[Federal Register Volume 78, Number 220 (Thursday, November 14, 2013)]
[Proposed Rules]
[Pages 68659-68685]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-27196]



[[Page 68659]]

Vol. 78

Thursday,

No. 220

November 14, 2013

Part III





Department of the Interior





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Fish and Wildlife Service





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50 CFR Part 17





 Endangered and Threatened Wildlife and Plants; 12-Month Finding on a 
Petition To List the Gunnison's Prairie Dog as an Endangered or 
Threatened Species; Proposed Rule

Federal Register / Vol. 78 , No. 220 / Thursday, November 14, 2013 / 
Proposed Rules

[[Page 68660]]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R6-ES-2013-0115; 4500030113]


Endangered and Threatened Wildlife and Plants; 12-Month Finding 
on a Petition To List the Gunnison's Prairie Dog as an Endangered or 
Threatened Species

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 12-month petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
12-month finding on a petition to list the Gunnison's prairie dog 
(Cynomys gunnisoni) as an endangered or threatened species under the 
Endangered Species Act of 1973, as amended (Act). After review of the 
best available scientific and commercial information on both subspecies 
of Gunnison's prairie dog, we find that listing either C. g. gunnisoni 
or C. g. zuniensis or both is not warranted at this time. The best 
available information indicates that populations of both subspecies are 
stable and that there are no threats causing or projected to cause 
either subspecies to be at risk of extinction. This action also removes 
the Gunnison's prairie dog from our candidate list. Although listing is 
not warranted at this time, we ask the public to submit to us any new 
information that becomes available concerning threats to the Gunnison's 
prairie dog or its habitat at any time.

DATES: This finding announced in this document was made on November 14, 
2013.

ADDRESSES: This finding is available on the Internet at http://www.regulations.gov at Docket Number FWS-R6-ES-2013-0115. 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, Colorado Field Office, 134 Union Blvd., 
Suite 670, Lakewood, CO 80228; telephone (303) 236-4773; facsimile 
(303) 236-4005. Please submit any new information, materials, comments, 
or questions concerning this finding to the above street address.

FOR FURTHER INFORMATION CONTACT: Susan Linner, Field Supervisor, U.S. 
Fish and Wildlife Service, Colorado Field Office (see ADDRESSES); by 
telephone at (303) 236-4773; or by facsimile at (303) 236-4005. 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 Act (16 U.S.C. 1531 et seq.) requires 
that, for any petition containing substantial scientific and commercial 
information that listing may be warranted, we make a finding within 12 
months of the date of receipt of the petition on whether 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 endangered or threatened, and whether expeditious progress is being 
made to add or remove qualified species from the Lists of Endangered 
and Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act 
requires that we treat a petition for which the requested action is 
found to be warranted but precluded as though resubmitted on the date 
of such finding; that is, requiring a subsequent finding to be made 
within 12 months. We must publish these 12-month findings in the 
Federal Register.

Previous Federal Actions

    On February 23, 2004, we received a petition from Forest Guardians 
(now called WildEarth Guardians) and 73 other organizations and 
individuals requesting that we list the Gunnison's prairie dog (found 
in Arizona, Colorado, New Mexico, and Utah) as endangered or 
threatened. On February 7, 2006, we published a 90-day finding in the 
Federal Register (71 FR 6241) determining that the petition did not 
present substantial scientific information indicating that listing the 
Gunnison's prairie dog species may be warranted.
    On December 13, 2006, Forest Guardians and eight other 
organizations or individuals filed a complaint challenging our finding. 
On June 29, 2007, we reached a settlement agreement with the plaintiffs 
and agreed to submit a 12-month finding to the Federal Register by 
February 1, 2008.
    On February 5, 2008, we published a 12-month finding on the 
petition to list the Gunnison's prairie dog (73 FR 6660). Our finding 
determined that the Gunnison's prairie dog warranted listing in a 
significant portion of its range, or SPR, in northcentral New Mexico 
and central and southcentral Colorado. In that finding, we determined 
that the Gunnison's prairie dog warranted listing in the montane 
portion of its range, but not in the prairie portion, due primarily to 
the effects of sylvatic plague, an exotic disease. In other words, the 
SPR determination recognized a difference in status between the montane 
and prairie portions of the Gunnison's prairie dog range. Although we 
found listing to be warranted, higher priority listing actions 
precluded the development of a proposed rule to list the species under 
the Act, and we added the Gunnison's prairie dog in the montane portion 
of its range to our candidate species list.
    On March 24, 2009, WildEarth Guardians filed a complaint with the 
courts challenging our interpretation of the Act's SPR language, as 
used in our February 5, 2008, 12-month finding. On September 30, 2010, 
the Court found that we determined something other than a species 
warranted listing, and ordered that we complete a new 12-month finding. 
Since that Court ruling, montane Gunnison's prairie dogs have remained 
on our candidate species list awaiting our reevaluation of their 
status.
    Through the annual candidate notice of review process (73 FR 75175, 
December 20, 2008; 74 FR 57804, November 9, 2009; 75 FR 69222, November 
10, 2010; 76 FR 66370, October 26, 2011; 77 FR 69993, November 21, 
2012), we continued to solicit information from the public regarding 
the status of the Gunnison's prairie dog, its taxonomy, its life 
history, its distribution, threats to the species, and ongoing 
conservation measures designed to protect the species.
    On December 9, 2011, the Service and the National Marine Fisheries 
Service (NMFS) published a notice (76 FR 76987) of draft policy to 
establish a joint interpretation and application of the Act's statutory 
phrase ``in danger of extinction throughout all or a significant 
portion of its range.'' To date we have not finalized our draft SPR 
policy, and as explained under Significant Portion of the Range, below, 
we do not follow the draft policy for this finding.
    On September 9, 2011, we entered into a multi-district litigation 
stipulated settlement agreement (WildEarth Guardians v. Salazar, No. 
1:10-mc-00377-EGS (D.D.C.); Center for Biological Diversity v. Salazar, 
No. 1:10-mc-00377-EGS (D.D.C.)), which requires that we submit to the 
Federal Register a new 12-month finding on the petition to list the 
Gunnison's prairie dog, and a proposed rule if warranted, before the 
end of Fiscal Year 2016. This not-warranted 12-month finding fulfills 
that requirement of the multi-district litigation stipulated settlement 
agreement.

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Summary of New Information

    Since our 2008 12-month finding, we have reviewed new information 
regarding Gunnison's prairie dog taxonomy and population trends, the 
dynamics of sylvatic plague, and conservation efforts for the 
Gunnison's prairie dog. Specifically:
     A genetics study supports the distinctness of two 
Gunnison's prairie dog subspecies: Cynomys gunnisoni gunnisoni and C. 
g. zuniensis (Martin and Sackett 2012, p. 1). The ranges of these two 
subspecies correspond roughly to the ``montane'' and ``prairie'' ranges 
described in our 2008 12-month finding, although the results of the 
genetics study clarify the location of the boundary between the 
subspecies (Martin and Sackett 2012, p. 14).
     Additional occupancy surveys completed rangewide in 2010 
augmented occupancy data collected by all four States in 2007, and by 
Colorado in 2005. These occupancy data indicate that populations of 
both subspecies are stable throughout their ranges and within 
individual population areas (Seglund 2012, p. 11).
     New studies indicate that dusting Gunnison's prairie dog 
burrows with insecticide effectively controls the intensity and 
frequency of plague (Biggins et al. 2010; Abbott et al. 2012, p. 244). 
In addition, recent laboratory trials have demonstrated the efficacy of 
an oral vaccine against plague for prairie dogs (Rocke et al. 2010, p. 
53; Abbott et al. 2012, p. 247). Field trails of the oral vaccine began 
in 2012, and continued in 2013 (Van Pelt 2013, p. 11).

Species Information

    Prairie dogs are ground-dwelling squirrels unique to North America, 
so named for their doglike ``barks'' and broad distribution across the 
Great Plains, Colorado Plateau, and eastern Great Basin, extending from 
southern Canada to northern Mexico (Hoogland 2011, p. 918; Fitzgerald 
et al. 2011, p. 136). The Gunnison's prairie dog (Cynomys gunnisoni) is 
one of five prairie dog species, including the white-tailed (C. 
leucurus), the Utah (C. parvidens), the black-tailed (C. ludovicianus), 
and the Mexican (C. mexicanus) prairie dogs (Goodwin 1995, pp. 100-101; 
Fitzgerald et al. 2011, p. 136). The ranges of the five prairie dog 
species meet, with limited overlap between Gunnison's prairie dogs and 
black-tailed prairie dogs in New Mexico (Goodwin 1995, p. 101; Sager 
1996, p. 1), and between Gunnison's prairie dogs and white-tailed 
prairie dogs in Colorado (Knowles 2002, p. 5), but the species do not 
likely interbreed due to evolutionary divergence. The Gunnison's 
prairie dog occupies a variety of grasslands and shrub-steppe of 
intermountain valleys in the southern Rocky Mountains of northern 
Arizona, southwestern and southcentral Colorado, northwestern New 
Mexico, and southeastern Utah (Pizzimenti and Hoffman 1973, p. 2; 
Goodwin 1995, p. 101).
    Although Cynomys gunnisoni gunnisoni and C. g. zuniensis may differ 
slightly in color, size (Pizzimenti and Hoffman 1973, p. 1), or habitat 
attributes, they share similar life histories, and therefore we discuss 
them together as a single species below.
    The Gunnison's prairie dog (including both subspecies) has fewer 
chromosomes (2n = 40) than the other prairie dog species (2n = 50), 
which suggests its early evolutionary divergence and uniqueness from 
the other prairie dogs (Pizzimenti and Hoffman 1973, p. 3; Pizzimenti 
1975, pp. 10, 14, 60; Goodwin 1995, p. 109). Additionally, the 
Gunnison's prairie dog is slightly smaller than the black-tailed 
prairie dog, but larger than the Utah prairie dog (Pizzimenti and 
Hoffman 1973, p. 1). The Gunnison's prairie dog is also distinguished 
from other prairie dogs by its darker body and shorter, grayish-white 
tail (Pizzimenti and Hoffman 1973, p. 1; Fitzgerald et al. 2011, p. 
138).
    Gunnison's prairie dogs dig their own burrows, and hibernate in 
their underground burrows for approximately 4 months during the winter, 
beginning in October and ending in mid-February to late-April 
(Fitzgerald and Lechleitner 1974, p. 150; Hoogland 1998, p. 888; 
Hoogland 2001, p. 918; Fitzgerald et al. 2011, p. 139). Burrows require 
well-drained, deep soils, with few rocks on the soil surface (Wagner 
and Drickamer 2004, pp. 188, 195; Seglund et al. 2006, pp. 5, 6; 
Underwood 2007, p. 3). Deep soils are important for establishing 
hibernation burrows below the frost line (Wagner and Drickamer 2004, 
pp. 188, 194; Underwood 2007, p. 3). The Gunnison's prairie dog likely 
evolved to hibernate in order to cope with its arid, nutrient-limited 
habitats, which feature erratic precipitation and temperature extremes 
(Rayor et al. 1987, p. 149; Seglund et al. 2006, p. 7). Prairie dogs 
hibernate and aestivate (sleep during the summer) when they are 
metabolically stressed or when the weather is cold (Harlow and Menkens 
1986, p. 795; Seglund et al. 2006, p. 7; Seglund and Schnurr 2010, p. 
14). Lack of precipitation, lack of forage, and extreme daily 
temperatures drive aestivation and hibernation (Seglund and Schnurr 
2010, p. 14), which allow the Gunnison's prairie dog to adapt to 
changing habitat conditions.
    After hibernating, Gunnison's prairie dogs typically breed in April 
or May, but latitude, elevation, and seasonal variations may influence 
breeding dates (Hoogland 1998, p. 888; Hoogland 2001, p. 923; 
Fitzgerald et al. 2011, p. 139). With adequate resources, females breed 
as yearlings, but may not breed until their second year if food is 
scarce (Hall 1981, p. 414; Hoogland 1999, p. 249; Hoogland 2001, p. 
923; Seglund et al. 2006, p. 7). Body mass, which is directly 
correlated to the availability of food, influences reproductive 
success, and underscores the importance of suitable habitats (Hoogland 
2001, p. 923; Underwood 2007, p. 4). Females may mate with up to five 
different males, a reproductive strategy that maximizes breeding 
success and promotes genetic diversity between pups (Hoogland 1998, p. 
882; Haynie et al. 2003, p. 1251; Seglund et al. 2006, p. 7; Underwood 
2007, p. 5).
    Compared to other small rodents, Gunnison's prairie dogs reproduce 
relatively slowly. Females are sexually receptive for several hours on 
only one day of the year and therefore wean a maximum of one small 
litter per year (Hoogland 1998, p. 889; Hoogland 2001, pp. 919, 921, 
923; Seglund et al. 2006, p. 7). Other small rodents often wean more 
than two litters per year (Hoogland 2001, p. 921; Seglund et al. 2006, 
p. 7). Litters are small, ranging in size from 2 to 7 pups, with an 
average of 3.77 pups (Fitzgerald et al. 2011, p. 139). When food is 
plentiful, reproduction is more successful, but females remain 
physiologically limited to only one litter per year (Hoogland 2001, p. 
923; Seglund et al. 2006, p. 7). In addition to breeding only once 
annually, small litter sizes, low annual survivorship, and delayed 
reproduction in yearling males also slow reproduction in the Gunnison's 
prairie dog (Hoogland 2001, p. 917; Seglund et al. 2006, p. 7; 
Underwood 2007, p. 5).
    Despite their relatively slow reproduction, Gunnison's prairie dogs 
reproduce more rapidly under certain conditions (Hoogland 2001, p. 
923). Young, expanding colonies reproduce faster because resources are 
more plentiful (Rayor 1985b, p. 2835; Hoogland et al. 2001, p. 923). 
Additionally, reproductive rates increase and colonies expand following 
dramatic population crashes caused by shooting, poisoning, or plague 
(Hoogland 2001, p. 923). For example, new colonies may triple in size 
each year following a plague outbreak as the surviving prairie dogs 
disperse and form new colonies, and as the juveniles grow

[[Page 68662]]

faster, survive longer, and breed at an earlier age (Cully 1997, pp. 
146, 153-154, 156; Wagner and Drickamer 2002, p. 16; Seglund et al. 
2006, p. 8; Underwood 2007, p. 7; Fitzgerald et al. 2011, p. 139). In 
general, this cycle of local extirpation and subsequent colonization 
allows populations to survive and expand rapidly following dramatic 
losses (Wagner and Drickamer 2002, p. 16; Seglund et al. 2006, pp. 8, 
16; Underwood 2007, p. 7). In Gunnison's prairie dogs, the ability to 
rebound after crashes depends largely on the maintenance of a 
metapopulation structure, as discussed below.
    Gunnison's prairie dogs live in family groups called clans, with 
adjacent clans forming a colony (Fitzgerald and Lechleitner 1974, p. 
149; Hoogland 1999, p. 243; Goodwin 2001, p. 918). Clans include 1 to 
19 individuals (mean 5.3) with 21 to 23 clans per colony (Hoogland 
1999, p. 245; Fitzgerald et al. 2011, p. 140; Underwood 2007, p. 4; 
Seglund and Schnurr 2010, p. 16). Clan members defend a home territory 
of approximately 2.5 acres (ac) (1 hectare (ha)), but commonly forage 
outside the home territory in the weakly defended peripheral sections 
of territories belonging to other clans (Hoogland 1998, pp. 887-888; 
Hoogland 1999, pp. 245, 248; Seglund et al. 2006, p. 6). Although clans 
display social cohesion, Gunnison's prairie dogs are not as socially 
organized as black-tailed prairie dogs and have a less defined social 
hierarchy (Fitzgerald and Lechleitner 1974, p. 155; Hall 1981, p. 414; 
Goodwin 1995, p. 101; Hoogland 1999, p. 248; Haynie et al. 2003, p. 
1245; Fitzgerald et al. 2011, p. 140).
    Gunnison's prairie dogs are a colonial species, historically 
occurring in large complexes of colonies over large areas. Within 
colonies, prairie dog densities vary widely, ranging from 2 to 23 
Gunnison's prairie dogs per ac (5 to 57 per ha) (Seglund et al. 2006, 
p. 8; Underwood 2007, p. 6; Fitzgerald et al. 2011, p. 140). Within 
colonies, burrows may be densely aggregated or scattered and isolated, 
the density likely driven by the quality and quantity of vegetation 
(Underwood 2007, p. 6). Colonial behavior offers an effective defense 
mechanism by aiding in the detection of predators, but it also can play 
an important role in the transmission of disease (Hoogland 1999, p. 
248; Biggins and Kosoy 2001, p. 911; Antolin et al. 2002, p. 19). 
Through their burrowing and grazing, colonies influence the abundance 
and diversity of other prairie species, and serve as a relatively 
constant prey base, such that the Gunnison's prairie dog is a keystone 
species (Kotliar et al. 1999, p. 183; Wagner and Drickamer 2002, p. 1; 
Seglund et al. 2006, p. 5; Underwood 2007, p. 7; Fitzgerald et al. 
2011, p. 139).
    Complexes of Gunnison's prairie dog colonies form metapopulations, 
or an ensemble of interacting, local populations linked together by 
dispersing individuals (Hanski and Gilpin 1991, pp. 4, 6; Wagner and 
Drickamer 2002, p. 15). Populations within a metapopulation may be 
isolated, such that the dispersing individuals must move across 
unsuitable habitats or may fail to locate another suitable habitat 
patch to colonize (Hanski and Gilpin 1991, p. 7).
    A metapopulation helps spread the risk of extinction across the 
multiple populations in order to increase survival during a stochastic 
(random) or catastrophic event (Den Boer 1968, p. 166). In other words, 
a metapopulation ensures that local extinctions are offset by 
dispersers from other local populations who establish new populations 
or colonize the empty habitats (Hanski and Gilpin 1991, pp. 7, 9). The 
metapopulation provides a ready cache of individuals to repopulate. The 
dispersing individuals link the populations within a metapopulation, so 
their dispersal capabilities are fundamentally important to the 
structure of the metapopulation. Factors that inhibit or impair 
dispersal would also impact the metapopulation. For example, habitat 
fragmentation may isolate colonies beyond dispersal distances such that 
the metapopulation collapses (Hanski and Gilpin 1991, p. 13; Wagner and 
Drickamer 2002, p. 16). Within suitable habitats, leap-frog 
colonization radiating from expanding colonies may eventually 
reestablish the metapopulation (Wagner and Drickamer 2002, p. 16).
    According to the cycle of local extirpation and recolonization, 
metapopulations of Gunnison's prairie dog populations expand or 
contract over time depending upon various natural factors (such as 
reproduction, food availability, and disease) and human-caused factors 
(such as poisoning and shooting). The Gunnison's prairie dog requires a 
metapopulation structure across the landscape to substantially augment 
depleted populations or replace populations without human intervention, 
so that migration between colonies is possible (Clark et al. 1982, pp. 
574-575; Gilpin and Soule 1986, p. 24; Lomolino and Smith 2001, p. 
938).
    Gunnison's prairie dogs disperse in the fall before hibernating, 
and in the spring before breeding (Travis et al. 1996, p. 95; Seglund 
2006, p. 8). When not dispersing, Gunnison's prairie dogs are 
relatively sedentary and tend to remain within the boundaries of their 
colony (Kotliar et al. 1999, p. 183; Wagner and Drickamer 2004, p. 
188). Approximately 95 percent of females remain in their natal 
territory for life, but only 5 percent of males remain in their natal 
territory for more than 1 year (Hoogland 1999, p. 247; Seglund et al. 
2006, p. 8). Dispersal distances range from 112 to 1,886 feet (34 to 
575 meters), and may be as long as 4.8 miles (7.7 kilometers) (Hoogland 
1999, p. 247; Seglund et al. 2006, p. 8; Seglund and Schnurr 2010, p. 
15). The disappearance of related kin motivates dispersal (Hoogland 
2013, p. 1205). Maximum travel distances have not been recorded for the 
Gunnison's prairie dog, but black-tailed prairie dogs may move up to 
6.2 miles (10 kilometers) when dispersing, frequently traveling along 
roads or cattle trails (Knowles 1985, pp. 37-38; Wagner and Drickamer 
2002, p. 16).

Taxonomy

    The genus Cynomys is split into two subgenera; Leucocrossuromys 
includes prairie dogs with white tails, and Cynomys includes prairie 
dogs with black tails. Gunnison's prairie dogs are included in the 
subgenus Leucocrossuromys along with the Utah and white-tailed prairie 
dogs (Clark et al. 1971, p. 1; Pizzimenti 1975, pp. 15-16; Seglund et 
al. 2006, p. 3).
    Early taxonomists divided the Gunnison's prairie dog into two 
subspecies, Cynomys gunnisoni gunnisoni and C. g. zuniensis, based on 
morphological differences (Hollister 1916, pp. 29-32). However, later 
morphological and genetic analyses disputed the designation of 
subspecies (Pizzimenti 1975, pp. 11, 15, 63; Goodwin 1995, pp. 100, 
101, 110; Seglund et al. 2006, p. 3). Later, an unpublished study used 
genetics to again support the designation of two subspecies (Hafner 
2004, p. 6; Hafner et al. 2005, p. 2; NMDGF 2008, p. 2). However, 
during the status review for our 2008 12-month finding, we determined 
that this genetics study was too preliminary to substantiate the 
designation of two subspecies, and we did not recognize the subspecific 
taxonomy of the Gunnison's prairie dog. However, we anticipated that an 
ongoing genetics study could clarify the taxonomy of the Gunnison's 
prairie dog.
    The results of this genetics study are now available in an 
unpublished report that provides support for the taxonomic 
differentiation of the Gunnison's prairie dog into two subspecies: 
Cynomys gunnisoni gunnisoni and C. g. zuniensis (Martin and Sackett 
2012, p. 14). Following a thorough analysis of 12

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different lines of genetic evidence, the report proposes two distinct 
subspecies of Gunnison's prairie dog that correspond roughly to the 
previously recognized ``montane'' and ``prairie'' forms (Martin and 
Sackett 2012). C. g. gunnisoni occurs in the ``montane'' northeastern 
part of the Gunnison's prairie dog's range in Colorado and New Mexico. 
C. g. zuniensis occurs in the ``prairie'' southwestern part of the 
range in southeastern Utah, southwestern Colorado, northwestern New 
Mexico, and northeastern Arizona (Figure 1). The genetics results 
support previous hypotheses that there are two geographically 
separated, but overlapping, genetic groups of Gunnison's prairie dog 
(Martin and Sackett 2012, p. 14). Although this report is currently 
awaiting peer-review and publication, it provides the best available 
information regarding the subspecific taxonomy of the Gunnison's 
prairie dog.
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    The genetics data also clarified the location of the boundary 
between the two subspecies. Previously, genetic analysis described the 
boundary as a diagonal line extending from south-central Colorado to 
northeastern New Mexico, but with a substantial, southwestern 
extension, or ``tongue'' of Cynomys gunnisoni gunnisoni extending into 
Albuquerque, New Mexico. Now, genetic data indicate that the boundary 
should be redrawn as a straight line, and provide little support for 
the southern extension, or ``tongue'' of Cynomys gunnisoni gunnisoni 
into northcentral New Mexico near Albuquerque (Martin and Sackett 2012, 
p. 14). We used this information to draw

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the approximate range of both subspecies, as illustrated in Figure 1. 
However, there is evidence of genetic mixing and overlap across this 
boundary, as individuals living in colonies along the boundary have 
genetic code from both subspecies (Martin and Sackett 2012, pp. 13-14). 
In other words, C. g. gunnisoni and C. g. zuniensis along the boundary 
have interbred or currently interbreed. However, the extent, scope, and 
taxonomic consequences of this genetic mixing along the boundary are 
unclear.
    Based on this new genetic analysis, we accept the subspecific 
taxonomy of the Gunnison's prairie dog as Cynomys gunnisoni gunnisoni 
and C. g. zuniensis. Both subspecies are valid taxonomic subspecies of 
the Gunnison's prairie dog and are listable entities under the Act. 
This finding evaluates both subspecies.
Habitat
    Gunnison's prairie dogs establish their colonies on gently sloping 
grasslands and semi-desert and montane shrublands, at elevations 
ranging from 4,600 to 12,000 feet (1,400 to 3,660 meters) (Bailey 1932, 
p. 125; Pizzimenti and Hoffman 1973, p. 1; Findley et al. 1975, p. 133; 
Wagner and Drickamer 2002, p. 4; NMDGF 2008, p. 9; Seglund et al. 2006, 
p. 4; Fitzgerald et al. 2011, pp. 138, 139). They primarily eat 
grasses, and will occasionally eat forbs, sedges, and shrubs 
(Pizzimenti and Hoffman 1973, p. 3; Shalaway and Slobodchikoff 1988, p. 
840; Seglund et al. 2006, p. 5; Fitzgerald et al. 2011, p. 139). 
Gunnison's prairie dog habitats are arid, unpredictable, and often 
characterized by limited vegetation and short growing seasons (Seglund 
and Schnurr 2010, pp. 17, 18).
    The two subspecies occupy similar prairie habitats at different 
elevations. Cynomys gunnisoni gunnisoni, in central and southcentral 
Colorado and northcentral New Mexico, occupies high-elevation, cool, 
and mesic (wet) plateaus, benches, and intermountain valleys. Grass-
shrub vegetation in low valleys and mountain meadows bordered by steep 
topography dominate these habitats (Seglund et al. 2005, p. 12). 
Cynomys gunnisoni zuniensis in southeastern Utah, southwestern 
Colorado, northwestern New Mexico, and northeastern Arizona occupies 
lower elevation, xeric (dry) plains and plateaus (Bailey 1932, pp. 125-
127; Pizzamenti and Hoffman 1973, pp. 1-2; Hall 1981, p. 7; Knowles 
2002, p. 4). C. g. zuniensis occupies grass-shrub prairies within these 
habitats (Seglund et al. 2005, p. 12).
Distribution, Abundance, and Trends
    As illustrated in Figure 1, we mapped the overall distribution of 
Cynomys gunnisoni gunnisoni and C. g. zuniensis as an approximate 
``overall range.'' However, the ``overall range'' is a gross estimate 
because the subspecies do not occupy or potentially occupy all lands 
within its boundaries (Seglund et al. 2006, p. 70). Instead, the 
``predicted range'' is a subset of the overall range and represents a 
more accurate spatial representation of the potential range of the 
subspecies (Seglund et al. 2006, p. 9; Seglund and Schnurr 2010, p. 
20). Habitat characteristics, such as vegetation and slope, built the 
predicted range model. Compared to the overall range, the predicted 
range provides a more accurate, spatial range for the Gunnison's 
prairie dog, but it similarly does not imply that all the areas are 
occupied or suitable.
    A predicted range model estimates that the Gunnison's prairie dog 
could occupy 23,459,525 ac (9,493,733 ha) across the four States in its 
range (Seglund et al. 2006, p. 70). At the species level, approximately 
27 percent of this potential Gunnison's prairie dog (Cynomys gunnisoni) 
range occurs in Arizona, 25 percent in Colorado, 45 percent in New 
Mexico, and 3 percent in Utah (Seglund et al. 2006, p. 70).
    We used a predicted range model (USGS 2011) for the Gunnison's 
prairie dog, with the revised overall range for both Cynomys gunnisoni 
gunnisoni and C. g. zuniensis and updated landownership data (BLM 2011; 
BLM 2012a; BLM 2012b; BLM 2013) to approximate the percentages of each 
subspecies' potential range by State and landowner (Table 1). Colorado 
supports the largest percentage, 81 percent, of Cynomys gunnisoni 
gunnisoni's potential range, with the remaining 19 percent in New 
Mexico. New Mexico and Arizona support the largest percentage of C. g. 
zuniensis' potential range, 48 and 42 percent respectively, with 7 
percent of C. g. zuniensis' potential range in Colorado and 3 percent 
in Utah (Table 1).
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    According to this predicted range model (USGS 2011), Tribal and 
private lands support the largest percentage of the Gunnison's prairie 
dog's (Cynomys gunnisoni's) predicted range at the species level, with 
36 percent and 27 percent respectively (Table 1). The Bureau of Land 
Management (BLM) manages approximately 16 percent of this predicted 
range, the U.S. Forest Service (USFS) manages approximately 9 percent, 
the National Park Service (NPS) manages approximately 1 percent, and 
the U.S. Department of Defense and the Service both manage less than 1 
percent of the Gunnison's prairie dog's predicted range (Table 1). The 
States manage approximately 9 percent of the Gunnison's prairie dog's 
predicted range. These percentages differ from the percentages reported 
in our last status review (February 5, 2008; 73 FR 6664) after we 
recalculated using the revised overall ranges for the subspecies, a 
different predicted range model (USGS 2011), and current landownership 
layers (BLM 2011; BLM 2012a; BLM 2012b; BLM 2013).
    According to the predicted range model (USGS 2011), the largest 
percentage of Cynomys gunnisoni gunnisoni's predicted range occurs on 
private lands (50 percent) followed by lands managed by the BLM with 32 
percent (Table 1). The USFS, the States, the Service, the NPS, and 
Tribes each manage less than 10 percent of C. g. gunnisoni's predicted 
range. Tribes manage the largest percentage of C. g. zuniensis's 
predicted range (40 percent), followed by private lands (25 percent) 
and the BLM (14 percent).
    Native American Tribes manage the largest percentage (36 percent) 
of the Gunnison's prairie dog's predicted range (Table 1). The Navajo 
Nation in Utah, Arizona, and New Mexico manages approximately 64 
percent of the Tribal lands within the overall range of the Gunnison's 
prairie dog (Cynomys gunnisoni) (Johnson et al. 2010, p. 8). The Hopi 
Tribe in Arizona manages 9 percent of the Tribal lands, while 4 percent 
are jointly managed by the Navajo Nation and Hopi Tribe (Johnson et al. 
2010, p. 8). The Gunnison's prairie dog also occurs on Hualapai Tribe 
lands in Arizona.
    Estimating the abundance of prairie dogs, or the number of 
individuals in a population, is notoriously difficult (Fitzgerald et 
al. 2011, p. 137). Densities of individuals range widely, with anywhere 
from 2 to 23 Gunnison's prairie dogs per ac (5 to 57 per ha) 
(Fitzgerald et al. 2011, p. 140). Additionally, the quality of 
habitats, season, colony age, precipitation, amount and quality of 
forage, predation, disease, poisoning, shooting, and other factors 
influence the number of prairie dogs present at a particular location 
(Knowles 2002, pp. 7-8). Prairie dogs also spend time in underground 
burrows, making them difficult to count. As a result, counting 
individual prairie dogs to estimate the population size is difficult, 
time-consuming, and only feasible for small areas (Biggins et al. 2006, 
p. 94).
    Instead of counting individual prairie dogs, most abundance 
estimates are expressed as the area (acres (ac) or hectares (ha)) of 
occupied habitat (Biggins et al. 2006, p. 94). Occupied area estimates 
are derived by mapping the boundaries of colonies. Although easier and 
more efficient than counting individuals, mapping is also time-
consuming, costly, and often inaccurate. Ground or aerial mapping of 
colonies over a predicted habitat range of 23 million ac (9.5 million 
ha) in 4 States would be required to develop a rangewide estimate of 
the area occupied by the Gunnison's prairie dog (Seglund et al. 2005, 
pp. 17-19). Mapping colonies across this large area is expensive and 
logistically unfeasible. Additionally, colony boundaries are often 
difficult to discern, whether on the ground or in the air, and the 
variability in distribution and activity levels of individuals makes 
mapping difficult and subjective (CDOW 2007, p. 18; WAFWA 2012, p. 1). 
Mapping may also overestimate the area of occupied habitats by 
including inactive burrows, which are especially difficult to identify 
or distinguish from active burrows by air or with remote imagery 
(Seglund et al. 2005, pp. 23-24; Johnson et al. 2006, p. 3; Seglund et 
al. 2006, pp. 15, 25; CDOW 2007, p. 18; Seglund 2012, p. 1). Mapping 
accuracy suffers over the longer time intervals necessary to visit 
large range portions, because colony area, location, and persistence on 
the landscape often change relatively quickly (Wagner et al. 2006, p. 
335).
    Occupancy modeling is a newer technique that improves the accuracy 
of abundance estimates and the evaluation of population trends for the 
Gunnison's prairie dog. Occupancy provides a powerful way to estimate 
abundance (Nicholson and Van Maner 2009, p. 233). An occupancy model 
estimates the percent of habitats that are occupied across a certain 
area and is a useful surrogate for estimating abundance (MacKenzie and 
Nichols 2004, pp. 461-466). Occupancy models detect changes over time 
in the proportion of habitats occupied by a species, which correlates 
to changes in population size (MacKenzie 2005, p. 849).
    For Gunnison's prairie dogs, surveys are used to develop an 
occupancy model by recording the presence or absence of prairie dogs 
within a sub-set of random plots distributed throughout the current and 
historic range of the subspecies. On a scale of 1 to 100, the model 
represents the percentage of surveyed plots occupied by the Gunnison's 
prairie dog. The percentage of random plots occupied across the 
predicted range builds the model, which extrapolates to a rangewide 
estimate of occupancy (MacKenzie et al. 2002, pp. 2248-2249; MacKenzie 
et al. 2003, pp. 2200-2201). Changes in occupancy over time result from 
local extinction and colonization (Nicholson and Van Mayer 2005, p. 
233). Therefore, occupancy trends also provide insight into 
metapopulation structure (MacKenzie 2005, p. 849).
    Unlike counts of individuals or acreage estimates, occupancy models 
are statistically derived, are more objective, and can be implemented 
across large areas in a single season (Andelt et al. 2006, pp. 1-2; 
CDOW 2007, pp. 18-19; WAFWA 2007, p. 4; CPW 2010, p. 27; WAFWA 2012, p. 
2). Occupancy models provide statistically derived trends over time 
(Seglund 2012, p. 2), and subsampling random plots for only presence-
absence data improves efficiency and consistency when collecting data. 
Furthermore, the results of individual surveys can be interpreted 
separately to assess prairie dog occupancy and document trends within 
specific areas of concern. Occupancy modeling is well-established in 
the literature and deemed adequate and reliable for the long-term 
monitoring of the Gunnison's prairie dog throughout its range (Seglund 
and Schnurr 2010, p. 10; USGS 2011, p. 20). Since 2005, all four States 
within the range of the Gunnison's prairie dog have adopted this 
approach and have successfully completed at least 2 years of occupancy 
surveys (Seglund 2012, p. 2).
    Unfortunately, occupancy modeling estimates are not directly 
comparable to estimates of occupied acres (including most historical 
estimates), because acreages are not recorded during the occupancy 
modeling surveys. When surveyors visit a random plot, observers record 
only presence or absence of Gunnison's prairie dogs, not the acres 
occupied. Without mapping, occupancy modeling provides no information 
about colony size or location within each random plot surveyed, and 
therefore cannot be directly correlated to previous approximations of 
occupied acres (USGS 2011, p. 17). However, the occupancy surveys and 
models are the best available information regarding the

[[Page 68668]]

Gunnison's prairie dog's current population status and trends.
    Below we briefly summarize the historical and current abundance 
data available for the Gunnison's prairie dog, extrapolating to the 
subspecies where possible.
Historical Estimates of Abundance
    Federal records from early poisoning campaigns provide historical 
estimates of Gunnison's prairie dog occupied habitat in Arizona and New 
Mexico. In 1916, approximately 6.6 million ac (2.7 million ha) of 
Gunnison's prairie dog occupied habitat occurred in Arizona (Cynomys 
gunnisoni zuniensis), and 11 million ac (4.4 million ha) occurred in 
New Mexico (C. g. zuniensis and C. g. gunnisoni) (Oakes 2000, pp. 169-
171). In our 90-day finding in 2006 (71 FR 6241; February 7, 2006), we 
calculated historical estimates (circa 1916) for Colorado (6 million ac 
(2.4 million ha), both subspecies) and Utah (700,000 ac (284,000 ha), 
C. g. zuniensis) from prairie dog information in various publications 
and reports, because data were not available for these States. By 
summation, based on the best available information, we estimated that 
the Gunnison's prairie dog (including both subspecies) historically 
occupied approximately 24.3 million ac (9.8 million ha) across its 
range in 1916. This historical estimate is similar to the predicted 
range model's rangewide estimate of 23,459,525 ac (9,493,733 ha) for 
the species based on habitat characteristics (Seglund et al. 2006, p. 
70).
    In 1961, the Gunnison's prairie dog occupied an estimated 445,000 
ac (180,000 ha) of habitat in Arizona; 116,000 ac (47,000 ha) in 
Colorado; 355,000 ac (144,000 ha) in New Mexico; and 100,000 ac (41,000 
ha) in Utah (Bureau of Sport Fisheries and Wildlife 1961, pp. 1, 5). By 
summation, in 1961, the Gunnison's prairie dog (including both 
subspecies) occupied approximately 1 million ac (405,000 ha) rangewide. 
When compared, these estimates indicate that, from 1916 to 1961, 
Gunnison's prairie dog populations decreased by approximately 93 
percent in Arizona, 98 percent in Colorado, 97 percent in New Mexico, 
and 86 percent in Utah, or by approximately 95 percent rangewide, 
largely because of disease and poisoning.
    To summarize the historical abundance data, between 1916 and 1961, 
habitat occupied by the Gunnison's prairie dog throughout its range 
declined by 95 percent as a result of disease and poisoning. However, 
historical declines do not necessarily imply that current populations 
continue to decline.
    After 1961, survey efforts documented declines, die-offs, or 
gradual increases in the acreage of occupied Gunnison's prairie dog 
habitats. Seglund et al. (2006, pp. 12-27) summarize the post-1961 
surveys for each of the four States, and each State's conservation 
assessment provides additional summaries (Underwood 2007; Lupis et al. 
2007; NMDGF 2008; Seglund and Schnurr 2010). We highlight several 
surveys for each State and Tribal lands below. However, because 
different survey methodologies were used, it is difficult to evaluate 
rangewide populations or assess trends from the post-1961 survey data. 
Additionally, surveys generally did not differentiate the Gunnison's 
prairie dog by subspecies; however, where possible, we have attempted 
to interpret data to the subspecies.
Arizona
    In 1990, colony mapping of eight complexes identified 34,214 ac 
(13,846 ha) of active Cynomys gunnisoni zuniensis colonies (Seglund et 
al. 2006, p. 12). In the Aubrey Valley, the subspecies occupied 19,368 
ac (7,838 ha) in 1990, and 29,655 ac (12,001 ha) in 1997, with burrow 
densities fluctuating yearly from 52 to 82 burrows per ac (21 to 33 
burrows per ha) between 1996 and 2001 (Seglund et al. 2006, p. 13). 
Populations at the Aubrey Valley increased following mild winters with 
above average rainfall, with lower numbers during droughts (Seglund et 
al. 2006, p. 13). Surveys in 2000 and 2001 across the range of C. g. 
zuniensis in Arizona, not including the Aubrey Valley and Tribal lands, 
identified approximately 11,184 ac (4,526 ha) of active colonies; 
however, this represented a 66 percent reduction in acreage from 
surveys conducted in 1987 (Wagner and Drickamer 2003; Seglund et al. 
2006, p. 14). Die-offs from plague resulted in this decline.
Colorado
    In 1980, Cynomys gunnisoni gunnisoni occupied approximately 15,568 
ac (6,300 ha) on BLM lands in Gunnison (Seglund et al. 2006, p. 19). In 
1988, C. g. gunnisoni occupied approximately 640 ac (259 ha), or 
approximately 0.9 percent of the San Luis Valley of Colorado (Seglund 
et al. 2006, p. 17). In 1990, the Colorado Agricultural Statistics 
Service estimated 438,876 ac (177,607 ha) of Gunnison's prairie dog in 
Colorado; however, the survey methodology likely overestimated the 
actual acreage of occupied habitat (Knowles 2002; Seglund et al. 2006, 
p. 17). In 1990, there were 5,800 ac (2,347 ha) of occupied C. g. 
gunnisoni habitats in Gunnison County, Colorado, but populations 
potentially declined by 94 percent within 12 years (Capodice and 
Harrell 2003; Seglund et al. 2006, p. 19). In 2002, Colorado supported 
approximately 151,547 ac (61,329 ha) of active colonies (Seglund et al. 
2006, p. 20). Plague was responsible for all observed declines and 
extirpations.
New Mexico
    In 1971, New Mexico supported approximately 87,748 ac (35,510 ha) 
of occupied Gunnison's prairie dog habitat (Seglund et al. 2006, p. 
21), which includes both Cynomys gunnisoni gunnisoni and C. g. 
zuniensis. Surveys of agricultural producers estimated 106,572 ac 
(43,128 ha) of occupied Gunnison's prairie dog colonies in New Mexico 
(Seglund et al. 2006, p. 22). The Estancia Valley had 43 active 
colonies in 1999 across 2,271 ac (919 ha), but only 27 were active a 
year later due to unknown causes (Seglund et al. 2006, p. 24). In 2004, 
surveys on BLM lands identified 2,378 ac (962 ha) of occupied habitat 
(Seglund et al. 2006, p. 24).
Utah
    In 1968, Utah supported approximately 22,007 ac (8,906 ha) of 
occupied Cynomys gunnisoni zuniensis habitat (Seglund et al. 2006, p. 
26). In 1984, C. gunnisoni zuniensis occupied 2,212 ac (895 ha) on BLM 
lands in San Juan County, Utah (Seglund et al. 2006, p. 26). Surveys in 
2002 on public, non-Tribal lands in Grand and San Juan Counties, Utah, 
identified 3,687 ac (1,492 ha) of active colonies with high prairie dog 
densities (Seglund et al. 2006, p. 27).
Tribal Lands
    Since 1961, only two surveys evaluated the Gunnison's prairie dog 
on Tribal lands of the Navajo Nation. In 1994 and 1996, 18 of 90 
colonies totaled 5,987 ac (2,423 ha), with an additional, estimated 
area of more than 988 ac (400 ha) of active colonies that were not 
surveyed. The limited survey area represented only a small portion of 
potentially occupied prairie dog habitat on the Navajo Nation (Navajo 
Natural Heritage Program 1996). Limited surveys along a linear transect 
within the road right-of-way along a 69 mile stretch of highway on the 
Navajo Nation in New Mexico supported 37 prairie dog colonies in 2001, 
but these colonies were largely abandoned in 2003 (Seglund et al. 2006, 
p. 24).

[[Page 68669]]

Current Rangewide and Statewide Estimates of Abundance
    In 2005, Colorado conducted occupancy surveys to assess the status 
of Gunnison's prairie dog populations throughout its historical and 
current range in the State. Following Colorado's effort, in 2007 and 
2010, Colorado, Utah, Arizona, and New Mexico all conducted occupancy 
surveys to assess the status of Gunnison's prairie dog populations 
throughout its historical and current range. To date, three occupancy 
surveys spanning 6 years have been completed in Colorado, and two 
surveys spanning 3 years have been completed in Utah, Arizona, and New 
Mexico, mostly on public and non-Tribal lands. Because prairie dogs 
have up to one litter per year and live for 3 years, two surveys 
spanning 3 years account for up to three generations of Gunnison's 
prairie dog. Therefore, 2 years of surveys provides the best available 
assessment of current population trends.
    The occupancy surveys and modeling reveal that the Gunnison's 
prairie dog occupied 20 percent of its potential habitat rangewide in 
2010 (Seglund 2012, p. 11). This percentage represents the current 
status of the Gunnison's prairie dog across its range. It does not 
imply an 80 percent decline from historical levels, because different, 
incomparable methodologies were used, and the species is 
discontinuously distributed across its potential range. Furthermore, 
the surveys indicate that between 2005 and 2010, the occupancy remained 
stable in Colorado and stable between 2007 and 2010 in Colorado, New 
Mexico, Utah, and Arizona. Occupancy for individual population areas in 
Colorado and New Mexico also remained stable between survey years. A 
rangewide occupancy of 20 percent likely reflects the Gunnison's 
prairie dog's colonial and discontinuous distribution across its 
predicted range. Colonial behavior and a naturally discontinuous 
distribution would prevent the species from ever achieving full, 100 
percent occupancy across its predicted range.
    Stable occupancy trends indicate that populations of both 
Gunnison's prairie dog subspecies are also stable and not declining. 
The stable trends indicate that the Gunnison's prairie dog has 
exhibited sufficient resiliency to recover from periodic disturbance, 
such as poisoning, shooting, or plague. Due to this stability, the 
States delayed the next occupancy surveys to 2016, rather than 2013 
(Van Pelt 2013, p. 5). Declines in occupancy of within any one 
individual population area will trigger rangewide conservation actions, 
including increased funding, personnel support, and annual occupancy 
surveys until the decline reverses (WAFWA 2007, p. 5; Seglund 2012, p. 
13).
    Below, we briefly summarize the available abundance data from each 
State and Tribe.
Arizona
    Only Cynomys gunnisoni zuniensis occurs in Arizona. In 2007, this 
subspecies occupied approximately 108,570 ac (40,500 ha) on non-Tribal 
lands in Arizona (Underwood 2007, p. 30), which is a gross 
underestimate because it did not include Tribal lands in Arizona, which 
occupy more than 50 percent of the Statewide potential habitat (Table 
1). Between 2007 and 2011, these occupied acres in Arizona increased by 
approximately 1 percent from 108,570 (40,500 ha) ac to 109,402 ac 
(44,273 ha) (Van Pelt 2012, p. 5). Lands managed by the Navajo Nation 
and Hopi Tribe in Arizona supported approximately 111,108 ac (44,965 
ha) of active colonies in 2008 (Johnson et al. 2010; Johnson 2013, p. 
1).
    At the Espee Ranch black-footed ferret reintroduction site in 
Arizona, occupied acres of Cynomys gunnisoni zuniensis dropped by 85 
percent between 2009 and 2010, from 8,000 ac (3,237 ha) to 1,200 ac 
(486 ha) due to plague (Van Pelt 2011, p. 4). However, in 2011, the 
occupied acres increased by 90 percent, with an approximate total of 
5,738 ac (2,322 ha) at the Espee Ranch (Van Pelt 2011, p. 4). Between 
2011 and 2012, the Espee Ranch population again increased, by 65 
percent, from 5,738 ac (2,322 ha) to 9,514 ac (3,850 ha) (Van Pelt 
2013, p. 6). The population rebound at the Espee Ranch illustrates the 
resiliency of the Gunnison's prairie dog to catastrophic events, 
including reoccurring outbreaks of plague.
    In 2012, Cynomys gunnisoni zuniensis occupied approximately 54,047 
ac (21,872 ha) in the Aubrey Valley complex (Van Pelt 2013, p. 6). 
Annual monitoring at the Aubrey Valley complex reveals that populations 
are increasing and may have some genetically-based resistance to 
sylvatic plague (Van Pelt 2013, p. 11). Overall, the acreage of habitat 
occupied by Cynomys gunnisoni zuniensis in Arizona has increased from 
the 1961 levels.
    In 2007, occupancy surveys in Arizona's three population areas 
ranged from 11 to 36 percent (Seglund 2013, p. 1). In 2010, occupancy 
surveys in Arizona's three population areas ranged from 14 to 37 
percent. Between 2007 and 2010, occupancy of Cynomys gunnisoni 
zuniensis was stable. Therefore, populations were also stable in 
Arizona, which also suggests that the metapopulation structure is 
intact.
Colorado
    In 1990, Gunnison's, white-tailed, and black-tailed prairie dogs 
occupied an estimated 1,553,000 ac (621,200 ha) in Colorado (CDA 1990, 
p. A-3). Based on species occurrence by county, Gunnison's prairie dogs 
occupied approximately 438,876 ac (177,607 ha) in Colorado in 1990 
(Seglund et al. 2005, p. 26).
    Between 2002 and 2005, the Colorado Parks and Wildlife (CPW) mapped 
approximately: 182,237 ac (72,895 ha) of active Gunnison's prairie dog 
colonies; 9,042 ac (3,617 ha) of inactive colonies; and 171,970 ac 
(68,788 ha) of colonies in unknown status within Colorado (CDOW 2007, 
p. 3). These abundance estimates suggest a 36 percent increase in 
abundance from the historical 1961 estimate of 115,650 ac (46,802 ha), 
although errors associated with mapping likely reduced the accuracy of 
these estimates.
    CPW selected individual population areas within Colorado to focus 
their management efforts. In Colorado, Cynomys gunnisoni gunnisoni 
occupy the Gunnison, San Luis Valley, South Park, and Southeast 
population areas. Cynomys gunnisoni zuniensis occupy the La Plata-
Archuleta and Southwest population areas. C. g. gunnisoni occupy 
approximately 80 percent of the potential habitat and 40 percent of the 
occupied habitat in Colorado (CDOW 2007, p. 28). C. g. zuniensis occupy 
approximately 20 percent of the potential habitat and about 60 percent 
of the occupied habitat in Colorado (CDOW 2007, pp. 3, 19). In other 
words, there is more potential habitat for C. g. gunnisoni in Colorado, 
but this subspecies occupies only 40 percent of the total occupied 
habitat. Comparatively, there is less potential habitat in Colorado 
available to C. g. zuniensis, but the subspecies occupies 60 percent of 
the total occupied Gunnison's prairie dog habitat in Colorado. This 
indicates that C. g. zuniensis is more abundant in Colorado than C. g. 
gunnisoni.
    Occupancy surveys confirmed that Cynomys gunnisoni zuniensis is 
more abundant than C. g. gunnisoni in Colorado. In 2005, C. g. 
gunnisoni occupied 4.5 percent and C. g. zuniensis occupied 17.3 
percent of the potential habitats in Colorado (Seglund 2013, p. 1). In 
2007, C. g. gunnisoni occupied 5.5 percent and C. g. zuniensis occupied 
18.4 percent of its potential habitats (Seglund 2013, p. 1). In 2010, 
C. g. gunnisoni occupied approximately 8.2

[[Page 68670]]

percent of the potential habitats in Colorado and C. g. zuniensis 
occupied approximately 14.2 percent of the potential habitats (Seglund 
2013, p. 1). These percentages provide both subspecies with sufficient 
redundancy to rebound and repopulate following declines from 
catastrophic events, such as plague outbreaks. Additionally, between 
2005 and 2010, occupancy rates for both subspecies were stable in all 
the individual population areas of Colorado (Seglund 2012, pp. 2, 11; 
Seglund 2013, p. 1). Stability between the individual population areas 
suggests that the metapopulation structure is intact in Colorado, as 
extirpated colonies are successfully recolonized. The data also 
indicate that both subspecies have demonstrated resiliency to plague, 
the primary factor impacting populations.
    It remains unclear why C. g. gunnisoni occupies a smaller 
percentage of its potential habitats than C. g. zuniensis in Colorado, 
although this percentage provides sufficient population redundancy for 
C. g. gunnisoni to rebound and repopulate following catastrophic 
events. Disease and poisoning may have initially contributed to this 
discrepancy, but both subspecies are resilient to periodic disturbance 
from these impacts. The difference may have more to do with habitat 
productivity. Although C. g. gunnisoni's habitats are generally 
moister, growing seasons are shorter at higher elevations, which may 
reduce the annual productivity of forage available to C. g. gunnisoni 
in Colorado.
New Mexico
    Both Cynomys gunnisoni gunnisoni and C. g. zuniensis occur in New 
Mexico. C. g. gunnisoni occupies approximately 17 percent of the 
potential Gunnison's prairie dog habitat in New Mexico, while C. g. 
zuniensis occupies approximately 83 percent of the potential habitat. 
However, historical and current estimates of abundance in New Mexico do 
not differentiate between the two subspecies, so percentages of habitat 
occupied by each subspecies are not available. Therefore, the data do 
not reveal whether one subspecies is more or less abundant.
    Estimates of habitat occupied by the Gunnison's prairie dog in New 
Mexico during the early 1980s range widely, from approximately 348,000 
ac (141,000 ha) to 75,000 ac (30,000 ha) (Bodenchuck 1981, p. 8; Oakes 
2000, p. 216; Knowles 2002, p. 22). In 2004, aerial mapping estimated a 
minimum of 9,108 ac (3,689 ha) of habitat occupied by the Gunnison's 
prairie dog in New Mexico (Seglund et al.2006, p. 24). On its lands in 
New Mexico, the Navajo Nation supported approximately 134,210 ac 
(54,314 ha) of active colonies in 2008 (Johnson et al. 2010; Johnson 
2013, p. 1).
    Occupancy in 2010 for the entire species was 18.1 percent (Seglund 
2010, p. 11). Between 2007 and 2010, occupancy was stable, suggesting 
that populations were also stable. Occupancy surveys in New Mexico did 
not differentiate between Cynomys gunnisoni gunnisoni in the northeast 
and C. g. zuniensis in the southwest part of the State. However, there 
is no information to indicate that abundance should differ 
significantly between the two subspecies in New Mexico.
Utah
    Only Cynomys gunnisoni zuniensis occurs in Utah; however surveys 
have been relatively limited compared to the other States. In 1968, 
Utah supported approximately 22,000 ac (8,906 ha) of occupied 
Gunnison's prairie dog (Cynomys gunnisoni zuniensis) habitat (Seglund 
et al. 2006, p. 26). In 2002, Gunnison's prairie dogs occupied at least 
3,678 ac (1,490 ha) in Utah (Knowles 2002, p. 21), although this was 
not a Statewide estimate. Occupied habitat may have decreased by 60 
percent between 1961 and 2007, from 100,000 ac (40,500 ha) in 1961 
(Bureau of Sport Fisheries and Wildlife 1961, p. 5), to 40,000 ac 
(16,000 ha) in 2007 (Lupis et al. 2007, p. 3); however, these data 
suffer from differing survey techniques. In 2008, the Navajo Nation in 
Utah supported approximately 3,334 ac (8,238 ha) of active Cynomys 
gunnisoni zuniensis colonies (Johnson et al. 2010; Johnson 2013, p. 1). 
The best available information indicates that C. g. zuniensis 
populations fluctuated over time in Utah.
    The Gunnison's prairie dog occupancy in Utah was estimated to be 
14.5 percent in 2007, and 15.1 percent in 2010 (Wright 2007, p. 3; 
Lupis et al. 2007, pp. 24, 60; Seglund 2012, p. 11). Occupancy surveys 
in 2008 revealed similar occupancy percentages on Tribal lands managed 
by the Navajo Nation (Seglund 2012, p. 8). Stable occupancy percentages 
indicate that populations of Cynomys gunnisoni zuniensis were stable in 
Utah.
Tribal Lands
    In 2010, the Navajo Nation in Arizona, New Mexico, and Utah, and 
the Reservation of the Hopi Tribe in Arizona, supported approximately 
253,567 ac (102,615 ha) of active Gunnison's prairie dog (Cynomys 
gunnisoni zuniensis) colonies spread throughout the land holdings of 
both Tribes (Johnson et al. 2010, p. 21). In Arizona, the Navajo Nation 
and Hopi Tribe in Arizona supported approximately 111,108 ac (44,965 
ha) of active colonies in 2008 (Johnson et al. 2010; Johnson 2013, p. 
1). In Utah, the Navajo Nation supported approximately 3,334 ac (8,238 
ha) of active Cynomys gunnisoni zuniensis colonies (Johnson et al. 
2010; Johnson 2013, p. 1). On its lands in New Mexico, the Navajo 
Nation supported approximately 134,210 ac (54,314 ha) of active 
colonies in 2008 (Johnson et al. 2010; Johnson 2013, p. 1).
    CPW completed occupancy modeling for Cynomys gunnisoni zuniensis on 
the Southern Ute and Ute Mountain Indian Reservation in the southwest 
corner of Colorado (Seglund 2012, p. 6). Occupancy was 26.5 percent in 
2010, with stability between 2007 and 2010. Occupancy surveys in Utah 
revealed similar occupancy percentages on Tribal lands managed by the 
Navajo Nation (Seglund 2012, p. 8). Although occupancy surveys for the 
Gunnison's prairie dog have not been completed on other Tribal lands, 
there is no information to indicate that occupancy percentages or 
trends differ.
Summary of Abundance and Trends
    Historical estimates of abundance indicate a rangewide 95 percent 
decline in the acres occupied by the Gunnison's prairie dog between 
1916 and 1961. Declines occurred within all four States, and 
populations fluctuated after 1961. However, the best available 
information indicates that population numbers have been stable since 
that time, especially as prairie dog eradication efforts decreased in 
magnitude. Current occupancy modeling indicates that the Gunnison's 
prairie dog occupies 20 percent of its available habitat, which 
provides sufficient redundancy of populations for continued stability. 
This percent occupancy represents the current status of the Gunnison's 
prairie dog across its range and does not represent an 80 percent 
decline. Furthermore, occupancy surveys and modeling completed 
throughout the ranges of both subspecies revealed that Gunnison's 
prairie dog occupancy, and hence populations, were stable throughout 
the ranges of both subspecies between 2007 and 2010 in Arizona, New 
Mexico, and Utah, and between 2005 and 2010 in Colorado. This stability 
rangewide and within individual population areas also suggests that any 
local extinctions are offset by recolonization, so the metapopulation 
structure is intact.

[[Page 68671]]

Summary of Information Pertaining to the Five Factors

    Section 4 of the Act (16 U.S.C. 1533) and implementing regulations 
(50 CFR part 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) 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) The inadequacy of existing regulatory mechanisms; or
    (E) Other natural or manmade factors affecting its continued 
existence.
    In making this finding, information pertaining to the Gunnison's 
prairie dog, and the subspecies Cynomys gunnisoni gunnisoni and C. g. 
zuniensis, in relation to the five factors provided in section 4(a)(1) 
of the Act is discussed below. When considering what factors might 
constitute threats, we must look beyond the mere exposure of the 
species (or in this case, subspecies) to the factor to determine 
whether the species responds to the factor in a way that causes actual 
impacts to the species. If there is exposure to a factor, but no 
response, or only a positive response, that factor is not a threat. If 
there is exposure and the species responds negatively, the factor may 
be a threat and we then attempt to determine how significant a threat 
it is. If the threat is significant, it may drive or contribute to the 
risk of extinction of the species such that the species warrants 
listing as endangered or threatened as those terms are defined by the 
Act. This does not necessarily require empirical proof of a threat. The 
combination of exposure and some corroborating evidence of how the 
species is likely impacted could suffice. The mere identification of 
factors that could impact a species negatively is not sufficient to 
compel a finding that listing is appropriate; we require evidence that 
these factors are operative threats that act on the species to the 
point that the species meets the definition of an endangered or 
threatened species under the Act.
    In making our 12-month finding on the petition, we considered and 
evaluated the best scientific and commercial information available.

Factor A. The Present or Threatened Destruction, Modification, or 
Curtailment of Its Habitat or Range

    Below, we examine the following potential factors that may affect 
the habitat or range of Cynomys gunnisoni gunnisoni or C. g. zuniensis 
including: (1) Agricultural land conversion; (2) grazing; (3) invasive 
plant species; (4) urbanization; and (5) oil and gas exploration and 
development.
Agricultural Land Conversion
    Agricultural land conversion describes a change in land use to an 
agricultural use, such as crops or pastures. Agricultural land 
conversion historically impacted Gunnison's prairie dog habitat by 
displacing Gunnison's prairie dogs from some of the more productive 
valley bottomlands in Colorado and New Mexico (Longhurst 1944, p. 36; 
Knowles 2002, p. 12). Agricultural land conversions may also increase 
mortality rates of prairie dogs when control efforts, such as poisoning 
and shooting, accompany the change in land use (Hoogland 2001, p. 917; 
Knowles 2002, p. 12).
    Today, agriculture currently impacts 2,063,930 ac (834,243 ha), or 
less than 3 percent of the Gunnison's prairie dog's range (Seglund et 
al. 2005, p. 43). In Arizona, agricultural development impacts 31,444 
ac (12,725 ha), or less than 1 percent of the predicted range of 
Cynomys gunnisoni zuniensis (Underwood 2007, pp. 9-10). Between 2002 
and 2007, acres of farmland in Colorado increased by 1.6 percent, but 
decreased by 3.5 percent in New Mexico, 5.4 percent in Utah, and 1.8 
percent in Arizona (USDA 2009). Gunnison's prairie dogs may benefit 
from agricultural land conversions because agricultural fields provide 
highly productive forage for Gunnison's prairie dogs, in place of the 
native, arid landscape (Crocker-Bedford 1976, pp. 73-74; Seglund et al. 
2005, p. 41). Further, control efforts that may accompany agriculture 
currently occur locally and do not result in rangewide population 
declines of either subspecies (see discussions of Factors C and E).
    Therefore, due to the small percentage of the range affected by 
agriculture and the small amount of land likely to be converted to 
agriculture in the future, agricultural land conversion is not a threat 
to either subspecies now nor is it likely to become so in the future.
Livestock Grazing
    Prairie dogs coevolved with native herbivores, such as bison (Bison 
bison), that grazed across the intermountain west before European 
settlers introduced domesticated livestock in the 1800s. By 1890, 
hundreds of thousands of cattle and large numbers of sheep grazed 
within the range of the Gunnison's prairie dog (Seglund et al. 2006, p. 
33). Livestock numbers peaked in the early 1900s (Oliphant 1968, p. 
vii; Young et al. 1976, pp. 194-195; Carpenter 1981, p. 106; Donahue 
1999, p. 15). However, the intensity of grazing on Federal lands has 
declined since the early 1900s (Laycock et al. 1996, p. 3). Between 
2000 and 2012, numbers of cattle, including calves, decreased by 13 
percent in Colorado, decreased by 15 percent in New Mexico, decreased 
by 12 percent in Utah, and increased by 9.5 percent in Arizona 
(National Agricultural Statistics Service 2013).
    In general, livestock grazing can alter the diversity of plants and 
disrupt the function and structure of ecosystems by decreasing cover by 
grasses and shrubs, total plant biomass, and the diversity and richness 
of rodents (Fleischner 1994, pp. 633-635; Seglund et al. 2006, p. 33). 
Fencing and roads associated with livestock grazing may fragment 
habitats, kill prairie dogs crossing roads, create perches for raptors, 
and provide access corridors for predators (Call and Maser 1985, p. 3; 
Connelly et al. 2000, p. 974; Connelly et al. 2004, pp. 1-2). 
Overgrazing occurs when the forage plants are unable to recover 
(Vallentine 1990, p. 329). Overgrazing may reduce the forage available 
to prairie dogs and may promote the establishment of invasive species, 
such as cheat grass (Bromus tectorum) (Masters and Sheley 2001, p. 
503). The intensity, duration, and distribution of livestock grazing 
influence the condition of rangeland more than the density of livestock 
(Aldridge et al. 2008, p. 990).
    Non-grazed habitats within the range of the Gunnison's prairie dog 
are rare, so evaluating potential impacts of livestock grazing on 
prairie dog habitats and populations is difficult (Seglund et al. 2006, 
p. 33). Overgrazing may impact prairie dogs by degrading the quality, 
quantity, and diversity of forage, and by decreasing forage 
availability during important breeding, rearing, and pre-hibernation 
periods (Seglund et al. 2006, p. 34). Altered hydrology, compacted 
soils, altered nutrient cycling, and decreased water infiltration 
resulting from overgrazing may also impact Gunnison's prairie dog 
habitats (Seglund et al. 2006, p. 34).
    When properly managed, livestock grazing may be beneficial to the 
Gunnison's prairie dog. Grazing benefited black-tailed prairie dog 
colonies by reducing the height of grasses, which improves visibility 
to detect predators (Uresk et al. 1981, p.

[[Page 68672]]

200; Cable and Timm 1987, p. 46). Well managed grazing also increases 
production of the prairie dog's preferred grass species (Seglund et al. 
2006, p. 34), and prairie dog densities increase in grazed habitats, 
likely because well-managed grazing is compatible with the shortgrass 
prairie environment preferred by prairie dogs (Fagerstone and Ramey 
1996, p. 88; Marsh 1984, p. 203; Slobodchikoff et al. 1988, p. 406). 
Prairie dogs and native herbivores coexisted before the arrival of 
domesticated livestock, so prairie dogs should be able to coexist with 
livestock that are properly grazed (Hoogland 1996, p. 6; Underwood 
2007, p. 8). In Arizona, some of the largest and recently expanding 
Cynomys gunnisoni zuniensis colonies are actively grazed (Underwood 
2007, p. 10).
    However, improperly managed grazing, or overgrazing, may reduce the 
forage available to the Gunnison's prairie dog. For example, Utah 
prairie dog densities declined in overgrazed habitats (Collier and 
Spillett 1975 p. 151; Cheng and Ritchie 2006, p. 550). As overgrazing 
reduced the diversity of plants, more Utah prairie dog colonies went 
extinct (Ritchie 1999, p. 12) and unfavorable shrub densities increased 
(Crocker-Bedford 1976, p. 88). At the same time, Utah prairie dogs 
preferred moderately grazed areas to ungrazed areas due to the 
availability of short grasses (Cheng and Ritchie 2006, p. 554). 
Therefore, overgrazing may negatively impact the Gunnison's prairie 
dog, but properly managed grazing may benefit the Gunnison's prairie by 
increasing visibility and the quality and quantity of preferred forage 
(Seglund et al. 2006, p. 34).
    We lack information regarding site-specific range conditions on 
Federal or non-Federal grazing allotments within the range of Cynomys 
gunnisoni gunnisoni or C. g. zuniensis. Range condition data are not 
collected in a biologically meaningful way that is relevant to small 
mammals. Gunnison's prairie dogs evolved with other herbivores in arid 
environments and can persist with limited forage. Prairie dogs 
hibernate and aestivate (sleep during the summer) when they are 
metabolically stressed (Harlow and Menkens 1986, p. 795; Seglund et al. 
2006, p. 7; Seglund and Schnurr 2010, p. 14), an adaptation which may 
allow the Gunnison's prairie dog to persist within overgrazed habitats. 
The point at which overgrazing makes habitats unsuitable is unclear, so 
quantifying the habitats that are overgrazed versus moderately grazed, 
and the impacts on prairie dogs, is difficult. The available literature 
indicates that prairie dogs can coexist with some level of properly 
managed grazing, and may benefit from well managed grazing in some 
cases (Uresk et al. 1981, p. 200; Marsh 1984, p. 203; Cable and Timm 
1987, p. 46; Slobodchikoff et al. 1988, p. 406; Fagerstone and Ramey 
1996, p. 88; Hoogland 1996, p. 6; Seglund et al. 2006, p. 34; Cheng and 
Ritchie 2006, p. 554; Underwood 2007, pp. 8, 10). Gunnison's prairie 
dogs have persisted under more intense grazing in the past, and 
stocking rates have decreased across most of the range, and increased 
slightly only in Utah. Therefore, grazing is not a threat to either 
subspecies now nor is it likely to become so in the future.
Invasive Plant Species
    The alteration of native prairie habitats throughout the western 
United States by the invasion of noxious weeds, such as cheat grass 
(Bromus tectorum) is well documented in the literature (Mack 1981, pp. 
145-165; D'Antonio and Vitousek 1992, pp. 63-87; Knapp 1996, pp. 37-52; 
Young and Allen 1997, pp. 530-535; Stohlgren et al. 1999, pp. 45-64; 
Pimental et al. 2005, pp. 273-288; Davies and Sheley 2007, p. 178; 
DiTomaso 2009, pp. 255-265). Invasive plant species displace native 
plants, degrade wildlife habitats, alter fire regimes, and promote 
continued invasions (Masters and Sheley 2001, p. 503). The continued 
expansion of juniper forests into semi-arid grasslands and shrublands 
may reduce native prairie habitats (Miller and Rose 1999, p. 550) and 
restrict or fragment Gunnison's prairie dog habitats (Seglund and 
Schnurr 2010, p. 159).
    Prairie dog densities increase when there are more native plants 
(Slobodichikoff et al. 1988, p. 406), and invasive plants may reduce 
densities by reducing the quality and quantity of the Gunnison's 
prairie dog's preferred forage. Although noxious weeds are now 
widespread throughout the range of the Gunnison's prairie dog, there is 
no evidence that the subspecies are impacted by invasive plant species 
at more than a localized scale. Additionally, although juniper 
encroachment may reduce available habitats, the available information 
indicates that juniper encroachment occurs at no more than a localized 
scale at the periphery of the overall range. Therefore, invasive plant 
species are not threats to either subspecies of Gunnison's prairie dog 
now nor are they likely to become so in the future.
Urbanization
    Urban development reduces and fragments habitats. More 
infrastructure, such as roads and transmission lines, accompany 
expansions of human population centers, which may impact habitats 
beyond the immediate urban area. Prairie dog control efforts, such as 
shooting and poisoning, may also be more prevalent next to urban areas 
(Seglund and Schnurr 2010, p. 171). Impacts to the Gunnison's prairie 
dog associated with urban and suburban development exist, but have not 
been quantified, in the five cities of Santa Fe and Albuquerque, New 
Mexico; Flagstaff, Arizona; and Gunnison and Durango, Colorado (CDOW 
2007, p. 4).
    The effects of urban development on the Gunnison's prairie dog have 
not been specifically studied, but the weights and sex ratios of black-
tailed prairie dogs living in urban environments were within the normal 
ranges for the species (Magle 2008, p. 116). However, within urban 
areas, black-tailed prairie dogs were more likely to occur on larger, 
continuous habitats, rather than smaller, highly fragmented urban 
parcels (Magle and Crooks 2009, p. 197). Existing black-tailed prairie 
dog colonies collapsed within highly fragmented urban environments 
(Magle and Crooks 2009, pp. 197, 199). In other words, black-tailed 
prairie dogs survived in habitats fragmented by urban areas, but 
populations decreased over time as habitats became more fragmented 
(Magle and Crooks 2009, p. 200). We expect that the impacts of urban 
development on Gunnison's prairie dogs would be similar.
    Today, urbanization affects approximately 577,438 ac (233,681 ha), 
or less than 2 percent, of the predicted range of the Gunnison's 
prairie dog (Seglund et al. 2005, p. 41; Seglund et al. 2006, p. 35). 
In Arizona, urban development impacts 42,371 ac (17,147 ha), or less 
than 1 percent of the predicted range for Cynomys gunnisoni zuniensis 
(Underwood 2007, p. 10). During surveys in Arizona, only one C. g. 
zuniensis colony became inactive due to urbanization (Wagner et al. 
2006, p. 334). Rates of urbanization with the western United States are 
below the national average (White et al. 2009, pp. 41-45). Low-density 
developments may actually be compatible with Gunnison's prairie dog 
populations where lawns and pastures provide high quality forage 
(Seglund et al. 2005, p. 41; Seglund et al. 2006, p. 35). Secondary 
effects of urbanization, such as shooting and poisoning, occur locally 
but do not significantly reduce rangewide populations. Near Santa Fe, 
New Mexico, Gunnison's prairie dogs are relocated to preserves before 
lands are urbanized, although this does not reduce the loss of habitat. 
Urbanization

[[Page 68673]]

is projected to occur rapidly on Colorado's western slope, and high 
density urban development may impact a larger percentage of the Cynomys 
gunnisoni zuniensis' range in western Colorado. However, urbanization 
is a concern only at localized scales primarily near the urban areas of 
Durango and Montrose (Seglund and Schnurr 2010, pp. 171, 176), and 
there is no evidence that urbanization negatively impacts C. g. 
zuniensis populations near these cities.
    To summarize, habitat loss and fragmentation due to urbanization 
may impact both subspecies of the Gunnison's prairie dog, but only in 
localized areas. There will not likely be significant increases in 
urbanization across the subspecies' ranges in the future. Therefore, 
urbanization is not a threat to either subspecies now or likely to 
become so in the future.
Oil and Gas Exploration and Development
    Oil and gas exploration and development occur throughout the ranges 
of both Gunnison's prairie dog subspecies. Between 2004 and 2008, 
political and economic incentives increased the exploration of oil and 
gas resources in the intermountain west. The 2005 Energy Policy Act 
expedited the leasing and permitting of energy development on Federal 
lands (42 U.S.C. 13201 et seq.; Seglund and Schnurr 2010, p. 121). 
Although the global recession of 2008 decreased energy demand and 
reduced the rate of development, demand will likely increase (Copeland 
et al. 2009, p. 1; EIA 2009, p. 109).
    Exploration for oil and gas may increase human activity within 
previously undisturbed habitats and introduce other disturbances, such 
as seismic waves, which may collapse burrows, impair hearing, and 
disrupt social systems (Underwood 2007, p. 10). The development of well 
pads and supporting infrastructure, such as roads and pipelines, may 
reduce or fragment available habitats (Seglund and Schnurr 2010, p. 
126). Prairie dog control, such as shooting or poisoning, and road 
mortality, may accompany the oil and gas developments (Gordon et al. 
2003, p. 12).
    Approximately 6 percent of the Gunnison's prairie dog's range is 
under authorized or pending Federal lease for oil and gas development 
(Seglund and Schnurr 2010, p. 117). We lack similar estimates for 
development on private lands. However, the available information does 
not indicate that Gunnison's prairie dogs are negatively impacted by 
oil and gas activities at the population, subspecies, or landscape 
levels. Increased mortality associated with control efforts or roads 
are similarly localized and do not result in widespread population 
reductions or losses, as evidenced by the stable occupancy trends. 
Furthermore, seismic exploration does not likely negatively affect 
prairie dogs (Menkens and Anderson 1985, p. 13). Therefore, oil and gas 
exploration and development are not threats to either subspecies of 
Gunnison's prairie dog now or likely to become so in the future.
Conservation Efforts To Reduce Habitat Destruction, Modification, or 
Curtailment of Its Range
    Current approved or draft resource management plans (RMPs) for BLM 
lands in Utah and New Mexico include specific conservation measures to 
avoid and minimize impacts to the Gunnison's prairie dog from oil and 
gas activities (as discussed below under Factor D). RMPs in Colorado 
and Arizona do not specifically address the Gunnison's prairie dog. 
Conservation measures include precluding oil and gas development and 
other surface-disturbing activities within 600 feet (183 meters) of 
active colonies and limiting the construction of power lines within 
colonies (BLM 2008a, pp. 138-139; BLM 2008b, pp. 122-123; BLM 2012, p. 
2-125; BLM 2013, pp. 19, 143). The BLM's RMPs confer conservation 
recommendations for the management of prairie dogs on BLM lands.
Summary of Factor A
    Agriculture, grazing, the spread of invasive plants, urbanization, 
and oil and gas exploration and development occur within the ranges of 
Cynomys gunnisoni gunnisoni and C. g. zuniensis and will continue to 
occur in the future. Agriculture and urbanization currently impact a 
small portion of the Gunnison's prairie dog's range. Urbanization may 
impact local populations, but it is not a rangewide threat. Grazing and 
oil and gas development likely impact some habitats, but there is no 
evidence that they are significantly impacting either subspecies. 
Additionally, there is no evidence that invasive plants are having a 
significant impact.
    Therefore, the best scientific and commercial information available 
indicates that the present or threatened destruction, modification, or 
curtailment of its habitat or range is not currently a threat to 
Cynomys gunnisoni gunnisoni or C. g. zuniensis, nor is it likely to 
become so in the future.

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

Recreational Shooting
    Gunnison's prairie dogs have been historically subjected to 
recreational shooting and shooting as a form of pest management on 
ranch and agricultural lands. State regulations in all four States 
allow shooting of Gunnison's prairie dogs.
    Colonial behavior makes prairie dogs vulnerable to shooting by 
providing shooters with easy access to many individuals at once 
(Seglund et al. 2005, p. 48). There is little information regarding 
shooting specific to the Gunnison's prairie dog (Seglund 2006, p. 41), 
but the effects of shooting on black-tailed prairie dogs are well 
documented and relevant to the Gunnison's prairie dog (CDOW 2007, p. 
41; Seglund and Schnurr 2010, p. 165). Shooting reduces prairie dog 
populations and alters behaviors of individual animals. The prairie 
dogs eat less and spend more time alert, which reduces the vigor of 
individual prairie dogs and the reproductive output of the colony 
(Knowles 1988, p. 54; Vosburgh 1996, pp. 32-33; Vosburgh and Irby 1998, 
p. 368; Pauli and Buskirk 2007, pp. 1223-1224). At specific sites, 
shooting can reduce prairie dog populations (Miller et al. 1993, p. 91; 
Vosburgh 1996, pp. 13-14; Vosburgh and Irby 1998, pp. 366-367; Knowles 
2002, p. 14), and shooting may have locally extirpated colonies in 
isolated circumstances in the past (Knowles 1988, p. 54).
    However, increased population growth rates or recovery from very 
low numbers following shooting have occurred (Knowles 1988, p. 54). 
Even small numbers of Gunnison's prairie dogs experience increased 
reproductive rates following population declines, a life history trait 
that likely mediates the effects of shooting and enables populations to 
recover. A population viability analysis confirmed that the probability 
of colony extirpation from recreation shooting alone is low (Seglund 
and Schnurr 2010, p. 168).
    Recreational shooting is permitted rangewide, but it is unlikely 
that all Gunnison's prairie dog colonies experience the same levels of 
shooting. Recreational shooting of prairie dogs is more concentrated on 
colonies with reasonably easy access (Gordon et al. 2003, p. 12). 
Higher elevation or more remote colonies may never experience shooting 
pressures due to the difficulty of access. Shooting is likely 
concentrated near urban areas and agricultural fields (Gordon et al. 
2003,

[[Page 68674]]

p. 12; Seglund et al. 2006, p. 33). However, urbanization and 
agriculture affect less than 3 percent of the Gunnison's prairie dog's 
range (see Factor A discussion).
    Unlike Arizona, Utah, or New Mexico, Colorado classifies both 
Cynomys gunnisoni gunnisoni and C. g. zuniensis as small game. 
Therefore, Colorado is the only State within the range of the 
Gunnison's prairie dog that requires a species-specific hunting permit 
to shoot prairie dogs. The Gunnison's prairie dog is a nongame mammal 
in Arizona, Utah, and New Mexico, so shooting is lawful under the 
auspices of a general hunting license (Seglund et al. 2006, pp. 28, 30, 
31; Underwood 2007, p. 11). Because permits are not required in other 
States, quantifying the number of prairie dogs killed by shooting is 
difficult. However, local residents generally shoot Gunnison's prairie 
dog, compared to the large numbers of nonresidents that travel to shoot 
black-tailed prairie dogs (Knowles 2002, p. 14; Seglund et al. 2006, p. 
39; Seglund and Schnurr 2010, p. 165).
    Harvest surveys for Colorado indicate that only 4.6 to 7.4 percent 
of hunters shot prairie dogs of any species between 2001 and 2005 (CDOW 
2001-2005). In 2005, the Statewide harvest estimate for all prairie dog 
species in Colorado was 388,714  154,520 and 328,936  36,787 in 2004 (CDOW 2005, p. 1). Hunting surveys after 2005 do 
not record the numbers of prairie dogs taken by each hunter, but 
shooters may hit from 40 to 100 black-tailed prairie dogs per day 
(Seglund et al. 2006, pp. 39-40). In Arizona, hunting surveys estimate 
that between 30,000 to 94,000 Cynomys gunnisoni zuniensis are taken 
each year and that the number of prairie dogs killed declined by 
approximately 56 percent between 2000 and 2006 (Wagner et al. 2006, p. 
336; Underwood 2007, pp. 11, 39). Using the minimum density estimate of 
2 prairie dogs per ac (5 per ha) (Fitzgerald et al. 2011, p. 140) and 
the predicated range for the Gunnison's prairie dog (Seglund et al. 
2006, p. 70), these harvest estimates represent less than 1 percent of 
the potential Gunnison's prairie dog population in Arizona and a 
maximum 4.5 percent of the potential population in Colorado. Therefore, 
these data indicate that shooting pressure is low on the Gunnison's 
prairie dog in Arizona and Colorado. There is no information to 
indicate that shooting pressures are greater in New Mexico or Utah. The 
Navajo Nation also requires a small game permit to hunt prairie dogs, 
but provided no data on numbers of animals taken.
Conservation Efforts To Reduce Overutilization for Commercial, 
Recreational, Scientific, or Educational Purposes
    Shooting closures during the breeding season reduce the impacts of 
recreational shooting (discussed below under Factor D). A population 
viability analysis for the Gunnison's prairie dog confirmed that 
shooting closures from March 1 through June 14 each year increased 
population growth rates and reduced the risk of extinction (CDOW 2007, 
pp. 135-137). Without a seasonal shooting closure, small populations 
subjected to intense shooting experienced a decrease in growth rate and 
an increased risk of extinction (CDOW 2007, pp. 135-137). Colorado, 
Utah, and Arizona (outside Tribal lands) have implemented seasonal 
closures on prairie dog shooting. These closures reduced population 
declines caused by shooting. Cynomys gunnisoni zuniensis populations at 
the Aubrey Valley Complex increased after Arizona instituted its 
seasonal shooting closure (SSA Workshop 2013). In Arizona, New Mexico 
and Utah, the Navajo Nation requires a small game permit but currently 
implements no closures on shooting because the level of shooting is low 
and localized (Cole 2007, p. 4; Johnson et al. 2010, p. 3).
Summary of Factor B
    The effects of recreational shooting may be high on specific, 
easily accessible, localized colonies. However, these effects do not 
result in rangewide population declines for either Cynomys gunnisoni 
gunnisoni or C. g. zuniensis. There are no other known threats due to 
commercial, scientific, or educational uses of the species.
    Therefore, the best scientific and commercial information available 
indicates that overutilization for commercial, recreational, 
scientific, or educational purposes is not currently a threat to 
Cynomys gunnisoni gunnisoni or C. g. zuniensis, nor is it likely to 
become so in the future.

Factor C. Disease or Predation

Predation
    Predation is a natural occurrence for Gunnison's prairie dogs. 
Numerous species, including coyotes, badgers, black-footed ferrets, and 
various raptor species, prey on the Gunnison's prairie dog. However, 
there is no information available to indicate that predation is a 
threat to the species. Stable or increasing populations within black-
footed ferret release areas suggest that predation is not a threat to 
Gunnison's prairie dog populations where the black-footed ferret has 
been reintroduced (Van Pelt 2013, p. 5). Therefore, predation is not a 
threat to either subspecies of the Gunnison's prairie dog now nor is it 
likely to become so in the future.
Sylvatic Plague
    Severe outbreaks of sylvatic plague, or plague, often kill more 
than 99 percent of the Gunnison's prairie dogs in a population and can 
extirpate entire populations within one season (Lechleitner et al. 
1962, pp. 190-192; Lechleitner et al. 1968, p. 736; Rayor 1985, p. 194; 
Cully 1989, p. 49; Fitzgerald et al. 2011, p. 139). Plague is an exotic 
disease caused by an infection of the Old World bacterium Yersinia 
pestis foreign to the evolutionary history of North American species, 
including the Gunnison's prairie dog (Barnes 1982, p. 238; Barnes 1993, 
p. 29; Biggins and Kosoy 2001, p. 907). Bites from infected fleas, 
direct contact with infected animals, or inhalation of infected 
respiratory droplets transmit the bacterium Y. pestis to rodents (Gage 
et al. 1995, pp. 695-696). Once infected, the bacterium multiplies 
within the host's bloodstream, and when highly concentrated, the hosts 
may die of septic shock, systemic inflammation, multi-organ failure, or 
hemorrhaging (Eisen and Gage 2009, p. 2).
    Prairie dogs are highly susceptible to plague, likely because of 
their dense populations, social nature, abundant flea vectors, and 
uniformly low resistance to the bacterium (Biggins and Kosoy 2001, p. 
913). After arriving in North America in 1908, plague was first 
detected in Gunnison's prairie dogs in the 1930s (Eskey and Hass 1940, 
p. 6), and the bacterium is now firmly established in the western 
United States, including the entire range of the Gunnison's prairie dog 
(Cully 1989, p. 49; Centers for Disease Control 1998, p. 1; Antolin et 
al. 2002, pp. 105-106; Girard et al. 2004, p. 8408). Gunnison's prairie 
dogs are likely more susceptible to plague than some other prairie dog 
species due to their less territorial nature, more social behaviors, 
and denser populations (Torres 1973, p. 31; Ruffner 1980, p. 20; 
Hubbard and Schmitt 1983, p. 51; Cully 1989, p. 51; Hoogland 1999, p. 
8; Cully and Williams 2001, p. 899; Turner 2001, p. iii; Antolin et al. 
2002, p. 14; Knowles 2002, p. 13).
    Plague maintains itself at low levels throughout the range of the 
Gunnison's prairie dog. The disease cycles through Gunnison's prairie 
dog populations like a wildfire, with periods of low and high 
intensities. It smolders relatively quietly at low intensities within a 
population until conditions such as temperature,

[[Page 68675]]

moisture, or host susceptibility fuel a more severe outbreak. These 
outbreaks can dramatically reduce the abundance of Gunnison's prairie 
dogs within specific populations (Gage et al. 1995, p. 696; Gage and 
Kosoy 2005, p. 506; Hanson et al. 2007, p. 790). Although the outbreak 
may reduce or extirpate entire populations, the outbreak eventually 
falls back to less severe levels, returning to smolder in the 
background in a maintenance state (Gage et al. 1995, p. 696). During 
this smoldering maintenance period, the bacterium establishes a stable 
reservoir that may later erupt into an outbreak (Girard et al. 2004, p. 
8413; Gage and Kosoy 2005, pp. 506-509). The plague bacterium may 
maintain itself in the soil, within fleas, or by slowly transmitting 
itself within the prairie dog community (Biggins et al. 2010, p. 17).
    The factors that cause plague outbreaks are not well understood, 
but may involve the density of hosts (including other mammals), the 
density of fleas, and climatic conditions (Cully 1989, p. 49; 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; Eisen 2006, p. 15380; Stapp et al. 2009, p. 807; Salkeld et al. 
2010, p. 14247). The number of fleas may increase during outbreaks 
(Tripp et al. 2009, p. 313). Successive plague outbreaks may reduce 
populations so that the loss of colonies exceeds the rate of 
recolonization (Knowles 2002, p. 13). Repeated plague outbreaks, and 
the subsequent recovery of the local population, result in a cycle of 
contraction and expansion within Gunnison's prairie dog colonies 
(Wagner and Drickamer 2002, p. 16; Underwood 2007, p. 14). Consequences 
of repeated plague outbreaks could potentially include isolation, 
decreases in genetic diversity, and range contraction (Wagner and 
Drickamer 2002, p. 17).
    Plague outbreaks do not erupt within all populations throughout the 
range of the Gunnison's prairie dog at the same time. Instead, 
outbreaks are patchy, occurring discretely in space and time within 
individual, local populations (Antolin et al. 2002, p. 102). Plague 
outbreaks are not large pandemics sweeping across the landscape 
(Antolin et al. 2002, p. 102). This sporadic, patchy pattern of 
outbreak eruption is consistent with a model of resistant hosts 
occasionally transmitting plague to susceptible, less-resistant hosts 
(Antolin et al. 2002, p. 109). The patchy distribution of outbreaks 
offers a temporal and spatial break for survivors and colonizers to 
repopulate.
    Plague is responsible for major declines and fluctuations in 
Gunnison's prairie dog populations throughout the subspecies' ranges 
over the last 80 years (Seglund et al 2006, p. 42). The literature 
documents plague's periodic outbreaks and the subsequent reduction, 
extirpation, or recovery of local Gunnison's prairie dog populations in 
all four States and on Tribal lands (Lechleitner et al. 1968, p. 734; 
Rayor 1985, p. 194; Cully 1989, p. 49; CDOW 2007, p. 4; Wagner and 
Drickamer 2002, p. 15; Wagner and Drickamer 2004, p. 14; Seglund et al. 
2005, p. 52; Luce 2005, p. 4; Seglund et al. 2006, pp. 42-43; Lupis et 
al. 2007, p. 32; Underwood 2007, p. 18; Johnson et al. 2010, p. 3).
    However, the Gunnison's prairie dog currently occupies many of the 
same habitats where plague has reduced or eliminated populations in the 
past. Some populations declined and remain low after plague outbreaks, 
while other populations declined and either partially or fully 
recovered. In specific cases, populations tripled annually following 
outbreaks (Cully 1997, p. 146), while others remain low or absent 
(Fitzgerald et al. 1993, p. 52). The Gunnison's prairie dog's 80-year 
history with plague is characterized by often-drastic population 
declines punctuated by gradual repopulation, and complete losses of 
populations in some areas, but overall persistence across the 
subspecies' ranges. Persistence is evidenced by the long-term 
continuance of Gunnison's prairie dog populations at sufficient levels 
to survive with minimal management assistance in a variety of locations 
across the subspecies' ranges. Stable populations, as evidenced by the 
stable occupancy trends, indicate that repopulation rates for Cynomys 
gunnisoni gunnisoni or C. g. zuniensis equal or exceed the rates of 
decline, likely a factor of an intact metapopulation structure. 
Although plague causes wide fluctuations in population numbers, the 
Gunnison's prairie dog has demonstrated the resiliency and redundancy 
to return to pre-outbreak numbers and remain viable in the future.
    Life-history traits may contribute to the subspecies' resiliency 
and continued viability in light of plague. The Gunnison's prairie dog 
reproduces more rapidly following intense population declines (Hoogland 
2001, p. 923), a strategy that allows populations to survive and expand 
rapidly, even when numbers are very small (Wagner and Drickamer 2002, 
p. 16; Seglund et al. 2006, pp. 8, 16). A population viability analysis 
confirmed this life-history trait: Under modeled demographic scenarios, 
even small Gunnison's prairie dog populations can have robust 
population growth rates (CDOW 2007, p. 128). The population viability 
analysis also identified that more frequent outbreaks increased the 
risk of extinction (CDOW 2007, p. 129). Hibernation slows transmission 
of plague, but may merely delay the onset of symptoms (Barnes 1993, p. 
35).
    Climate change may affect the frequency of plague. As discussed 
under Factor E, yearly precipitation will vary, but temperature will 
increase over the next 40 years. Increased rainfall, particularly in 
the spring, significantly increases plague outbreaks (Stapp et al. 
2004, p. 237; Sn[auml]ll et al. 2008, pp. 245; 2008, pp. 245-246). 
However, outbreaks are less frequent when temperatures are hotter and 
there are more hot days per year (Snapp et al. 2004, p. 238; Sn[auml]ll 
et al. 2008, p. 245).
    Annual rainfall totals will vary due to climate change (Stapp et 
al. 2004, pp. 504-505). As a result, plague outbreaks will vary with 
the precipitation. Warmer winters can increase the transmission of 
plague (Stapp et al. 2004, p. 236; Salkeld and Stapp 2008, p. 620), 
likely because hibernation is shorter (Rayor 1985, p. 195), more fleas 
survive the winter, and habitats are more productive (Stapp et al. 
2004, pp. 237-238). However, winters will also vary due to climate 
change, with both wet and dry years (Karl et al. 2009, p. 505). 
Seasonal variation may result in pulses of winter or early spring 
plague outbreaks during wetter years that decrease in intensity over 
time as hotter summer temperatures reduce plague in the environment. 
Plague occurrences are likely to decrease in black-tailed prairie dogs 
due to the effects of climate change (Sn[auml]ll et al. 2009, p. 505). 
As temperatures rise throughout the ranges of both Gunnison's prairie 
dog subspecies due to climate change, the frequency of plague outbreaks 
and the prevalence of the Yersinia pestis bacterium within Gunnison's 
prairie dog habitats will likely decrease. Climate change may have less 
of a moderating effect on plague if the Gunnison's prairie dog shifts 
its range in response to increasing temperatures.
    Plague occurs throughout the ranges of Cynomys gunnisoni gunnisoni 
and C. g. zuniensis. However, we found no evidence that plague impacts 
one subspecies more than the other or is more frequent or more intense 
within any portion of either subspecies' range. Plague historically 
reduced or eliminated large populations of both subspecies, but 
occupancy trends for both subspecies indicate that populations are 
stable and not declining. Therefore, both subspecies

[[Page 68676]]

have demonstrated resiliency to the disease.
    In our previous 2008 finding, we determined that plague affected 
Gunnison's prairie dogs living in wetter, higher elevation, ``montane'' 
habitats more than those in drier, lower elevation, ``prairie'' 
habitats. We reached this conclusion largely because we reasoned that 
the abundance of fleas within a colony was the primary factor 
influencing plague in the Gunnison's prairie dog (February 5, 2008; 73 
FR 6668) and that environments that are more humid generally support 
more fleas, which favors the transmission of plague (Stenseth et al. 
2006, p. 13111). As a result, we reasoned that plague affected Cynomys 
gunnisoni gunnisoni more than C. g. zuniensis due to its moister, 
higher elevation habitats that supported more plague-transmitting 
fleas. Because we implicated plague as the only threat responsible for 
whole population declines and extirpations, we deduced that the disease 
affected C. g. gunnisoni more than C. g. zuniensis, resulting in its 
lower percent occupancy (February 5, 2008; 73 FR 6670, 6677). More 
frequent plague outbreaks, coupled with smaller, more isolated 
populations that we reasoned were unable to recolonize due to 
mountainous topography, led to our conclusion that plague was a greater 
risk to C. g. gunnisoni than to C. g. zuniensis.
    New research has improved our understanding of how plague is 
transmitted and reveals that fleas are not the sole instigators behind 
plague outbreaks. Fleas obviously play an important role in the 
transmission and maintenance of plague, as evidenced by the success of 
insecticide dusting to prevent and reduce outbreaks (Webb et al. 2006, 
p. 6238; Tripp et al. 2009, pp. 314, 319). Although infected fleas may 
be important plague vectors at the start of an outbreak, a short-term, 
plague reservoir that persists longer than the short lifecycles of 
infected fleas or prairie dogs is required to produce and sustain an 
outbreak (Webb et al. 2006, p. 6236; Eisen and Gage 2009, p. 6). This 
short-term infectious reservoir may include: Prairie dogs or other 
rodents that are resistant to the disease; recently dead or decaying 
carcasses; cannibalism of infected animals; plague bacteria in the 
soil; or longer living, infected fleas that continue to bite prairie 
dogs (Webb et al. 2006, pp. 6236, 6239; Eisen and Gage 2009, p. 6; 
Stapp et al. 2009, p. 807; Salkeld et al. 2010, pp. 14247, 14249). In 
other words, a combination of vectors, not just the abundance of fleas, 
helps drive plague outbreaks, so the presence of more fleas in C. g. 
gunnisoni's ``montane'' habitats does not necessarily make plague worse 
or more frequent. In the future, continued colony dusting with 
insecticide and drying by climate change may limit the role that fleas 
play during plague outbreaks in C. g. gunnisoni colonies.
    The mountainous topography of Cynomys gunnisoni gunnisoni's higher 
elevation habitats may isolate colonies more than the flat, lower 
elevation habitats of C. g. zuniensis. Mountainous terrain may minimize 
the zone of contact between populations (Knowles 2002, p. 3) and make 
recolonization more difficult. After a plague outbreak, smaller prairie 
dog colonies and greater inter-colony distances may further isolate 
colonies and reduce the probability of recolonization (Wagner and 
Drickamer 2002, p. 17; Cully et al. 2010, p. 13). However, C. g. 
gunnisoni colonies may also benefit from greater inter-colony 
distances, because isolation also isolates the colony from plague. 
Isolated prairie dog colonies have lower transmission rates of plague, 
which lessens the impact of an outbreak and ultimately enhances the 
persistence of the population (Cully et al. 2010, p. 7). Therefore, 
mountainous habitats and isolation do not necessarily render C. g. 
gunnisoni more susceptible to plague-related population declines than 
C. g. zuniensis. Furthermore, the new occupancy surveys indicate that 
C. g. gunnisoni populations are not declining, which suggests that 
mountainous terrain and isolation have not impeded recolonization.
    To summarize, the best available information currently indicates 
that Cynomys gunnisoni gunnisoni is not more susceptible or less able 
to resist the effects of plague than C. g. zuniensis. Although moister 
habitats may support more fleas, plague outbreaks are driven by more 
than flea abundance. Isolated colonies experience reduced transmission 
rates, so isolation may protect C. g. gunnisoni populations from 
plague. Despite historic losses to plague, population monitoring shows 
evidence of recovery of C. g. gunnisoni and indicates that mountainous 
terrain has not impeded movements or recolonization. Therefore, we find 
that plague is not significantly impacting one subspecies of Gunnison's 
prairie dog more than the other. Plague is not a threat to either 
subspecies, or the species as a whole now, nor is it likely to become 
so in the future.
Tularemia, Monkeypox, and Other Diseases
    Captive black-tailed prairie dogs kept as pets have infected humans 
with tularemia (Francisella tularensis) and monkeypox (Orthopoxvirus 
spp.) (Anderson et al. 2003, p. 1093; Avashia et al. 2004, p. 483; 
Seglund and Schnurr 2010, p. 116), rare diseases that could potentially 
infect the Gunnison's prairie dog. West Nile Virus has infected wild 
black-tailed prairie dogs in Colorado (Seglund et al. 2006b, p. 58). 
However, we have no information to indicate that these or other 
diseases currently infect or impact the Gunnison's prairie dog. 
Therefore, these diseases are not a threat to either subspecies of 
Gunnison's prairie dog now, nor are they likely to become so in the 
future.
Conservation Efforts To Reduce Disease or Predation
    Dusting (applying) insecticide on Gunnison's prairie dog burrows 
effectively reduces fleas and increases prairie dog survival rates from 
plague (Biggins et al. 2010; Abbott et al. 2012, p. 244). Dusting 
reduces fleas on prairie dogs from 45 to 86 percent for 10 months after 
application (Biggins et al. 2010, p. 17; Abbott et al. 2012, p. 246). 
Rangewide, State wildlife agencies and private landowners dusted 
approximately 5,209 ac (2,108 ha) of occupied Gunnison's prairie dog 
colonies in 2011 (Van Pelt 2012, p. 8), and dusted 1,010 ac (409 ha) in 
2012 (Van Pelt 2013, p. 10). In 2011, private landowners, CPW, and the 
BLM preemptively dusted 651 acres within 19 different Cynomys gunnisoni 
gunnisoni colonies in Colorado to prevent plague outbreaks; the dusting 
appeared to stabilize colony occupancy (Van Pelt 2012, p. 9). Dusting 
colonies with insecticide has effectively reduced population declines 
from plague and has likely contributed to the population stability. 
Pursuant to its Statewide conservation plan, CPW will continue to 
proactively manage plague by dusting colonies in Colorado on private, 
State, and Federal lands (Seglund and Schnurr 2010, p. 115; Seglund 
2012, p. 1).
    A new vaccine that effectively inoculates black-footed ferrets from 
plague may also benefit Gunnison's prairie dogs in the future. This 
vaccine increased the survival of released black-footed ferrets as 
effectively as dusting (Matchett et al. 2010, p. 27; Abbott et al. 
2012, 246). In the laboratory, 94 percent of the vaccinated prairie 
dogs survived plague (Rocke et al. 2010, p. 53; Abbott et al. 2012, p. 
247). State agencies completed safety trials of the vaccine in 2012, 
and distributed vaccine-laden bait to eight Gunnison's prairie dog 
sites in 2012 (Van Pelt 2013, p. 11) and to four sites in 2013 (Rocke 
2013, p. 1). Success of the prairie dog vaccine would reduce mortality 
from plague and prevent a population decline (Abbott et al. 2012, p. 
248). Although researchers are still

[[Page 68677]]

developing and testing the plague vaccine for use in prairie dogs, 
promising early results suggest that this tool will be available in the 
future to address the threat of plague. Because of the uncertainty 
surrounding the efficacy and feasibility of delivering the vaccine at a 
large enough scale, we do not rely on the vaccine in making this 
finding.
Summary of Factor C
    Plague occurs throughout the ranges of Cynomys gunnisoni gunnisoni 
and C. g. zuniensis and maintains itself in local populations. Plague 
reduced populations from historical levels, extirpated some local 
populations, and may have isolated or fragmented colonies. However, the 
Gunnison's prairie dog continues to occupy approximately 20 percent of 
its potential habitats rangewide, and occupancy trends are stable 
rangewide and within individual population areas (Seglund 2012, p. 11). 
This percentage of occupied habitats provides the Gunnison's prairie 
dog with sufficient population redundancy to rebound and repopulate 
following declines, as evidenced by stable trends. Therefore, plague 
has not eliminated Gunnison's prairie dogs from large portions of its 
range even after at least 80 years of exposure to the disease. Affected 
colonies have demonstrated partial or complete recovery after plague 
outbreaks and populations of both subspecies continue to persist at the 
landscape level and within individual population areas. Plague 
outbreaks are temporally and spatially localized, which may mediate 
effects to the subspecies. Climate change may reduce the frequency of 
plague outbreaks in the future. Plague does not impact one subspecies 
more than the other. Therefore, while plague is affecting Cynomys 
gunnisoni gunnisoni and C. g. zuniensis, it is not a threat that is 
causing or projected to cause the species to be at risk of extinction. 
Furthermore, managers and researchers have successfully implemented 
plague control mechanisms, such as insecticide dusting. Vaccines were 
successful in the laboratory, and if successful in the wild, should 
alleviate population fluctuations and declines due to plague in the 
future.
    Therefore, the best scientific and commercial information available 
indicates that neither disease nor predation is currently a threat to 
Cynomys gunnisoni gunnisoni or C. g. zuniensis, nor is either likely to 
become so in the future. Continued plague monitoring and research will 
allow us to assess the level of impact this disease plays in the long-
term conservation of the Gunnison's prairie dog.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

State Regulations and Private Land Management
    Approximately 50 percent and 5 percent of Cynomys gunnisoni 
gunnisoni's potential range occurs on private and State lands 
respectively (Table 1). Approximately 25 percent of C. g. zuniensis' 
potential range occurs on private lands and 10 percent on State lands 
(Table 1).
    State laws and regulations may provide specific authority for the 
conservation of the Gunnison's prairie dog on State-owned lands. State 
laws and regulations may also provide broad authority to regulate and 
protect wildlife on all lands within the State. These regulations may 
provide the States with a mechanism for indirect conservation through 
the regulation of threats to the species (e.g., noxious weeds). In 
general, States have broad authority to regulate and protect wildlife 
within their borders.
    Potential impacts to the species that State agencies or private 
entities can manage include recreational shooting, shooting to protect 
agricultural interests, and oil and gas development on non-Federal 
mineral estates. In addition, State wildlife agencies can contribute to 
species conservation by supporting research and monitoring efforts, 
including plague management.
    The Western Association of Fish and Wildlife Agencies (WAFWA) 
coordinates management efforts of the Gunnison's prairie dog and other 
species among the western States. The WAFWA prepared a rangewide 
conservation assessment and conservation plan for the Gunnison's 
prairie dog (Seglund et al. 2006; Seglund et al. 2007). The 
conservation plan required that each State develop and implement an 
objective, repeatable estimation technique to monitor long-term 
Gunnison's prairie dog population trends. Under the plan, all four 
States agreed to conduct occupancy surveys modeling (Seglund 2012, p. 
1). Although WAFWA's conservation documents provide expertise, 
recommendations, and coordination for the conservation of the 
Gunnison's prairie dog, they do not provide regulatory protection.
    Private lands comprise a large portion, approximately 27 percent, 
of the predicted range of the species (Cynomys gunnisoni) and 
approximately 50 percent of the predicted range for C. g. gunnisoni and 
25 percent for C. g. zuniensis (Seglund et al. 2006, p. 71; Table 1). 
Private landowners can control prairie dogs on their land as necessary 
in Colorado, New Mexico, Arizona, and Utah. However, trespass laws 
generally limit public access and hunting on private lands throughout 
the subspecies' ranges. We have no evidence that the control activities 
or the policies of individual private landowners are impacting the 
species.
    Oil and gas development occurs across the gross range of the 
species, including on lands managed by the four States. We are not 
aware of any regulations or land use plans that address Gunnison's 
prairie dogs on State and private lands. However, based on available 
information, we do not consider oil and gas development a factor that 
significantly affects the subspecies (see Factor A discussion, above).
Arizona
    Arizona considers the Gunnison's prairie dog a Species of Greatest 
Conservation Need in its Comprehensive Wildlife Conservation Strategy 
(AGF 2006, p. 136). Species of Greatest Conservation Need are a 
conservation priority in Arizona (AGF 2006, p. 13), but this 
designation provides no regulatory protection. Private lands in Arizona 
support approximately 22 percent of Cynomys gunnisoni zuniensis' 
potential range within the State (Table 1).
    Regulations in Arizona address recreational shooting of Gunnison's 
prairie dogs. Arizona classifies all prairie dogs as nongame mammals 
and requires a hunting license to shoot them (Underwood 2007, p. 27). 
However, Arizona prohibits shooting Gunnison's prairie dogs on all 
Federal, State, and private lands between April 1 and June 15 to 
protect populations during the breeding season (Seglund et al. 2006, p. 
28; Underwood 2007, p. 28).
Colorado
    Colorado's Comprehensive Wildlife Conservation Strategy considers 
the Gunnison's prairie dog a Species of Greatest Conservation Need 
(CDOW 2006, p. 17); however this designation provides no regulatory 
protection. Colorado also completed a Conservation Strategy for the 
Gunnison's prairie dog to guide conservation efforts for the species at 
the State and local levels (CDOW 2010, p. 1). This document guides 
conservation strategies, management priorities, and guidance, but it 
does not provide regulatory protection.
    Colorado classifies the Gunnison's prairie dog as a small game 
species, and hunters may take animals by rifle, handgun, shotgun, 
handheld bow, crossbow, pellet gun, slingshot,

[[Page 68678]]

falconry, and toxicants (CDOW 2007, pp. 41-42). Hunting Gunnison's 
prairie dogs requires a small game license, with the exception of 
private landowners who may take Gunnison's prairie dogs causing damage 
on their lands without a permit. Shooting Gunnison's prairie dogs on 
public lands is prohibited by regulation in Colorado between March 1 
and June 14 to protect breeding individuals and young (CDOW 2007, pp. 
41-42). During the open season, no bag or possession limits exist; 
however, contestants in shooting events may take no more than five 
prairie dogs per event (CDOW 2007, pp. 41-42). Colorado's seasonal 
shooting closure does not apply on private or Tribal lands.
    The Colorado Oil and Gas Commission requires that oil and gas 
companies consult with State wildlife officials from CPW regarding 
impacts of their proposed developments to wildlife (COGCC 2009, p. 
1200-1). The consultation process promotes best management practices 
and allows Colorado to set reasonable conservation conditions in 
sensitive wildlife areas (COGCC 2009, pp. 1200.1-1200.5). However, 
State wildlife officials voluntarily choose whether to consider prairie 
dogs during the consultation process, and it is unclear how frequently 
this occurs.
New Mexico
    New Mexico classifies the Gunnison's prairie dog as a Species of 
Greatest Conservation Need (NMDGF 2006, p. 55) and drafted a Gunnison's 
prairie dog Conservation Plan (NMDGF 2008). This plan provides 
guidance, but does not confer regulatory protections.
    Gunnison's prairie dogs are not a game animal in New Mexico and may 
be taken year-round without a permit by residents. However, non-
residents must obtain a New Mexico hunting license to shoot prairie 
dogs within the State (Seglund et al. 2005, pp. 31, 32). New Mexico 
prohibits recreational shooting of the Gunnison's prairie dog on State 
lands (Seglund et al. 2006, p. 30).
    We are aware of one city regulation that addresses potential 
impacts to Cynomys gunnisoni gunnisoni from urbanization. The City of 
Santa Fe, New Mexico, prohibits intentional destruction or other harm 
to the Gunnison's prairie dog on any lands within Santa Fe at any time 
in relation to development (Santa Fe 2013). Without an exemption, 
Gunnison's prairie dogs must be relocated to a city-approved relocation 
site (Santa Fe 2013). Although this regulation reduces direct mortality 
associated with development, it does not address the loss of habitat 
from urbanization. However, we have not found the loss of habitat from 
urbanization to be a threat to the subspecies.
Utah
    The Gunnison's prairie dog is a Species of Concern and a Sensitive 
Species in Utah (UDWR 2005, p. 5-4; Seglund et al. 2006, p. 31), but 
this designation does not confer any regulatory protections. Utah 
completed a conservation agreement and Conservation Strategy for the 
Gunnison's and white-tailed prairie dogs in 2007 (Lupis et al. 2007). 
The Conservation Strategy outlines conservation priorities, but does 
not provide regulatory protection.
    In Utah, shooting of Gunnison's prairie dogs is prohibited on 
public lands from April 1 to June 15, but they may be taken on private 
lands year-round. Utah does not require a license to shoot Gunnison's 
prairie dogs, and there is no bag limit (Lupis et al. 2007, pp. 18-19).
Tribal Laws and Regulations
    Tribes manage approximately 36 percent of the Gunnison's prairie 
dog's potential habitat (Table 1). Tribes manage the most (53 percent) 
of Cynomys gunnisoni zuniensis habitat in Arizona (Table 1). Tribes 
manage very little of C. g. gunnisoni's potential range in Colorado and 
New Mexico (Table 1). However, we are aware of only a few Tribal laws 
and regulations that specifically address potential impacts to the 
Gunnison's prairie dog.
    For example, the Navajo Nation (overlapped by Arizona, New Mexico, 
and Utah) and Reservation of the Hopi Tribe in Arizona contain 
approximately 235,567 ac (102,615 ha) of active Cynomys gunnisoni 
zuniensis colonies, but these Tribes have limited regulatory mechanisms 
specific to the Gunnison's prairie dog, other than those that address 
hunting (Johnson et al. 2010, pp. 3, 21). The Navajo Nation classifies 
C. g. zuniensis as small game and requires a hunting license for 
shooting, but there is no seasonal shooting closure (Cole 2007, p. 4; 
Johnson et al. 2010, p. 3). The Navajo Nation also allows lethal and 
nonlethal removal of C. g. zuniensis for agricultural, human health, 
and safety purposes (Cole 2007, pp. 4, 5). The Hualapai Tribe in 
Arizona classifies C. g. zuniensis as small game, and requires a permit 
to hunt with a bag limit of 15, but has no seasonal closure (Hualapai 
2013, pp. 1, 4, 7).
    In general, Tribal members can hunt freely on Tribal lands, but 
trespass laws generally make it difficult for non-Tribal members to 
hunt on Tribal lands without a permit. Therefore, Tribal hunting 
regulations may provide some protection to the Gunnison's prairie dog 
from impacts related to shooting. However, we determined that 
recreational shooting is not a threat to either subspecies.
    Other than hunting regulations that may provide some protection 
from recreational shooting, we are not aware of any other Tribal laws 
or ordinances that specifically address the Gunnison's prairie dog, its 
habitat, or other potential impacts. Tribal ordinances that address 
issues such as agriculture, transportation, and zoning for various 
types of land uses could potentially influence the Gunnison's prairie 
dog or its habitat. For example, zoning that protects open space might 
retain suitable habitat, and zoning that allows a housing development 
might destroy or fragment habitat.
    Although Tribes manage a large percentage of potential Gunnison's 
prairie dog habitats, we have no evidence that Tribal management 
practices have a significant impact on either subspecies.
Federal Laws and Regulations
    Federal agencies are responsible for managing approximately 26 
percent of the Gunnison's prairie dog potential range, or about 25 
percent of Cynomys gunnisoni zuniensis's and 45 percent of C. g. 
gunnisoni's potential range (Table 1). The BLM is the primary Federal 
agency managing Gunnison's prairie dog's potential range (16 percent), 
followed by the USFS (9 percent), and the National Park Service (1 
percent) (Table 1). The Service and the Department of Defense each 
manage less than 1 percent of the species' potential range (Table 1). 
Potential impacts to the subspecies that could be managed by Federal 
land management agencies include oil and gas development, grazing, 
poisoning, and recreational shooting.
Bureau of Land Management
    The Federal Land Policy and Management Act of 1976 (FLPMA) (43 
U.S.C. 1701 et seq.) governs most land uses on BLM lands and 
specifically recognizes that BLM lands should be managed for the 
benefit of fish and wildlife resources (section 102(a)(8)). Under the 
FLMPA, the BLM must consider the needs of wildlife, including general 
considerations of Gunnison's prairie dogs, when conducting activities 
in their habitat. Typically, the BLM considers impacts to the 
Gunnison's prairie dog when planning projects and may adopt 
conservation measures intended to avoid or minimize impacts. The BLM 
must also adhere to

[[Page 68679]]

environmental planning requirements under the National Environmental 
Policy Act, or NEPA (73 FR 61292, October 15, 2008; 42 U.S.C. 4321 et 
seq.), a Federal law that requires Federal agencies to consider the 
effects of their actions on the environment, including wildlife, before 
implementing a project.
    The BLM's resource management plans (RMPs) are the basis for all of 
its actions and authorizations involving BLM-administered lands and 
resources. The RMPs establish allowable resource uses, general 
management practices, program constraints, and other parameters of 
project design (43 CFR 1601.0-5(n)). The RMPs provide programmatic 
guidance for site-specific activity plans and may include conservation 
measures to protect wildlife.
    Current approved or draft RMPs for BLM lands in Utah and New Mexico 
include specific conservation measures for Cynomys gunnisoni zuniensis 
in Arizona and C. g. zuniensis and C. g. gunnisoni in New Mexico. 
Conservation measures include precluding oil and gas development and 
other surface-disturbing activities within 600 feet (183 meters) of 
active colonies, limiting the construction of power lines within 
colonies, and restricting shooting during the breeding season (BLM 
2008a, pp. 138-139; BLM 2008b, pp. 122-123; BLM 2012, p. 2-125; BLM 
2013, pp. 19, 143). Draft RMPs do not confer any regulatory protection 
to either subspecies. Although RMPs in Colorado and Arizona do not 
include the Gunnison's prairie dog, they are outdated or currently 
under revision. However, the BLM in Colorado and Arizona recognize the 
Gunnison's prairie dog as a BLM sensitive species (BLM 2009, p. 1; BLM 
2010, p. 2; BLM 2011, p. 2). The BLM evaluates the effects of their 
actions on sensitive species and initiates proactive conservation 
measures to reduce or eliminate threats in order to minimize the 
likelihood and need for listing sensitive species under the Act (BLM 
2008c, p. 3). The BLM in Colorado has actively participated in plague 
vaccine trails and dusting (Van Pelt 2012, p. 9). The BLM in Utah and 
New Mexico does not recognize the Gunnison's prairie dog as a sensitive 
or special status species, but RMPs provide conservation guidance and 
restrictions on BLM lands in these States.
U.S. Forest Service
    The USFS recognizes the Gunnison's prairie dog as a Sensitive 
Species in New Mexico and Colorado (USFS 2007, line 135). As a 
Sensitive Species, the USFS evaluates potential impacts to the species 
and recommends mitigating potential effects. Policy directs the USFS to 
analyze and document the potential impacts to sensitive species from 
proposed management activities in a biological evaluation. However, the 
sensitive species designation does not confer regulatory protection to 
either subspecies.
    The National Forest Management Act (NFMA) (16 U.S.C. 1600 et seq.), 
as amended, guides the management of Federal activities on National 
Forest System lands. The NFMA specifies that all national forests and 
grasslands must have a land and resource management plan (LRMP) to 
guide and set standards for natural resource management activities. The 
NFMA requires the USFS to incorporate standards and guidelines into 
LRMPs. Provisions to manage plant and animal communities for diversity, 
based on the suitability and capability of a specific land area, are 
developed in order to meet overall multiple-use objectives. In 
Colorado, the San Juan National Forest's LRMP addresses the Gunnison's 
prairie dog, but provides only conservation recommendations (USFS 2013, 
p. T-15).
    The USFS manages approximately 9 percent of Cynomys gunnisoni 
gunnisoni's predicted range and 10 percent of C. g. zuniensis's 
predicted range (Table 1). While a USFS sensitive species designation 
and following the recommendations contained in the 2005 RCP (GSRSC 
2005, entire) can provide some conservation benefits, they are 
voluntary in nature. Therefore, the USFS has minimal regulatory 
authority to address either subspecies of Gunnison's prairie dog.
Other Federal Agencies
    The National Park Service, the Department of Defense, and the 
Service each manage 1 percent or less of the Gunnison's prairie dog's 
overall range (Table 1). Therefore, their management strategies are 
unlikely to significantly impact the subspecies throughout their 
respective ranges.
    The federally endangered black-footed ferret (Mustela nigripes) has 
been reintroduced into two Gunnison's prairie dog (Cynomys gunnisoni 
zuniensis) colonies in Arizona (Van Pelt 2013, p. 5). The Act's 
protections of the black-footed ferret may indirectly benefit C. g. 
zuniensis at these relocation sites. Black-footed ferrets have not been 
reintroduced into C. g. gunnisoni colonies.
    To summarize, Federal agencies have very few regulations that 
specifically address potential impacts to the Gunnison's prairie dog. 
Surface use restrictions on BLM lands in Utah likely minimize the 
impacts of oil and gas development to Cynomys gunnisoni zuniensis. The 
lack of protective measures for the subspecies in the other States that 
specifically address oil and gas development may impact the species in 
the future. However, the available information does not indicate that 
oil and gas development will significantly impact either subspecies in 
the future. Federal regulations also control poisoning. Therefore, the 
available evidence does not indicate that the Federal regulations are 
inadequate to protect either subspecies.
Summary of Factor D
    Regulatory mechanisms may reduce potential impacts associated with 
oil and gas development, urbanization, grazing, poisoning, and 
recreational shooting. However, none of these potential activities and 
their potential impacts rise to the level of a threat to either 
subspecies. Existing regulatory mechanisms adequately reduce impacts 
associated with shooting and poisoning. Seasonal shooting closures in 
Colorado, Utah, and Arizona reduced population declines due to 
shooting. Federal regulation and prohibition of pesticides on Federal 
lands reduced the historical threat of poisoning.
    Although the available information does not indicate that current 
levels of management are inadequate to address potential impacts, the 
Gunnison's prairie dog will benefit from continued coordination between 
State, Federal, Tribal, and private landowners, and other partners, 
particularly to address future plague outbreaks and habitat 
fragmentation.

Factor E. Other Natural or Manmade Factors Affecting Its Continued 
Existence

Poisoning
    Poisoning of Gunnison's prairie dogs historically occurred 
throughout the range of both subspecies (Seglund et al. 2005, pp. 56-
57). The U.S. Department of Agriculture's Bureau of Biological Survey 
and the Agricultural Appropriations Act of 1915 planned and authorized 
the elimination of prairie dogs across the western United States (Oakes 
2000). From 1914 to 1964, 2,310,203 ac (934,906 ha) of Gunnison's 
prairie dog habitat were poisoned in Arizona; 23,178,959 ac (9,380,192 
ha) of habitat were poisoned in Colorado; 20,501,301 ac (8,296,582 ha) 
of habitat were poisoned in New Mexico; and 2,715,930 ac (1,099,098 ha) 
of habitat were poisoned in Utah. Between 1921 and 1961, poisoning 
reduced the amount of occupied Gunnison's prairie

[[Page 68680]]

dog habitat in Arizona by 92 percent (Oakes 2000; Underwood 2007, pp. 
16, 22). Poisoning campaigns led to a reduction in occupied habitat, 
extirpation from local areas, fragmentation, and isolation of colonies. 
The poisoning campaigns targeted black-tailed prairie dogs due to their 
visibility on the landscape, but Gunnison's and white-tailed prairie 
dogs were also poisoned (Seglund and Schnurr 2010, p. 140). Poisoning 
in all States became less common after Federal regulations of 
pesticides were enacted in the 1970s (Seglund et al. 2006, p. 47).
    Today, State and Federal agencies are rarely involved in Gunnison's 
prairie dog control efforts unless human health and safety are at risk 
(Seglund et al. 2005, p. 57; Seglund et al. 2006 p. 47). The BLM 
restricts poisoning of prairie dogs on its lands unless required for 
human health and safety or if resource damage meets specific 
requirements (Hoogland 2005, p. 228). Individual landowners may still 
control prairie dogs on their private property. Poisoning occurs on the 
Navajo Nation within at least one large agricultural area (Johnson et 
al. 2010, p. 3).
    Poisons can effectively control prairie dog populations. Baited 
poisons can result in 75 to 85 percent mortality, and fumigants can 
reduce populations by 95 percent (Seglund and Schnurr 2010, p. 141). 
Although poisoning was historically widespread, there is no information 
to indicate that poisoning occurs at more than a localized scale today. 
The four States within the range of the Gunnison's prairie dog do not 
compile records of pesticide sales, so it is difficult to quantify the 
amounts of poisons sold to control prairie dogs. Rozol, a poison used 
to control rodents, is not authorized for use on Gunnison's prairie 
dogs (Andelt and Hopper 2012, p. 3), which restricts its use rangewide. 
There is no information to indicate that pesticide applicators violate 
this regulation or that Rozol's use on other species impacts either 
Cynomys gunnisoni gunnisoni or C. g. zuniensis.
    Black-trailed prairie dogs recover quickly from poisoning due to an 
increase of their population growth rate (Seglund and Schnurr 2010, p. 
140). Poisoned black-tailed prairie dog colonies that declined by 45 
percent rebounded within 10 months, while eradicated colonies returned 
to pre-poisoning densities after 5 years (Apa et al. 1990, pp. 107, 
110; Seglund and Schnurr 2010, p. 140). Gunnison's prairie dogs likely 
rebound similarly from poisoning.
    Although poisoning historically impacted Gunnison's prairie dog 
populations and may continue to impact local populations, there is no 
evidence that it is a threat to either subspecies of the Gunnison's 
prairie dog now nor is it likely to become so in the future.
Road Mortality
    Vehicles may crush prairie dogs as the animals attempt to cross 
roads. Road-related Gunnison's prairie dog mortality is likely 
concentrated near specific human population areas, such as cities and 
towns. Oil and gas development and urbanization require new roads, so 
road-related mortality may increase near these areas.
    However, there is no information that specifically quantifies road 
mortality of Gunnison's prairie dogs. Most road mortality likely occurs 
locally, near urbanized areas; however, urbanization currently impacts 
less than 2 percent of the Gunnison's prairie dog's range (Seglund et 
al. 2005, p. 41). Stable population trends suggest that Gunnison's 
prairie dog populations are able to recover from losses due to road 
mortality. Therefore, road mortality is not a threat to either 
subspecies of the Gunnison's prairie dog now nor is it likely to become 
so in the future.
Drought and Climate Change
    Our analyses under the Act include consideration of ongoing and 
projected changes in climate. The terms ``climate'' and ``climate 
change'' are defined by the Intergovernmental Panel on Climate Change 
(IPCC). The term ``climate'' refers to the mean and variability of 
different types of weather conditions over time, with 30 years being a 
typical period for such measurements, although shorter or longer 
periods also may be used (IPCC 2007a, p. 78). The term ``climate 
change'' thus refers to a change in the mean or variability of one or 
more measures of climate (e.g., temperature or precipitation) that 
persists for an extended period, typically decades or longer, whether 
the change is due to natural variability, human activity, or both (IPCC 
2007a, p. 78).
    Scientific measurements spanning several decades demonstrate that 
changes in climate are occurring, and that the rate of change has been 
faster since the 1950s. Examples include warming of the global climate 
system, and substantial increases in precipitation in some regions of 
the world and decreases in other regions. (For these and other 
examples, see IPCC 2007a, p. 30; and Solomon et al. 2007, pp. 35-54, 
82-85). Results of scientific analyses presented by the IPCC show that 
most of the observed increase in global average temperature since the 
mid-20th century cannot be explained by natural variability in climate, 
and is ``very likely'' (defined by the IPCC as 90 percent or higher 
probability) due to the observed increase in greenhouse gas (GHG) 
concentrations in the atmosphere as a result of human activities, 
particularly carbon dioxide emissions from use of fossil fuels (IPCC 
2007a, pp. 5-6 and figures SPM.3 and SPM.4; Solomon et al. 2007, pp. 
21-35). Further confirmation of the role of GHGs comes from analyses by 
Huber and Knutti (2011, p. 4), who concluded it is extremely likely 
that approximately 75 percent of global warming since 1950 has been 
caused by human activities.
    Scientists use a variety of climate models, which include 
consideration of natural processes and variability, as well as various 
scenarios of potential levels and timing of GHG emissions, to evaluate 
the causes of changes already observed and to project future changes in 
temperature and other climate conditions (e.g., Meehl et al. 2007, 
entire; Ganguly et al. 2009, pp. 11555, 15558; Prinn et al. 2011, pp. 
527, 529). All combinations of models and emissions scenarios yield 
very similar projections of increases in the most common measure of 
climate change, average global surface temperature (commonly known as 
global warming), until about 2030. Although projections of the 
magnitude and rate of warming differ after about 2030, the overall 
trajectory of all the projections is one of increased global warming 
through the end of this century, even for the projections based on 
scenarios that assume that GHG emissions will stabilize or decline. 
Thus, there is strong scientific support for projections that warming 
will continue through the 21st century, and that the magnitude and rate 
of change will be influenced substantially by the extent of GHG 
emissions (IPCC 2007a, pp. 44-45; Meehl et al. 2007, pp. 760-764 and 
797-811; Ganguly et al. 2009, pp. 15555-15558; Prinn et al. 2011, pp. 
527, 529). (See IPCC 2007b, p. 8, for a summary of other global 
projections of climate-related changes, such as frequency of heat waves 
and changes in precipitation. Also see IPCC 2011 (entire) for a summary 
of observations and projections of extreme climate events.)
    Various changes in climate may have direct or indirect effects on 
species. These effects may be positive, neutral, or negative, and they 
may change over time, depending on the species and other relevant 
considerations, such as interactions of climate with other variables 
(e.g., habitat fragmentation) (IPCC 2007, pp. 8-14, 18-19). Identifying 
likely effects often involves

[[Page 68681]]

aspects of climate change vulnerability analysis. Vulnerability refers 
to the degree to which a species (or system) is susceptible to, and 
unable to cope with, adverse effects of climate change, including 
climate variability and extremes. Vulnerability is a function of the 
type, magnitude, and rate of climate change and variation to which a 
species is exposed, its sensitivity, and its adaptive capacity (IPCC 
2007a, p. 89; see also Glick et al. 2011, pp. 19-22). There is no 
single method for conducting such analyses that applies to all 
situations (Glick et al. 2011, p. 3). We use our expert judgment and 
appropriate analytical approaches to weigh relevant information, 
including uncertainty, in our consideration of various aspects of 
climate change.
    As is the case with all stressors that we assess, even if we 
conclude that a species is currently affected or is likely to be 
affected in a negative way by one or more climate-related impacts, it 
does not necessarily follow that the species meets the definition of an 
``endangered species'' or a ``threatened species'' under the Act. If a 
species is listed as endangered or threatened, knowledge regarding the 
vulnerability of the species to, and known or anticipated impacts from, 
climate-associated changes in environmental conditions can be used to 
help devise appropriate strategies for its recovery.
    Global climate projections are informative, and, in some cases, the 
only or the best scientific information available for us to use. 
However, projected changes in climate and related impacts can vary 
substantially across and within different regions of the world (e.g., 
IPCC 2007a, pp. 8-12). Therefore, we use ``downscaled'' projections 
when they are available and have been developed through appropriate 
scientific procedures, because such projections provide higher 
resolution information that is more relevant to spatial scales used for 
analyses of a given species (see Glick et al. 2011, pp. 58-61, for a 
discussion of downscaling).
    We reviewed climate records and projections for western North 
America, to evaluate potential impacts of climate change on both 
subspecies of Gunnison's prairie dog. Climate models predict a trend of 
continued warming, with hotter summers, warmer winters, decreased 
snowpack, earlier spring melts, increased evaporation, more droughts, 
and reduced summer flows throughout the subspecies' ranges.
    Increased magnitude and frequency of droughts may reduce the 
availability of grasses for both subspecies of Gunnison's prairie dogs. 
Extensive drought in New Mexico may be responsible for a slight 
contraction in the southern part of the range. However, we lack 
specific information to indicate that drought has a negative rangewide 
effect on either subspecies of Gunnison's prairie dog. Furthermore, the 
Gunnison's prairie dog is well adapted to its arid and unpredictable 
habitats. Both subspecies disperse, hibernate, or aestivate when food 
is scarce or temperatures are hot, adaptations that may allow the 
subspecies to cope under drought regimes.
    Specific impacts to the Gunnison's prairie dog under predicted 
future climate change scenarios are relatively unclear. As climates 
warm and native prairies become hotter and drier, prairie dogs will 
likely shift their ranges but occupy the same amount of habitat. Hotter 
and drier conditions may also reduce the frequency and intensity of 
plague outbreaks by reducing the abundance of fleas (see Factor C 
discussion). Hot, dry conditions may also make recreational shooting 
less appealing. Furthermore, the Gunnison's prairie dog disperses, 
hibernates, and aestivates to cope with environmental variability, such 
as reduced forage and extreme temperatures, adaptations which may help 
the species adapt to a changing climate.
    Although both subspecies of Gunnison's prairie dogs may shift their 
occupied ranges in response to the effects of global climate change, 
both subspecies are well adapted to environmental variability. 
Therefore, drought and climate change are not threats to either 
subspecies now nor are they likely to become so in the future.
Summary of Factor E
    Historically, poisoning contributed to large declines in areas 
occupied by Gunnison's prairie dogs. However, the available information 
does not indicate that poisoning currently occurs beyond a localized 
scale or that poisoning will increase in the future. Drought may reduce 
the availability of forage, but populations should be able to shift to 
more favorable habitats. Warming and drying associated with climate 
change may increase the frequency and intensity of droughts, but may 
also reduce the intensity and frequency of plague outbreaks.
    Therefore, the best scientific and commercial information available 
indicates that other natural or manmade factors affecting its continued 
existence are not a threat to Cynomys gunnisoni gunnisoni or C. g. 
zuniensis now or nor are they likely to become so in the future.

Cumulative Effects of Factors A Through E

    All four States within the Gunnison's prairie dog's range are 
actively involved in its management and prepared their own conservation 
assessments and plans for the two subspecies of Gunnison's prairie dog 
(Seglund and Schnurr 2010; Underwood 2007; Lupis et al. 2007; NMGFD 
2008). These plans provide comprehensive conservation strategies to 
guide conservation efforts at the State and local levels. Each plan 
intends to provide conservation and management strategies and 
recommendations to reduce impacts and maintain viable populations. 
Although the States' conservation agreements and strategies are not 
regulatory documents, they provide important direction to mitigate 
potential threats to the subspecies.
    Agriculture, grazing, the introduction of invasive plants, 
urbanization, oil and gas development, shooting, plague, and poisoning 
may impact Cynomys gunnisoni gunnisoni or C. g. zuniensis in at least 
localized areas. Historically, each of these factors impacted the 
subspecies and likely acted cumulatively to reduce the abundance of 
Gunnison's prairie dogs from historical levels. However, agriculture, 
grazing, and poisoning declined over time and are not currently 
impacting the subspecies with the same intensity. Today, many of these 
threats may act synergistically to impact populations, but colonies 
persist in many of these areas and populations are stable rangewide. 
Urbanization and shooting will likely continue into the future, but 
they currently impact local populations, with potential impacts most 
likely concentrated near urban areas. Plague, invasive plants, and 
climate change will also likely continue into the future, but plague 
outbreaks occur locally, while climate change and conservation efforts 
may mediate the effects of plague. The two subspecies are adapted to 
dry, arid habitats, but may shift their ranges in response to invasive 
plants and the effects of climate change. Therefore, we do not believe 
cumulative factors are a threat to the continued existence of C. g. 
gunnisoni or C. g. zuniensis now, nor are they likely to become so in 
the future.

Finding

    As required by the Act, we considered the five factors to assess 
whether Cynomys gunnisoni gunnisoni or C. g. zuniensis, the two 
subspecies of the Gunnison's prairie dog, or both meets the definition 
of an endangered or threatened species throughout all of its

[[Page 68682]]

range. We examined the best scientific and commercial information 
available regarding the past, present, and future threats faced by the 
two subspecies. We reviewed the petition, information available in our 
files, and other available published and unpublished information, and 
we consulted with recognized Gunnison's prairie dog experts and other 
Federal, State, Tribal, and local agencies.
    We identified and evaluated the risks of the present or threatened 
destruction, modification, or curtailment of the habitat or range of 
the two subspecies of Gunnison's prairie dog: (1) Agricultural land 
conversion; (2) grazing; (3) invasive plant species; (4) urbanization; 
and (5) oil and gas exploration and development. While these factors 
impact the subspecies, they impact only small portions of each 
subspecies' range or occur locally.
    We identified and evaluated the risks from overutilization for 
commercial, recreational, scientific, or education purposes. Although 
recreational shooting kills individuals and may reduce populations in 
easily accessible colonies, the available evidence indicates that the 
magnitude or intensity of shooting is not having rangewide impacts to 
either subspecies.
    Plague impacts populations throughout both of the subspecies' 
ranges. However, colonies persist and populations are stable in their 
post-plague environments, which demonstrates a rangewide resiliency to 
the disease. Life-history characteristics, such as increased 
reproductive rates within small populations and a metapopulation 
structure, allow Gunnison's prairie dog populations to rebound and 
persist following plague outbreaks. Additionally, plague affects only 
portions of the range at one time. Climate change and management 
actions, such as dusting and vaccines, may decrease the threat of 
plague. Other diseases, such as tularemia, monkey-pox, or West Nile 
virus, are not threats to either Cynomys gunnisoni gunnisoni or C. g. 
zuniensis. Additionally, although numerous species prey on Gunnison's 
prairie dogs, there is no evidence that predation adversely impacts 
either subspecies.
    Based on our analysis of the existing regulatory mechanisms, we 
determined that the States are actively involved in managing the 
subspecies through conservation agreements and strategies. Although 
these agreements are not regulatory, they provide an important 
mechanism for conservation, monitoring, and research. Existing 
regulatory mechanisms on State, Federal, and Tribal lands are limited. 
Seasonal shooting closures provide some protection for the Gunnison's 
prairie dog in Arizona and Colorado. Bag limits and permit requirements 
may provide protection from shooting on the Navajo Nation and the 
Hualapai Tribe.
    We also assessed the potential risks to Cynomys gunnisoni gunnisoni 
and C. g. zuniensis from poisoning, roads, and the effects of climate 
change. The available evidence indicates that poisoning or road 
mortality do not occur at more than a local scale. C. g. gunnisoni and 
C. g. zuniensis may shift their ranges in response to climate change, 
but climate change may reduce the frequency and intensity of plague 
outbreaks.
    In the past, many of these factors may have synergistically 
impacted both subspecies of the Gunnison's prairie dog. Today, many of 
these factors occur locally or are less intense or frequent than they 
were historically.
    Therefore, based on our review of the best available scientific and 
commercial information pertaining to the five factors, we find that the 
threats are not of sufficient imminence, intensity, or magnitude to 
indicate that Cynomys gunnisoni gunnisoni or C. g. zuniensis is in 
danger of extinction (endangered), or likely to become endangered 
within the foreseeable future (threatened), throughout all of their 
respective ranges. To summarize, although a variety of factors impact 
both subspecies of Gunnison's prairie dog, such as the loss or 
modification of habitats from urbanization, oil and gas development, 
grazing, agriculture, invasive plants, or other factors, such as 
recreational shooting, poisoning, and plague, most of these factors 
occur locally and do not impact rangewide populations of either 
subspecies. Plague is the primary impact to both subspecies and plague 
outbreaks can reduce individual populations by more than 99 percent. 
However, our review determined that colonies and populations of both C. 
g. gunnisoni and C. g. zuniensis recover and persist following plague 
outbreaks, due largely to the spatial and temporal separation of plague 
outbreaks and life history characteristics that allow populations to 
recover following dramatic declines. Additionally, ongoing conservation 
efforts, such as dusting burrows with insecticide, will likely continue 
to mediate the effects of plague outbreaks in the future and climate 
change may reduce the frequency and intensity of plague outbreaks. 
Therefore, we do not consider plague or any other impacts to be a 
threat such that either subspecies of Gunnison's prairie dog is 
warranted for listing as an endangered or threatened species under the 
Act.
    Under the Act, a ``species'' is defined as including any subspecies 
of fish or wildlife or plants, and any distinct population segment 
(DPS) of any species of vertebrate fish or wildlife which interbreeds 
when mature (16 U.S.C. 1532(16)). For this finding, we evaluated 
potential threats to the two recognized subspecies of Gunnison's 
prairie dog, whose combined ranges comprise the entire species' range. 
By evaluating both subspecies (Cynomys gunnisoni gunnisoni and C. g. 
zuniensis), which comprise the entire species, we effectively assessed 
the status of the entire species (C. gunnisoni). Because we found that 
neither subspecies is threatened or endangered throughout all of its 
respective range, the Gunnison's prairie dog at the species level is 
similarly not in danger of extinction or likely to become endangered 
within the foreseeable future throughout the range of the species.

Distinct Population Segment Analysis

    After assessing whether Cynomys gunnisoni gunnisoni or C. g. 
zuniensis is endangered or threatened throughout its range, we 
evaluated whether any distinct vertebrate population segment (DPS) of 
either subspecies exists and is threatened or endangered. We consider 
three elements when evaluating a potential distinct vertebrate 
population segment under our Policy Regarding the Recognition of 
Distinct Vertebrate Population Segments Under the Endangered Species 
Act, or DPS Policy (February 7, 1996; 61 FR 4722). The three elements 
include:
    (1) The discreetness of a population in relation to the remainder 
of the taxon to which it belongs;
    (2) The significance of the population segment to the taxon to 
which it belongs; and
    (3) The population segment's conservation status in relation to the 
Act's standards for listing, delisting, or reclassification.
    Under our DPS policy, we consider a population segment of a 
vertebrate taxon discrete if it satisfies either of the following 
conditions:
    (1) The segment 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; or
    (2) The segment is delimited by international governmental 
boundaries within which differences in control of exploitation, 
management of habitat, conservation status, or regulatory

[[Page 68683]]

mechanisms exist that are significant in light of section 4(a)(1)(D) of 
the Act.
    We did not identify any population segment of Cynomys gunnisoni 
gunnisoni or C. g. zuniensis so markedly separated from other 
Gunnison's prairie dog populations by physical, physiological, 
ecological, or behavioral factors such that it may be considered 
discrete. The Gunnison's prairie dog is a colonial species that 
inhabits large landscapes, potentially occupying 23,459,500 ac 
(9,493,733 ha) across four States (Seglund et al. 2006, p. 79). 
Available colony mapping indicates that populations across these 
landscapes are discontinuous, or patchy, and occupied habitats 
dynamically shift as individuals disperse, recolonize, or establish new 
colonies. However, this discontinuous distribution is natural for the 
Gunnison's prairie dog, as dispersers move and interact between 
populations within the larger ecological framework of the 
metapopulation. The metapopulation links the individual populations and 
promotes genetic exchange. The best available population monitoring 
information indicates that the metapopulation structure is intact and 
that any discontinuity between occupied habitats is not impeding 
dispersers or markedly separating any population segment. Additionally, 
Gunnison's prairie dogs are very social and live in complex family 
groups, so populations are not markedly separated by behavioral factors 
and the available information does not indicate that physiological 
differences occur between populations. Therefore, ecological, 
behavioral, or physiological factors are not markedly separating a 
population segment of either C. g. gunnisoni or C. g. zuniensis from 
other populations.
    Mountainous topography may isolate Gunnison's prairie dog 
populations, particularly in the higher elevation habitats of Cynomys 
gunnisoni gunnisoni. However, the available information does not 
indicate that terrain markedly separates one population segment from 
any other population. The best available population monitoring data 
indicate that the metapopulation structure operates despite physical 
boundaries. For instance, mountainous terrain delineates the 
approximate boundary between C. g. gunnisoni and C. g. zuniensis in 
northern New Mexico and southcentral Colorado, but the two subspecies 
have shared genetic material across the boundary. Quantitative measures 
indicate that there is no genetic discontinuity between the two 
subspecies. Although steeper mountainous terrain separates C. g. 
gunnisoni populations in central Colorado from those in New Mexico, the 
available information does not indicate that populations in Colorado, 
or any segment of a population, are genetically or morphologically 
different from any other population. Dispersal of prairie dogs along 
valley bottoms between the steep terrain likely maintains the 
metapopulation link between C. g. gunnisoni populations. Therefore, the 
available information does not indicate that any physical factors have 
resulted in genetically or morphologically discreet population segments 
of C. g. gunnisoni or C. g. zuniensis that are markedly separated from 
any other populations.
    To summarize, based on the best available information, we determine 
that no population segment within the range of the Gunnison's prairie 
dog or either of the two subspecies of Gunnison's prairie dog meets our 
DPS Policy's discreteness criteria. Because we did not identify any 
population segment as discrete, we do not evaluate significance under 
our DPS policy. Therefore, no population segment of Gunnison's prairie 
dog, C. gunnisoni gunnisoni, or C. g. zuniensis qualifies as a DPS and 
is therefore not a listable entity under the Act.

Significant Portion of the Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is endangered or threatened throughout all or a 
significant portion of its range. The Act defines ``endangered 
species'' as any species which is ``in danger of extinction throughout 
all or a significant portion of its range,'' and ``threatened species'' 
as any species which is ``likely to become an endangered species within 
the foreseeable future throughout all or a significant portion of its 
range.'' The definition of ``species'' is also relevant to this 
discussion. The Act defines the term ``species'' to include ``any 
subspecies of fish or wildlife or plants, and any distinct population 
segment [DPS] of any species of vertebrate fish or wildlife which 
interbreeds when mature.'' The phrase ``significant portion of its 
range'' (SPR) is not defined by the statute, and we have never 
addressed in our regulations: (1) The consequences of a determination 
that a species is either endangered or likely to become so throughout a 
significant portion of its range, but not throughout all of its range; 
or (2) what qualifies a portion of a range as ``significant.''
    Two recent district court decisions have addressed whether the SPR 
language allows the Service to list or protect less than all members of 
a defined ``species'': Defenders of Wildlife v. Salazar, 729 F. Supp. 
2d 1207 (D. Mont. 2010), vacated as moot, 2012 U.S. App. Lexis 26769 
(9th Circ. Nov. 7, 2012), concerning the Service's delisting of the 
Northern Rocky Mountain gray wolf (74 FR 15123, April 2, 2009); and 
WildEarth Guardians v. Salazar, 2010 U.S. Dist. LEXIS 105253 (D. Ariz. 
September 30, 2010), concerning the Service's 2008 finding on a 
petition to list the Gunnison's prairie dog (73 FR 6660, February 5, 
2008) (see Previous Federal Actions). The Service had asserted in both 
of these determinations that it had authority, in effect, to protect 
only some members of a ``species,'' as defined by the Act (i.e., 
species, subspecies, or DPS), under the Act. Both courts ruled that the 
determinations were arbitrary and capricious on the grounds that this 
approach violated the plain and unambiguous language of the Act. The 
courts concluded that reading the SPR language to allow protecting only 
a portion of a species' range is inconsistent with the Act's definition 
of ``species.'' The courts concluded that once a determination is made 
that a species (i.e., species, subspecies, or DPS) meets the definition 
of ``endangered species'' or ``threatened species,'' it must be placed 
on the list in its entirety and the Act's protections applied 
consistently to all members of that species (subject to modification of 
protections through special rules under sections 4(d) and 10(j) of the 
Act).
    Consistent with the district court decisions discussed above, and 
for the purposes of this finding, we now interpret the phrase 
``significant portion of its range'' in the Act's definitions of 
``endangered species'' and ``threatened species'' to provide an 
independent basis for listing; thus there are two situations (or 
factual bases) under which a species would qualify for listing: A 
species may be endangered or threatened throughout all of its range; or 
a species may be endangered or threatened in only a significant portion 
of its range. If a species is in danger of extinction throughout a 
significant portion of its range, the species is an ``endangered 
species.'' The same analysis applies to ``threatened species.'' Based 
on this interpretation and supported by existing case law, the 
consequence of finding that a species is endangered or threatened in 
only a significant portion of its range is that the entire species 
shall be listed as endangered or threatened, respectively, and the 
Act's protections shall be applied across the species' entire range.
    We conclude, for the purpose of this finding, that interpreting the 
significant portion of its range phrase as providing

[[Page 68684]]

an independent basis for listing is the best interpretation of the Act 
because it is consistent with the purposes and the plain meaning of the 
key definitions of the Act; it does not conflict with established past 
agency practice, as no consistent, long-term agency practice has been 
established; and it is consistent with the judicial opinions that have 
most closely examined this issue. Having concluded that the phrase 
``significant portion of its range'' provides an independent basis for 
listing and protecting the entire species, we next turn to the meaning 
of ``significant'' to determine the threshold for when such an 
independent basis for listing exists.
    Although there are potentially many ways to determine whether a 
portion of a species' range is ``significant,'' we conclude for the 
purposes of this finding that the significance of the portion of the 
range should be determined based on its biological contribution to the 
conservation of the species. For this reason, we describe the threshold 
for ``significant'' in terms of an increase in the risk of extinction 
for the species. We conclude that a biologically based definition of 
``significant'' best conforms to the purposes of the Act, is consistent 
with judicial interpretations, and best ensures species' conservation. 
Thus, for the purposes of this finding, and as explained further below, 
a portion of the range of a species is ``significant'' if its 
contribution to the viability of the species is so important that 
without that portion, the species would be in danger of extinction.
    We evaluate biological significance based on the principles of 
conservation biology using the concepts of redundancy, resiliency, and 
representation. Resiliency describes the characteristics of a species 
and its habitat that allow it to recover from periodic disturbance. 
Redundancy (having multiple populations distributed across the 
landscape) may be needed to provide a margin of safety for the species 
to withstand catastrophic events. Representation (the range of 
variation found in a species) ensures that the species' adaptive 
capabilities are conserved. Redundancy, resiliency, and representation 
are not independent of each other, and some characteristic of a species 
or area may contribute to all three. For example, distribution across a 
wide variety of habitat types is an indicator of representation, but it 
may also indicate a broad geographic distribution contributing to 
redundancy (decreasing the chance that any one event affects the entire 
species), and the likelihood that some habitat types are less 
susceptible to certain threats, contributing to resiliency (the ability 
of the species to recover from disturbance). None of these concepts is 
intended to be mutually exclusive, and a portion of a species' range 
may be determined to be ``significant'' due to its contributions under 
any one or more of these concepts.
    For the purposes of this finding, we determine if a portion's 
biological contribution is so important that the portion qualifies as 
``significant'' by asking whether without that portion, the 
representation, redundancy, or resiliency of the species would be so 
impaired that the species would have an increased vulnerability to 
threats to the point that the overall species would be in danger of 
extinction (i.e., would be ``endangered''). Conversely, we would not 
consider the portion of the range at issue to be ``significant'' if 
there is sufficient resiliency, redundancy, and representation 
elsewhere in the species' range that the species would not be in danger 
of extinction throughout its range if the population in that portion of 
the range in question became extirpated.
    We recognize that this definition of ``significant'' (a portion of 
the range of a species is ``significant'' if its contribution to the 
viability of the species is so important that without that portion, the 
species would be in danger of extinction) establishes a threshold that 
is relatively high. On the one hand, given that the consequences of 
finding a species to be endangered or threatened in a significant 
portion of its range would be listing the species throughout its entire 
range, it is important to use a threshold for ``significant'' that is 
robust. It would not be meaningful or appropriate to establish a very 
low threshold whereby a portion of the range can be considered 
``significant'' even if only a negligible increase in extinction risk 
would result from its loss. Because nearly any portion of a species' 
range can be said to contribute some increment to a species' viability, 
use of such a low threshold would require us to impose restrictions and 
expend conservation resources disproportionately to conservation 
benefit: Listing would be rangewide, even if only a portion of the 
range of minor conservation importance to the species is imperiled. On 
the other hand, it would be inappropriate to establish a threshold for 
``significant'' that is too high. This would be the case if the 
standard were, for example, that a portion of the range can be 
considered ``significant'' only if threats in that portion result in 
the entire species' being currently endangered or threatened. Such a 
high bar would not give the significant portion of its range phrase 
independent meaning, as the Ninth Circuit held in Defenders of Wildlife 
v. Norton, 258 F.3d 1136 (9th Cir. 2001).
    The definition of ``significant'' used in this finding carefully 
balances these concerns. By setting a relatively high threshold, we 
minimize the degree to which restrictions will be imposed or resources 
expended that do not contribute substantially to species conservation. 
However, we have not set the threshold so high that the phrase ``in a 
significant portion of its range'' loses independent meaning. 
Specifically, we have not set the threshold as high as it was under the 
interpretation presented by the Service in the Defenders of Wildlife v. 
Norton litigation. Under that interpretation, the portion of the range 
would have to be so important that current imperilment there would mean 
that the species would be currently imperiled everywhere. Under the 
definition of ``significant'' used in this finding, the portion of the 
range need not rise to such an exceptionally high level of biological 
significance. (We recognize that if the species is imperiled in a 
portion that rises to that level of biological significance, then we 
should conclude that the species is in fact imperiled throughout all of 
its range, and that we would not need to rely on the significant 
portion of its range language for such a listing.) Rather, under this 
interpretation we ask whether the species would be endangered 
everywhere without that portion, i.e., if that portion were completely 
extirpated. In other words, the portion of the range need not be so 
important that even the species being in danger of extinction in that 
portion would be sufficient to cause the species in the remainder of 
the range to be endangered; rather, the complete extirpation (in a 
hypothetical future) of the species in that portion would be required 
to cause the species in the remainder of the range to be endangered.
    The range of a species can theoretically be divided into portions 
in an infinite number of ways. However, there is no purpose to 
analyzing portions of the range that have no reasonable potential to be 
significant or to analyzing portions of the range in which there is no 
reasonable potential for the species to be endangered or threatened. 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

[[Page 68685]]

in danger of extinction there or likely to become so within the 
foreseeable future. Depending on the biology of the species, its range, 
and the threats it faces, it might be more efficient for us to address 
the significance question first or the status question first. Thus, if 
we determine that a portion of the range is not ``significant,'' we do 
not need to determine whether the species is endangered or threatened 
there; if we determine that the species is not endangered or threatened 
in a portion of its range, we do not need to determine if that portion 
is ``significant.'' In practice, a key part of the determination that a 
species is in danger of extinction in a significant portion of its 
range 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 to the species occurs only in 
portions of the species' range that clearly would not meet the 
biologically based definition of ``significant,'' such portions will 
not warrant further consideration.
    Our review determined that there are not any concentrations of 
threats in any part of the ranges occupied by Cynomys gunnisoni 
gunnisoni or C. g. zuniensis. Plague is the most substantial factor 
currently affecting both subspecies of the Gunnison's prairie dog. The 
entire ranges of both subspecies are operating in a post-plague 
environment. There is variation between colonies and populations in 
their ability to maintain abundance following outbreaks. However, 
variation occurs throughout the range of both subspecies and is not 
concentrated in any one geographic location. Although C. g. gunnisoni 
has a lower occupancy than C. g. zuniensis, we have no evidence that 
plague outbreaks today are more frequent or more intense in any one 
part of the range. Rather, populations for both subspecies have 
remained stable throughout their respective ranges and within 
individual population areas. Therefore, at this time, there is no 
evidence to suggest that plague affects portions of either C. g. 
gunnisoni's or C. g. zuniensis's range differently now or will within 
the foreseeable future. Because there are no concentrations of threats 
in any portion of the range of C. g. gunnisoni or C. g. zuniensis, we 
did not evaluate whether any portions meet the definition of 
``significant.''

Conclusion

    Our review of the best available scientific and commercial 
information indicates that neither Cynomys gunnisoni gunnisoni nor C. 
g. zuniensis is in danger of extinction (endangered), nor likely to 
become endangered within the foreseeable future (threatened), 
throughout all or a significant portion of its range. Therefore, we 
find that listing C. g. gunnisoni or C. g. zuniensis as endangered or 
threatened subspecies under the Act is not warranted at this time.
    We request that you submit any new information concerning the 
status of, or threats to, C. g. gunnisoni or C. g. zuniensis to our 
Colorado Field Office (see ADDRESSES) whenever it becomes available. 
New information will help us monitor these two subspecies and encourage 
their conservation. If an emergency situation develops for either of 
these subspecies, we will act to provide immediate protection.

References Cited

    A complete list of all references cited in this document is 
available on the Internet at http://www.regulations.gov and upon 
request from the Colorado Field Office (see ADDRESSES).

Authors

    The primary authors of this notice are staff located at the 
Colorado Field Office.

Authority

    The authority for this action is section 4 of the Endangered 
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: November 1, 2013,
Rowan W. Gould,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2013-27196 Filed 11-13-13; 8:45 am]
BILLING CODE 4310-55-P