent survey in 2006. It consisted of a combination
of line transect (a survey along a straight path of standard width
where the presence of appropriate habitat is recorded when observed)
and interpretation of National Agriculture Imagery Program photographs
(Van Pelt 2009, p. 15). No record of ground-truthing information was
available. Because the State did not determine percent of habitat
occupied, the estimate is less accurate than if they had ground-truthed
a percentage of the lands surveyed and addressed percent occupancy.
Nevertheless, the estimate is the most recent and best available
information regarding the amount of black-tailed prairie dog habitat
within the State.
Estimates of percent occupancy provided in 10 recent Statewide
surveys range from 73-89 percent, with an average of 81 percent (EDAW
2000, p. 20; Sidle et al. 2001, p. 930; Bischof et al. 2004. p. 2;
Johnson et al. 2004, p. 11; Knowles 2007, p. 2; Odell et al. 2008, p.
1311; Emmerich 2009, p. 2; Hanauska-Brown 2009, p. 1). If the current
Kansas estimate of 173,593 ac (70,251 ha) of occupied habitat were
assumed to have 81 percent occupancy, this would equate to 140,610 ac
(56,903 ha).
Distribution - Historically, black-tailed prairie dog occupied
habitat existed in the western two-thirds of Kansas (Hall and Kelson
1959, p. 365). Currently, distribution appears to be scattered in
remnant populations throughout at least 75 percent of the historical
range (Van Pelt 2009, p. 16).
Abundance - Historically, approximately 2,000,000 ac (809,000 ha)
(Lantz 1903, p. 150) to 7,503,000 ac (3,036,000 ha) (BFFRF 1999, p. 4)
of black-tailed prairie dog occupied habitat existed in Kansas. The
Kansas Department of Wildlife and Parks completed the most recent
survey in 2006 (Van Pelt 2009); it did not note percent occupancy. The
most recent estimate is 173,593 ac (70,251 ha) (Van Pelt 2009, p. 15).
The next survey is scheduled for 2009 (Van Pelt 2009, p. 15).
Trends - Kansas contains approximately 10 percent of the potential
habitat (Ernst 2008, p. 2) and approximately 7 percent of currently
occupied habitat in the United States. In 1961, 50,000 ac (20,000 ha)
of black-tailed prairie dog occupied habitat were estimated to occur in
Kansas (BSFW 1961, p. 1). Currently 173,593 ac (70,251 ha) of occupied
habitat are estimated to occur (Koch 2009, p. 7). This area represents
an apparent three-fold increase since 1961.
Montana
Survey methodology - The most recent survey conducted by the
Montana Department of Fish, Wildlife and Parks in 2008 consisted of an
aerial line intercept survey, patterned after Sidle et al. (2001, pp.
929-931), White et al. (2005, pp. 266-268), and Odell et al. (2008, pp.
1312-1313). No information was provided by the Montana Department of
Fish, Wildlife and Parks regarding ground-truthing efforts in their
preliminary report, although estimates for active and inactive colonies
were provided, and percent occupancy was addressed (Hanauska-Brown
2009, p. 1).
Distribution - Historically, black-tailed prairie dog occupied
habitat existed in the eastern two-thirds of Montana, with the
exception of the northeastern corner of the State (Hall and Kelson
1959, p. 365). Currently, distribution appears to be scattered in
remnant populations throughout over 90 percent of the historical range
(Van Pelt 2009, p. 20).
Abundance - Historically, approximately 1,471,000 ac (595,000 ha)
(Flath and Clark 1986, p. 67) to 10,667,000 ac (4,317,000 ha) (BFFRF
1999, p. 4) of black-tailed prairie dog occupied habitat existed in
Montana. The most recent survey was completed by the Montana Department
of Fish, Wildlife and Parks in 2008 (Van Pelt 2009, p. 19). The percent
of habitat occupied was 85 percent (Hanauska-Brown 2009, p. 1).
Adjusted to account for 85 percent occupancy, the most recent estimate
of occupied habitat is 193,862 ac (78,453 ha) (Hanauska-Brown 2009, p.
1). The next survey is scheduled for 2011.
Trends - Montana contains approximately 12 percent of the potential
habitat (Ernst 2008, p. 2) and approximately 8 percent of currently
occupied habitat in the United States. In 1961, an estimated 28,000 ac
(11,000 ha) of black-tailed prairie dog occupied habitat occurred in
Montana (BSFW 1961, p. 1). Currently, 193,862 ac (78,453 ha) of
occupied habitat are estimated to occur (Hanauska-Brown 2009, p. 1).
This area represents nearly a seven-fold increase since 1961.
Nebraska
Survey methodology - The Nebraska Game and Parks Commission
conducted the most recent survey in 2003, consisting of an aerial line
intercept survey by county using variably spaced transects based on the
estimated number of occupied acres in each county, with more transects
in the more densely populated counties (Bischof et al. 2004, pp. 3-6).
Methodology was patterned after Sidle et al. (2001, pp. 929-931). Based
on the information provided regarding methodology, ground-truthing was
not conducted; however, habitat was only classified as active
(occupied) if black-tailed prairie dogs were seen (Bischof et al. 2004,
pp. 3-6). Additional habitat was classified as ``possibly active'' if
no prairie dogs were visible but evidence of recent activity was
present.
Distribution - Historically, black-tailed prairie dog occupied
habitat existed throughout most of Nebraska west of the 97\th\
meridian, with the exception of most of the Sandhills region in the
north-central portion of the State (Hall and Kelson 1959, p. 365). The
current distribution is unknown, but the species occurs in less than 75
percent of counties with historical records (Luce 2003, p. 17).
[[Page 63350]]
Abundance - Historically, approximately 6,000,000 ac (2,428,000 ha)
(Knowles 1998, p. 12) to 9,021,000 ac (3,651,000 ha) (BFFRF 1999, p. 4)
of black-tailed prairie dog occupied habitat existed in Nebraska. The
most recent survey was completed by the Nebraska Game and Parks
Commission in 2003 (Amack and Ibach 2009, p. 1). The percent of habitat
occupied was 74 percent (Bischoff et al. 2004, p. 6). Adjusted to
account for 74 percent occupancy, the most recent estimate of occupied
habitat is 136,991 ac (55,438 ha) (Amack and Ibach 2009, p. 1). An
additional 102,828 ac (41,613 ha) were not verified and were classified
as possibly active. No future surveys are scheduled at this time (Amack
and Ibach 2009, p. 2).
Trends - Nebraska contains approximately 11 percent of the
potential habitat (Ernst 2008, p. 2) and approximately 6 percent of
currently occupied habitat in the United States. In 1961, 30,000 ac
(12,000 ha) of black-tailed prairie dog occupied habitat were estimated
to occur in Nebraska (BSFW 1961, p. 1). Currently, 136,991 ac (55,438
ha) of occupied habitat are estimated to occur (Amack and Ibach 2009,
p. 1). This area represents nearly a five-fold increase since 1961.
New Mexico
Survey methodology - New Mexico Department of Game and Fish
conducted the most recent survey in 2003, which consisted of
examination of digital orthophoto quadrangle imagery, followed by an
effort to ground-truth 15 percent of recorded colonies (dependent upon
landowner permission) (Johnson et al. 2004, pp. 3-4). Due to lack of
permission in some cases, the actual amount of habitat ground-truthed
was slightly less than 15 percent.
Distribution - Historically, black-tailed prairie dog occupied
habitat existed in the eastern and southwestern two-thirds of the State
(Hall and Kelson 1959, p. 365). Currently, distribution appears to be
scattered in remnant populations in 54 percent of the counties that had
historical records (Van Pelt 2009, p. 28).
Abundance - Historically, approximately 6,640,000 ac (2,687,000 ha)
(Bailey 1932, pp. 14 and 16) to 8,950,000 ac (3,622,000 ha) (BFFRF
1999, p. 4) of black-tailed prairie dog occupied habitat existed in New
Mexico. The most recent survey was completed by the New Mexico
Department of Game and Fish in 2003 (Johnson et al. 2004, p. 11). The
percent of habitat occupied was 81 percent (Johnson et al. 2004, p.
11). Adjusted to account for 81 percent occupancy, the most recent
estimate of occupied habitat is 40,000 ac (16,187 ha) (Johnson et al.
2004, p. 11). The next survey is underway and scheduled to be completed
in 2009 (Van Pelt 2009, p. 27).
Trends - New Mexico contains approximately 12 percent of the
potential habitat (Ernst 2008, p. 2) and approximately 2 percent of
currently occupied habitat in the United States. In 1961, 17,000 ac
(7,000 ha) of black-tailed prairie dog occupied habitat were estimated
to occur in New Mexico (BSFW 1961, p. 1). Currently, 40,000 ac (16,187
ha) of occupied habitat are estimated to occur (Johnson et al. 2004, p.
11). This area represents an apparent two-fold increase since 1961.
North Dakota
Survey methodology - The most recent survey conducted by the North
Dakota Game and Fish Department in 2006 consisted of aerial surveys,
followed by an effort to ground-truth all active colonies that they
were able to get landowner permission to visit and then map colonies
using GPS (Knowles 2007, p. 3).
Distribution - Historically, black-tailed prairie dog occupied
habitat existed in the southwestern third of North Dakota, west of the
Missouri River (Hall and Kelson 1959, p. 365). Currently, distribution
appears to be scattered in remnant populations in 79 percent of
counties that historically contained prairie dogs (Van Pelt 2009, p.
24).
Abundance - Historically, approximately 2,000,000 ac (809,000 ha)
(Knowles 1998, p. 12) to 2,201,000 ac (891,000 ha) (BFFRF 1999, p. 4)
of black-tailed prairie dog occupied habitat existed in North Dakota.
The most recent survey was completed by the North Dakota Game and Fish
Department in 2006 (Knowles 2007, p. 1). 89 percent of acres were
occupied (Knowles 2007, p. 2). Adjusted to account for 89 percent
occupancy, the most recent estimate of occupied habitat is 22,597 ac
(9,145 ha) (Knowles 2007, p. 1). The next survey is scheduled for 2010
(Van Pelt 2009, p. 24).
Trends - North Dakota contains approximately 3 percent of the
potential habitat (Ernst 2008, p. 2) and approximately 1 percent of
currently occupied habitat in the United States. In 1961, 20,000 ac
(8,000 ha) of black-tailed prairie dog occupied habitat were estimated
to occur in North Dakota (BSFW 1961, p. 1). Currently, 22,597 ac (9,145
ha) of occupied habitat are estimated to occur (Knowles 2007, p. 7).
Occupied habitat has apparently remained relatively stable since 1961.
Oklahoma
Survey methodology - The Oklahoma Department of Wildlife
Conservation conducted the most recent survey in 2002, which consisted
of interpretation of aerial maps and on-site ground-truthing with input
from county game wardens (Van Pelt 2009, p. 30).
Distribution - Historically, black-tailed prairie dog occupied
habitat existed throughout approximately the western two-thirds of
Oklahoma west of the 97\th\ meridian (Hall and Kelson 1959, p. 365).
Currently, distribution is largely limited to the panhandle, although
scattered remnant populations occur elsewhere throughout 87 percent of
the historical range (Van Pelt 2009, p. 30).
Abundance - Historically, approximately 950,000 ac (384,000 ha)
(Knowles 1998, p. 12) to 4,625,000 ac (1,872,000 ha) (BFFRF 1999, p. 4)
of black-tailed prairie dog occupied habitat existed in Oklahoma.
Ground-truthing was conducted in the most recent survey completed by
the Oklahoma Department of Wildlife Conservation in 2002 (Van Pelt
2009, p. 30), however the percent of habitat occupied was not noted
(Van Pelt 2009). The most recent estimate of occupied habitat is 57,677
ac (23,341 ha) (Koch 2009, p. 7) based upon the 2002 survey (Van Pelt
2009, p. 30). The next survey is scheduled for 2008 through 2009 (Van
Pelt 2009, p. 30). We have not yet received any survey results.
Trends - Oklahoma contains approximately 6 percent of the potential
habitat (Ernst 2008, p. 2) and approximately 2 percent of currently
occupied habitat in the United States. In 1961, 15,000 ac (6,000 ha) of
black-tailed prairie dog occupied habitat were estimated to occur in
Oklahoma (BSFW 1961, p. 1). Currently, 57,677 ac (23,341 ha) of
occupied habitat are estimated to occur (Koch 2009, p. 7). This area
represents a nearly four-fold increase since 1961.
South Dakota
Survey methodology - The South Dakota Department of Game, Fish, and
Parks conducted the most recent survey conducted in 2009 which
consisted of interpretation of aerial photographs (Kempema et al. 2009,
p. 2; Vonk 2009, p. 1). Ground-truthing was conducted on 25 percent of
the surveyed area (Kempema et al. 2009, pp. 3, 5).
Distribution - Historically, black-tailed prairie dog occupied
habitat existed throughout the western three-fourths of the State (Hall
and Kelson 1959, p. 365). Currently, distribution appears to be
scattered in remnant
[[Page 63351]]
populations throughout 78 percent of the counties within the historical
range (Van Pelt 2009, p. 34).
Abundance - Historically, approximately 1,757,000 ac (711,000 ha)
(Linder et al. 1972, p. 29) to 6,411,000 ac (2,594,000 ha) (BFFRF 1999,
p. 4) of black-tailed prairie dog occupied habitat existed in South
Dakota. The most recent survey was completed by the South Dakota
Department of Game, Fish, and Parks in 2009. Percent occupancy was 93
percent (Kempema et al. p. 5). Adjusted to account for 93 percent
occupancy, the most recent estimate of occupied habitat is 630,849 ac
(255,296 ha). The next survey is scheduled for 2011 (Van Pelt 2009, p.
32).
Trends - South Dakota contains approximately 9 percent of the
potential habitat (Ernst 2008, p. 2) and approximately 26 percent of
currently occupied habitat in the United States. In 1961, 33,000 ac
(13,000 ha) of black-tailed prairie dog occupied habitat were estimated
to occur in South Dakota (BSFW 1961, p. 1). Currently, 630,849 ac
(255,296 ha) of occupied habitat are estimated to occur (Kempema et al.
2009, p. 4; Vonk 2009, p. 1). This represents an apparent 19-fold
increase since 1961.
Texas
Survey methodology - The Texas Parks and Wildlife Department in
2006 conducted the most recent survey which consisted of interpretation
of Digital Orthoimagery Quarter Quadrangles (DOQQs) and ground-truthing
(Van Pelt 2009, p. 37). The proportion of habitat that was ground-
truthed was not noted.
Distribution - Historically, black-tailed prairie dog occupied
habitat existed throughout approximately the northwestern one-third of
Texas (Hall and Kelson 1959, p. 365). Currently, distribution appears
to be scattered in remnant populations throughout 75 percent of the
historical range (Van Pelt 2009, p. 38).
Abundance - Historically, approximately 57,600,000 ac (23,310,000
ha) (Bailey 1905, p. 90) to 16,703,000 ac (6,759,000 ha) (BFFRF 1999,
p. 4) of black-tailed prairie dog occupied habitat existed in Texas.
The Texas Parks and Wildlife Department completed the most recent
survey in 2006 (Van Pelt 2009, p. 37). Percent occupancy was not noted.
The most recent estimate of occupied habitat is 115,000 ac (46,539 ha)
based upon the 2006 survey (Koch 2009, p. 7). The next survey is
scheduled for 2010 (Van Pelt 2009, p. 37).
Trends - Texas contains approximately 21 percent of the potential
habitat (Ernst 2008, p. 2) and approximately 5 percent of currently
occupied habitat in the United States. In 1961, 26,000 ac (11,000 ha)
of black-tailed prairie dog occupied habitat were estimated to occur in
Texas (BSFW 1961, p. 1). Currently, 115,000 ac (46,539 ha) of occupied
habitat are estimated to occur (Koch 2009, p. 7). This area represents
an apparent four-fold increase since 1961.
Wyoming
Survey methodology - The Wyoming Game and Fish Department conducted
the most recent survey in 2006 which consisted of delineation of colony
boundaries from interpretation of DOQQs, followed by aerial survey to
confirm status (Grenier et al. 2007b, pp. 115-116).
Distribution - Historically, black-tailed prairie dog occupied
habitat existed in the eastern half of Wyoming, east of the Rocky
Mountains (Hall and Kelson 1959, p. 365). Currently, distribution
appears to be scattered in remnant populations throughout at least 75
percent of the historical range (Van Pelt 2009, p. 40).
Abundance - Historically, approximately 5,786,000 ac (2,342,000 ha)
(BFFRF 1999, p. 4) to 16,000,000 ac (6,475,000 ha) (Knowles 1998, p.
12) of black-tailed prairie dog occupied habitat existed in Wyoming.
The most recent survey was completed by the Wyoming Game and Fish
Department in 2006 (Emmerich 2009, p. 2). Occupied habitat was
categorized as healthy (87 percent) or impacted (13 percent) (Grenier
et al. 2007a, p. 125. Adjusted to account for 87 percent occupancy, the
most recent estimate of occupied habitat is 229,607 ac (92,919 ha)
(Grenier et al. 2007a, p. 125). The next survey is scheduled for 2009
(Van Pelt 2009, p. 39).
Trends - Wyoming contains approximately 6 percent of the potential
habitat (Ernst 2008, p. 2) and nearly 10 percent of currently occupied
habitat in the United States. In 1961, 49,000 ac (20,000 ha) of black-
tailed prairie dog occupied habitat were estimated to occur in Wyoming
(BSFW 1961, p. 1). Currently, 229,607 ac (92,919 ha) of occupied
habitat are estimated to occur (Grenier et al. 2007a, p. 125). This
area represents an apparent nearly five-fold increase since 1961.
Canada
Survey methodology - The most recent survey was described as
mapping with GPS (Koch 2009, p. 7). We do not have more detailed
information concerning the methods used, including whether data was
ground-truthed or corrected for occupancy.
Distribution - Historically, black-tailed prairie dog occupied
habitat existed in southernmost Saskatchewan (Hall and Kelson 1959, p.
365). Currently, distribution is limited to remnant populations within
the same range, primarily in Grasslands National Park (Tuckwell and
Everest 2009, p. 2).
Abundance - Historically, approximately 2,000 ac (809 ha) of black-
tailed prairie dog occupied habitat existed in Canada (Knowles 1998, p.
12). Surveys are conducted every other year (Tuckwell and Everest 2009,
p. 16). The most recent survey was completed in 2007 (Van Pelt 2009, p.
64). Percent occupancy was not noted. The most recent estimate of
occupied habitat is 4,485 ac (1,815 ha) based upon the 2007 survey
(Koch 2009, p. 3).
Trends - Canada represents the periphery of the black-tailed
prairie dog's range and habitat has always been limited, but the amount
of occupied habitat appears stable (Tuckwell and Everest 2009, p. 2).
Mexico
Survey methodology - Recent survey techniques and extent of ground-
truthing efforts was not reported.
Distribution - Historically, black-tailed prairie dog occupied
habitat existed throughout the northern portion of the Mexican States
of Chihuahua and Sonora (Hall and Kelson 1959, p. 365). Currently,
distribution appears limited to remnant populations in a small area of
northern Chihuahua (List 1997, p. 141).
Abundance - Historically, approximately 1,384,000 ac (560,000 ha)
of black-tailed prairie dog occupied habitat existed in Mexico
(Ceballos et al. 1993, p. 109). The most recent survey was completed in
2006 (Koch 2009, p. 3). Percent occupancy was not noted. The most
recent estimate is 36,561 ac (14,796 ha) of occupied habitat (Koch
2009, p. 3). The year of the next survey is not known.
Trends - Mexico experienced a prolonged drought in recent years,
which resulted in dramatic loss of vegetation, followed by a reduction
in black-tailed prairie dog occupied habitat (Larson 2008, p. 87). The
most recent estimate is 36,561 ac (14,796 ha) of occupied habitat in
2006 (Koch 2009, p. 3). Occupied habitat appears to be declining in
recent years.
Summary of Factors Affecting the Species
We have considered all scientific and commercial information
available in our files, including pertinent information received during
this status review. We relied primarily on published, peer-
[[Page 63352]]
reviewed literature; information provided by affected state wildlife
agencies; and information provided by the Western Association of Fish
and Wildlife Agencies. We received more than 18,000 comment letters
from individuals, agencies, organizations, and companies. Most were
form letters that expressed support or opposition to listing the black-
tailed prairie dog. However, we cite several submissions that provided
useful information in this finding. Much of the data refers to the 98
percent of occupied habitat that occurs in the United States, but we
include data on Canada and Mexico where available.
Section 4 of the Act (16 U.S.C. 1533), and its implementing
regulations (50 CFR 424) set forth procedures for adding species to,
removing species from, or reclassifying species on the Federal Lists of
Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of
the Act, a species may be determined to be endangered or threatened
based on any of the following five factors: (A) present or threatened
destruction, modification, or curtailment of its habitat or range; (B)
overutilization for commercial, recreational, scientific, or education
purposes; (C) disease or predation; (D) the inadequacy of existing
regulatory mechanisms; or (E) other natural or manmade factors
affecting its continued existence.
We addressed the potential threats discussed in the petition under
the most appropriate factor; however, we recognize that several
potential threats might be considered under more than one factor. For
example, poisoning can affect habitat (Factor A), and can be affected
by state and Federal regulatory mechanisms (Factor D), but is primarily
addressed in this finding under other factors (Factor E). In making
this finding, information pertaining to the black-tailed prairie dog ,
in relation to the five factors provided in section 4(a)(1) of the Act
is discussed below.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of its Habitat or Range
Some black-tailed prairie dog habitat has been destroyed, modified,
or curtailed by:
(1) conversion of native prairie habitat to cropland;
(2) urbanization;
(3) oil, gas, and mineral extraction;
(4) habitat loss caused by loss of prairie dogs; and
(5) livestock grazing, fire suppression, and weeds.
In some instances, black-tailed prairie dog habitat continues to be
impacted by these same stressors. The Black-tailed Prairie Dog
Conservation Team developed conservation plans that address issues of
habitat loss. Each is discussed below.
Conversion of native prairie habitat to cropland
The present or threatened destruction of habitat due to cropland
development affects portions of the black-tailed prairie dog's range.
Regular cultivation precludes burrow development by the species. This
practice is the most substantial cause of habitat destruction that we
are able to quantify. Conversion of native prairie to cropland has
largely progressed across the species' range from east to west. The
most intensive agricultural use is in the eastern portion of the black-
tailed prairie dog's range, in portions of North Dakota, South Dakota,
Nebraska, Kansas, Oklahoma, and Texas, where higher rainfall amounts
and generally better soils result in greater agricultural production.
Land with the highest potential for traditional farming uses was
converted many years ago. Consequently, the present and future
destruction of habitat through cropland conversion is likely much less
than in the early days of agricultural development in the Great Plains.
A detailed assessment using the National Land Cover Dataset
determined that there are approximately 110 million ac (45 million ha)
of cropland and 283 million ac (115 million ha) of rangeland within the
species' range at present (Ernst 2008, pp. 10-19). When the 2.4 million
ac (1 million ha) of currently occupied habitat is contrasted with the
283 million ac (115 million ha) of rangeland, it appears that
sufficient potential habitat still occurs within the range of the
species in the United States to accommodate large expansions of prairie
dog populations. These areas could be colonized over time by expansion
of existing colonies if the landowners and public sentiment allows.
In recent years, ethanol production from corn has expanded in the
United States (Westcott 2007, p. 1). However, most corn is cultivated
east of the range of the black-tailed prairie dog (Westcott 2007, p.
3). Additionally, the increase in corn production largely occurs by
adjusting crop rotations between corn and soybeans (Westcott 2007, p.
7). We do not anticipate that increased ethanol production will result
in a substantial loss in the species' occupied or potential habitat.
The current status of the black-tailed prairie dog, as indicated by
increasing trends in the species' occupied habitat since the early
1960s, suggests that the present or threatened destruction of habitat
due to cropland development is not a limiting factor for the species.
Urbanization
The present or threatened destruction of habitat due to
urbanization affects portions of the black-tailed prairie dog's range,
particularly east of the Front Range in Colorado. However, in a
Statewide or range wide context, loss of habitat due to urbanization is
not substantial. In Colorado, approximately 502,000 ac (203,000 ha) of
urban lands and 21.6 million ac (8.8 million ha) of rangeland occur
within the species' range (Ernst 2008, pp. 10-11). This equates to
approximately 2 percent of potential habitat lost to urbanization in
Colorado. Throughout the United States, approximately 2.4 million ac (1
million ha) of urban lands occur within the species' historic range
(Ernst 2008, pp. 10-18), while approximately 283 million ac (115
million ha) of rangeland exist within the species' range. This equates
to less than 1 percent of potential habitat lost to urbanization in the
United States. A very small percentage of potential prairie dog habitat
has been lost to urbanization. As a consequence, it appears that
sufficient potential habitat still occurs within the range of the
species, including Colorado, to accommodate existing or large
expansions of prairie dog populations, even if some local prairie dog
populations may be lost to urbanization in the future.
The current status of the black-tailed prairie dog, as indicated by
increasing trends in the species' occupied habitat since the early
1960s, indicates that the present or threatened destruction of habitat
due to urbanization is not a limiting factor for the species.
Oil, gas, and mineral extraction
The present or threatened curtailment of habitat due to oil, gas,
and mineral extraction may affect portions of black-tailed prairie dog
occupied habitat; however, we have no information that quantifies these
impacts. Qualitative information was submitted on behalf of the
Petroleum Association of Wyoming, the Public Lands Advocacy, the
Montana Petroleum Association, the New Mexico Oil and Gas Association,
Oklahoma Independent Petroleum Association, and the Independent
Petroleum Association of Mountain States. Mapping in colonies within
oil and gas development areas in Wyoming indicates increased prairie
dog occupancy in these areas (Sorensen et al. 2009, pp. 5-6). Although
we have not confirmed this conclusion, the current status of the black-
tailed prairie dog, as
[[Page 63353]]
indicated by increasing trends in the species' occupied habitat since
the early 1960s, indicates that the present or threatened curtailment
of habitat due to energy development is not a limiting factor for the
species in Wyoming or elsewhere throughout its range.
Habitat loss caused by loss of prairie dogs
The present or threatened modification of habitat due to the
extirpation of black-tailed prairie dogs may affect portions of the
species' range. The petitioners theorized that the loss of prairie dogs
from their habitats may create a negative feedback loop, resulting in
their habitat becoming less suitable. Documentation of the species'
effects on habitat is mixed. In some instances, prairie dogs may have a
positive effect on habitat (Koford 1958, pp. 43-62; Kotliar et al.
1999, p. 178; Johnson-Nistler et al. 2004, p. 641; Lantz et al. 2006,
p. 2671). Positive effects have been particularly notable in the
southwestern portion of the species' range where the foraging and
clipping habits of prairie dogs destroy seedlings of undesirable shrub
and tree species that might otherwise invade and eventually convert
grasslands to scrublands. The aeration of soil from burrow construction
may increase the growth of grasses (Koford 1958, pp. 43-62; Davis 1974,
p. 156; Fagerstone and Ramey 1996, p. 89; List 1997, p. 150; Weltzin et
al. 1997, pp. 758-760). Prairie dogs may also have a negative habitat
effect by reducing grass species and causing conversion to less
desirable forb species (Koford 1958, pp. 43-62; Bonham and Lerwick
1976, p. 225; Klatt and Hein 1978, p. 316; Fagerstone and Ramey 1996,
p. 88; Johnson-Nistler et al. 2004, p. 641). However, the current
status of the black-tailed prairie dog, as indicated by increasing
trends in the species' occupied habitat since the early 1960s,
indicates that the present or threatened modification of habitat due to
the presence or absence of prairie dogs on their habitat is not a
limiting factor for the species.
Livestock grazing, fire suppression, and weeds
The present or threatened modification of habitat due to livestock
grazing, fire suppression, and weeds may affect portions of the black-
tailed prairie dog's range. Nonnative plant species may increase as a
result of overgrazing and in the absence of fire, may modify the
habitat. However, the impact of plant composition on habitat
suitability for prairie dogs is contradictory. Some studies suggest
that prairie dogs cause deterioration in forage quality, while others
contend that livestock grazing causes a deterioration in forage quality
(Koford 1958, pp. 43-62; Uresk et al. 1981, p. 200; Cerovski 2004, p.
101; Vermeire et al. 2004, p. 691; Detling 2006, p. 115). Available
information indicates that livestock grazing typically encourages
black-tailed prairie dog expansion by maintaining vegetation at a lower
height that improves visibility for prairie dogs (Osborn and Allan
1949, p. 330; Koford 1958, p. 68; Snell and Hlavachick 1980, p. 240;
Uresk et al. 1981, p. 200; Hubbard and Schmitt 1983, p. 30; Marsh 1984,
p. 203; Snell 1985, p. 30; Groombridge 1992, p. 290; U.S. Forest
Service 1995, p. 5; Fagerstone and Ramey 1996, p. 88; Wuerthner 1997,
pp. 460-461; U.S. Forest Service 1998, p. 4; Forest 2005, p. 528;
Andelt 2006, p. 131).
The current status of the black-tailed prairie dog, as indicated by
increasing trends in the species' occupied habitat since the early
1960s, indicates that the present or threatened modification of habitat
due to livestock grazing, fire suppression, or weeds is not a limiting
factor for the species.
The Black-tailed Prairie Dog Conservation Assessment and Strategy
Following the 1998 petitions to list the black-tailed prairie dog,
a group of representatives from each State within the historical range
of the species formed the Black-tailed Prairie Dog Conservation Team.
The team intended to reduce threats to the species and increase the
amount of habitat occupied by the species. The Team developed ``The
Black-tailed Prairie Dog Conservation Assessment and Strategy'' (Van
Pelt 1999), which initiated development of ``A Multi-State Conservation
Plan for the Black-tailed Prairie Dog, Cynomys ludovicianus, in the
United States'' (Multi-State Plan) (Luce 2002).
The purpose of the Multi-State Plan was to provide adaptive
management goals for future prairie dog management within the 11
States. The Multi-State Plan identified the following minimum 10-year
target objectives:
(1) maintain at least the currently occupied acreage of black-
tailed prairie dog habitat in the United States;
(2) increase occupied habitat to at least 1,693,695 ac (685,414 ha)
in the United States by 2011;
(3) maintain at least the current occupied acreage in the two
complexes greater than 5,000 ac (2,023 ha) that then occurred on and
adjacent to Conata Basin-Buffalo Gap National Grassland, South Dakota,
and Thunder Basin National Grassland, Wyoming;
(4) develop and maintain a minimum of 9 additional complexes
greater than 5,000 ac (2,023 ha), with each State managing or
contributing to at least one complex greater than 5,000 ac (2,023 ha)
by 2011;
(5) maintain at least 10 percent of total occupied acreage in
colonies or complexes greater than 1,000 ac (405 ha) by 2011; and
(6) maintain distribution over at least 75 percent of the counties
in the historical range, or at least 75 percent of the historical
geographic distribution.
Objectives 1, 2, and 3 have been achieved. Objectives 4, 5, and 6
have not yet been demonstrated in all States. The progress of
individual states in achieving these objectives is described in more
detail under Factor D.
The States also agreed to draft Statewide management plans for the
black-tailed prairie dog. The States approve their own Statewide
management plans. Colorado and Wyoming have finalized grassland
conservation plans that support and meet the objectives of the Multi-
State Plan. South Dakota has a finalized management plan that supports
and meets the Multi-State Plan's objectives, but reserves the right to
preserve its own management authority and identify its own goals and
objectives. Kansas, Oklahoma, and Texas have finalized management plans
that support the Multi-State Plan objectives, but have not yet met all
of those objectives. Montana, New Mexico, and North Dakota have
finalized management plans that do not support or meet all of the
objectives of the Multi-State Plan. Arizona has a draft plan that
supports the Multi-State Plan's objectives, but their Wildlife
Commission did not approve it. Nevertheless, Arizona continues to work
toward the Multi-State Plan's objectives. Nebraska has a draft plan
that supports the Multi-State Plan objectives, but it its Wildlife
Commission did not approve it. In Nebraska, work toward the Multi-State
Plan's objectives has been halted.
As a result of the development of the Multi-State and Statewide
management plans, state wildlife agencies are surveying and monitoring
black-tailed prairie dogs on a more regular basis. These efforts will
enable the States to monitor the status of the black-tailed prairie dog
and the progress of the conservation programs.
Summary of Factor A
Cropland conversion, urbanization, energy development, conversion
to scrubland in the absence of prairie dogs, and invasion of non-native
species all occur within the historical range of the black-tailed
prairie dog, and will likely
[[Page 63354]]
continue to occur in the future. However, when the approximately 2.4
million ac (1 million ha) of currently occupied habitat is contrasted
with the extant 283 million ac (115 million ha) of rangeland, it
appears that sufficient potential habitat still occurs within the range
of the species in the United States to accommodate prairie dog
expansions over time despite some habitat loss from these stressors.
Since the early 1960s, occupied habitat has increased in every State.
The species' occupied habitat in the United States is estimated to have
increased by over 600 percent from 1961 until the present time. This
increase has occurred despite continued impacts to the species' habitat
and impacts from other factors. The current status of the black-tailed
prairie dog, as indicated by increasing trends in the species' occupied
habitat since the early 1960s, indicates that the present or threatened
destruction, modification, or curtailment of habitat or range is not a
limiting factor for the species. The most significant impact to the
species' habitat that we are able to quantify is habitat loss due to
cropland conversion, and the rate of conversion is likely much less
than in the early days of agricultural development in the Great Plains.
Consequently, we do not anticipate that impacts from habitat loss are
likely to negatively impact the status of the species in the
foreseeable future.
We conclude that the best scientific and commercial information
available indicates that the black-tailed prairie dog is not now, or in
the foreseeable future, threatened by the present or threatened
destruction, modification, or curtailment of its habitat or range to
the extent that listing under the Act as a threatened or endangered
species is warranted at this time. Abundant suitable habitat in the
form of rangeland exists and is not a limiting factor for the species.
The present or threatened modification of prairie dog habitat presented
by sylvatic plague is addressed under Factor C, and the present or
threatened curtailment of prairie dog habitat presented by poisoning is
addressed under Factor E.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Recreational shooting of black-tailed prairie dogs can reduce
population densities, cause behavioral changes, diminish reproduction
and body condition, increase emigration, and cause extirpation in
isolated circumstances (Stockrahm 1979, pp. 80-84; Knowles 1988, p. 54;
Vosburgh 1996, pp. 13, 15, 16, and 18; Vosburgh and Irby 1998, pp. 366-
371; Pauli 2005, p. 1; Reeve and Vosburgh 2006, p. 144). This may be
due to the colonial nature of prairie dogs, their sensitivity to social
disruption, and the intense nature of some recreational shooting.
However, available information from several of the same studies
indicates that populations can also often recover from very low numbers
following intensive shooting (Knowles 1988, p. 54; Vosburgh 1996, pp.
16, 31; Dullum et al. 2005, p. 843; Pauli 2005, p. 17; Cully and
Johnson 2006, pp. 6-7). Based on the research cited above, it appears
that a typical scenario is either: (1) once populations have been
reduced, shooters go elsewhere and populations recover; or (2)
continued shooting maintains reduced population size at specific sites.
Some landowners maintain prairie dog populations and derive income from
charging people for recreational shooting. Monetary gain from shooting
fees may motivate landowners to preserve prairie dog colonies for
future shooting opportunities. This is currently an alternative to
eradicating them by poisoning (Vosburgh and Irby 1998, pp. 366-371;
Reeve and Vosburgh 2006, pp. 154-155).
Pauli (2005) studied five colonies not exposed to shooting and
compared population effects with five colonies where shooting occurred.
He found that in the colonies with shooting, reproductive output
decreased by 76 percent from 2003-2004 on the shot colonies (Pauli
2005, p. 29). However, all colonies but one expanded from 2003-2004,
although expansion was greater in control colonies (49.6 percent) than
in colonies where shooting occurred (25.0 percent) (Pauli 2005, p. 17).
The colony that did not expand was a control colony that experienced
plague (Pauli et al. 2006, p. 77). A second paper on the same research
project noted a decline in reproductive output in colonies with
shooting, of 82 percent from 2003-2004, but did not discuss colony
expansion (Pauli and Buskirk 2007a, p. 1228).
Recreational shooting may increase the potential for lead poisoning
in predators and scavengers consuming shot prairie dogs (Reeve and
Vosburgh 2006, p. 154). This risk may extend to prairie dogs, which
have occasionally been observed to cannibalize carcasses (Hoogland
1995, p. 14). Recreational shooters primarily use bullets designed to
expand on impact and rarely remove carcasses. In one study, expanding
bullets left an average of 3.426 grains (228.4 milligrams (mg)) of lead
in a prairie dog carcass, while non-expanding bullets averaged 0.297
grains (19.8 mg) of lead (Pauli and Buskirk 2007b, p.103). The authors
noted that the amount of lead in a single prairie dog carcass shot with
an expanding bullet is potentially sufficient to acutely poison
scavengers or predators, and may provide an important portal for lead
entering wildlife food chains. A wide range of sublethal toxic effects
are also possible from smaller quantities of lead (Pauli and Buskirk
2007, p.103).
Black-tailed prairie dogs are occasionally collected for the pet
trade, plague research, and zoo displays. However, we have no
information indicating any adverse effects resulting from possible
overutilization for commercial (pet trade), scientific (plague
research), or educational (zoo displays) purposes.
Summary of Factor B
Recreational shooting of prairie dogs can cause localized effects
on a population. However, literature documenting effects from shooting
of prairie dogs also frequently describes subsequent rebounds in local
populations. Extirpations due to recreational shooting, while
documented, are rare and therefore not considered a significant threat
overall to the species. Recent Statewide estimates of occupied habitat
further reinforce this observation by documenting population increases
in States that allow shooting. There is no information available to
indicate that the type of bullet used to shoot prairie dogs poses a
substantial risk of lead poisoning to surviving prairie dogs due to
scavenging carcasses. However, the risk to other species that may
scavenge prairie dog carcasses should be a management consideration if
intensive recreational shooting occurs. Since the early 1960s, occupied
habitat has increased in every State. Throughout the United States,
occupied habitat is estimated to have increased by over 600 percent
from 1961 until the present time. This increase has occurred despite
recreational shooting and impacts from other factors.
The current status of the black-tailed prairie dog, as indicated by
increasing trends in the species' occupied habitat since the early
1960s, indicates that recreational shooting is not a limiting factor
for the species. Consequently, we do not anticipate that impacts from
recreational shooting are likely to negatively impact the status of the
species in the foreseeable future.
We conclude that the best scientific and commercial information
available indicates that the black-tailed prairie dog is not now, or in
the foreseeable future, threatened by overutilization for commercial,
recreational, scientific, or educational purposes to the extent that
listing under the Act as a threatened or
[[Page 63355]]
endangered species is warranted at this time. Regulations specific to
shooting are described under Factor D.
C. Disease and Predation
Plague is an exotic disease foreign to the evolutionary history of
North American prairie dogs. It is caused by the bacterium Yersinia
pestis, which fleas acquire by biting infected animals and subsequently
transmit via a bite to other animals (Gage and Kosoy 2005, pp. 516-
517). The disease can also be transmitted through pneumonic (airborne)
or septicemic (blood) pathways from infected to disease-free animals
(Barnes 1993, p. 28; Ray and Collinge 2005, p. 203; Cully et al. 2006,
p. 158; Rocke et al. 2006, p. 243; Webb et al. 2006, p. 6236). Plague
was first observed in wild rodents in North America near San Francisco,
California, in 1903 (Eskey and Haas 1940, p. 1), and was first
documented in black-tailed prairie dogs in Texas in 1946 (Miles et al.
1952, p. 41). Plague spread approximately 1,400 mi (2,250 km) eastward
from its initial introduction in San Francisco into the species'
habitat in approximately 40 years, but eastward expansion has since
slowed (Adjemian et al. 2007, p. 365). Plague has only spread a few
hundred miles in the past 50-60 years.
Plague is maintained in nature through fleas and certain rodent
hosts that have sufficient resistance to maintain the disease at a low
level of transmission with little evident mortality in animals carrying
plague (enzootic cycle). Occasionally, the disease spreads from
enzootic hosts to more susceptible animals, resulting in a rapidly
spreading die-off affecting a large number of animals (epizootic cycle)
(Barnes 1993, p. 29; Biggins and Kosoy 2001, p. 909; Cully and Williams
2001, p. 900; Gage and Kosoy 2005, pp. 506-508). The factors that cause
a change from an enzootic to epizootic cycle are still being
researched, but may include host density, flea density, and climatic
conditions (Cully 1989, p. 49; Parmenter et al. 1999, p. 814; Cully and
Williams 2001, pp. 899-903; Enscore et al. 2002, p. 186; Lomolino et
al. 2003, pp. 118-119; Stapp et al. 2004, p. 237; Gage and Kosoy 2005,
p. 509; Ray and Collinge 2005, p. 204; Stenseth et al. 2006, p. 13110;
Adjemian et al. 2007, p. 372; Snall et al. 2008, p. 246).
Black-tailed prairie dogs are very sensitive to plague, and
mortality frequently reaches 100 percent (Barnes 1993, p. 28). Two
patterns of die-offs are typically described for black-tailed prairie
dogs: (1) A rapid and nearly 100 percent die-off with incomplete
recovery, such as has occurred at the Rocky Mountain Arsenal and the
Comanche National Grassland in Colorado (Cully and Williams 2001, pp.
899-903); and (2) a partial die-off resulting in smaller, but stable,
populations and smaller, more dispersed colonies, such as has occurred
at the Cimarron National Grassland in Kansas (Cully and Williams 2001,
pp. 899-903) and Pawnee National Grassland in Colorado (Derner et al.
2006, p. 459).
Several reports have suggested that the response of black-tailed
prairie dogs to plague may vary based on population density or degree
of colony isolation (Cully 1989, p. 49; Cully and Williams 2001, pp.
899-903; Lomolino et al. 2003, pp. 118-119). Colony complexes with a
history of recurring plague are typically composed of smaller colonies
with greater intercolony distances. A frequent assumption of
metapopulation conservation is that larger and closer populations are
preferable to smaller and more isolated populations; however, this may
not be the case when populations are exposed to a highly virulent
pathogen such as plague that can be transferred from patch to patch by
species movement (Johnson 2005, pp. 73-74).
Table 2 illustrates die-offs and extent of recovery for several
well-studied sites that have experienced plague epizootics (outbreak),
although some of these sites may have also been influenced by
poisoning. Any conclusions as to decreasing or increasing trends in
black-tailed prairie dog populations described in Table 2 are temporal
in nature and site-specific. Long-term, large-scale population trends
appear to be increasing.
Table 2. Site-specific Population Estimates of Occupied Black-tailed Prairie Dog Habitat Pre- and Post-Plague (PP = Post-Plague)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Site 1\st\ Estimate 2\nd\ Estimate 3\rd\ Estimate 4\th\ Estimate 5\th\ Estimate 6\th\ Estimate
--------------------------------------------------------------------------------------------------------------------------------------------------------
Comanche NG, CO 5,000 (2,023), 1,600 (647), 10,700 (4,330), 3,000 (1,214), ..................
1995 \1\ 1999 \1\ (PP)..... 2005 \1\ 2006 \1\ (PP)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Meadow Springs Ranch, CO 3,336 (1,351), 1,393 (564), 2007 360 (146), 2008 ..................
2006 \2\ \2\ (PP) \2\ (PP)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pawnee NG, CO 731 (296), 1998 744 (301), 1999 983 (398), 2000 3,300 (1,337), 2,398 (971), 2008 ..................
\3\ \4\ \4\ 2005 \5\ \5\ (PP)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pueblo Chemical Depot, CO 4,333 (1,753), 67 (27), 2000 \6\ 3,423 (1,385), 2,712 (1,097), ..................
1998 \6\ (PP) 2005 \6\ 2006 \6\ (PP)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rocky Mt. Arsenal, CO 4,574 (1,851), 247 (99), 1989 \7\ 2,429 (982), 22 (8), 1995 \7\ 1,646 (666), 314 (127), 2002
1988 \7\ (PP) 1994 \7\.......... (PP) 2000 \7\.......... \8\ (PP)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cimarron NG, KS 1,716 (695), 1,287 (521), 1,688 (684), 2,639 (1,069), 3,321 (1,345), 1,337 (541), 2008
1988 \3\.......... 1998 \3\.......... 1999 \4\.......... 2001 \4\.......... 2002 \9\.......... (PP) \5\
--------------------------------------------------------------------------------------------------------------------------------------------------------
CMR NWR, MT 4,859 (1,968), 2,064 (836), 1,729 (700), ..................
2004 \10\ 2007 \10\ (PP).... 2008 \10\ (PP)....
--------------------------------------------------------------------------------------------------------------------------------------------------------
Ft. Belknap Res., MT 24,000 (9,720), 11,000 (4,455), 13,475 (5,457), 14,230 (5,763), 12,987 (5,260), 12,989 (5,261),
1990 \11\ 1996 \11\ (PP) 1998 \11\ 1999 \12\ 2000 \12\ 2002 \12\
--------------------------------------------------------------------------------------------------------------------------------------------------------
N Cheyenne Res., MT 10,720 (4,338), 378 (152), 1995 3,300 (1,335), 3,913 (1,585), 5,683 (2,299), ..................
1990 \13\ \14\ (PP) 2002 \15\ 2003 \15\ 2006 \13\
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 63356]]
Kiowa/Rita Blanca NG, TX, OK, NM 1,600 (647), 6,800 (2,751), 4,500 (1,821), 3,000 (1,214), ..................
1999 \9\.......... 2003 \9\ 2004 \9\ (PP) 2005 \9\ (PP)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cimarron County, OK 1,837 (744), 5,500 (2,228), 10,406 (4,214), 2,370 (960), 1,975 (800), 13,523 (5,477),
1967 \16\......... 1972 \17\ 1989 \18\ 1991 \19\ (PP).... 1999 \20\......... 2002 \21\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Buffalo Gap NG, SD 42,600 (17,253), 13,270 (5,374), 18,105 (7,333), ~38,000 (15,400), 28,993 (11,742), ..................
1980 \4\ 1998 \3\ 2002 \4\ 2007 \5\ 2008 \5\ (PP)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Thunder Basin NG, WY 6,301 (2,552), 18,340 (7,428), 18,239 (7,387), 15,864 (6,425), 9,000 (3,642), 3,700 (1,500),
1980 \4\ 1997 \4\ 1998 \3\ 2001 \4\ (PP) 2003 \22\ (PP) 2008 \5\ (PP)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Augustine et al. 2008
\2\ Bachland 2008
\3\ Sidle 1999
\4\ Thompson 2002
\5\ Sidle 2009b
\6\ Young 2008
\7\ Seery 2001
\8\ Seery 2002
\9\ Cully and Johnson 2006
\10\ Dullum 2009
\11\ FaunaWest 1998
\12\ Vosburg 2002
\13\ Larson 2008
\14\ Fourstar 1998
\15\ Vosburg 2003
\16\ Tyler 1968
\17\ Lewis and Hassien 1973
\18\ Shackford et al. 1990
\19\ Shaw et al. 1993
\20\ Lomolino 1999
\21\ Luce 2002
\22\ Byer 2003
Some studies have documented the development of antibodies in
black-tailed prairie dogs surviving a plague epizootic. Over 50 percent
of survivors developed antibodies at one Colorado site (Pauli 2005, pp.
1, 71). The degree of evolved resistance, assuming little or no
resistance initially, is not known. However, a preliminary assessment
of natural resistance to plague found that prairie dogs collected from
South Dakota (minimal plague), Texas (historical plague outbreaks), and
Colorado (ongoing plague outbreaks) had differing levels of resistance.
When challenged with the same doses of plague inoculum, nearly all
South Dakota animals died, but 60 percent and 50 percent of animals
from Texas and Colorado respectively survived over all doses (Rocke
2009, p. 1). Laboratory research indicates that at low levels of
exposure a small percentage of black-tailed prairie dogs show some
immune response and consequently some resistance to plague, indicating
that development of a plague vaccine may be feasible (Creekmore et al.
2002, pp. 32, 38). Research on development of a plague vaccine has
demonstrated significantly higher antibody levels and survival rates in
vaccinated black-tailed prairie dogs that were challenged with the
plague bacterium (Mencher et al. 2004, pp. 5, 8-9; Rocke et al. 2008,
p. 930). Oral vaccination may be effective for managing plague
epizootics in select free-ranging prairie dog populations by reducing
mortality in exposed individuals (Mencher et al. 2004, pp. 8-9).
However, we need to conduct field tests before using it as a management
tool.
Since our last evaluation of the status of the black-tailed prairie
dog in 2004, when it was removed from the candidate list, plague has
expanded its range into South Dakota, previously the only State where
plague had not been documented in prairie dogs (U.S. Fish & Wildlife
Service 2005a, p. 1). The disease reached Conata Basin in 2008, despite
3 years of treating prairie dog burrows in portions of the affected
area with insecticide in an effort to kill fleas and thereby limit
plague transmission (a process referred to as ``dusting'').
Conata Basin is one of the largest remaining black-tailed prairie
dog complexes and is the most successful recovery site in North America
for the endangered black-footed ferret. Approximately 10,505 ac (4,251
ha) have been affected by plague through May 2009 in Conata Basin
(Griebel 2009, p. 1). Within the plague zone, there are typically
scattered individuals or small pockets of 1 to 2 ac (0.4 to 0.8 ha)
where prairie dogs either have natural immunity or escaped exposure by
chance (Griebel 2008, p. 4).
Plague has also been documented on Pine Ridge and Cheyenne River
Reservations in South Dakota (Mann-Klager 2008, pp. 1-2). Creekmore et
al. (2002, p. 38) noted that the establishment of sylvatic plague in
South Dakota could have a substantial impact on population dynamics of
both the black-tailed prairie dog and the black-footed ferret in South
Dakota. However, at this time less than 2 percent of occupied habitat
in the State has been affected by plague and occupied habitat continues
to increase Statewide. Occupied habitat also continues to increase in
States that have had plague present for more than 50 years.
Sylvatic plague remains a significant population stressor and the
spread and effects of plague on the species could be exacerbated by
climate change in the future. The extent to which the spread of plague
may expand or contract in the future is not clear. Regardless of how
plague is affected by climate change, the black-tailed prairie dog has
proven to be
[[Page 63357]]
a resilient species. In spite of the past and current effects of plague
and climate change and resulting impacts acting on the species,
occupied habitat (a surrogate measure for population trends and status)
in the United States has increased by more than 600 percent since the
early 1960s. Although the effects of plague could be exacerbated by
climate change in the future, the current status of the black-tailed
prairie dog does not suggest that plague, or the combined effects of
plague and climate change, are a limiting factors for the species in
the foreseeable future, and we do not believe these will result in
significant population-level impacts. The present or threatened
curtailment of prairie dog habitat presented by climate change is
addressed further under Factor E.
Tularemia and monkey pox are diseases that have had impacts on
captive black-tailed prairie dogs associated with the pet trade;
however, we have no information to indicate that either of these
diseases are a concern for wild prairie dogs.
Many species prey upon the black-tailed prairie dog; however, we
have no information to indicate that predation is a concern.
Summary of Factor C
Plague has expanded its range to all States within the range of the
black-tailed prairie dog in recent years and has caused local
population declines at several sites. These declines are typically
followed by partial or complete recovery. Development of a vaccine to
protect prairie dog populations has begun, and resistance to plague has
been observed in some individuals. Since the early 1960s, occupied
habitat has increased in every State, even in those States where plague
has been present for over 50 years. Throughout the United States,
occupied habitat is estimated to have increased by over 600 percent
from 1961 until the present time. This increase has occurred despite
continued impacts from plague and other factors.
The current status of the black-tailed prairie dog, as indicated by
increasing trends in the species' occupied habitat since the early
1960s, indicates that plague is not a limiting factor for the species.
Although Sylvatic plague remains a population stressor and the spread
and effects of plague on the species could be exacerbated by climate
change in the long term future, the black-tailed prairie dog has proven
to be a resilient species. In spite of the past and current effects of
plague and climate change and resulting impacts on the species, black-
tailed prairie dog occupied habitat (a surrogate measure for population
trends and status) in the U.S. has increased by more than 600 percent
since the early 1960s. Although the effects of plague could be
exacerbated by climate change in the future, the current status of the
black-tailed prairie dog does not suggest that the combined effects of
climate change and plague, are a limiting factor for the species in the
foreseeable future, and we do not believe these will result in
significant population-level impacts. Consequently, we do not
anticipate that impacts from the disease are likely to negatively
impact the status of the species in the foreseeable future. Therefore,
we have no reason to suspect that plague poses a significant threat to
the species.
We conclude that the best scientific and commercial information
available indicates that the black-tailed prairie dog is not now, or in
the foreseeable future, threatened by disease or predation to the
extent that listing under the Act as a threatened or endangered species
is warranted at this time.
D. The Inadequacy of Existing Regulatory Mechanisms
Traditionally, resident species that are not federally threatened
or endangered are usually managed by States or Tribes. Federal land
management agencies may have additional management policies on their
lands. The three primary means by which agencies can effectively
influence black-tailed prairie dog populations are via shooting
regulations, poisoning regulations, and proactive management. Detailed
information regarding existing regulatory and management measures
affecting the species is provided below.
Arizona
Classification - The species is classified as nongame (animals that
are not traditionally hunted, fished, or trapped) (Voyles 2009, p. 2).
Shooting - A hunting license is required to shoot prairie dogs. The
hunting season for black-tailed prairie dogs has been closed since 1999
(Voyles 2009, p. 2).
Poisoning - Toxicants are permitted for use on prairie dogs in
Arizona, typically in conjunction with human health related to plague
or safety concerns; however, plague has not been identified within the
range of the black-tailed prairie dog in Arizona since its
reintroduction in 2008, and no poisoning has occurred (Voyles 2009, p.
2).
Management Plans - Arizona is a signatory to the interstate
Conservation Assessment and Strategy (Van Pelt 1999, p. 71). The
Statewide management plan (Van Pelt et al. 2001) for Arizona supports,
but does not meet, the objectives described in the Multi-State Plan.
The Statewide management plan for Arizona has not been approved. The
Statewide comprehensive wildlife strategy recognizes the black-tailed
prairie dog as a species of concern (Arizona Game and Fish Dept. 2006,
pp. 443-445). However, this designation does not result in any
protection for the species.
Colorado
Classification - The black-tailed prairie dog is classified as
small game (CDOW 2009, p. 2).
Shooting - In 2006, the State removed the ban on hunting black-
tailed prairie dogs on public land (Nesler 2009, p. 5). The hunting
season is year-round on private land and June 15 through the end of
February on public land. A small game license is required. There is no
bag limit (CDOW 2009, p. 2).
Poisoning - Chemical control is jointly regulated by the Colorado
Department of Agriculture, and the CDOW and is limited to those
pesticides legally permitted for use on black-tailed prairie dogs.
Prairie dogs may also be taken by use of explosive gases where
necessary to control damage on private lands (CDOW 2009, p. 4).
Management Plans - Colorado is not a signatory to the interstate
Conservation Assessment and Strategy (Van Pelt 1999, p. 71). The
Statewide management plan (CDOW 2003) for Colorado supports and meets
all of the objectives described in the Multi-State Plan. The Statewide
management plan for Colorado has been approved. The Statewide
comprehensive wildlife strategy recognizes the black-tailed prairie dog
as a species of concern (CDOW 2006, p. 98). However, this designation
does not result in any protection for the species.
Kansas
Classification - The Kansas Department of Wildlife and Parks
classifies the species as wildlife (Kansas Department of Wildlife and
Parks 2009, p. 1).
Shooting - The hunting season is year-round on private and public
lands. A hunting license is required for residents and nonresidents.
There is no bag limit (Kansas Department of Wildlife and Parks 2009, p.
2).
Poisoning - The most recent information available to us indicates
that a permit is required to use any poisonous gas or smoke, but is not
required to use above ground toxicants (Mitchener 2003, p. 2).
According to Kansas Statutes 80-1201, 1202, and
[[Page 63358]]
1203, control may be legislated at a local level. For example, several
townships have imposed mandatory control requirements. In some cases,
landowners are instructed to control prairie dogs on their land; if
they fail to do so, it is done by the county at the landowner's expense
(Kansas Legislature 2009, pp. 1-8).
Management Plans - Kansas is a signatory to the interstate
Conservation Assessment and Strategy (Van Pelt 1999, p. 71). The
Statewide management plan (Kansas Department of Wildlife and Parks
2002) for Kansas supports, but does not meet, all of the objectives
described in the Multi-State Plan. Kansas does not meet the objective
of maintaining at least 10 percent of total occupied area in complexes
greater than 1,000 ac (405 ha) (Van Pelt 2009, p. 16). The Statewide
management plan for Kansas has been approved. The Statewide
comprehensive wildlife strategy recognizes the black-tailed prairie dog
as a species of concern (Wasson et al. 2005, Appendix 1). However, this
designation does not result in any protection for the species.
Montana
Classification - The species is classified as a vertebrate pest
under the Montana Department of Agriculture (Bamber 2009, pp. 1-2). The
State legislature allowed the dual status of ``nongame wildlife in need
of management'' and ``vertebrate pest'' to expire in 2007 (Bamber 2009,
pp. 1-2). A bill to resume dual classification and management of the
black-tailed prairie dog failed to pass in the 2009 Montana legislative
session (Hanauska-Brown 2009, p. 2).
Shooting - The hunting season is year-round on private and public
lands. No hunting license is required for residents or nonresidents
(Van Pelt 2009, p. 21). There is no bag limit.
Poisoning - Chemical control is regulated by the Montana Department
of Agriculture. The Department employs a vertebrate pest specialist to
assist Federal, State, and County agencies and private landowners with
training and certification of pesticide applicators. There is no
funding or personnel for the Montana Department of Agriculture to
conduct prairie dog control programs. No control is currently occurring
on Federal or tribal lands, and the level of control on private and
State lands has remained stable in recent years (Bamber 2009, pp. 1-2).
Management Plans - Montana is a signatory to the interstate
Conservation Assessment and Strategy (Van Pelt 1999, p. 71). The
Statewide management plan (Montana Department of Fish, Wildlife and
Parks 2002) for Montana does not support or meet the occupied area
objective. The Statewide management plan for Montana has been approved.
The Statewide comprehensive wildlife strategy recognizes the black-
tailed prairie dog as a species of concern (Montana Fish, Wildlife and
Parks 2005, pp. 375-378). However, this designation does not result in
any protection for the species.
Nebraska
Classification - The species is classified as unprotected nongame
(Amack and Ibach 2009, p. 2).
Shooting - The hunting season is year-round on private and public
lands. No hunting license is required for residents. Nonresidents must
have a small game hunting license. There is no bag limit (Amack and
Ibach 2009, p. 2).
Poisoning - Chemical control is regulated by the Nebraska
Department of Agriculture and is limited to those pesticides legally
permitted for use on black-tailed prairie dogs. The U. S. Animal and
Plant Health Inspection Service and landowners conduct control work
(Amack and Ibach 2009, p. 3).
Management Plans - Nebraska is a signatory to the interstate
Conservation Assessment and Strategy (Van Pelt 1999, p. 71). The
Statewide management plan (Nebraska Game and Parks Commission 2001) for
Nebraska supports, but does not meet, all of the objectives described
in the Multi-State Plan. Nebraska does not meet the objective of
managing or contributing to at least one complex greater than 5,000 ac
(2,023 ha) and does not meet the objective of maintaining distribution
throughout at least 75 percent of the historic range in the State (Van
Pelt 2009, p. 26). The Statewide management plan for Nebraska has not
been approved. The Statewide comprehensive wildlife strategy does not
recognize the black-tailed prairie dog as a species of concern
(Schneider et al. 2005, pp. 203, 236).
New Mexico
Classification - The species is not classified as having any status
by the State other than that described by the Statewide comprehensive
wildlife strategy (Van Pelt 2009, p. 28).
Shooting - The hunting season is year-round on private and public
lands. No hunting license is required for residents. Nonresidents must
have a hunting license (Van Pelt 2009, p. 28). There is no bag limit.
Poisoning - Chemical control is limited to pesticides legally
permitted for use on black-tailed prairie dogs.
Management Plans - New Mexico is a signatory to the interstate
Conservation Assessment and Strategy (Van Pelt 1999, p. 71). The
Statewide management plan (New Mexico Black-tailed Prairie Dog Working
Group 2001) for New Mexico does not support or meet all of the
objectives described in the Multi-State Plan. New Mexico does not
support the objective of managing or contributing to at least one
complex greater than 5,000 ac (2,023 ha), although it does meet that
objective (Van Pelt 2009, p. 28). It does not meet the occupied area
objective or the objective of maintaining distribution throughout at
least 75 percent of the historic range in the State (Van Pelt 2009, p.
28). The Statewide management plan for New Mexico has been approved.
The Statewide comprehensive wildlife strategy recognizes the black-
tailed prairie dog as a species of concern (New Mexico Department of
Game and Fish 2006, pp. 55, 577). However, this designation does not
result in any protection for the species.
North Dakota
Classification - The species is classified as a pest species by the
North Dakota Department of Agriculture (McKenna 2009, p. 1).
Shooting - The hunting season is year-round on private and public
lands. No hunting license is required for residents. Nonresidents must
have a nongame or furbearers license (McKenna 2009, p. 2). There is no
bag limit.
Poisoning - Current regulations allow landowners to poison black-
tailed prairie dogs if they are certified applicators (McKenna 2009, p.
2).
Management Plans - North Dakota is not a signatory to the
interstate Conservation Assessment and Strategy (Van Pelt 1999, p. 71).
The Statewide management plan (North Dakota Game and Fish Department
2001) for North Dakota does not support or meet all of the objectives
described in the Multi-State Plan. North Dakota does not support any of
the objectives and does not meet any objectives except distribution
over at least 75 percent of the historical range (Van Pelt 2009, p.
24). The Statewide management plan for North Dakota has been approved.
The Statewide comprehensive wildlife strategy recognizes the black-
tailed prairie dog as a species of concern (Hagen et al. 2005, pp. 27,
305-307). However, this designation does not result in any protection
for the species.
Oklahoma
Classification - The species is classified as wildlife-nongame (Van
Pelt 2009, p. 30).
[[Page 63359]]
Shooting - The hunting season is year-round on private and public
lands. Residents and nonresidents must have a valid State hunting
license. There is no bag limit (Van Pelt 2009, p. 30).
Poisoning - A permit from the Oklahoma Department of Wildlife
Conservation is required. No permit will be issued in a county with
less than 100 ac (40 ha) of black-tailed prairie dog occupied habitat
(Van Pelt 2009, p. 30).
Management Plans - Oklahoma is a signatory to the interstate
Conservation Assessment and Strategy (Van Pelt 1999, p. 71). The
Statewide management plan (Hoagland 2001) for Oklahoma supports, but
does not meet all of the objectives described in the Multi-State Plan.
Oklahoma does not meet the occupied area objective (Van Pelt 2009, p.
30). The Statewide management plan for Oklahoma has not been approved.
The Statewide comprehensive wildlife strategy recognizes the black-
tailed prairie dog as a species of concern (Oklahoma Department of
Wildlife Conservation 2005, pp. 358, 360). However, this designation
does not result in any protection for the species.
South Dakota
Classification - The State of South Dakota modified the designation
of ``species of management concern'' for the black-tailed prairie dog
by designating it as a pest if plague is reported east of the Rocky
Mountains, the Statewide population is greater than approximately
145,000 ac (59,000 ha), or the species is colonizing within a 1 mi (1.6
km) buffer around concerned landowners (South Dakota State Legislature
2005, pp. 3-4). Currently, all of these criteria are being met;
therefore, the species is considered a pest in South Dakota.
Shooting - The hunting season is year-round on private lands and
open from June 15 through February 28 on public lands, except for a
year-round closure in Conata Basin. Residents and nonresidents must
have a valid South Dakota hunting license. There is no bag limit (Van
Pelt 2009, p. 34).
Poisoning - Chemical control is limited to pesticides legally
permitted for use on black-tailed prairie dogs.
Management Plans -South Dakota is a signatory to the interstate
Conservation Assessment and Strategy (Van Pelt 1999, p. 72). The
Statewide management plan (Cooper and Gabriel 2005) for South Dakota
supports and meets all of the objectives described in the Multi-State
Plan (Vonk and Even 2009, pp. 3-4). South Dakota's management plan also
notes that the state has identified its own goals and objectives,
specific to South Dakota, and reserves the right to preserve their own
management authority. The Statewide management plan for South Dakota
has been approved. The Statewide comprehensive wildlife strategy does
not recognize the black-tailed prairie dog as a species of concern
(South Dakota Department of Game, Fish, and Parks 2006, pp. 65-69).
Texas
Classification - The species is classified as nongame (Van Pelt
2009, p. 38).
Shooting - The hunting season is year-round on private and public
lands. Residents and nonresidents must have a valid State hunting
license. There is no bag limit for shooting. A nongame commercial
dealer's permit is required for capture and selling of more than 25
individuals (Van Pelt 2009, p. 38).
Poisoning - Chemical control is limited to pesticides legally
permitted for use on black-tailed prairie dogs.
Management Plans - Texas is a signatory to the interstate
Conservation Assessment and Strategy (Van Pelt 1999, p. 72). The
Statewide management plan (Texas Black-tailed Prairie Dog Working Group
2004) for Texas supports, but does not meet all of the objectives
described in the Multi-State Plan. Texas does not meet the occupied
area objective (Van Pelt 2009, p. 37). The Statewide management plan
for Texas has been approved. The Statewide comprehensive wildlife
strategy recognizes the black-tailed prairie dog as a species of
concern (Texas Parks and Wildlife Department 2005, p. 744). However,
this designation does not result in any protection for the species.
Wyoming
Classification - The species is classified as a nongame mammal by
the Wyoming Game and Fish Department and as a pest by the Wyoming
Department of Agriculture. A Memorandum of Understanding exists to
coordinate management of the species between the two Departments if
survey results indicate that occupied habitat for the species is less
than the Wyoming Game and Fish Department objectives (Emmerich 2009, p.
3).
Shooting - The hunting season is year-round on private and public
lands. Residents and nonresidents are not required to have a State
hunting license. There is no bag limit for shooting (Van Pelt 2009, p.
40). Unlike most States, the Wyoming Game and Fish Commission has the
authority to implement a shooting closure if it deems it necessary
(Emmerich 2009, p. 3).
Poisoning - Chemical control is limited to pesticides legally
permitted for use on black-tailed prairie dogs.
Management Plans - Wyoming is a signatory to the interstate
Conservation Assessment and Strategy (Van Pelt 1999, p. 72). The
Statewide management plan (Kruckenberg et al. 2001) for Wyoming
supports and meets all of the objectives described in the Multi-State
Plan. The Statewide management plan for Wyoming has not been approved.
However, a grasslands conservation plan (Wyoming Game and Fish
Department 2006, pp. 23-29, 94-130) addresses the species and has
specific management objectives consistent with the Multi-State Plan
(Emmerich 2009, pp. 3-4). The Statewide comprehensive wildlife strategy
recognizes the black-tailed prairie dog as a species of concern
(Wyoming Game and Fish Department 2005, pp. 10, 141-143). However, this
designation does not result in any protection for the species.
Tribes
There are several Indian Reservations within the range of the
black-tailed prairie dog in Montana, New Mexico, North Dakota, and
South Dakota. However, we are only aware of nine Tribes that have
black-tailed prairie dog occupied habitat within their Reservations
(Cheyenne River Sioux Indian Reservation, SD; Crow Indian Reservation,
MT; Crow Creek Indian Reservation, SD; Fort Belknap Indian Reservation,
MT; Lower Brule Indian Reservation, SD; Northern Cheyenne Indian
Reservation, MT; Pine Ridge Indian Reservation, SD; Rosebud Indian
Reservation, SD; and Standing Rock Indian Reservation in ND and SD).
Tribes did not provide any new information. It is our understanding
that hunting black-tailed prairie dogs on tribal lands requires a
permit. The season is typically year-round, and there are no bag
limits. Poisoning is prohibited or requires a permit. Tribes generally
meet or exceed their proportional requirements for occupied habitat, as
described in the Multi-State Plan.
Federal Agencies
There are numerous Federal laws, acts, and policies in addition to
the Act that encourage coordination of activities that may impact
wildlife and promote conservation of wildlife. Some of the most
frequently encountered that may influence black-tailed prairie dog
management are described. The Fish and Wildlife Coordination Act (16
U.S.C. 661 et seq.) requires consultation between the Service and other
Federal agencies and equal consideration of
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wildlife conservation with water resource development programs. The
Fish and Wildlife Conservation Act (16 U.S.C. 2901 et seq.) authorizes
financial and technical assistance to States for the development of
conservation plans and programs for nongame fish and wildlife. The
National Environmental Policy Act (42 U.S.C. 4321 et seq.) requires all
Federal agencies to examine the environmental impacts of their actions,
incorporate environmental information, and utilize public participation
in the planning and implementation of all actions. Specific information
for affected Federal agencies is provided as follows.
U.S. Air Force - The most recent available information indicates
that no recreational shooting is allowed on Ellsworth Air Force Base
and Badlands Bombing Range in South Dakota; however, some chemical
control has been conducted (Morgenstern 2003, pp. 3-4). Similarly, at
Buckley Air Force Base in Colorado there is no recreational shooting,
but some chemical control (Friese 2003, pp. 2, 4). We have no
information on black-tailed prairie dog management policies from other
bases.
Department of Agriculture, U.S. Animal and Plant Health Inspection
Service (APHIS) - APHIS, Wildlife Services (WS) does not manage any
Federal lands. However, it supports prairie dog control programs in
several States. In 2008, 129 projects were conducted regarding the
control of black-tailed prairie dogs (primarily personal consultations)
in Colorado, Nebraska, New Mexico, North Dakota, Oklahoma, Texas, and
Wyoming (APHIS 2009, pp. 1-7). At a black-footed ferret reintroduction
site in Kansas, the Service has an agreement with APHIS-WS to provide a
staff person to control prairie dogs if neighboring landowners request
control (LeValley 2009, pp. 1-2). APHIS-WS also has supported several
research efforts in recent years regarding disease, control, non-target
impacts that can be accessed on their website.
U.S. Army - The most recent available information indicates that
the U.S. Army manages approximately 8,800 ac (3,600 ha) of black-tailed
prairie dog occupied habitat (Hoefert 2002, pp. 2-6). The majority of
occupied habitat (approximately 7,000 ac/2,800 ha) occurs on Fort
Carson Garrison in Colorado (Larson 2008, p. 73).
U.S. Bureau of Indian Affairs - The U.S. Bureau of Indian Affairs'
involvement in black-tailed prairie dog management has been principally
through management of funding for prairie dog control programs on
tribal lands in Montana, North Dakota, and South Dakota. The last
large-scale chemical control effort for the species was directed by
U.S. Bureau of Indian Affairs on the Pine Ridge/Oglala Sioux
Reservation in South Dakota in the 1980s (Roemer and Forrest 1996, p.
353).
U.S. Bureau of Land Management - The most recent available
information indicates that the U.S. Bureau of Land Management (BLM)
manages approximately 39,000 ac (16,000 ha) of black-tailed prairie dog
occupied habitat in Arizona, Colorado, Montana, New Mexico, North
Dakota, South Dakota, and Wyoming (Lawton 2003, p. 14). The BLM manages
prairie dogs to meet multiple-use resource objectives including
production of livestock forage and prevention of prairie dog
encroachment onto adjacent lands. The BLM generally adheres to State
regulations regarding shooting, although some additional closures exist
at black-footed ferret recovery sites.
U.S. Environmental Protection Agency - The U.S. Environmental
Protection Agency (EPA) influences regulatory mechanisms through its
pesticide labeling programs that determine which pesticides can be
legally used to poison prairie dogs, who can apply them, and what other
label restrictions apply. The EPA has approved several chemicals for
control of black-tailed prairie dogs. The impacts of poisoning by these
chemicals are described in greater detail under ``Poisoning'' in Factor
E below. Here, we describe the regulatory process employed by the EPA.
The EPA approved zinc phosphide as a legal prairie dog control
chemical in 1973 (Forrest and Luchsinger 2006, p. 124). The EPA has not
responded to our request to provide information on the amount of area
poisoned with zinc phosphide or the amount of chemical sold. This
information would enable us to better monitor the extent and effects of
poisoning with zinc phosphide on black-tailed prairie dogs.
The EPA recently permitted the use of chlorophacinone and
diphacinone (both anticoagulants) to poison prairie dogs. Use of these
two chemicals to control prairie dogs constitutes new uses for these
poisons. Since 2004, State agricultural departments have issued Special
Local Needs permits under the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA, 7 U.S. C. 136 et seq.) Section 24(c)
authorizing the use of chlorophacinone for poisoning prairie dogs in
Colorado, Kansas, Nebraska, Oklahoma, Texas, and Wyoming and
authorizing the use of diphacinone for poisoning prairie dogs in
Colorado, Kansas, Nebraska, Texas, and Wyoming. In 2009, the EPA
further broadened the potential scope of chlorophacinone by registering
it under FIFRA section 3, which allows its use throughout the 11 States
within the range of the black-tailed prairie dog. Prairie dogs are
highly susceptible to both chlorophacinone and diphacinone, which is
why the chemicals are popular as a control mechanism. Unlike zinc
phosphide, secondary poisoning of several species is documented from
chlorophacinone and diphacinone (Erickson and Urban 2004, pp. 48, 51;
Lydick 2006, pp. 1-2; Klataske 2009, pp. 1-6; Service 2007, pp. 1-10).
We have limited information regarding the number of prairie dogs
that are killed by anticoagulants or the amount of habitat treated. We
are concerned about the impacts to both the black-tailed prairie dog
and the secondary poisoning of other species, such as black-footed
ferrets, other mammals, eagles, and other raptors. Despite this
concern, the amount of habitat occupied by the black-tailed prairie dog
throughout the United States increased by over 600 percent from 1961
until the present time.
U.S. Fish and Wildlife Service - The Service manages over 500
National Wildlife Refuges and their satellites, but only about 15
refuges, satellites, or Waterfowl Production Areas have black-tailed
prairie dogs. Three refuges have a majority of occupied habitat on
Service lands (approximately 6,000 ac/2,400 ha). On Charles M. Russell
and UL Bend National Wildlife Refuges in Montana, black-tailed prairie
dog habitat is managed to enhance its value as a black-footed ferret
reintroduction site. The Rocky Mountain Arsenal National Wildlife
Refuge in Colorado is managed to support black-tailed prairie dogs and
a diversity of wildlife. Current Service management policy allows
managers on Service lands to:
(1) control the species as needed for public health and safety,
(2) translocate up to 30 percent of the population annually with
proper coordination with State wildlife agencies, and
(3) control the species to accommodate wildlife and habitat
objectives after completion of a prairie dog management plan and
evaluation by a Service review committee (Service 2005b, pp. 1-2).
Managers of Service lands are also encouraged to work cooperatively
with neighboring landowners and local governments through the use of
agreements and technical and financial assistance.
Department of Agriculture, U.S Forest Service - The U.S. Forest
Service (USFS) reduced their restrictions on
[[Page 63361]]
poisoning by rescinding a 2000 policy letter regarding control of
black-tailed prairie dogs and allowing expanded poisoning on their
lands (Manning 2004, pp. 2-4). The USFS manages an estimated 57,606 ac
(23,312 ha) of black-tailed prairie dog occupied habitat (Sidle 2009b,
p. 3). The USFS manages prairie dogs to meet multiple-use resource
objectives including production of livestock forage and prevention of
prairie dog encroachment onto adjacent lands. Recreational shooting is
typically regulated by the State and is allowed on most National
Grasslands, although some additional closures exist at black-footed
ferret recovery sites. In 2008, the USFS poisoned 3,679 ac (1,489 ha)
of black-tailed prairie dog occupied habitat (Sidle 2009b, p. 3). This
control addressed encroachment of prairie dogs onto adjacent private
lands. Most of this (2,489 ac/1,008 ha) was on Buffalo Gap National
Grassland. Nevertheless, lands poisoned on Buffalo Gap constitute less
than 0.4 percent of occupied habitat in South Dakota.
U.S. National Park Service - The U.S. National Park Service manages
approximately 13,777 ac (5,575 ha) of black-tailed prairie dog occupied
habitat (Van Pelt 2009, p. 71). A majority of occupied habitat (8,993
ac/3,642 ha) occurs on Badlands National Park in South Dakota (Van Pelt
2009, p. 71). Some poisoning with zinc phosphide and shooting by
National Park Service rangers occurs in boundary areas for ``good
neighbor'' purposes (Davila 2009, p. 1). The most recent National Park
Service guidance notes that black-tailed prairie dogs are managed under
policies for conserving native species, but that some control may be
necessary for ``good neighbor'' and human health reasons. The use of
anticoagulants is not approved due to impacts on non-target species
(Davila 2009, pp. 3-4).
Canada - The black-tailed prairie dog is designated as vulnerable
by the Committee on the Status of Endangered Wildlife in Canada. The
management plan for the black-tailed prairie dog in Canada notes that
the species will be allowed to naturally fluctuate on land managed by
the Province of Saskatchewan, but if colonies expand beyond their 2007
boundaries, the affected land manager may implement control measures
under authority of a permit issued by Saskatchewan Environment, with
nonlethal control measures encouraged (Tuckwell and Everest 2009, p.
15).
Mexico - The most recent available information indicates that there
is no shooting of black-tailed prairie dogs and little chemical control
in Mexico (List 2001, p. 1). The species is listed as threatened by the
Lista de las Especies Amerzadas, the official endangered and threatened
species list of the Mexican government (SEMARNAP 1994).
Summary of Factor D
The affected State and Federal agencies are engaged in black-tailed
prairie dog management and monitoring to a much greater extent than
they were 10 years ago, before creation of the Prairie Dog Conservation
Team. Nevertheless, agencies continue to have conflicting policies
regarding prairie dog management. For example, Kansas has an approved
management plan that supports all of the objectives described in the
Multi-State Plan, and their Statewide comprehensive wildlife strategy
recognizes the black-tailed prairie dog as a species of concern.
However, the State's only complex greater than 5,000 ac (2,023 ha),
which satisfies an objective from the Multi-State Plan and is also a
black-footed ferret recovery site, potentially could be reduced or
eliminated by the Logan County Commission, which under state law has
authority to control prairie dogs, against the landowners' wishes and
at the landowners' expense (Haverfield and Haverfield 2009, pp. 1-6).
In some cases, Statewide occupied habitat is increasing in spite
of, rather than because of, agency actions, which indicates that the
species has been persistent despite state management contradictions.
However, there is no evident correlation between the magnitude of
increase in the species' population in a particular State and the
extent to which a State is engaged in proactive management. Since the
early 1960s, occupied habitat has increased in every State. Throughout
the United States, occupied habitat is estimated to have increased by
over 600 percent from 1961 until the present time. This increase has
occurred despite regulatory mechanisms that favor control of the
species and other factors.
The current status of the black-tailed prairie dog, as indicated by
increasing trends in the species' occupied habitat since the early
1960s, indicates that inadequate regulatory mechanisms are not a
limiting factor for the species. Consequently, we do not anticipate
that impacts from inadequate regulatory mechanisms are likely to
negatively impact the status of the species in the foreseeable future.
We conclude that the best scientific and commercial information
available indicates that the black-tailed prairie dog is not now, or in
the foreseeable future, threatened by inadequate regulatory mechanisms
to the extent that listing under the Act as an endangered or threatened
species is warranted at this time.
E. Other Natural or Manmade Factors Affecting Its Continued Existence
Under this factor we evaluate poisoning, drought, and climate
change.
Poisoning
Early poisoning of prairie dogs typically was conducted with
strychnine and carbon bisulphide, with Compound-1080 becoming popular
after World War II (Forrest and Luchsinger 2006, p. 122). Early
poisoning efforts led to extirpation of the black-tailed prairie dog in
Arizona by approximately 1940 (Arizona Game and Fish Dept. 1988, p.
26). Both Compound-1080 and strychnine can cause secondary poisoning of
non-target predators and scavengers that prey on poisoned prairie dogs.
Concern over secondary poisoning from strychnine and Compound-1080 led
to a report by Cain et al. (1972, p. 6). The Council on Environmental
Quality and the Department of the Interior requested this report and
instructed the authors to evaluate existing animal control programs and
provide recommendations. One of the recommendations was to remove from
registration all toxicants used for predator control and those
toxicants used for rodent control that resulted in secondary poisoning
of non-target animals, because such methods were likely to be inhumane
(Cain et al. 1972, pp. 5-6).
These recommendations led to Executive Order 11643, which in 1972
banned the use of toxicants that might cause secondary poisoning on
public lands or via Federal programs. In 1982, this order was revoked
by Executive Order 12342. However, poisoning prairie dogs with
strychnine and Compound-1080 did not resume. The total area throughout
the range of the species that was poisoned from 1915-1965 was likely
more than 37 million ac (15 million ha) (Forrest and Luchsinger 2006,
p. 120). The broad-scale, government sponsored poisoning that occurred
during the first half of the twentieth century likely contributed to
the species reaching a low point of 364,000 ac (147,000 ha) of occupied
habitat in the early 1960s. Since then, poisoning has generally
occurred on a more local scale and been conducted by individual
landowners.
Since 1973, the two most commonly used toxicants have been zinc
phosphide (administered via oats or other grain) and fumigants
(administered via insertion into
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burrows) (Forrest and Luchsinger 2006, p. 124). Both toxicants can pose
a risk to non-target wildlife from primary exposure. In recent years
anticoagulants such as chlorophacinone (trade name Rozol) and
diphacinone (trade name Kaput) have become popular, as described under
Factor D. In addition to risks of primary toxicity to non-target
wildlife, these products pose a risk of secondary poisoning to non-
target wildlife that is not a concern with zinc phosphide. These risks
from secondary poisoning are similar to those raised 37 years ago by
Cain et al. (1972, p. 6). Secondary poisoning has been documented in
badgers (Lydick 2006, pp. 1-2; Klataske 2009, pp. 1-6) and a bald eagle
(Service 2007, pp. 1-10) as a result of legal application of
chlorophacinone for control of black-tailed prairie dogs.
Anticoagulants such as chlorophacinone and diphacinone cause a more
prolonged period of distress for the black-tailed prairie dog prior to
mortality than zinc phosphide. Anticoagulants act as blood thinners,
with poisoned animals loosing blood through various orifices, including
eventually the skin membranes, over a period of weeks (Erickson and
Urban 2004, p. 3). For example, two weeks after an illegal application
of chlorophacinone on 160 ac (65 ha) in South Dakota in 2005, we found
dying prairie dogs. In contrast, zinc phosphide causes mortality in a
matter of hours. We do not have any information on the amount of
anticoagulants sold for prairie dog control or the amount of land
treated.
The most complete information that we have regarding the amount of
black-tailed prairie dog habitat poisoned or the amount of poison sold
is from the South Dakota Department of Agriculture, which jointly
manages prairie dog control with the South Dakota Department of Game,
Fish and Parks. South Dakota is the only State that has been permitted
by EPA to manufacture and sell zinc phosphide. Sales from the South
Dakota bait station are largely limited to South Dakota, Wyoming, and
Nebraska. The available information indicates that sales from the South
Dakota bait station fluctuate, but in general have increased since we
removed the black-tailed prairie dog from the candidate list in 2004
(Cerovski 2004, p. 101; Kempema 2007, p. 8). Figure 1 includes the
total sales of zinc phosphide bait by the South Dakota bait station in
the 4 years prior to candidate removal and the 4 years following
candidate removal.
Figure 1. Sales of Zinc Phosphide Bait Prior (Fridley 2003, p. 2)
and Subsequent to (Josten 2009, p. 3) our 2004 Removal of the Black-
tailed Prairie Dog from the Federal Candidate List. Total sales for
2009 not yet tabulated.
[GRAPHIC] [TIFF OMITTED] TP03DE09.079
Zinc phosphide sales do not necessarily reflect effective
application. For example, individuals may stockpile poison, re-treat
previously poisoned land, or apply it at rates different than the
recommended rate of 1/3 pound per acre (Hygnstrom and Virchow 1994, p.
B89). Additionally, the South Dakota bait station is only one of
several suppliers of prairie dog poison. However, to provide some
perspective, if all of the zinc phosphide bait were applied at the
recommended rate of 1/3 pound per acre, enough poison has been sold by
this one facility since removal of the black-tailed prairie dog from
the candidate list in 2004 to theoretically poison over 3.5 million ac
(1.4 million ha). This equates to more than all estimated occupied
habitat in the United States with enough remaining to poison an
additional one million ac (400,000 ha).
Some additional information regarding the extent of poisoning is
available for other States within the range of the black-tailed prairie
dog. In Kansas, an estimated 40,000 ac (16,200 ha) of private land have
been poisoned recently (Van Pelt 2009, p. 16). There has been no
indication of an increase in poisoning in Montana in recent years
(Bamber 2009, p. 2). The most recent survey in North Dakota noted that
approximately 43 percent of colonies on private land (approximately
9,700 ac/3,900 ha) had some indication of poisoning, although total
occupied habitat increased (Knowles 2007, p. 2). An estimated 900 ac
(400 ha) have been poisoned recently in Oklahoma (Van Pelt 2009, p.
30). The Texas Wildlife
[[Page 63363]]
Damage Management Service estimated 3,500 ac (1,420 ha) were poisoned
in 2008 (Van Pelt 2009, p. 38). As described under Factor D, the USFS
estimated 3,679 ac (1,490 ha) were poisoned on their lands in 2008; the
majority was 2,489 ac (1,008 ha) in Buffalo Gap National Grassland,
South Dakota, and 670 ac (271 ha) in Pawnee National Grassland,
Colorado (Sidle 2009b, p. 3). No other recent estimates regarding
poisoning were available.
If we total poison estimates for 2008 from the South Dakota Bait
Station, Kansas, North Dakota, Oklahoma, Texas, and Pawnee National
Grasslands, the amount of black-tailed prairie dog occupied habitat
poisoned in 2008 was approximately 801,000 ac (324,000 ha), or 33
percent of estimated range wide occupied habitat. This figure does not
include estimates for Montana or New Mexico, and only partial estimates
are available for Colorado, Nebraska, and Wyoming.
In a review of available research, Andelt (2006, p. 135) concluded
that colony size increases by about 30 percent annually for several
consecutive years following poisoning; after intense but not total
elimination, colony size can initially increase by as much as 71
percent annually. Colonies usually require 3 to 5 years to attain pre-
treatment size. The author further notes that complete eradication with
100 percent mortality is ``formidably elusive.'' Earlier, government
sponsored poisoning efforts such as those that led to the eradication
of the black-tailed prairie dog in Arizona were likely more effective
due to a synchronized effort by the Federal government over a large
landscape. In recent years poisoning has typically been conducted over
a smaller landscape such as the property of a single landowner. Despite
the long-term and widespread poisoning of the black-tailed prairie dog,
increasing population trends both range wide and Statewide indicate
that localized poisoning is not adversely impacting the species' status
and long-term conservation.
The current status of the black-tailed prairie dog, as indicated by
increasing trends in the species' occupied habitat since the early
1960s, indicates that poisoning is not a threat to the species. There
is no evidence that poisoning poses a significant threat to the species
now or into the future.
Drought
Drought is a natural and cyclical occurrence within the range of
the black-tailed prairie dog to which the animal has adapted (Forrest
2005, p. 528). In at least some instances, occupied habitat tends to
increase during periods of drought and densities decrease, because
animals spread out in search of food (Young 2008, p. 5). However, we
are aware of no information that quantifies the effect of drought,
singly or in conjunction with other threats, on the species range wide.
The current status of the black-tailed prairie dog, as indicated by
increasing trends in the species' occupied habitat since the early
1960s, suggests that drought is not a limiting factor for the species.
Therefore, we have no reason to suspect this poses a significant threat
to the species.
Climate Change
No information on the direct relationship between climate change
and black-tailed prairie dog population trends is available. However,
climate change could potentially impact the species. According to the
Intergovernmental Panel on Climate Change (IPCC 2007, p. 6), ``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 20\th\ 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. 6). 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. 6). 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.
6).
Changes in the global climate system during the 21\st\ century are
likely to be larger than those observed during the 20\th\ century (IPCC
2007, p. 19). For the next 2 decades, a warming of about 0.2 [deg]C
(0.4 [deg]F) per decade is projected (IPCC 2007, p. 19). Afterward,
temperature projections increasingly depend on specific emission
scenarios (IPCC 2007, p. 19). Various emissions scenarios suggest that
by the end of the 21\st\ century, average global temperatures are
expected to increase 0.6-4.0 [deg]C (1.1-7.2 [deg]F), with the greatest
warming expected over land (IPCC 2007, p. 20).
The IPCC (2007, pp. 22, 27) report outlines several scenarios that
are virtually certain or very likely to occur in the 21\st\ century
including:
(1) over most land, there will be warmer and fewer cold days and
nights, and warmer and more frequent hot days and nights;
(2) areas affected by drought will increase; and
(3) the frequency of warm spells and heat waves over most land
areas will likely increase.
The IPCC predicts that the resiliency of many ecosystems is likely
to be exceeded this century by an unprecedented combination of climate
change associated disturbances (e.g., flooding, drought, wildfire, and
insects), and other global drivers. With medium confidence, IPCC
predicts that approximately 20 to 30 percent of plant and animal
species assessed so far are likely to be at an increased risk of
extinction if increases in global average temperature exceed 1.5 - 2.5
[deg]C (3 - 5 [deg]F).
The black-tailed prairie dog, along with its habitat, will likely
be affected in some manner by climate change. A shift in the species'
geographic range may occur due to an increase in temperature and
drought, although climate change would likely not pose as great a risk
to prairie dog habitat as it would to species in polar, coastal, or
montane ecosystems. Additionally, a strong relationship between plague
outbreaks and climatic variables has been established (Parmenter et al.
1999, p. 814; Enscore et al. 2002, p. 186; Stapp et al. 2004, p. 237;
Gage and Kosoy 2005, p. 509; Ray and Collinge 2005, p. 204; Stenseth et
al. 2006, p. 13110; Adjemian et al. 2007, p. 372; Snall et al. 2008, p.
246). The key climatic variables influencing plague appear to be
maximum daily summer temperature (plague is enhanced by cooler summer
temperatures) and late winter precipitation (plague is enhanced by
increased precipitation). Modeling efforts indicate that shifts in
plague distribution may be a result of shifts of pathogen, vector, or
host distribution due to climate change scenarios (Nakazawa et al.
2007, p. 537). The distribution of plague may expand north and east
(Nakazawa et al. 2007, p. 537). The recent expansion of plague into
South Dakota supports this. However, variables associated with climate
change and increased plague activity conflict. Plague is enhanced by
cooler summer temperatures and by increased precipitation.
Consequently, the extent to which plague may shift due to climate
change versus expand or contract is supposition. Although the black-
tailed prairie dog will likely be affected by climate change, it is not
apparent that a net loss in occupied habitat or a significant impact to
the status of the species will result. The species is adaptable to a
wide array of
[[Page 63364]]
climes, as evidenced by a geographic range that includes 11 States,
Canada, and Mexico. Unlike vulnerable species in polar, coastal, and
montane ecosystems, a shift in range could be possible.
The current status of the black-tailed prairie dog, as indicated by
increasing trends in the species' occupied habitat since the early
1960s, indicates that climate change is not a threat to the species.
Summary of Factor E
Poisoning has impacted black-tailed prairie dogs from the early
1900s until the present time. Efforts to obtain more detailed
information regarding the extent of poisoning, as well as efforts to
interpret the additional recent impacts of anticoagulants, have been
unsuccessful. Drought is a natural phenomenon throughout the range of
the black-tailed prairie dog to which we believe the species has
adapted. Continued climate change will likely cause shifts in the
species' range, as well as changes in occurrence of plague. Additional
information, particularly regarding impacts from poisoning and climate
change, would improve our understanding of the effects on the species.
The current status of the black-tailed prairie dog, as indicated by
increasing trends in the species' occupied habitat since the early
1960s, shows that poisoning, drought, climate change, or other factors
are not threats to the species. Consequently, we do not anticipate that
impacts from these stressors are likely to negatively impact the status
of the species in the foreseeable future.
We conclude that the best scientific and commercial information
available indicates that the black-tailed prairie dog is not now, or in
the foreseeable future, threatened by poisoning, drought, or climate
change to the extent that listing under the Act as an endangered or
threatened species is warranted at this time.
Finding
As required by the Act, we considered the five factors in assessing
whether the black-tailed prairie dog is threatened or endangered
throughout all or a significant portion of its range. We have carefully
examined the best scientific and commercial information available
regarding the status and the past, present, and future threats faced by
the black-tailed prairie dog. We reviewed information provided by the
petitioners, information in our files, other available published and
unpublished information, and information provided by other interested
parties during the status review. We also consulted with Federal and
State land managers. On the basis of the best scientific and commercial
information available, we find that the magnitude and imminence of
threats do not indicate that the black-tailed prairie dog is in danger
of extinction (endangered), or likely to become endangered within the
foreseeable future (threatened), throughout its entire range.
There have been several impacts to the black-tailed prairie dog, in
particular habitat loss due to conversion to cropland, sylvatic plague,
and poisoning. Sylvatic plague and poisoning remain significant
population stressors and are exacerbated by conflicting Federal and
state management policies. Additionally, climate change may potentially
impact the species in future decades. The effects of plague could be
exacerbated by climate change in the future. However, the current
status of the black-tailed prairie dog does not suggest that plague, or
the combined effects of plague and climate change, are limiting factors
for the species in the foreseeable future, and we do not believe these
will result in significant population-level impacts. In spite of these
stressors and resulting impacts on the species, occupied habitat (a
surrogate measure for population trends and status) in the United
States has increased by more than 600 percent since the early 1960s.
The species has proven to be quite resilient and is not expected to be
significantly affected by these stressors in the future.
Improved management and continued research regarding plague and
climate change could further improve the status of the black-tailed
prairie dog. Continuing research will help increase our understanding
of how plague, climate change, and the combined effects of these
stressors will affect the species in the future. This will allow for
informed management decisions related to these stressors that could
further improve the status of the species. It could also improve the
status of the many species that depend upon the prairie dog as a food
source or upon prairie dog burrows for shelter. The smaller, more
scattered prairie dog complexes that are typical today cannot support
the diversity of wildlife that historically depended upon the prairie
dog. For example, the black-footed ferret requires large, healthy
prairie dog complexes for its survival.
Our review of the information pertaining to the five factors does
not support the assertion that there are threats of sufficient
imminence, intensity, or magnitude to cause substantial losses of
population distribution or viability of the black-tailed prairie dog.
Therefore, we do not find that the black-tailed prairie dog is in
danger of extinction (endangered), nor is it likely to become
endangered within the foreseeable future (threatened) throughout its
entire range. Therefore, listing the species as threatened or
endangered under the Act is not warranted at this time.
Distinct Vertebrate Population Segments and Significant Portion of the
Range
After assessing whether the species is threatened or endangered
throughout its range, we next consider whether a distinct vertebrate
population segment (DPS) exists or whether any significant portion of
the black-tailed prairie dog's range meets the definition of endangered
or is likely to become endangered in the foreseeable future
(threatened).
Distinct Vertebrate Population Segments
To interpret and implement the distinct vertebrate population
segment (DPS) provisions of the Act, the Service and the National
Oceanic and Atmospheric Administration published the Policy Regarding
the Recognition of Distinct Vertebrate Population Segments Under the
Endangered Species Act in the Federal Register on February 7, 1996 (61
FR 4722). Under the DPS Policy, three elements are considered in the
decision regarding the establishment and classification of a population
of a vertebrate species as a possible DPS:
(1) The discreteness of a population in relation to the remainder
of the species to which it belongs;
(2) the significance of the population segment to the species to
which it belongs; and
(3) the population segment's conservation status in relation to the
Act's standards for listing, delisting, or reclassification.
Both discreteness and significance are required for a species
population to meet our criteria for classification as a DPS. If any
portion of a species population is considered a valid DPS, we may list,
delist, or reclassify that DPS under the Act. We address these elements
with respect to the black-tailed prairie dog.
Discreteness
Under the DPS policy, a population segment of a vertebrate species
may be considered discrete if it satisfies either one of the following
conditions.
[[Page 63365]]
(1) It is markedly separated from other populations of the same
taxon as a consequence of physical, physiological, ecological, or
behavioral factors. Quantitative measures of genetic or morphological
discontinuity may provide evidence of this separation.
(2) It is delimited by international governmental boundaries
within which differences in control of exploitation, management of
habitat, conservation status, or regulatory mechanisms exist that are
significant in light of section 4(a)(1)(D) of the Act.
We do not consider any population segment of black-tailed prairie
dog to be markedly separated from other populations of the same taxon
as a consequence of physical, physiological, ecological, or behavioral
factors. As a colonial species, black-tailed prairie dogs are naturally
distributed across the landscape in a discontinuous fashion. Black-
tailed prairie dog occupied habitat exists in a constantly shifting
mosaic throughout an estimated 283 million ac (115 million ha) of
suitable habitat that occurs across a range of approximately 440
million ac (178 million ha). Because this discontinuous distribution is
the ``baseline'' condition for the species, for us to consider any
geographic discontinuity as being evidence of marked separation (i.e.,
discreteness) under the DPS policy, we would need the best available
information to indicate that the amount of discontinuity is over and
above what is considered to be normal for the species.
We do not have detailed mapping of occupied habitat throughout the
range of the species. We recognize the likely occurrence of some small,
isolated black-tailed prairie dog colonies, but have very limited
information available that identifies their locations. Therefore, we
looked for other measures of discontinuity, such as measures of genetic
or morphological differences as guided by the DPS policy, to determine
whether any populations showed evidence of marked separation. There is
minimal information available to us to indicate that any population
segments express any genetic or morphological discontinuity due to
separation from other prairie dog populations. We are aware of one
study that found measurable genetic divergence in certain populations
in Texas (Biggs 2007, p. 51). However, other studies have concluded
that genetic differences are often as great among individuals from
local populations as those from vastly different parts of their range
(Chesser 1983, p. 329; Trudeau et al. 2004, p. 205). Therefore, we do
not believe that genetic or morphological discontinuity provides
evidence of discrete prairie dog populations.
The black-tailed prairie dog spans international boundaries between
the United States, Canada, and Mexico, with approximately 98 percent of
occupied habitat occurring in the United States. However, there are no
substantial differences in exploitation, habitat management, or
regulatory mechanisms between the three countries. Additionally, the
relative distribution of prairie dogs between the three countries has
remained constant in recent years. Therefore, we do not believe that
international boundaries provide evidence of discrete prairie dog
populations.
We determine, based on a review of the best available information,
that no black-tailed prairie dog population segments meet the
discreteness conditions of the 1996 DPS policy. Therefore, no black-
tailed prairie dog population segment qualifies as a DPS under our
policy and is not a listable entity under the Act. The DPS policy is
clear that significance is analyzed only when a population segment has
been identified as discrete. Because no discrete populations of black-
tailed prairie dogs exist, we did not further analyze whether any
populations meet the criteria in the DPS policy for significance.
Significant Portion of the Range (SPR)
Having determined that the black-tailed prairie dog does not meet
the definition of a threatened or endangered species range wide or in a
DPS, we must next consider whether there are any significant portions
of the range where the black-tailed prairie dog is in danger of
extinction or is likely to become endangered in the foreseeable future.
On March 16, 2007, a formal opinion was issued by the Office of the
Solicitor of the Department of the Interior, ``The meaning of `In
Danger of Extinction Throughout All or a Significant Portion of Its
Range''' (USDI 2007c). 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 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 determining whether a species is threatened or endangered in a
significant portion of its range, we first identify any portions of the
range of the species that warrant further consideration. The range of a
species can theoretically be divided into portions an infinite number
of ways. However, there is no purpose to analyzing portions of the
range that are not reasonably likely to be significant and threatened
or endangered. To identify only 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
species' range that are not significant, such portions will not warrant
further consideration.
If we identify portions that warrant further consideration, we then
determine whether the species is threatened or endangered in these
portions of its range. Depending on the biology of the species, its
range, and the threats it faces, the Service may address either the
significance question or the status question first. Thus, if the
Service considers significance first and determines that a portion of
the range is not significant, the Service need not determine whether
the species is threatened or endangered there. Likewise, if the Service
considers status first and 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. However, if the Service
determines that both a portion of the range of a species is significant
and the species is threatened or endangered there, the Service will
specify that portion of the range as threatened or endangered under
section 4(c)(1) of the Act.
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 disturbance. 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. 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
[[Page 63366]]
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, we evaluate the historical value of the portion and how
frequently the portion is used by the species, if possible. 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 does not
mean that any portion that provides redundancy is necessarily 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, each area must be examined
based on whether that area provides an increment of redundancy that is
important to the conservation of the species.
Adequate representation ensures that the species' adaptive
capabilities are conserved. Specifically, the portion should be
evaluated 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.
SPR Evaluation for black-tailed prairie dog
We evaluated the black-tailed prairie dog's current range in the
context of the primary stressors affecting the species (plague,
inadequate regulatory mechanisms, and poisoning) to determine if there
is any apparent geographic concentration of these stressors. If effects
to the species from all of these stressors are not disproportionate in
any portion of the species' range, no portion is likely to warrant
further consideration; and a determination of significance based upon
resiliency, redundancy, or representation is not necessary.
Plague - We regard sylvatic plague as the most substantial impact
on the black-tailed prairie dog at the present. However, with the
spread of plague into South Dakota, the disease now is present in
portions of every State within the species' range, and the effects of
plague are presumably no longer geographically concentrated in the
western portion of the range. The current status of the black-tailed
prairie dog, as indicated by increasing trends in the species' occupied
habitat in every State, since the early 1960s, indicates that plague is
not a limiting factor for the species in any State. These increasing
trends are evident even in States with a long history of plague. Plague
does not appear to result in disproportionate impacts to the black-
tailed prairie dog in any portion of its range. Therefore, a
determination of significance based upon resiliency, redundancy, or
representation is not necessary.
Inadequate regulatory mechanisms - We evaluated the differences in
management between States. All States within the historical range of
the black-tailed prairie dog demonstrate both positive and negative
management practices with regard to the species. Some States are more
engaged than others; however, all have had stable to increasing black-
tailed prairie dog populations since 1961. Additionally, there is no
evident correlation between the status of the species' population in a
particular State and the extent to which a State is engaged in
proactive management. Differences in management and the adequacy of
regulatory mechanisms do not appear to result in disproportionate
impacts to the black-tailed prairie dog in any portion of its range.
Therefore, a determination of significance based upon resiliency,
redundancy, or representation is not necessary.
Poisoning - The most complete information with regard to the extent
of poisoning is probably available for Arizona, South Dakota, Kansas,
North Dakota, Oklahoma, and Texas. Only partial estimates are available
for Colorado, Nebraska, and Wyoming. Little or no information is
available for Montana and New Mexico. However, black-tailed prairie dog
populations have been stable to increasing in all States. Some of the
most intensive poisoning we are aware of has occurred in South Dakota,
which is also the State with the largest percentage increase in the
species' population. Poisoning does not appear to result in
disproportionate impacts to the black-tailed prairie dog in any portion
of its range. Therefore, a determination of significance based upon
resiliency, redundancy, or representation is not necessary.
We do not find that the black-tailed prairie dog is in danger of
extinction now, nor is it likely to become endangered within the
foreseeable future throughout all or a significant portion of its
range. Therefore, listing the black-tailed prairie dog as threatened or
endangered under the Act is not warranted at this time.
We request that you submit any new information concerning the
status of, or threats to, this species to our South Dakota Ecological
Services Office (see ADDRESSES section) whenever it becomes available.
New information will help us monitor this species and encourage its
conservation. If an emergency situation develops for this species or
any other species, we will act to provide immediate protection.
References Cited
A complete list of all cited references is available on the
Internet at http://www.regulations.gov and on request from the South
Dakota Ecological Services Office (see ADDRESSES section).
Author
The primary authors of this document are the staff members of the
U.S. Fish and Wildlife Service, South Dakota Ecological Services Office
(see ADDRESSES).
Authority
The authority for this action is the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et seq.).
Dated: November 18, 2009.
Sam D. Hamilton,
Director, U.S. Fish and Wildlife Service.
[FR Doc. E9-28852 Filed 12-2-09; 8:45 am]
BILLING CODE 4310-55-S