[Federal Register: June 2, 2008 (Volume 73, Number 106)]
[Proposed Rules]               
[Page 31418-31424]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]



Fish and Wildlife Service

50 CFR Part 17

[FWS-R2-ES-2008-0070; 1111 FY07 MO-B2]

Endangered and Threatened Wildlife and Plants; 90-Day Finding on 
a Petition To List the Cactus Ferruginous Pygmy-Owl (Glaucidium 
ridgwayi cactorum) as Threatened or Endangered With Critical Habitat

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding and initiation of status 


SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
90-day finding on a petition to list the cactus ferruginous pygmy-owl 
(Glaucidium ridgwayi cactorum) (pygmy-owl) as threatened or endangered 
under the Endangered Species Act of 1973, as amended (Act). We find 
that the petition presents substantial scientific or commercial 
information indicating that listing the pygmy-owl may be warranted. 
Therefore, with the publication of this notice, we are initiating a 
status review of the species, and we will issue a 12-month finding on 
our determination as to whether the petitioned action is warranted. To 
ensure that the status review of the pygmy-owl is comprehensive, we are 
soliciting information and data regarding this species. We will make a 
determination on critical habitat for this species if and when we 
initiate a listing action.

DATES: We made the finding announced in this document on June 2, 2008. 
To allow us adequate time to conduct this review, we request that 
information be submitted on or before August 1, 2008.

ADDRESSES: You may submit comments by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the instructions for submitting comments.
     U.S. mail or hand delivery: Public Comments Processing, 
Attn: [FWS-R2-ES-2008-0070]; Division of Policy and Directives 
Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, 
Suite 222; Arlington, VA 22203.

We will not accept e-mail or faxes. We will post all submissions on 
http://www.regulations.gov. This generally means that we will post any 
personal information you provide us (see the Information Solicited 
section below for more information).

FOR FURTHER INFORMATION CONTACT: Steven Spangle, Field Supervisor, 
Arizona Ecological Services Office, U.S. Fish and Wildlife Service, 
2321 West Royal Palm Road, Suite 103, Phoenix, AZ 85021; telephone 602/
242-0210; facsimile 602/242-2513. If you use a telecommunications 
device for the deaf (TDD), call the Federal Information Relay Service 
(FIRS) at 800-877-8339.


Information Solicited

    When we make a finding that a petition presents substantial 
information to indicate that listing a species may be warranted, we are 
required to promptly commence a review of the status of the species. To 
ensure that the status review is complete and based on the best 
available scientific and commercial information, we are soliciting 
information on the status of the pygmy-owl. We request any additional 
information from the public, other concerned governmental agencies, 
Native American Tribes, the scientific community, industry, or any 
other interested parties concerning the status of the pygmy-owl. We are 
seeking information regarding the species' historical and current 
status and distribution, its biology and ecology, ongoing conservation 
measures for the species and its habitat; and threats to the species or 
its habitat. Specifically,

[[Page 31419]]

we are requesting input related to the genetics and taxonomy of 
ferruginous pygmy-owls, and the status, distribution, and threats to 
the pygmy-owl in Mexico.
    If we determine that listing the pygmy-owl is warranted, it is our 
intent to propose critical habitat to the maximum extent prudent and 
determinable at the time we propose to list the species. Therefore, 
with regard to areas within the geographical range currently occupied 
by the pygmy-owl, we also request data and information on what may 
constitute physical or biological features essential to the 
conservation of the species, where these features are currently found, 
and whether any of these features may require special management 
considerations or protection. In addition, we request data and 
information regarding whether there are areas outside the geographical 
area occupied by the species that are essential to the conservation of 
the species. Please provide specific information as to what, if any, 
critical habitat you think we should propose for designation if the 
species is proposed for listing, and why such habitat meets the 
requirements of the Act.
    We will base our 12-month finding on a review of the best 
scientific and commercial information available, including all 
information received during the public comment period. Please note that 
submissions merely stating support or opposition to the action under 
consideration without providing supporting information, although noted, 
will not be considered in making a determination, as section 4(b)(1)(A) 
of the Act directs that determinations as to whether any species is a 
threatened or endangered species shall be made ``solely on the basis of 
the best scientific and commercial data available.'' At the conclusion 
of the status review, we will issue the 12-month finding on the 
petition, as provided in section 4(b)(3)(B) of the Act.
    You may submit your information concerning this status review by 
one of the methods listed in the ADDRESSES section. We will not 
consider submissions sent by e-mail or fax or to an address not listed 
in the ADDRESSES section.
    If you submit information via http://www.regulations.gov, your 
entire submission--including any personal identifying information--will 
be posted on the Web site. If your submission is made via a hardcopy 
that includes personal identifying information, you may request at the 
top of your document that we withhold this personal identifying 
information from public review. However, we cannot guarantee that we 
will be able to do so. We will post all hardcopy submissions on http://
    Information and materials we receive will be available for public 
inspection on http://www.regulations.gov, or by appointment, during 
normal business hours, at the U.S. Fish and Wildlife Service, Arizona 
Ecological Services Office (see FOR FURTHER INFORMATION CONTACT).


    Section 4(b)(3)(A) of the Act requires that we make a finding on 
whether a petition to list, delist, or reclassify a species presents 
substantial scientific or commercial information indicating that a 
petitioned action may be warranted. We are to base this finding on 
information provided in the petition, supporting information submitted 
with the petition, and information otherwise available in our files at 
the time we make the determination. To the maximum extent practicable, 
we are to make the finding within 90 days of our receipt of the 
petition, and publish our notice of this finding promptly in the 
Federal Register.
    Our standard for ``substantial information,'' as defined in the 
Code of Federal Regulations at 50 CFR 424.14(b), with regards to a 90-
day petition finding is ``that amount of information that would lead a 
reasonable person to believe that the measure proposed in the petition 
may be warranted.'' If we find that substantial information was 
presented, we are required to promptly commence a status review of the 
    We base this finding on information provided by the petitioner that 
we determined to be reliable after reviewing sources referenced in the 
petition and available in our files. We evaluated that information in 
accordance with 50 CFR 424.14(b). Our process for making this 90-day 
finding under section 4(b)(3)(A) of the Act is limited to a 
determination of whether the information in the petition meets the 
``substantial information'' threshold.
    On March 20, 2007, we received a formal petition dated March 15, 
2007, from the Center for Biological Diversity and Defenders of 
Wildlife requesting that we list the pygmy-owl as a threatened or 
endangered species under the Act (CBD and DOW 2007). Additionally, the 
petition requested the designation of critical habitat concurrent with 
listing. The petition clearly identified itself as a petition and 
included the identification information, as required in 50 CFR 
424.14(a). We sent a letter to the petitioners dated June 25, 2007, 
stating that we were proceeding with a review of the petition.
    The petitioners petitioned us on three potentially listable 
entities of the pygmy-owl: (1) The Arizona distinct population segment 
(DPS) of the pygmy-owl; (2) the Sonoran Desert DPS of the pygmy-owl; 
and (3) the western subspecies of the pygmy-owl, which they identified 
as Glaucidium ridgwayi cactorum. As an immediate action, the 
petitioners requested that we promulgate an emergency listing rule for 
the pygmy-owl. In our June 25, 2007, response letter to the 
petitioners, we stated our determination that emergency listing was not 
warranted for the pygmy-owl and that the designation of critical 
habitat would be considered if listing one of the proposed entities of 
the pygmy-owl was found to be warranted.

Previous Federal Actions

    On May 26, 1992, a coalition of environmental organizations (Galvin 
et al. 1992) petitioned us to list the entire cactus ferruginous pygmy-
owl subspecies as endangered under the Act. We published a finding that 
the petition presented substantial scientific or commercial information 
indicating that listing of the pygmy-owl may be warranted and commenced 
a status review of the subspecies (58 FR 13045, March 9, 1993). As a 
result of information collected and evaluated during the status review, 
including information collected during a public comment period, we 
proposed to list the pygmy-owl as endangered with critical habitat in 
Arizona and threatened in Texas (59 FR 63975, December 12, 1994). After 
a review of all comments received in response to the proposed rule, we 
published a final rule listing the Arizona DPS of the pygmy-owl as 
endangered (62 FR 10730, March 10, 1997). In that final rule, we 
determined that listing in Texas was not warranted and that critical 
habitat designation for the Arizona population was not prudent.
    In September 1998, we formed the Cactus Ferruginous Pygmy-owl 
Recovery Team, comprised of biologists (pygmy-owl experts and raptor 
ecologists) and representatives from affected and interested parties 
(e.g., Federal and State agencies, local governments, the Tohono 
O'odham Nation, and private groups) to develop a pygmy-owl recovery 
    On December 30, 1998, in response to an October 31, 1997, lawsuit 
filed in the District Court of Arizona by the Southwest Center for 
Biological Diversity, we proposed to designate critical habitat in 
Arizona for the

[[Page 31420]]

pygmy-owl (63 FR 71820). On April 15, 1999, we released a draft 
economic analysis of the proposed critical habitat designation and 
reopened a public comment period for 30 days (64 FR 18596). On July 12, 
1999, we published our final critical habitat determination (64 FR 
37419), essentially designating the same areas as were proposed.
    On January 9, 2001, a coalition of plaintiffs filed a lawsuit with 
the District Court of Arizona challenging the validity of the Service's 
listing of the Arizona DPS of the pygmy-owl as an endangered species 
and the designation of its critical habitat. On September 21, 2001, the 
District Court upheld the listing of the pygmy-owl in Arizona but, at 
our request, and without otherwise ruling on the critical habitat 
issues, remanded the designation of critical habitat for preparation of 
a new economic analysis and other effects of the designation (Natl. 
Ass'n of Home Builders v. Norton, No. Civ.-00-0903-PHX-SRB). The 
District Court vacated the critical habitat designation during this 
remand. Subsequently, the District Court ordered that we submit a new 
proposed critical habitat rule to the Federal Register on or before 
November 15, 2002. On November 27, 2002, we published the proposed rule 
to designate critical habitat for the pygmy-owl (67 FR 71032) and 
opened a public comment period on the proposed rule and the draft 
economic analysis until February 25, 2003. We extended the comment 
period on February 25, 2003, until April 25, 2003 (68 FR 8730). We then 
reopened the comment period on April 28, 2003, until June 27, 2003 (68 
FR 22353). Due to a lack of funding, work on the final rule to 
designate critical habitat for the pygmy-owl was suspended in April 
    On January 9, 2003, we published in the Federal Register (68 FR 
1189) a notice of availability and opening of a public comment period 
(until April 9, 2003) for the draft pygmy-owl recovery plan. On April 
30, 2003 (68 FR 23158), we reopened the public comment period on the 
recovery plan until June 30, 2003.
    The plaintiffs appealed the District Court's ruling on the listing 
of the pygmy-owl as a distinct population segment in Arizona. On August 
19, 2003, the Ninth Circuit Court of Appeals upheld the Service's 
determination that the Arizona pygmy-owl population was discrete, but 
found that the Service did not articulate a rational basis for finding 
that the Arizona pygmy-owl population was significant to its taxon 
(Natl. Ass'n of Home Builders v. Norton, 340 F.3d. at 852). The Ninth 
Circuit reversed the judgment of the District Court and remanded the 
case to the District Court for further proceedings consistent with the 
Ninth Circuit's opinion.
    On October 1, 2003, the intervenor-appellees (CBD and DOW) 
petitioned for a rehearing from the Ninth Circuit Court. That request 
was denied. On November 12, 2003, the plaintiffs filed a motion with 
the District Court seeking removal of the Arizona DPS listing based on 
the Ninth Circuit Court's ruling. On December 10, 2003, the Service 
filed a response agreeing that removal of the listing was appropriate. 
The response also indicated that the Service was undertaking an 
internal review of the current status of the pygmy-owl in the United 
States and Mexico and was engaged in ongoing surveys of the species. 
The interveners in the case opposed the plaintiffs' motion to remove 
the Arizona DPS listing and disputed the contention that the listing 
rule should be removed.
    On June 25, 2004, the District Court of Arizona (CV 00-0903 PHX-
SRB) remanded the listing rule to the Service for reconsideration 
consistent with the Ninth Circuit's ruling and ordered that the pygmy-
owl listing should remain in place for the duration of the Service's 
deliberations. On January 31, 2005, pursuant to the District Court's 
order, we filed a status report with the District Court regarding our 
reconsideration of the listing rule for the pygmy-owl. As a result of 
our reconsideration, we published a proposed rule on August 3, 2005, to 
delist the pygmy-owl (70 FR 44547). On April 14, 2006, following public 
comment, we published a final rule removing the pygmy-owl from the 
Federal List of Endangered and Threatened Wildlife (71 FR 19452).
    The interveners in the above lawsuit filed a request with the 
Arizona District Court for a temporary restraining order (denied by the 
District Court in May 2006) and a preliminary injunction to halt the 
delisting of the pygmy-owl and, concurrently, a lawsuit arguing that 
the delisting of the pygmy-owl was arbitrary and capricious. The 
Arizona District Court heard the case in October 2006 and issued an 
opinion on March 9, 2007, upholding the Federal delisting of the pygmy-
owl and denying the request for a preliminary injunction. Defenders of 
Wildlife and the Center for Biological Diversity have appealed the 
District Court's decision, and the case is currently pending in the 
Ninth Circuit Court of Appeals (9th Cir. No. 07-15854).

Species Information

    The pygmy-owl is in the order Strigiformes and the family 
Strigidae. It is a small bird, approximately 17 centimeters (6.75 
inches) long. In Arizona, male pygmy-owls average 58 grams (g) (2.0 
ounces (oz)) and females average 70 g (2.4 oz) (AGFD 2007, p. 2). The 
pygmy-owl is reddish brown overall, with a cream-colored belly streaked 
with reddish brown. Color may vary, with some individuals being more 
grayish brown.
    One of the primary issues presented by the petitioners is related 
to the taxonomy of the pygmy-owl. Until recently, we considered the 
cactus ferruginous pygmy-owl to occur from lowland central Arizona 
south through western Mexico to the States of Colima and Michoacan, and 
from southern Texas south through the Mexican States of Tamaulipas and 
Nuevo Leon (Proudfoot and Johnson 2000, p. 4). The petitioners request 
a revised taxonomic consideration for the cactus ferruginous pygmy-owl 
based on Proudfoot et al. (2006a, p. 9; 2006b, p. 946) and K[ouml]nig 
et al. (1999, pp. 160, 370-373), classifying it as Glaucidium ridgwayi 
cactorum. The revised consideration would include recognition of two 
subspecies in Mexico and the U.S., G. r. cactorum in western Mexico and 
Arizona and G. r. ridgwayi in eastern Mexico and Texas. We find this 
request to be reasonable, as Proudfoot and Johnson (2000, p. 4) 
indicate that a thorough taxonomic revision for the ferruginous pygmy-
owl is needed. Other authors have also proposed the ``ridgwayi'' 
classification of the subspecies of pygmy-owl in question (Heidrich et 
al. 1995, pp. 37-39; Navarro-Sig[uuml]enza and Peterson 2004, p. 5).
    The literature suggests that the taxonomy of the pygmy-owl has been 
inconsistent and ever-changing (Coues 1872, p. 370, Bendire 1888, p. 
366; Fischer 1893, pp. 199-200; Gilman 1901, p. 145, Howell 1916, p. 
211). The use of genetics (Proudfoot et al. 2006a; Proudfoot et al. 
2006b), morphology, and vocalizations (K[ouml]nig et al. 1999, pp. 160, 
370-373; Heidrich et al. 1995, pp. 25-27) to clarify pygmy-owl taxonomy 
may provide the basis for taxonomic revision. The petitioners report 
that recent studies suggest that North and Central American ferruginous 
pygmy-owls fall into the species ridgwayi, and South American 
ferruginous pygmy-owls fall into the species brasilianum (Proudfoot 
2006a, p. 9; K[ouml]nig et al. 1999). Proudfoot (2006a, p. 9) further 
divides ridgwayi into two subspecies, one found in Arizona, Sonora, and 
Sinaloa (Glaucidium ridgwayi cactorum), and one found in Texas, 
Tamaulipas, and regions of South-Central Mexico (Glaucidium ridgwayi 
ridgwayi). This

[[Page 31421]]

finding addresses the petitioned subspecies G. r. cactorum, which the 
petitioners referred to as the cactus ferruginous pygmy-owl.
    Some have suggested that the proposed taxonomic change should not 
be accepted until it is acknowledged by the American Ornithologist's 
Union (AOU) (Johnson and Carothers 2007, pp. 16-17). While the AOU 
checklist undergoes vigorous review, it presently does not list entries 
at the subspecies level and does not provide the most current 
information related to taxonomic classifications at this level (AOU 
2007). The Service is not restricted to existing taxonomic checklists 
in determining a listable entity. Rather, the Service is required to 
use the best available scientific and commercial information. The 
information presented by Proudfoot (2006a, 2006b) is found in peer-
reviewed professional journal articles, and the work of K[ouml]nig et 
al. (1999) was published by a reputable institution. We judge these 
sources to be reliable with regard to the information they present. 
Information in our files supports the supposition of the petitioners 
that Proudfoot (2006a, 2006b), K[ouml]nig et al. (1999), and Heidrich 
et al. (1995) represent the best available scientific information 
regarding the taxonomy of the pygmy-owl. We find that the petitioners 
have provided reliable and substantial scientific information that a 
taxonomic revision may be warranted.
    Historically (i.e., late 1800s and early 1900s), pygmy-owls 
occupied areas of south-central Arizona--from New River, about 56 
kilometers (km) (35 miles (mi)) north of Phoenix, south to the U.S./
Mexico border, west to Agua Caliente near Gila Bend and Cabeza Prieta 
Tanks, and east to Tucson, and, rarely, the San Pedro River (Bent 1938, 
pp. 435-438; Monson and Phillips 1981, pp. 71-72; Johnson et al. 2003, 
pp. 390-391). The geographic area historically occupied by pygmy-owls 
in Arizona includes portions of Gila, Pima, Pinal, Maricopa, Graham, 
Santa Cruz, Cochise, Greenlee, and Yuma Counties. No pygmy-owls have 
been recorded in New Mexico (Hubbard 1978, p. 6) or from the lower 
Colorado River valley of both the United States (Rosenberg et al. 1991, 
pp. 206-210) and Mexico (van Rossem 1945, p. 111).
    Currently, the known locations of pygmy-owls in Arizona are 
restricted to two counties, Pima and Pinal (USFWS 2007). As the 
petition contends (CBD and DOW 2007, p. 15) and our records support 
(Abbate et al. 1996, pp. 8-12; 1999, pp. 14-17; 2000, pp. 15-16; 
Johnson et al. 2003, p. 390), the current distribution of pygmy-owls 
within Arizona is much reduced when compared to its historical 
distribution. Recent data indicate that there are fewer than 50 adult 
pygmy-owls and fewer than 10 nest sites in Arizona in any given year 
(Abbate et al. 2000, pp. 15-16).
    The petitioners provide information indicating that pygmy-owl 
populations in Arizona and Sonora, Mexico are declining (CBD and DOW 
2007, pp. 15-17). The information in our files is consistent with the 
population numbers reported in the petition. We judge the information 
regarding a decline in pygmy-owl numbers in northern Sonora (Flesch and 
Steidl 2006) to be substantial and reliable.
    In Arizona, pygmy-owls rarely occur below 300 meters (m) (1,000 
feet (ft)) or above 1,220 m (4,000 ft) (Proudfoot and Johnson 2000, p. 
5), except perhaps during dispersal (AGFD 2007, p. 2). Historically, 
pygmy-owls were documented in cottonwood (Populus fremontii)-mesquite 
(Prosopis spp.) forest and mesquite woodland along the Gila and Salt 
rivers and major tributaries (Gilman 1909, pp. 148-149; Johnson et al. 
1987). Currently, most pygmy-owls in southern Arizona are found in 
Sonoran desertscrub communities as described by Brown (1982, pp. 181-
221). These communities include dense thickets bordering dry desert 
washes consisting of palo verde (Cercidium spp.), ironwood (Olneya 
tesota), mesquite, acacia (Acacia spp.), and saguaro (Carnegiea 
gigantea) (Johnson and Haight 1985, p. 145; Millsap and Johnson 1988, 
p. 138). In the 1990s and early 2000s, pygmy-owls were also found in 
suburban areas containing exotic landscaping supported by irrigation 
(Abbate et al. 1996, p. 26). Pygmy-owls have also been located in 
semidesert and Sonoran savanna grasslands with washes (e.g., the Altar 
Valley) (Abbate et al. 2000, p. 27, Flesch 2003, pp. 153-156). Dominant 
tree species in riparian areas include mesquite, ash (Fraxinus 
velutina), and hackberry (Celtis spp.).
    In Mexico, the pygmy-owl occurs from sea level to 1,219 m (4,000 
ft) (Friedmann et al. 1950, p. 145). It is a resident of primarily 
giant cactus associations, in western Sonora (van Rossem 1945, p. 111). 
It also occurs in desertscrub, tropical thornscrub, and tropical 
deciduous forest (Russell and Monson 1998, p. 141). The pygmy-owl is 
absent from tropical deciduous forest and higher vegetation zones in 
west Mexico, where it is replaced by G. minutissimum and G. gnoma 
(Schaldach 1963, p. 40). Flesch (2003, p. 37) reported that pygmy-owls 
occurred in the greatest numbers and highest frequencies within the 
Arizona Upland subdivision of Sonoran desertscrub in northern Sonora, 
Mexico. Densities were greatest in the Plains of Sonora and lowest in 
Sinaloan Thornscrub. Density of owls was relatively high in the Central 
Gulf Coast, but frequency of occurrence was low. Semidesert grasslands 
were second only to Arizona Upland for frequency of occurrence of 
pygmy-owls in Sonora, Mexico.

Threats Analysis

    Section 4 of the Act (16 U.S.C. 1533), and its implementing 
regulations at 50 CFR part 424, set forth the procedures for adding 
species to the Federal List of Endangered and Threatened Wildlife and 
Plants. A species may be determined to be an endangered or threatened 
species due to one or more of the five factors described in section 
4(a)(1) of the Act: (A) The present or threatened destruction, 
modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) inadequacy of 
existing regulatory mechanisms; or (E) other natural or manmade factors 
affecting its continued existence.
    In making this 90-day finding, we evaluated whether information on 
threats to the pygmy-owl, as presented in the petition and other 
information available in our files at the time of the petition review, 
is substantial, thereby indicating that the petitioned action may be 
warranted. Our evaluation of this information is presented below.

A. Present or Threatened Destruction, Modification, or Curtailment of 
the Species' Habitat or Range

    The petitioners claim that numerous threats to pygmy-owl habitat 
occur in both Arizona and Sonora, Mexico, and that these threats have 
resulted in the loss and fragmentation of pygmy-owl habitat (CBD and 
DOW 2007, p. 18). As a result, pygmy-owls have been lost from portions 
of their range and are declining in abundance in the United States and 
Mexico (Phillips et al. 1964, p. 52; Johnson et al. 1979, p. 51; Hunter 
1988, pp. 3-6; Millsap and Johnson 1988, pp. 137-139; Johnson et al. 
2003, pp. 393-398; Flesch and Steidl 2006, pp. 869-870). The 
petitioners (CBD and DOW 2007, pp. 18-24) specifically identified 
riparian forest destruction, urban sprawl, woodcutting, vegetation 
clearing for agriculture, livestock grazing, border issues, and exotic 
plant species invasions as threats to the pygmy-owl (Ohmart 1994, pp. 
276-281; Flesch 2003, p. 134; Abouhaider 1989, pp. 58-59; Burquez and 

[[Page 31422]]

1997, pp. 383-388; Burquez-Montijo et al. 2002, pp. 134-138; Flesch and 
Steidl 2006, pp. 869-870).
    The petitioners indicate that widespread destruction of riparian 
woodlands in Arizona and Sonora has occurred within the range of the 
pygmy-owl and has led to a subsequent decline in pygmy-owl abundance 
(CBD and DOW 2007, p. 19). They cite papers, also found in our files, 
estimating that between 85 and 90 percent of riparian bottomland 
forests in the southwestern United States have been modified or lost, 
and that these alterations and losses are attributable to woodcutting, 
urban and agricultural encroachment, water diversion and impoundment, 
channelization, groundwater pumping, livestock overgrazing, and 
hydrologic changes resulting from various land-use practices (Carothers 
1977, pp. 2-3; Kusler 1985, p. 6; Jahrsdoerfer and Leslie 1988, pp. 17-
36; USGAO 1988, p. 8; Szaro 1989, pp. 73-81; State of Arizona 1990, pp. 
1-5; Bahre 1991, pp. 119-151). Information provided by the petitioners 
was found to be reliable and corroborated by information found in our 
files. Information from our files indicates that threats to riparian 
communities are also evident in Mexico. Deloya (1985, pp. 11-12) 
expressed concern over the declining trend of riparian ecosystems there 
and a lack of strategy to reverse it.
    The petitioners state that continued population growth in both 
Arizona and Mexico will continue to contribute to the loss of important 
riparian resources. They cite specific examples of the San Pedro River 
in Arizona and the Rio Magdelena in Mexico, including Flesch and Steidl 
(2006b), who stated that the Rio Magdalena watershed had the largest 
human population of the watersheds they studied, which likely reduces 
habitat quality for the pygmy-owl (CBD and DOW 2007, p. 20).
    The petition cites urban sprawl as a significant threat to pygmy-
owls in both Arizona and Mexico (USFWS 2005, Burquez and Martinez-
Yrizar 1997) (CBD and DOW, p. 20). Impacts to pygmy-owls and pygmy-owl 
habitat from urbanization are related to housing development, lighting, 
roads, traffic, predation by domestic pets, and the alteration of 
hydrologic patterns supporting important pygmy-owl habitat elements. 
Petitioners point out that low-density urban development may provide 
some benefit to pygmy-owl habitat elements and that pygmy-owls have 
occurred in these types of areas in the past. However, most recent 
urbanization in Arizona cannot be categorized as low density (AZ Daily 
Star 2006, p. B-1); therefore, it is usually not beneficial to the 
pygmy-owl. In addition, the petitioners point out a concern that if the 
beneficial habitat elements in low-density developments attract pygmy-
owls, these areas may act as population sinks (a population with a 
negative balance between productivity and mortality) if there is 
increased mortality from automobile and window collisions, pet 
predation, and other urban factors. Information in our files supports 
the petitioners' claims of increasing human population growth along the 
border in both Mexico and Arizona (AZ Daily Star 2000a, 2000b; Clement 
et al. 2003, p. 60; DES 1997, East Valley Tribune 2005; Ewing et al. 
2005, pp. 7-16; PAG 2003; Pineiro 2001, p. 1). The impacts of 
urbanization on pygmy-owls and their habitat have been identified and 
discussed in numerous documents within our files (USFWS 2005b, 2005c, 
2005d), and we find that the information presented by the petitioners 
is reliable.
    According to the petition, the conversion of native vegetation to 
non-native grasses for livestock grazing represents a threat to pygmy-
owl habitat in Arizona and Mexico. The petition states that the 
conversion to and invasion by buffelgrass (Pennisetum ciliaris) results 
in the direct loss and fragmentation of pygmy-owl habitat by 
eliminating large columnar cacti (nest substrates) and other vegetation 
required by pygmy-owls for nesting, perching, and cover; reduces prey 
availability; and increases fire frequency in a non-fire-adapted 
vegetation community (CBD and DOW 2007, p. 22). The petitioners point 
out that this threat is widespread (8-10 million acres (3.2-4 million 
hectares) in northern Mexico and the southwestern U.S.) and will likely 
result in permanent impacts to pygmy-owls and pygmy-owl habitat. They 
cite Van Devender and Dimmit (2000), who state that the introduction of 
buffelgrass into fire-intolerant desert communities results in a 
permanent conversion to a buffelgrass savanna with reduced plant cover 
and diversity (CBD and DOW 2007, p. 22). Information within our files 
supports the magnitude of this threat identified by the petitioners, 
and we find that the information presented is reliable. In some cases 
the conversion to buffelgrass has been so complete that consequences 
are irreversible in the short term (Burquez et al. 1998, p. 21). 
Talking about the potential extent of the threat of buffelgrass 
conversion in Sonora, Mexico, Arriaga et al. (2004, pp. 1507-1510) 
predict that buffelgrass could cover up to 53 percent of Sonora and 
affect 26 percent of the desertscrub, 12 percent of the mesquite 
woodlands, and 8 percent of the tropical deciduous forest. However, 
regional efforts to reduce the extent of buffelgrass are being 
initiated in southern Arizona.
    The petition points out that the introduction of fire into non-
fire-adapted communities, such as the Sonoran Desert, has significant 
effects on the native vegetation. The petitioners state that many 
desert trees, shrubs, and cacti, including saguaros, are not fire-
adapted and cannot withstand fires. This is particularly significant in 
relation to the pygmy-owl because of effects to nest cavities and prey 
availability. As the conversion of native habitat to non-native plant 
communities is primarily a human-facilitated issue, and because many 
current fires are human-caused, the issue of fire in an environment of 
increasing non-native plant communities and increasing population 
growth is a legitimate threat to pygmy-owl habitat. The information 
available in our files corroborates the increased occurrence and 
severity of fires within the range of the pygmy-owl, and the 
significant conversion of native plant communities to non-native 
grassland savannahs in both the United States and Mexico.
    The petitioners indicate that livestock grazing eliminates and 
modifies pygmy-owl habitat, especially in sensitive riparian areas (CBD 
and DOW 2007, p. 23). They contend that overgrazing results in the 
direct removal of riparian vegetation, changes channel morphology, and 
has been a primary factor in the loss of most riparian woodlands in the 
southwest. With specific regard to pygmy-owl habitat elements, our 
files indicate that overgrazing can affect saguaro (nest sites) 
recruitment (Abouhaidar 1989, pp. 58-59), cause a loss of riparian 
species diversity and cover (Belsky et al. 1999, pp. 425-428), and 
reduce prey diversity (Jones 1981, pp. 109-114; Krueper 1996, pp. 288-
294). The threats to pygmy-owl habitat from livestock overgrazing as 
raised by the petitioners were found to be reliable based on 
information in our files. However, it is important to note that such 
effects are typically the result of overgrazing and not well-managed 
livestock grazing that occurs under an appropriate livestock-grazing 
system, which under certain conditions, can have beneficial effects to 
wildlife (Holochek et al. 1982, p. 208; Smith et al. 1996, p. 492). In 
addition, no studies specifically related to the effects of livestock 
grazing on pygmy-owls have been done.
    The petitioners indicate that border activities can affect pygmy-
owls and pygmy-owl habitat. In particular, they

[[Page 31423]]

point to the current construction of a wall along the U.S./Mexico 
border intended to impede illegal immigration and smuggling activities. 
They cite Flesch and Steidl (2007), who state that pygmy-owls often fly 
short distances just above the ground when crossing vegetation 
openings. The petitioners therefore claim that construction of the 
border wall will preclude movement of individuals between Arizona and 
Sonora. Our observations of pygmy-owl movements in the landscape 
indicate that tall fences, in association with a zone cleared of 
vegetation, would likely result in an impediment to pygmy-owl movements 
in that area, and could affect local movements within territories, as 
well as immigration and dispersal across the international border 
(Abbate et al. 1999, p. 28-29; Flesch and Steidl 2007, p. 35, Scott 
Richardson, personal observations). The effects to natural resources 
resulting from illegal border crossing and smuggling, and the response 
of enforcement agencies to such activities, such as the construction of 
fences, is documented in our files, and we find the information 
presented by the petitioners to be reliable (Cohn 2007, p. 96; Marris 
2006, pp. 1-2).
    In summary, we find that the information provided in the petition, 
as well as other information in our files, presents substantial 
scientific or commercial information indicating that the petitioned 
action may be warranted due to the present or threatened destruction, 
modification, or curtailment of the habitat or range of the subspecies 
of ferruginous pygmy-owl defined in the petition. Information in our 
files identifies the top ten threats to the natural resources of the 
Sonoran bioregion, which includes many of the threats proposed by the 
petitioners and described above (Nabhan and Holdsworth 1998, pp. 1-3).

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    According to the petition, overutilization is not considered a 
major factor in pygmy-owl declines past or present.

C. Disease or Predation

    The petition names a number of diseases or disease-related issues 
that could potentially affect the status of the pygmy-owl population 
throughout its range. These include hematozoa (blood parasites), 
trichomoniasis, external parasites, and West Nile Virus. Information in 
our files indicates that the information presented in the petition is 
reliable and that ectoparasites, in particular, represent potential 
threats to pygmy-owl populations (Proudfoot et al. 2005, pp. 186-187; 
Proudfoot et al. 2006c, pp. 874-875). While little is known of the 
natural occurrence of disease within pygmy-owl populations (Proudfoot 
and Johnson 2000, p. 13), more is known regarding the occurrence of 
parasites (Proudfoot et al. 2005, p. 186; Proudfoot et al. 2006, p. 
873). Proudfoot et al. (2005, p. 186) could not rule out that blood 
loss from external parasites, in combination with other factors, may 
have contributed to the loss of an entire clutch of pygmy-owls in 
Arizona. Serious disease problems have not been documented to date in 
pygmy-owl populations; however, should such an event occur, the 
population effects are clear given that fewer than 10 pygmy-owl nest 
sites are typically documented in Arizona on an annual basis (Abbate et 
al. 2000, pp. 15-16). The effects of an introduced virus, like the West 
Nile Virus, on pygmy-owls are of particular concern (Ganez et al. 2004, 
pp. 2135-2136).
    The petitioners point out that predation on pygmy-owls has been 
documented throughout its range. Recently-fledged young are 
particularly vulnerable to predation, affecting the overall 
productivity of pygmy-owls in Arizona (Abbate et al. 1999, p. 50). With 
so few nests documented in Arizona, reduced productivity due to 
predation can have population-level effects. Predation occurs naturally 
within pygmy-owl populations; however, ongoing drought conditions 
contribute to increasing predation rates due to lack of vegetation 
cover and poor condition of individual pygmy-owls (USFWS 2004, AGFD 
unpublished data). Information in our files indicates that this 
information is reliable and that predation can affect the status of 
local pygmy-owl populations. Non-native predators may increase 
predation rates above natural levels. Introduced predators in urbanized 
areas, such as domestic cats, have been documented as pygmy-owl 
predators and are an ongoing threat to pygmy-owls and other wildlife as 
urbanization increases (Evans 1995, pp. 4-5; Coleman et al. 1997, pp. 
2-3; Winter and Wallace 2006, p. 3).
    In summary, we find that the information provided in the petition, 
as well as other information in our files, presents substantial 
scientific or commercial information indicating that the petitioned 
action may be warranted due to disease, especially given the low 
population size of the pygmy-owl, and predation, particularly of 

D. Inadequacy of Existing Regulatory Mechanisms

    The petition includes four levels of current regulation that the 
petitioners contend fall short in their protection of pygmy-owls and 
pygmy-owl habitat. The petitioners indicate that Federal laws such as 
the Migratory Bird Treaty Act and the National Environmental Policy Act 
do not require protection of pygmy-owl habitat. The Arizona Game and 
Fish Department includes the pygmy-owl as an endangered species on its 
Species of Special Concern list (AGFD 1996, p. 15), but this list does 
not afford the pygmy-owl any legal or regulatory protections. While 
State wildlife laws prohibit the illegal take of pygmy-owls, they do 
not address impacts to pygmy-owl habitat. Some local conservation 
mechanisms, such as habitat conservation plans, are in development in 
southern Arizona. These plans include conservation measures for pygmy-
owls, but are several years from completion and, as drafts, do not 
afford the pygmy-owl any level of protection or conservation (although 
some pygmy-owl habitat has been conserved through acquisitions related 
to these plans). There are no regulations or laws in Mexico that 
provide any specific protection to pygmy-owl habitat. Based on the 
information in our files, the information presented by the petitioners 
regarding existing regulatory mechanisms is reliable.

E. Other Natural or Manmade Factors Affecting the Species' Continued 

    The petition identifies two issues under this factor, genetic 
stochasticity and fire, that affect the continued existence of the 
pygmy-owl. The petitioners indicate that the incidence of inbreeding 
and the low genetic diversity within the pygmy-owl population may make 
the population susceptible to stochastic genetic events. Caughley and 
Gunn (1996, p. 166) are cited, noting that small populations can become 
extinct entirely by chance even when their members are healthy and the 
environment favorable (CBD and DOW 2007, p. 28). Information in our 
files supports the contention that there is low genetic variability 
within genetic samples obtained from pygmy-owls in the United States 
and northern Mexico (Proudfoot and Slack 2001, p. 5; Proudfoot et al. 
2006a, p. 9), and that pairings within family groups have been 
documented in this same area (Abbate et al. 2000, p. 21).
    The issue of fire and its effects on pygmy-owl habitat is related 
to the issue

[[Page 31424]]

of non-native plant species and is more appropriately discussed earlier 
in this document within the context of Factor A, rather than under 
Factor E.

Distinct Vertebrate Population Segments and Significant Portion of the 

    The petition asserts that the pygmy-owl occurs in two possible DPSs 
and implies that, as a subspecies, the pygmy-owl is also threatened or 
endangered throughout a significant portion of its range. We conclude 
that the petition presents substantial information that listing the 
entire subspecies may be warranted (see Finding below). Therefore, we 
have not specifically evaluated whether the petition provides 
substantial information with respect to the two potential DPSs outlined 
within the petition, or the extent to which the pygmy-owl is endangered 
or threatened throughout a significant portion of its range. An 
analysis of these additional entities will occur during the 12-month 
status review if we determine that listing of the entire subspecies is 
not warranted.


    We have reviewed the petition and the literature cited in the 
petition, and evaluated the information to determine whether the 
sources cited support the claims made in the petition. We also reviewed 
reliable information that was readily available in our files to 
evaluate the petition.
    The petitioners presented substantial information indicating that 
the pygmy-owl may be threatened by Factors A, C, D, and E throughout 
the entire range of the subspecies defined in the petition in Arizona 
and northwest Mexico. The petitioners did not assert that Factor B is 
currently, or in the future, considered a threat to this species. Based 
on this review and evaluation, we find that the petition has presented 
substantial scientific or commercial information that listing the 
pygmy-owl throughout all or a portion of its range may be warranted due 
to current and future threats under Factors A, C, D, and E. As such, we 
are initiating a status review to determine whether listing the pygmy-
owl under the Act is warranted. As part of our status review of the 
pygmy-owl, we will examine whether the purported subspecific 
designation is appropriate; whether the Arizona or Sonoran Desert DPSs 
of the pygmy-owl warrant listing under the Act; or if the subspecies is 
in danger of extinction within a significant portion of its range. We 
will issue a 12-month finding as to whether any of the petitioned 
actions are warranted.

References Cited

    A complete list of references cited is available on the Internet at 
http://www.regulations.gov and upon request from the Arizona Ecological 


    The primary authors of this document are the staff of the Arizona 
Ecological Services Office (see FOR FURTHER INFORMATION CONTACT).


    The authority for this action is the Endangered Species Act of 
1973, as amended (U.S.C. 1531 et seq.).

    Dated: May 20, 2008.
Kenneth Stansell,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. E8-12168 Filed 5-30-08; 8:45 am]