[Federal Register Volume 75, Number 104 (Tuesday, June 1, 2010)]
[Proposed Rules]
[Pages 30338-30363]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-12599]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R6-ES-2008-0053]
[MO 92210-0-0008-B2]
Endangered and Threatened Wildlife and Plants; 12-month Finding
on a Petition to List the White-tailed Prairie Dog as Endangered or
Threatened
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of a 12-month petition finding.
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SUMMARY: We, the U.S. Fish and Wildlife Service announce a 12-month
finding on a petition to list the white-tailed prairie dog (Cynomys
leucurus) as endangered or threatened under the Endangered Species Act
of 1973, as amended. After a review of all available scientific and
commercial information, we find that listing the white-tailed prairie
dog is not warranted at this time. However, we ask the public to submit
to us any new information that becomes available concerning the threats
to the white-tailed prairie dog or its habitat at any time.
DATES: The finding announced in this document was made on June 1, 2010.
ADDRESSES: This finding is available on the Internet at http://www.regulations.gov at Docket Number FWS-R6-ES-2008-0053. 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, Utah Field Office, 2369 West Orton Circle,
Suite 50, West Valley City, UT 84119. Please submit any new
information, materials, comments, or questions concerning this finding
to the above street address.
FOR FURTHER INFORMATION CONTACT: Larry Crist, Field Supervisor, Utah
Field Office (see ADDRESSES); by telephone at 801-975-3330; or by
facsimile at 801-975-3331. If you use a telecommunications device for
the deaf (TDD), please call the Federal Information Relay Service
(FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Endangered Species Act of 1973, as
amended (Act) (16 U.S.C. 1531 et seq.), requires that, for any petition
to revise the Federal Lists of Endangered and Threatened Wildlife and
Plants that contains substantial scientific or commercial information
that listing the species may be warranted, we make a finding within 12
months of the date of receipt of the petition. In this finding, we will
determine that the petitioned action is: (1) Not warranted, (2)
warranted, or (3) 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 expeditious progress is being made to add or remove qualified
species from the Federal 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 Action
On July 15, 2002, we received a petition dated July 11, 2002, from
the Center for Native Ecosystems, Forest Guardians, Biodiversity
Conservation Alliance, and Terry Tempest Williams, requesting that the
white-tailed prairie dog (Cynomys leucurus) be listed as endangered or
threatened across its entire range. We acknowledged the receipt of the
petition in a letter to the petitioners, dated August 27, 2002. In that
letter we also stated that higher priority actions precluded addressing
the petition immediately, but it would be addressed when funding
allowed.
Section 4(b)(3)(B) of the Act requires that for any petition to
revise the Lists of Threatened and Endangered Wildlife and Plants, to
the maximum extent practicable, within 90 days after receiving the
petition, we make a finding as to whether the petition presents
substantial scientific or commercial information indicating that the
petitioned action may be warranted. On November 9, 2004, we announced
our 90-day finding (69 FR 64889) that the petition did not present
substantial scientific or commercial information indicating that
listing may be warranted. On July 12, 2007, in a Director's memorandum,
the U.S. Fish and Wildlife Service (Service) announced that we would
review the November 9, 2004, finding after questions were raised about
the integrity of scientific information used and whether the decision
was consistent with the appropriate legal standards. We received notice
of a lawsuit from the Center for Native Ecosystems, and three other
entities, on November 27, 2007, regarding our not-substantial 90-day
finding. We agreed in a stipulated
[[Page 30339]]
settlement agreement on February 22, 2008, to submit a notice
initiating a 12-month finding for the white-tailed prairie dog to the
Federal Register on or before May 1, 2008, and to submit a 12-month
finding for the white-tailed prairie dog to the Federal Register on or
before June 1, 2010. Due to the stipulated settlement agreement, the
petitioners dismissed the lawsuit on February 26, 2008. This notice
constitutes the 12-month finding under the stipulated settlement
agreement on the petition to list the white-tailed prairie dog as
endangered or threatened.
Species Information
Species Description
White-tailed prairie dogs are between 340 to 370 millimeters (mm)
(13.4 to 14.6 inches (in)) in length with a 40- to 65-mm (1.6- to 2.6-
in) long tail (Clark et al. 1971, p. 1). The tail has a grayish white
tip and is white on the terminal half. The coat is generally yellow-tan
with distinctive dark brown or black cheek patches that extend above
the eye with a lighter black stripe that extends below the eye onto the
cheek (Clark et al. 1971, p. 1).
Taxonomy
The white-tailed prairie dog is one of five prairie dog species
that inhabit western North America (Clark et al. 1971, p. 1; Pizzimenti
1975, pp. 62-63). Prairie dogs are in the squirrel family, Sciuridae,
and belong to the genus Cynomys (Hollister 1916, p. 5). The genus is
split into two subgenera; Leucocrossuromys includes prairie dogs with
white tails and Cynomys includes prairie dogs with black tails. White-
tailed prairie dogs are included in the subgenus Leucocrossuromys along
with Utah and Gunnison prairie dogs (Clark et al. 1971, p. 1;
Pizzimenti 1975, pp. 15-16). Due to this consensus, we determined that
the white-tailed prairie dog is a valid taxonomic species and a
listable entity under the Act.
Ecology and Life History
White-tailed prairie dogs occur at elevations ranging from 1,150
meters (m) (3,773 feet (ft)) (Flath 1979, p. 63) to 3,200 m (10,500 ft)
(Tileston and Lechleitner 1966, p. 295). Unlike the grass-dominated
habitats of black-tailed prairie dogs, white-tailed prairie dogs
inhabit drier landscapes with shrubland vegetation (Tileston and
Lechleitner 1966, p. 295; Clark 1977, pp. 3-5; Collins and Lichvar
1986, pp. 88-91; Gadd 2000, pp. 15-16). Their habitats are generally
flat (Collins and Lichvar 1986, p. 92).
Prairie dogs are primarily herbivorous and mainly eat grasses and
forbs (Kelso 1939, pp. 7-11). However, they consume other plants
seasonally. Prairie dog selection of plants is somewhat dependent on
site-specific conditions and seasonality. For example, white-tailed
prairie dogs eat sagebrush and saltbush during early spring, grasses in
the summer, and seed heads and rabbitbrush flowers in the fall (Kelso
1939, p. 10; Tileston and Lechleitner 1966, p. 302). White-tailed
prairie dogs eat the least amount of grass of any prairie dog species
and the most saltbush (Kelso 1939, p. 11). White-tailed prairie dogs
also eat insects (Stockard 1929, p. 476). Prairie dogs obtain most of
their water by eating vegetation and can become water-stressed if
sufficient succulent vegetation is unavailable (Seglund et al. 2006, p.
7).
White-tailed prairie dogs prefer areas with lower vegetation
heights (Collins and Lichvar 1986, p. 92), but they may use dense
sagebrush adjacent to grassier areas (Tileston and Lechleitner 1966, p.
314). White-tailed prairie dogs use the dense vegetation within
sagebrush habitat to hide from predators (Hoogland 1981, pp. 266-268;
Gadd 2000, pp. 24-26), reducing their need to visually search for
predators and consequently reducing their need for dense colonies and
cohesive social structures. This habitat use differs from black-tailed
prairie dogs, who actively work to maintain the grassland vegetation
surrounding their burrows for visibility.
White-tailed prairie dogs dig their own burrows. Burrow
construction requires deep, well-drained soils. Preferred soils are
derived from sandstone or shale and may be clay-loam, silty clay, or
sandy loam (Lupis et al. 2007, p. 6). Burrows are used throughout the
year for hibernation, cover from temperature extremes, predator
avoidance, and birthing and raising young (Clark 1977, p. 9; Hoogland
1981, pp. 258-264). Burrow complexes are usually widespread with
numerous entrances, tunnels, and chambers. The number of burrows in an
area varies greatly from location to location, ranging from 0.12 to
47.75 per hectare (ha) (0.3 to 118 per acre (ac)) with a mean of 0.32
to 6.79 per ha (0.8 to 16.8 per ac) (Tileston and Lechleitner 1966, p.
314; Menkens and Anderson 1989, p. 84; Seglund and Schnurr 2009, p.
94).
For purposes of this finding, a group of burrows is referred to as
a colony. A complex is a collection of colonies grouped on the
landscape. There is usually a high degree of connectivity between
colonies in the same complex.
White-tailed prairie dog colonies have fewer animals per unit area
with less obvious borders than black-tailed prairie dog colonies
(Tileston and Lechleitner 1966, pp. 297, 314; Hoogland 1981, p. 252).
Home range sizes range from 0.2 to 1.9 ha (0.5 to 4.7 ac) (Clark 1977,
p. 65; Cooke 1993, p. 23), which are generally larger than black-tailed
prairie dog home ranges (Clark 1977, p. 65).
White-tailed prairie dogs can live up to 8 years in captivity but
may not live past 4 years in the wild (Pauli et al. 2006, p. 18).
Prairie dog annual mortality rates average 30 to 60 percent, largely
due to disease and predation (Tileston and Lechleitner 1966, p. 305;
Clark 1977, pp. 80-81).
Adult sex ratios are approximately one male to two females (Clark
1977, p. 76; Hoogland 2010, pers. comm.). White-tailed prairie dogs can
reproduce at 1 year of age, and they have a single litter once a year
averaging four to five pups (Bakko and Brown 1967, pp. 110-111).
Breeding occurs from late March to mid-April (Tileston and Lechleitner
1966, p. 303). Pups are born in the burrows after a gestation period of
approximately 30 days (Tileston and Lechleitner 1966, p. 304), and
emerge from the burrow for the first time 4 to 6 weeks after birth
(Bakko and Brown 1967, p. 103). They begin to disperse from the colony
in June and July when population densities are the highest (Clark 1977,
p. 72). Migration is recognized as an important factor to white-tailed
prairie dog population dynamics (Clark 1977, p. 80). Plague in this
species often results in near extirpation of colonies. Rapid
recolonization of some areas post-plague with few or no surviving
reproductive adults suggests the species is highly mobile (Seglund et
al. 2006, p. 10). Dispersal distances of up to 8 kilometers (km) (4.8
miles (mi)) have been observed (Cooke 1993 in Seglund et al. 2006, p.
10)
White-tailed prairie dogs have the least cohesive social structure
of any prairie dog species. Their social system is organized around
family groups or ``clans,'' comprised of several reproductive females,
one or two males of reproductive age, and dependent young (Clark 1977,
p. 62; Cooke 1993, p. 22). Adult white-tailed prairie dogs spend little
time displaying social behavior, and most of their time feeding or in
alert postures (Clark 1977, p. 44). Pups spend a large amount of time
playing during their first few weeks (Tileston and Lechleitner 1966, p.
300).
White-tailed prairie dog populations exhibit large fluctuations of
more than
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50 percent from year to year (Menkens and Anderson 1989, p. 345).
Population fluctuations are likely due to disease cycles, vegetation
quantity and quality, and drought (Seglund and Schnurr 2009, p. 16)
(see Factor A. Climate Change; Factor C. Disease). We do not know the
level at which population fluctuations are a natural part of white-
tailed prairie dog ecology, or the result of environmental or human-
caused threat factors. In many cases, prairie dog colonies persist
despite large population fluctuations (see Factor C. Disease). We
define ``persistence'' as the long-term continuance of white-tailed
prairie dog colonies, at a high enough level to exist in the long-term
with minimal management assistance.
White-tailed prairie dogs are diurnal (active during the day)
(Tileston and Lechleitner 1966, p. 200). They are active approximately
5 to 7 months per year from early spring to fall and hibernate during
late fall and winter (Clark 1977, pp. 59-60; Cooke 1993, p. 11). Time
spent hibernating is determined by available food resources (Clark
1977, p. 60). In warm weather, even in mid-winter, white-tailed prairie
dogs will feed if grasses are growing (Hollister 1916, p. 6; Goodrich
and Buskirk 1998, p. 177). If resources are not sufficient, prairie
dogs become inactive and spend more time in their burrows (Harlow and
Menkens 1986, p. 795). During periods of high summer temperatures,
white-tailed prairie dogs avoid the highest temperatures of midday by
foraging in the cooler morning and evening hours (Clark 1977, p. 58).
Distribution and Abundance
The overall species' distribution is mapped as ``gross range.'' The
available white-tailed prairie dog literature uses the term ``gross
range'' to describe the outer boundary identifying the overall
rangewide distribution of the white-tailed prairie dog (Figure 1).
However, not all lands within the species' gross range are occupied or
have the potential to be occupied by white-tailed prairie dogs (Seglund
et al. 2006, p. 100). The predicted range is a subset of the gross
range and thus represents a more accurate spatial representation of the
potential range of the white-tailed prairie dog (Seglund et al. 2006,
pp. 16, 110; Seglund and Schnurr 2009, p. 23). Predicted range is
defined using habitat characteristics of vegetation, land use, slope,
and elevation (Seglund et al. 2006, pp. 14-39). Depending on available
data, we use gross range, predicted range, or mapped occupied habitat
throughout this document to evaluate status and threats to the species.
For example, gross range mapping data was available for our use for all
States across the species' range. However, the data for the predicted
range map (Seglund et al. 2006, p. 110; Seglund and Schnurr 2009, p.
23) was only available for the State of Colorado. Information regarding
mapped occupied habitat (all areas mapped on Federal lands as occupied
by white-tailed prairie dogs since 1985) was available for the State of
Utah, but not for any other States.
BILLING CODE 4310-55-S
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[GRAPHIC] [TIFF OMITTED] TP01JN10.000
BILLING CODE 4310-55-C
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The white-tailed prairie dog occurs from a small area in south-
central Montana, throughout much of Wyoming, into western Colorado, and
northeastern Utah. There are 20,224,801 ha (49,976,572 ac) within the
gross range of the white-tailed prairie dog and 13,066,887 ha
(32,288,981 ac) within the species' predicted range (Seglund et al.
2006, p. 91). Therefore, approximately 65 percent of the gross range
has the characteristics necessary to support the white-tailed prairie
dog. Wyoming contains the largest amount of white-tailed prairie dog
predicted range (75 percent) (Knowles 2002, p. 4). Less than 1 percent
of predicted range occurs in Montana (Table 1). The majority of white-
tailed prairie dog predicted range (56 percent) occurs on land managed
by the Bureau of Land Management (BLM). A significant portion of the
predicted range occurs on private land (37 percent). Very little of the
predicted range is managed by the Service (0.4 percent), U.S. Forest
Service (USFS) (0.5 percent), or National Park Service (NPS) (0.9
percent) (Table 1).
TABLE 1. Percent Predicted Range by State and Land Management Entity (Seglund et al. 2006, pp. 91, 98, 100, 104, 109).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total Range Private BLM USFS NPS USFWS State Other
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Colorado 11 37 56 < 1 1 < 1 5 < 1
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Montana < \*\ 1 49 44 2 0 0 5 < 1
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Utah 13 20 60 < 1 < 1 < 1 11 7
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Wyoming 75 33 54 < 1 < 1 < 1 6 6
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Total 37 56 < 1 < 1 < 1 5 < 1
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* < less than
Historical abundance and distribution are not well documented for
white-tailed prairie dogs prior to the 1980s (Pauli et al. 2006, p. 13;
Seglund et al. 2006, p. 11). The distribution of white-tailed prairie
dogs has not changed appreciably since historic times (Knowles 2002,
pp. 5-6). The only recorded change in distribution is in Montana, where
white-tailed prairie dogs were previously captured 40 miles north of
currently occupied habitat (Knowles 2002, p. 5). However, abundance
declined as a result of past control efforts and plague (Cully 1993, p.
38; Knowles 2002, pp. 1-2) (see Factor B. Overutilization and Factor C.
Disease). We are not able to quantify changes in occupied habitat for
the species because mapping did not use standardized methods, and we do
not have accurate estimates of historical occupied habitat (Seglund et
al. 2006, p. 13).
We do not have rangewide population trend information due to a lack
of historical population information and inconsistencies in survey
methodologies (Seglund et al. 2006, pp. 4, 13). Surveys for white-
tailed prairie dog distribution and occupancy rates were recently
conducted across portions of the species' gross range (Grenier and
Filipi 2009, entire; Seglund and Schnurr 2009, p. 27; Wright 2009,
entire). While occupancy surveys are intended to determine population
trends (Seglund and Schnurr 2009, p. 10), the data are not yet
available to provide trend information. In addition, each State used
different methods to conduct ground surveys and determine occupancy
rates; thus, the results are not comparable. We present State-by-State
information below with the caveat that comparing colony occupancy rates
across the gross range of the species is not possible.
Colorado
White-tailed prairie dog predicted range includes Moffat, Routt,
Rio Blanco, Garfield, Mesa, Delta, Montrose, Eagle, Jackson, Ouray, and
Larimer Counties in northwestern Colorado (Seglund et al. 2004, p.
133). Approximately 1,246,441 ha (3,104,733 ac) of predicted white-
tailed prairie dog habitat occurs in three Individual Population Areas
(IPAs): Grand Valley-Uncompahgre IPA, North IPA, and Northwest IPA
(Hotze 2010, pp. 9-10). An IPA is an area physically separated from
other populations that may face a unique subset of threats (Seglund and
Schnurr 2009, p. 1). These population areas are geographically
separated from each other but connected to population areas in Utah and
Wyoming (Seglund and Schnurr 2009, p. E-5).
Colorado completed Statewide white-tailed prairie dog surveys in
2004 and 2008; occupancy rates were 24.1 and 23.1 percent,
respectively, a statistically insignificant difference (Seglund and
Schnurr 2009, pp. 27-28). Occupancy rate is the number of randomly
selected plots in predicted habitat with prairie dogs, and is not a
measure of abundance. We do not have population trend information
across the entire predicted range of the species in Colorado. Localized
declines and habitat degradation were reported in the Grand Valley-
Uncompahgre IPA due largely to urbanization (Seglund and Schnurr 2009,
p. 54). Information in the North IPA is restricted to colonies
associated with black-footed ferret reintroduction; a historical record
of ferrets in this area suggests it once supported abundant populations
of prairie dogs (Seglund and Schnurr 2009, p. 58). Only two colonies
remain, although they have remained stable for the past 20 years
(Seglund and Schnurr 2009, p. 58). Population densities and
distribution in the Northwest IPA appear to fluctuate greatly in large
part due to the prevalence of plague (Seglund and Schnurr 2009, pp. 63-
76).
Montana
White-tailed prairie dogs occur in one population area in Carbon
County, along the Montana-Wyoming border (Seglund et al. 2006, p. 25).
Fifteen colonies were mapped in the 1970s across 312.8 ha (773 ac)
(Flath 1979, p. 63). White-tailed prairie dogs were previously reported
in north Sage Creek in Carbon County (Hollister 1916, p. 27), and in
Yellowstone County just northeast of Carbon County (Kelso 1939, p. 7),
but no animals were found in these locations in later surveys (Flath
1979, entire).
Current occupied area of white-tailed prairie dogs in Montana
includes 112 ha (277 ac) across 11 colonies; 8 colonies were considered
active in 2009 (MFWP 2009a, p. 1). The apparent loss in occupied
habitat is likely due to plague and agricultural land conversion (Parks
et al. 1999 in Knowles 2002, p. 15). We do not have population trend
data for the white-tailed prairie dog in Montana.
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Utah
White-tailed prairie dogs occur in Rich, Summit, Daggett, Uintah,
Duchesne, Carbon, Emery, and Grand Counties (Seglund et al. 2004, p.
140) in northern and eastern Utah. In 2002 and 2003, 57,463 ha (141,808
ac) of occupied white-tailed prairie dog habitat were documented,
mostly within Uintah and Duchesne Counties (Lupis et al. 2007, p. 17).
Smaller population areas are found in the Cisco Desert in Emery and
Grand Counties (10,869 ha (26,856 ac)), and in Rich County (73 ha (180
ac)) (Lupis et al. 2007, p. 15). Surveys did not include private lands;
therefore, the amount of occupied habitat is an underestimate. These
population areas are mostly disconnected from each other, but connect
to population areas in Wyoming and Colorado. Based on surveys conducted
in 2008, the white-tailed prairie dog occupancy rate was 46 percent of
sampled plots (Wright 2009, p. 5).
We do not have information on long-term population status or trends
for white-tailed prairie dogs in Utah. Surveys in black-footed ferret
management areas in the Uintah basin recorded fluctuating population
levels: increasing densities since the early 1990s, declines in 1999
and 2003, and population recoveries in 2004-2008 (Seglund et al. 2006,
p. 28; Maxfield 2009, pers. comm.) (see Factor A. Climate Change).
Wyoming
White-tailed prairie dogs are found in the Counties of Big Horn,
Park, Hot Springs, Natrona, Fremont, Sublette, Sweetwater, Lincoln,
Uinta, Carbon, and Albany in northern and southern central Wyoming
(Seglund et al. 2004, p. 130). Wyoming Fish and Game documented
11,511,356 ha (27,822,847 ac) of potential habitat and 1,170,952 ha
(2,893,487 ac) of occupied habitat in 2008 by aerial survey (Grenier
and Filipi 2009, p. 5). The majority of these acres are in Albany and
Carbon Counties. Habitat in Wyoming is mostly continuous and not split
into discrete population areas. Approximately 68 percent of the
surveyed areas were estimated to be occupied (Grenier and Filipi 2009,
p. 5). This estimate is not a statistically determined ``occupancy
rate.'' Occupancy from these aerial surveys cannot be compared with
ground surveys from Colorado and Utah, because the observed location of
colony boundaries varies between methods, presumably due to the
difficulty in measuring colony boundaries from the air (Andelt et al.
2005, p. 3). We do not have long-term status or trend information for
white-tailed prairie dogs in Wyoming.
Summary of White-Tailed Prairie Dog Population Status
We do not have reliable long-term historical or current white-
tailed prairie dog status, trend, or distribution data. White-tailed
prairie dog populations are likely below historical levels, though
their overall distribution has not substantially changed (Knowles 2002,
p. 6). Large acreages of occupied habitat exist across the species'
range, particularly in Wyoming. Each State plans to continue occupancy
surveying, so more information may be available in the future.
Evaluation of Information Pertaining to the Five Threat Factors
Section 4 of the Act and implementing regulations (50 CFR 424) set
forth procedures for adding species to, removing species from, or
reclassifying species on the Federal Lists of Endangered and Threatened
Wildlife and Plants. Under section 4(a)(1) of the Act, a species may be
determined to be endangered or threatened based on any of the following
five factors:
(A) 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 12-month finding, information pertaining to the
white-tailed prairie dog in relation to the five factors provided in
section 4(a)(1) of the Act is discussed below. In making our 12-month
finding on the petition we considered and evaluated the best available
scientific and commercial information.
Factor A. The present or threatened destruction, modification, or
curtailment of the species' habitat or range.
The following potential factors that may affect the habitat or
range of the white-tailed prairie dog are discussed in this section,
including: (1) Oil and gas exploration and development, (2) oil shale
and tar sands development, (3) mineral development, (4) renewable
energy development--wind and solar, (5) urbanization, (6) agricultural
land conversion, (7) grazing, (8) fire occurrence and suppression, (9)
invasive plant species and (10) climate change.
Oil and Gas Exploration and Development
Exploration and development of oil and gas resources is widespread
throughout the gross range of the white-tailed prairie dog (Hotze 2010,
pp. 11-26). Between 2004 and 2008, exploration of oil and gas in the
intermountain west increased substantially because of political and
economic incentives (National Petroleum Council 2007, pp. 5-7). The
2005 Energy Policy Act expedited the leasing and permitting process on
Federal lands (42 U.S.C. 15801). The global recession of 2008 resulted
in decreased energy demand resulting in a reduced rate of energy
development. Fossil fuel production is expected to regain and surpass
the early 2008 levels in 2010-2030 (Copeland et al. 2009, p. 1; Energy
Information Administration (EIA) 2009, p. 109).
Energy development includes exploration, drilling, production, and
reclamation phases (Tribal Energy and Environmental Information
Clearinghouse (TEEIC) 2009, entire), each of which may potentially
impact the white-tailed prairie dog or its habitat. During the
exploration phase, oil and gas resources are delineated using a variety
of technologies, including seismic shot-hole surveys (planting and
detonation of underground explosives to produce vibrations that reveal
locations of mineral resources) and vibroseis trucks (vehicle with a
vibration plate used to survey mineral resources) (TEEIC 2009, p. 6).
These activities may result in mortality and the crushing of vegetation
along the seismic route, but there are no permanent structures
established during the exploration phase. If oil and gas resources are
proven, the lessee moves into the drilling phase. During the drilling
phase, access roads and well pads are constructed, pipelines are
installed, and the infrastructure necessary for the production phase
(such as compressor stations) is developed and constructed (TEEIC 2009,
p. 9). This phase typically results in longer-term disturbance to
white-tailed prairie dog habitat. The production phase includes
maintaining the wells and infrastructure as well as continuing the
extraction of the oil and gas resources. Wells may be in the production
phase for up to 20 to 30 years for gas wells (TEEIC 2009, p. 5) and up
to 100 years for oil wells (Connelly et al. 2004, p. 7:41). The final
phase begins when a well is no longer producing oil or gas because the
[[Page 30344]]
resource is depleted. The lessee is responsible for reclaiming the land
back to its original condition, or as close to the original condition
as possible (BLM 2007a, p. 2; TEEIC 2009, p. 15).
Oil and gas developments are typically configured as point (e.g.,
well pads, compressors) and line (e.g., roads, pipelines) disturbances
across broad areas. The amount of direct habitat loss may encompass 5
to 10 percent of leased areas. However, the extent of disturbance to
white-tailed prairie dogs may reach far beyond the direct habitat loss,
due to the loss and fragmentation of habitats; the alteration of
vegetation resources, which often promotes nonnative invasive plant
species; increased noise levels; increased vehicle traffic; and
increased human access to previously remote areas (Pauli et al. 2006,
p. 27; Seglund et al. 2006, p. 46; Seglund and Schnurr 2009, p. 126;
Wyoming Game and Fish Department (WGFD) 2009, p. 10). The amount of
direct habitat loss and total fragmentation varies greatly depending on
well density (number of acres per well) and spacing (distance between
individual well pads). Increasing wells per unit area decreases the
amount of habitat available for wildlife. Well densities and spacing
are typically designed to maximize recovery of the resource and are
administered by State oil and gas agencies and the BLM on Federal
mineral estate. Each geologic basin has a standard spacing, but
exemptions are granted (Connelly et al. 2004, pp. 7-39 to 7-40). Within
the range of the white-tailed prairie dog, well spacing can vary from 5
to 160 acres per well. Larger well spacing is often characterized by
more wells drilled per pad. Increasing the number of wells per pad
increases the size of the individual pad but decreases the amount of
habitat fragmented. The variation in well and well pad spacing results
in a variation in the intensity of effects across the species' range.
However, we are unable to determine how the ultimate effects to the
species vary with well density. The threshold levels of oil and gas
development that result in reduced populations or eliminated colonies
are unknown.
Resulting impacts to white-tailed prairie dogs from oil and gas
development may include direct mortality from vehicles; direct
mortality associated with increased access by recreational shooters who
utilize the new access routes (Gordon et al. 2003, p. 12); increased
disturbance responses from increased human activity; direct loss of
habitat and forage resources during exploration, drilling, and
production; and indirect loss of forage resources from invasive,
nonnative plant species (Seglund and Schnurr 2009, p. 126).
No studies have been done regarding the short-term or long-term
impact of oil and gas development on individual white-tailed prairie
dogs or their colonies. White-tailed prairie dogs can be negatively
impacted by the direct loss of habitat that occurs as a result of
development. For example, white-tailed prairie dog burrow densities
were lower at well locations compared to areas further from the well
pads (Biggins et al. 1984, p. 12). Dead prairie dogs were found in oil
and gas reserve pits (Esmoil 1995 in Peterson 2008, p. 5), although the
extent of population level impact is not known. The use of vibroseis
trucks in prairie dog colonies appears to impact vegetation, but
preliminary results did not document prairie dog mortality or burrow
collapse (Young and Sawyer 1981, pp. 1-2; Menkens and Anderson 1985, p.
7).
However, as described above, exposure to a factor does not
necessarily indicate that the factor is a threat. We know that white-
tailed prairie dog colonies exist in areas with long-term oil and gas
development. Some of the largest and most robust colonies are located
near areas of intense oil and gas development (see Distribition and
Abundance, above, and our discussion under Factor C, below). For
example, the Coyote Basin, Kennedy Wash, and Snake John colonies in
Uintah County, Utah, occur within a landscape fragmented by oil and gas
infrastructure, although their immediate occupied habitats have not
sustained significant energy development. Fifty percent of the mapped
occupied habitat in this region has been leased with 17 percent
currently producing (See Utah, below). Populations in this area have
fluctuated; although this has been attributed to drought (See Climate
Change, below). Despite the high amount of leasing in this area,
populations have recovered to their 20 year recorded peak. Similarly,
Coyote Basin and Wolf Creek are historically Colorado's most robust
colonies and occur within the Northwest IPA where oil and gas
development is high. Forty one percent of this IPA has already been
leased, with 7 percent currently producing (Hotze 2010, p. 20). Prairie
dogs continue to occupy a moderately sized complex within the Coal Oil
Basin (Colorado's largest oil field) despite an active drilling history
that extends back to 1944 (Wolf Creek Work Group 2001, p. 15).
Available information does not indicate that white-tailed prairie
dogs are currently reacting to oil and gas activities on a local
landscape scale or at the population or species level. We also do not
know if there is a level of oil and gas development at which the status
of prairie dogs at the population or species level would be negatively
impacted. As described above, white-tailed prairie dogs persist in
several areas with oil and gas activity.
To evaluate the extent to which oil and gas development may affect
white-tailed prairie dogs in the foreseeable future, we overlaid BLM-
authorized oil and gas leases with the species' gross range. More
specific information was available for Utah and Colorado, so we
overlaid oil and gas development with white-tailed prairie dog
predicted range (Seglund and Schnurr 2009, p. 24) in Colorado and
mapped occupied habitat in Utah (Hotze 2010, p. 7). We also reviewed
information on State-specific potential oil and gas reserves where that
information was available. The results are presented below and in the
State-by-State analysis sections.
In additional to managing lands in Wyoming, Colorado, and Utah, the
BLM manages the Federal mineral estate, including authorizing oil and
gas leases. Leases may be producing or non-producing. Producing leases
are those being actively developed. Non-producing leases are leased;
however, the resources for which they were leased are not currently
being extracted. Non-producing leases may become developed in the
future, but development is not guaranteed (Thompson 2010, pers. comm.).
We consider these leases to be indicative of potential development.
However, we do not know the percent of non-producing leases that will
become developed in the future because the variables governing
development are complex and include the price of gas, the number of
other leases the company holds, the actual amount of resource the lease
contains (often unknown at the time of lease), and other complex
economic and social factors.
In addition to the producing and non-producing leases, BLM has
authorized a significant amount of the Federal mineral estate that may
be leased in the future. Each BLM field office developed a resource
management plan that delineates areas available for leasing and depicts
surface access constraints (e.g., BLM 2008a, p. 7). The areas that are
available for leasing are larger than those that have already been
authorized, and include areas that may be developed in the future
should proven reserves be located. Development of the entire area
available for leasing is unlikely due to BLM's multi-use mandate, but
the area available for
[[Page 30345]]
leasing represents a potential maximum of oil and gas development. Non-
Federal mineral estates are managed by State, tribal, and private
mineral rights owners under different programs and using different
processes.
We were unable to specifically quantify the impacts of development
on non-Federal mineral rights. Total active and plugged wells are
available as GIS layers from each State's oil and gas development
commission. However, number of wells is not a biologically meaningful
measure to the white-tailed prairie dog because the effects depend on
the amount of land leased and well density and spacing. As previously
stated, the impacts to the species at different well spacing densities
are not well understood. Approximately two-thirds of wells within the
species range are located on Federal versus non-Federal estate (BLM
2009; Colorado Oil and Gas Conservation Commission 2010; Wyoming Oil
and Gas Conservation Commission 2010; Utah Division of Oil and Mining
2010; unpublished data). Similarly, approximately two-thirds of the
species range is in Federal vs. non-Federal ownership. We assume that a
similar ratio of development of non-Federal minerals is likely to occur
in the future as is occurring for Federal minerals. Because leasing
does not guarantee development, and the fact that we are unable to
estimate leasing rates on non-Federal estate, we consider the numbers
presented below (in the State-by-State analysis) as an approximate
measurement of Federal and non-Federal development that could occur in
the foreseeable future.
The BLM has authorized 5,687,259 ha (14,053,523 ac) of producing
and non-producing leases for oil and gas development, representing
approximately 28 percent of the white-tailed prairie dog's gross range
(Hotze 2010, p. 18). Producing leases occur across 1,435,580 ha
(3,547,395 ac), or 7 percent, of the species' gross range (Hotze 2010,
p. 18). Future exploration and development of fossil fuels is likely to
focus in areas of highest potential return. Highest potential return is
defined by several geological characteristics including permeability
and porosity of the underlying rock (BLM 2005a, p. 41). For example, in
the BLM Little Snake field office of northwest Colorado, approximately
96 percent of new wells will be drilled in areas with high oil and gas
potential (BLM 2007b, p. 3:100). In high and moderate potential areas
in Wyoming, a single well can produce 4 to 30 times as much as a well
in low potential areas (BLM 2008b, p. A20:6). Therefore, we assume
these areas will be the focus of future leasing.
Colorado
In Colorado, the BLM authorized oil and gas leases on 30 percent of
the white-tailed prairie dog's predicted range in the State (Hotze
2010, p. 20) across the Northwest, North, and Grand Valley-Uncompahgre
IPAs. Of the authorized oil and gas leases within the predicted range
in Colorado, there are 61,334 ha (151,560 ac) of producing leases,
which comprise approximately 5 percent of the predicted State range
(Hotze 2010, p. 14). Non-producing leases encompass 311,650 ha (770,104
ac), or approximately 25 percent of the predicted State range (Hotze
2010, p. 14).
Northwest Individual Population Area (IPA)
The Northwest IPA in Moffat and Rio Blanco Counties is within the
Greater Green River Basin (DOI et al. 2006, p. 20) and has the highest
potential for oil and gas development (Seglund and Schnurr 2009, p.
61). This IPA comprises approximately 54 percent of white-tailed
prairie dog predicted habitat in Colorado (Hotze 2010, p. 10).
Authorized lease areas in 2009 encompassed approximately 41 percent of
the Northwest IPA (Hotze 2010, p. 20), and oil and gas development is
projected to significantly increase over the next 20 years (Seglund and
Schnurr 2009, p. 128). For example, the BLM anticipates authorizing the
drilling of 3,031 oil and gas wells over the next 20 years in Routt and
southwestern Moffat Counties (BLM 2007b, p. 3:100), whereas the
previous 20 years resulted in 594 drilled wells (BLM 2007b, p. 3:99).
Similarly, the BLM anticipates between 17,800 and 21,200 new wells will
be drilled over the next 20 years in Rio Blanco and central and
northern Moffat Counties, whereas there were 5,800 wells drilled
previously (Seglund and Schnurr 2009, p. 129). However, the majority of
these wells will occur outside of the white-tailed prairie dog's
predicted range (Seglund and Schnurr 2009, p. 129). Approximately 96
percent of new wells will be drilled in areas with high oil and gas
potential as defined by the BLM (2007b, p. 3:100); we believe this
localizes the development to some extent and thus limits the amount of
prairie dog habitat impacted.
Three potential coal bed methane areas partially overlap white-
tailed prairie dog habitat in the Northwest IPA: eastern Sand Wash
Basin, Lower White River, and Danforth Hill (BLM 2007b, p. 3:102).
However, the majority of the coal bed methane areas occur outside the
predicted range for the species within Colorado (BLM 2007b, Figure 3-
16; Seglund and Schnurr 2009, p. 119).
Grand Valley-Uncompahgre IPA
There is potential for energy development to occur in a corridor of
the Grand Valley-Uncompahgre IPA in Mesa, Montrose, and Ouray Counties
(Seglund and Schnurr 2009, p. 54). Approximately 14 percent of the
white-tailed prairie dog's predicted range in this IPA is authorized
for lease or contains pending leases from the BLM (Seglund and Schnurr
2009, p. 131; Hotze 2010, p. 20). The BLM estimates authorizing 3,600
wells on 1,519 pads over the next 20 years in this IPA (Ewing 2009,
pers. comm.). The total area disturbed is estimated at 13,200 ac (5,342
ha) of short-term disturbance and 4,100 ac (1,659 ha) of long-term
disturbance (Ewing 2009, pers. comm.). We do not know where this
development will occur with respect to known prairie dog colonies.
However, 85 percent of this IPA remains unleased, and future wells
represent a relatively small (less than 2 percent of this IPA) amount
of additional disturbance.
North IPA
Crude oil was historically produced in the North IPA to a limited
degree. However, EOG Resources discovered a large reservoir of crude
oil in this area in 2008, and subsequently acquired a lease for 100,000
ac (40,469 ha) of land in the area (Seglund and Schnurr 2009, p. 129).
Approximately 25 percent of the white-tailed prairie dog's predicted
range in the North IPA has authorized or pending leases (Seglund and
Schnurr 2009, p. 131; Hotze 2010, p. 20).
In summary, BLM has authorized and has pending leases on
approximately 30 percent of the predicted range of the species within
Colorado for oil and gas development (Seglund and Schnurr 2009, p. 131;
Hotze 2010, p. 20). The largest potential for overlap and impacts to
white-tailed prairie dogs occurs in the Northwest IPA; oil and gas
development is projected to increase substantially in this IPA over the
next 20 years (Seglund and Schnurr 2009, p. 129). We expect the
majority of future oil and gas development to occur in this IPA. We do
not know the exact locations of energy development facilities with
respect to locations of white-tailed prairie dog colonies. Oil and gas
development will likely impact white-tailed prairie dogs, causing
individual mortalities and habitat loss and fragmentation. However, the
majority of oil and gas development will occur in
[[Page 30346]]
areas of high potential energy reserves, and particularly in the
Northwest IPA, so impacts to the species are likely to be more
localized, and are not expected to occur at high levels across the
species' predicted range in Colorado. Based on the available
information, we do not believe oil and gas development in Colorado is a
threat to the species now or in the foreseeable future.
Montana
White-tailed prairie dog habitat in Montana represents less than 1
percent of the gross range of the species (Seglund et al. 2006, p. 91),
and is contained entirely within Carbon County. Therefore we did not
calculate the area impacted by oil and gas leasing. The area containing
the South Sage Creek white-tailed prairie dog colony was leased in
January 2002, but is not yet developed (Begley 2010a, pers. comm.). The
South Sage Creek colony occupies less than 6 ha (15 ac), or 5 percent
of the occupied habitat in Montana (MFWP 2009b, p. 3). The area
containing the Robertson Draw colony is available for leasing but has
not yet been leased (Begley 2010a, pers. comm.). Oil and gas
development is not impacting the remaining six colonies in Montana
(Seglund et al. 2006, p. 26). Because of the small amount of habitat
impacted, oil and gas development is not a significant threat in this
State, now or in the foreseeable future.
Utah
The BLM has authorized oil and gas leases on 31 percent of the
white-tailed prairie dog's gross range in Utah (Hotze 2010, p. 18). The
highest overlap between the gross range of the white-tailed prairie dog
and oil and gas development potential occurs in Uintah, Duchesne,
Grand, and Carbon Counties (Hotze 2010, pp. 21-22; Utah Department of
Natural Resources 2004 in Seglund et al. 2006, p. 33).
The Uinta and Piceance Basin areas of Utah have significant oil and
gas resources (BLM 2008a, p. 3:38). Approximately 82 percent of 18,982
existing well locations in Utah occur in the Uinta Basin in Duchesne
and Uintah Counties (Hotze 2010, pp. 15-16). There are 97,266 ha
(240,350 ac) of mapped occupied white-tailed prairie dog habitat in
Uinta and Duchesne Counties (Hotze 2010, pp. 7-8). The BLM has
authorized oil and gas leasing on approximately 51 percent of this
mapped occupied habitat (Hotze 2010, p. 22). The BLM estimates that
approximately 2,055 new oil wells, 4,345 new gas wells, and 130 new
coal bed methane wells will be drilled within the Uinta Basin during
the 15- to 20-year planning period (BLM 2008a, p. 3:36). Approximately
73 percent of the Federal mineral rights open to leasing in the Uinta
Basin area have already been authorized (Hotze 2010, p. 24). Therefore,
the authorized leases represent a fair assessment of the potential
impact to white-tailed prairie dogs. These leases have a 201-meter
(660-ft) no surface occupancy stipulation adjacent to occupied prairie
dog colonies, which will minimize direct mortality of prairie dogs and
the loss of habitat from future development (see Factor D. Inadequacy
of Regulatory Mechanisms, below, for a discussion of these
stipulations).
There are 14627 ha (36,144 ac) of mapped white-tailed prairie dog
habitat in Carbon and Emery Counties (Hotze 2010, p. 8). The BLM has
authorized oil and gas leasing on approximately 52 percent of this
occupied mapped habitat (Hotze 2010, p. 22). About 2300 ha (5,600 ac)
(15 percent) of this habitat is located within areas considered to have
high potential for oil and gas resources (BLM 2004, p. 4:119). These
leases also have a no surface occupancy stipulation for prairie dog
colonies (see Factor D).
In summary, oil and gas leasing and development is authorized by
BLM across 31 percent of the species' gross range in Utah. The majority
of current and future project development occurs in the Uinta Basin in
northeastern Utah, and thus potential impacts to the species could be
greatest in this area, particularly because 52 percent of the species'
mapped occupied habitat is leased. We consider the Uinta Basin to be
the highest potential development area in Utah. Exploration and
drilling, as previously discussed, can result in mortality of
individual prairie dogs and the loss and fragmentation of habitats.
However, robust white-tailed prairie dog colonies continue to persist
in the Uinta Basin, in areas associated with existing oil and gas
development. The BLM imposes a no surface occupancy stipulation that
prohibits activity within 201 meters (660 ft) of white-tailed prairie
dog colonies in the Uinta Basin (see Factor D), which will minimize
direct mortality of prairie dogs and the loss of habitat from future
development. The likely concentration of oil and gas development in
high potential resource areas should also minimize the amount of white-
tailed prairie dog habitat directly lost to development. Due to these
factors, we do not believe oil and gas development in Utah is a threat
to the species now or in the foreseeable future.
Wyoming
Seventy-seven percent of the species' gross range in Wyoming
overlaps potential energy resources in Wyoming (Seglund et al. 2006, p.
39). However, not all potential energy resources will be developed.
Therefore, we further reviewed leases and potential energy resources to
determine the extent of development in the foreseeable future (the next
20 years).
Approximately 3,443,269 ha (88,508,503 ac) of land, or 27 percent
of the species' gross range in Wyoming, is authorized for leasing by
BLM (Hotze 2010, p. 18). These leases are either producing or are non-
producing. However, we expect the majority of new wells will be drilled
in areas with high oil and gas potential. In high and moderate
potential areas in Wyoming, a single well can produce 4 to 30 times as
much as a well in low potential areas (BLM 2008b, p. A20:6). Most wells
will be drilled in areas of high potential oil and gas resources
(Copeland et al. 2009). Only 415,649 ha (1,027,057 ac), or 4.2 percent
of the species' predicted range in Wyoming, occurs in high potential
oil and gas resource in areas as defined by Seglund et al. (2006, p.
39). Low and medium potential oil and gas resources overlap 73 percent
of the gross range of white-tailed prairie dog (Seglund et al. 2006, p.
39). Twenty-three percent of the gross range has no oil or gas
resources. Given the existing development, we consider the area in
southern Wyoming between Rawlins and Rock Springs to be a high
potential area (Hotze 2010, p. 11).
Oil and gas development and reserves occur throughout the gross
range in Wyoming. We do not know the exact locations of future energy
development facilities with respect to locations of white-tailed
prairie dog colonies. Oil and gas development will likely impact white-
tailed prairie dogs, causing individual mortalities and habitat loss
and fragmentation. However, as previously discussed, only a small
portion (4.2 percent) of the species' gross range overlaps areas of
high potential energy reserves. Energy development is most likely to be
concentrated in areas of high potential reserves, so impacts to the
white-tailed prairie dog will not occur at high levels across the
species' entire gross range in Wyoming. Based on the available
information, we do not believe oil and gas development in Wyoming is a
threat to the species now or in the foreseeable future.
[[Page 30347]]
Summary of Oil and Gas Development
Table 2 (below) gives a summary of the percentage of BLM-leased
area for oil and gas in gross, predicted, and mapped occupied range, by
State. Generally, the area attributed to producing leases makes up a
small portion of the species' range, although up to 28 percent of the
species' gross range has been leased for potential development.
TABLE 2. Percentage of leased area for oil and gas in gross, predicted,
and mapped occupied range of the white-tailed prairie dog.
(Totals include a small amount of land authorized for leasing but not
yet leased; and therefore not included in the other two categories.)
------------------------------------------------------------------------
Percent Percent Non- Total
State Producing Producing Percent
Leases Leases Leased*
------------------------------------------------------------------------
Colorado (Gross) 9 20 30
------------------------------------------------------------------------
Northwest IPA 7 34 41
(Predicted)
------------------------------------------------------------------------
North IPA (Predicted) 2 22 25
------------------------------------------------------------------------
Grand Valley/ 3 11 14
Uncompahgre IPA
(Predicted)
------------------------------------------------------------------------
Total, Predicted range 5 25 30
------------------------------------------------------------------------
Utah (Gross) 10 19 31
------------------------------------------------------------------------
Uintah Basin (mapped 17 32 51
occupied)
------------------------------------------------------------------------
Carbon and Emery 4 48 52
Counties (mapped
occupied)
------------------------------------------------------------------------
Wyoming (Gross) 6 21 27
------------------------------------------------------------------------
Total (Gross) 7 20 28
------------------------------------------------------------------------
Oil and gas development is a major cause of development in the
gross range of the species and is likely to continue into the
foreseeable future at similar rates of development. Twenty-eight
percent of the species' gross range is authorized for leasing. Leasing
does not guarantee development, and therefore we consider the area
leased Federally to be an estimate of the rangewide development,
including non-Federal estate. A minimum of 13,000 additional wells will
be authorized in the foreseeable future. However, energy development
will not occur uniformly across the landscape. Most development will
occur in areas of high resource potential. Development is also mediated
by variations in well density and spacing. There are localized regions
across the white-tailed prairie dog's gross range where development is
most prevalent, including the Uinta Basin in Utah, the Northwest IPA in
northwestern Colorado, and the southwestern region of Wyoming. The
impacts to white-tailed prairie dogs would thus be greater in these
locations than in other parts of the species' gross range.
In areas where energy development overlaps occupied white-tailed
prairie dog habitats, the resulting habitat loss and fragmentation
likely has negative effects on individuals and populations, including
mortality, noise disturbance, and habitat loss and fragmentation.
Presumably, there is a threshold level wherein habitat loss and
fragmentation may threaten the white-tailed prairie dog, at least in
localized regions. However, our available information indicates energy
development does not currently significantly threaten the species; for
example, large prairie dog complexes continue to persist in areas of
high energy development (see Colorado and Utah, above). Based on the
information available to us, we have determined that oil and gas
development does not significantly threaten the white-tailed prairie
dog now or in the foreseeable future.
Development of Oil Shale, Tar Sands, and Other Minerals
Extraction of oil shale and tar sands results in the removal of
wide swaths of habitat. Oil shale and tar sands development results in
a loss of habitat of the entire lease, although only portions of the
lease would be impacted at a given time. Impact footprints for oil
shale leases for strip mines are approximately 2,331 ha (5,760 ac) in
size (BLM 2008c, p. 4:4), and each surface retort mine (an underground
mine with processing of the material above ground) is approximately 668
ha (1,650 ac) (BLM 2008c, p. 4:8). When an area is processed, the
impact footprint shifts to another portion of the lease, and mined
areas are reclaimed. The success of reclamation varies dependent on
site conditions (BLM 2008c, p. 4:71). Oil shale and tar sand
development activities can result in long- term or permanent habitat
loss and fragmentation of white-tailed prairie dog habitats (BLM 2008c,
p. 4:109) depending on the quality and success of habitat reclamation.
Oil shale and tar sands resources occur across 8 percent of the
gross range of the species (Hotze, 2010, p. 34). Approximately
1,228,100 ha (3,034,696 ac) of potentially productive land for oil
shale and tar sands occurs in Wyoming and Utah (BLM 2008c, p. 2:113),
and the BLM made available 660,215 ha (1,631,424 ac) of Federal land
for leasing in this area (BLM 2008c, p. ES:7). A very small portion of
the white-tailed prairie dog's gross range is identified for leasing in
Colorado (Seglund and Schnurr 2009, p. 121).
Oil shale and tar sands development has failed to materialize due
largely to technological problems and unfavorable economics.
Significant economic questions remain regarding the development of the
Green River formation oil shale and tar sands resources (Bartis et al.
2005, pp. 15, 53; BLM 2006, pp. 7, 15-19, 31, 34-36). The cost
associated with an essentially new industry using new and innovative
technologies is likely to be great.
[[Page 30348]]
Economic success of oil shale- and tar sands-derived petroleum will
depend on continuing high and stable petroleum prices. Due to past
fluctuation of petroleum prices, private industry has exhibited a
reluctance to proceed with research, development, and subsequent
commercial production of oil shale. This situation will likely continue
unless the petroleum industry is convinced that petroleum prices will
remain high well into the future (Bartis et al. 2005, pp. 59-61; Bunger
et al. 2004, pp. 7-9).
Oil shale and tar sands extraction and development remains a
speculative industry. At this time, we believe it is unlikely that the
BLM will begin leasing the identified properties for development within
the foreseeable future, which we define as approximately 10-15 years.
In addition, while oil shale and tar sands resources overlap 8 percent
of the species' gross range, actual oil shale and tar sands development
facilities overlap with only a small portion (less than 0.1 percent) of
the species' gross range. We do not believe development of oil shale
and tar sands is a significant threat to the species now or in the
foreseeable future.
Mineral Development
Coal, uranium, sand, and gravel mining can result in the removal of
habitat (BLM 2004, p. 4:12). These activities have the potential to
result in long-term or permanent habitat loss and fragmentation,
depending on the quality and success of habitat reclamation. These
activities are not common land uses on BLM holdings in the gross range
of the species. The BLM solid mineral leases total 108,170 ha (445,209
ac), less than 1 percent of the species' gross range (Hotze 2010, p.
30). The BLM coal leases total 88,167 ha (217,866 ac), also less than 1
percent of the species' gross range (Hotze 2010, p. 32). Available
evidence does not suggest solid mineral leases are more common on
private lands. Available information does not suggest they will become
more widespread within the species' gross range in the future. Given
the small percentage of the gross range impacted by these activities,
we do not believe mineral development is a significant threat to the
species now or in the foreseeable future.
Renewable Energy Development--Wind and Solar
The BLM has accessed areas of renewable resource potential with the
objective of allowing the industries to focus development in the areas
of highest potential (BLM and DOE 2003, p. 2). The majority of the
species' gross range (Federal and non-Federal lands) has a low (~ 5kWh/
m2/day) amount of direct solar resources (BLM and DOE 2003, p. A2).
Currently, less than 1 percent of the species' range has been leased by
BLM for development of solar resources (BLM 2009, unpublished data). We
are unaware of solar developments on private land within the gross
range of the species. The majority of the land containing the species'
range is federally owned, and therefore we consider potential solar
developments on non-Federal land to be insufficient to threaten the
species. Given the limited solar resources and lack of development to
date in the species' range, we do not consider solar energy to be a
significant threat to the species now or in the foreseeable future.
Wind energy could impact the species by creating habitat loss,
disturbance, or fragmentation; increasing the amount of invasive
vegetation; increasing direct mortality; and increasing disturbance
from noise and human presence (BLM 2005b, p. 5:42). Wind power has
experienced a rate of expansion greater than any other renewable energy
resource, and continued increases are predicted through 2030 (EIA 2009,
pp. 47, 74). Depending on costs, wind power production could increase
nationwide by as much as 38 percent by 2030 (EIA 2009, p. 74).
The BLM manages more land areas of high wind resource potential
than any other land management agency. In 2005, the BLM completed the
Wind Energy Final Programmatic Environmental Impact Statement (EIS)
that provides an overarching guidance for wind project development on
BLM-administered lands (BLM 2005b, entire). Best management practices
are prescribed to minimize impacts of all phases of construction and
operation of a wind production facility. We do not have information on
how or where the EIS guidance was applied since 2005 and, therefore,
cannot evaluate its effectiveness.
Wind energy developments leased by the BLM total 823,358 ha
(2,034,562 ac), or approximately 4 percent of the species' gross range
(Hotze 2010, p. 28). Only 5 to 10 percent of a development will have
long-term surface disturbances (i.e., roads, foundations, substation,
fencing) (BLM 2005b, p. 5:2).
To evaluate the potential of future wind energy developments to
impact the species, we examined the potential locations for
development. Within the species' gross range in Colorado and Utah, only
poor and marginal wind power resources exist (NREL 2003, entire; NREL
2004, entire). In Wyoming, there are pockets of good, excellent, and
outstanding wind power within the species' gross range in Fremont,
Natrona, and Carbon Counties (NREL 2002, entire). The majority (more
than 75 percent) of these counties are federally owned land. However,
better wind power resources (rated as outstanding and superb, based on
wind speeds) are available east of the species' gross range (NREL 2002,
entire). We expect areas with the best wind resources will be developed
first and receive more total development.
We are unable to quantify the wind development scenario for private
lands in the species' gross range. No central organization currently
tracks wind development on private lands. Given the small amount of
private land that coincides with an economically developable wind
resource, we assume a maximum development of less than 10 percent of
the species' gross range in Wyoming.
The BLM maximum potential development scenario for wind energy in
the entire State of Wyoming is an estimated total of 3,197,937 ha
(7,902,000 ac) of potentially developable lands, but a much smaller
amount is likely to be developed on BLM-administered lands (1,497 ha
(3,700 ac)) (BLM 2005b, p. 5:2). The BLM estimates that only 5 to 10
percent of BLM area, or 150 ha (370 ac) of lands, will have long-term
surface disturbance (BLM 2005b, p. 5:2). We expect that much of the
economically developable land exists outside the species' gross range,
and given the small size of the total area on Federal lands likely to
be developed in Wyoming (1,497 ha (3,700 ac)), and that the majority of
the species' range occurs on Federal lands, we do not expect wind
energy development to have a significant impact on the species.
Because only small portions of the species' gross range are
currently impacted by wind development and expected to be impacted in
the future, we do not believe wind energy development represents a
significant threat to the species. Given that projected development is
small in regard to the size of the species' gross range, and that the
majority of development will take place where better resources exist,
we expect the overall impact of wind development on the white-tailed
prairie dog to be low.
Urbanization
Conversion of land for urban development results in a permanent
loss of habitat and fragmentation for many species, including the
white-tailed prairie dog. Increases in major population centers result
in increased infrastructure, such as roads and
[[Page 30349]]
transmission lines. These infrastructure features may impact habitats
beyond the immediate urban area. Increased urbanization can introduce
domestic animals, such as dogs and cats, that may prey on some prairie
dogs (Magle and Crooks 2009, p. 198). Human population growth may
result in an increased use of surrounding public lands for recreation
(Seglund and Schnurr 2009, p. 54).
The effects of urban fragmentation on the white-tailed prairie dog
have not been studied. Some information exists for the black-tailed
prairie dog. Weights and sex ratios of black-tailed prairie dogs in
urban environments were within normal ranges for the species (Magle
2008, p. 116). However, black-tailed prairie dogs were more likely to
occur on larger, contiguous habitats within the urban environments
rather than smaller, highly fragmented parcels (Magle and Crooks 2009,
p. 197). Collapses of existing colonies were observed within highly
fragmented urban environments (Magle and Crooks 2009, pp. 197, 199).
This information suggests that some prairie dogs can survive in
fragmented habitat, but population loss increases with degree of
fragmentation and amount of time since fragmentation occurred (Magle
and Crooks 2009, p. 200).
The rate of urbanization within the Rocky Mountain region is below
the national average (White et al. 2009, pp. 41-42). As of 2004,
urbanization affected 0.2 percent of the white-tailed prairie dog's
gross range (Seglund et al. 2006, p. 45). Much of the existing and
future predicted urbanization is localized to specific population
centers, as further described below.
Colorado
Twenty-eight percent of the overall white-tailed prairie dog's
predicted range is expected to be impacted by high density urban
development (i.e., less than 16 ha (40 ac) per housing unit), 5 percent
by moderate density urban development (16 to 32 ha (40 to 80 ac) per
housing unit), and 8 percent by low density urban development (greater
than 32 ha (80 ac) per housing unit) by 2020 in Colorado (Seglund and
Schnurr 2009, p. 171). Public land comprises 59 percent of the species'
predicted range in Colorado and is not expected to be impacted by
urbanization (Seglund and Schnurr 2009, p. 171). We expect that only
moderate and high density urban development will negatively impact the
species, because low density developments still provide large expanses
of area for colonies to exist and allow for connectivity between
colonies.
The majority of urban development is predicted to occur in the
Grand Valley-Uncompahgre IPA (Seglund and Schnurr 2009, pp. 52, 54).
Urbanization has already fragmented white-tailed prairie dog habitats
in this IPA (Seglund and Schnurr 2009, p. 54). By 2020, 37 percent of
the IPA is expected to be impacted by high or moderate density urban
development (Seglund and Schnurr 2009, p. 174). However, urbanization
will be localized largely to the Grand Junction and Montrose urban
areas. High or moderate density urban development will occur across
much less of the North IPA (0.9 percent) and Northwest IPA (0.4
percent) (Seglund and Schnurr 2009, p. 174).
Urbanization has the potential to impact the species in Colorado,
particularly in portions of the Grand Valley/Uncompahgre IPA. However,
as noted above, high-density urbanization will be localized primarily
to the human population centers of Grand Junction and Montrose. Because
of its localized impact and the availability of large acreages of
Federal, non-urbanized lands in the species' predicted range, we do not
consider urbanization to be a significant threat to the species in
Colorado now or in the foreseeable future.
Montana
In Montana, 49 percent of the species' predicted range is privately
owned (Table 1, above). Private land uses include grazing, agriculture,
and housing; a metropolitan area is located in nearby Carbon County. At
one time, 31 distinct white-tailed prairie dog colonies occurred in
Montana. Urbanization resulted in the loss of 3 colonies to road
construction and development (Begley 2010b, pers. comm.). An additional
20 colonies were lost to impacts associated with mining, agriculture,
or other unknown causes not directly attributable to urban development
(Begley 2010b, pers. comm.).
Of the eight remaining colonies in Montana, four occur on privately
owned land (Begley 2010b, pers. comm.). Three of these colonies are in
areas that support livestock grazing (Begley 2010b, pers. comm.). We
are unaware of any plans to develop these properties in the foreseeable
future. The remaining four colonies occur on Federal lands and are thus
not threatened by urbanization. Therefore, we do not consider
urbanization in Montana to significantly threaten the species now or in
the foreseeable future.
Utah
Urban development is expected to expand by 188,600 ha (466,041 ac)
across the State of Utah by the year 2030 (White et al. 2009, p. 44).
However, development is localized to metropolitan areas along the
Wasatch front in Weber, Morgan, Summit, Davis, Salt Lake, Toole, Utah,
and Juab Counties (U.S. Department of Agriculture (USDA) 2008, p. 2;
U.S. Census Bureau (USCB) 2005a, p. 1). These areas do not overlap the
species' gross range.
The majority of white-tailed prairie dogs in Utah occur in the
Uinta basin (Lupis et al. 2007, p. 17). The potential for future urban
development in the Uinta Basin is associated largely with the city of
Vernal (USCB 2005a, p. 1). Vernal is a support and staging area for the
oil and gas development (see Factor A. Oil and Gas Exploration and
Development) of the Uinta basin; increased urbanized development is
primarily the result of increased oil and gas expansion. However, much
of the required urban infrastructure is already in place, and the
majority of gross range in Utah is managed by Federal agencies (Table
1, above). The gross range and mapped occupied habitat of the white-
tailed prairie dog in the Uinta basin does not overlap the developing
areas associated with the city of Vernal; thus we expect that most of
the predicted development through 2030 will occur outside of the
species' gross range.
We evaluated the likely centers for urbanization in Utah through
2030 and compared these to the gross range and mapped occupied habitat
of the white-tailed prairie dog. Based on our evaluation, we do not
consider urbanization to be a significant threat to the species in Utah
now or in the foreseeable future.
Wyoming
Wyoming has the largest amount of white-tailed prairie dog habitat
and the smallest amount of predicted development. Over 46 percent of
the species' gross range occurs in counties with no urban development:
Park, Big Horn, Washakie, Hot Springs, Sublette, and Carbon Counties
(USCB 2005b, p. 1). Only localized, small portions of the remaining
counties will be impacted in the metropolitan area of Casper and the
micropolitan areas of Riverton, Evanston, Rock Springs, and Laramie
(USCB 2005b, p. 1). Given these factors, we do not believe urbanization
is a significant threat to the species in this State now or in the
foreseeable future.
In summary, habitat loss and fragmentation due to urbanization may
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impact the white-tailed prairie dog, but only in localized areas. There
is no indication that there will be significant increases in
urbanization across the species' gross range in the future. Therefore,
we do not believe urbanization to be a threat to the species now or in
the foreseeable future.
Agricultural Land Conversion
Agricultural land conversion is the change in land use from any use
to an agricultural use, including crops and pastures. Agricultural
crops can benefit prairie dogs by providing highly nutritious forage
(Crocker-Bedford 1976, pp. 73-74; Seglund and Schnurr 2009, p. 95).
However, these colonies also are subject to additional mortality
factors including higher lethal control efforts (see Factor B. Shooting
and Factor E. Poisoning) to protect crops (Knowles 2002, p. 12),
increased habitat fragmentation from fences and roads, and increased
urban predators (Seglund and Schnurr 2009, p. 95).
The impact of past agricultural conversion is difficult to
determine given how little we know about the historical range of white-
tailed prairie dogs. Historical population declines occurred for all
prairie dog species, and range contractions were documented for white-
tailed prairie dogs in localized areas in Colorado and Montana (Knowles
2002, p. 12). However, we do not know if these losses were the result
of agricultural conversion or other factors; it is likely that
historical population losses were the result of a combination of
impacts across the range of the species. Agricultural land conversion
probably displaced some white-tailed prairie dogs in areas of Colorado
and the Big Horn Basin in Wyoming (Knowles 2002, p. 12).
Today, agriculture occurs across 3.7 percent of the gross range of
the white-tailed prairie dog (Seglund et al. 2006, p. 50). Many of the
areas currently inhabited by white-tailed prairie dogs are arid and
semi-arid with short growing seasons (Seglund et al. 2006 pp. 4-5) and
therefore have limited potential for crops. In Colorado, the counties
containing white-tailed prairie dogs saw a decrease in the amount of
agricultural land by an average of 37 percent between 1954 and 2002
(calculated from data in Seglund and Schnurr 2009, p. 96). Farm land
(e.g., crops, pasture, grazing (not including Federal grazing permits),
USDA 2009, p. B:14) acreages have continued to decline across all
States and counties that occur within the gross range of the white-
tailed prairie dog (see Table 3, below). There is not a direct
correlation between the decline in farm lands and increases in other
land uses, although it is likely that the farmland has been re-
converted to other rural uses, such as grazing, or has become urbanized
(see Factor A. Urbanization).
TABLE 3. Percentage Decrease of Farm Land, Statewide and in Counties
partly or wholly contained within the Range of the White Tailed Prairie
Dog, Between 2002 and 2007 (USDA 2009, pp. CO 316, UT 249, WY 268, 316).
------------------------------------------------------------------------
Counties
Within
White-
State Statewide tailed
Prairie Dog
Range
------------------------------------------------------------------------
Wyoming 12.1 14.0
------------------------------------------------------------------------
Colorado 7.6 9.5
------------------------------------------------------------------------
Utah 2.3 13.1
------------------------------------------------------------------------
Average 7.3 12.2
------------------------------------------------------------------------
In summary, agricultural land conversion was likely a major
historical impact on the species. However, many of the areas currently
inhabited are not suitable for crop lands, and appear to be supporting
sufficient populations of the species. The effects of land conversion
on the species are mixed, and currently very limited land is being
converted to agricultural uses. Therefore, we do not consider
agricultural land conversion to be a significant threat to the species
now or in the foreseeable future.
Grazing
Native herbivores, such as pronghorn antelope (Antilocarpo
americana), mule deer (Odocoileus hemionus), and bison (Bison bison),
occurred in the sagebrush-steppe region prior to European settlement of
western States (Osborne 1953, p. 267; Miller et al. 1994, p. 111), and
prairie dogs co-evolved with these grazers. Domestic livestock grazing
in the intermountain west began with the arrival of European settlers
in the 1800s. The numbers of livestock were unregulated, and peaked in
the early 1900s (Oliphant 1968, p. vii; Young et al. 1976, pp. 194-195,
Carpenter 1981, p. 106; Donahue 1999, p. 15; Seglund et al. 2006, pp.
49, 51), with an estimated 19.6 million cattle and 25 million sheep in
the West (BLM, 2009, pp. 1-2).
Excessive grazing by domestic livestock during the late 1800s and
early 1900s, along with severe drought, significantly impacted
sagebrush ecosystems (Knick et al. 2003, p. 616). Livestock grazing
continues to be the most widespread type of land use across the
sagebrush biome (Knick et al. 2003, p. 616; Connelly et al. 2004, pp.
7-29; Knick et al., in press, p. 27). However, the intensity of grazing
on all Federal lands has declined since the early 1900s (Laycock et al.
1996, p. 3).
Livestock grazing can affect ecosystem functions and structures,
including a general decrease in grass and shrub cover, total plant
biomass, and rodent species diversity and richness (Fleischner 1994,
pp. 633-635; Jones 2000, pp. 160-161). Fencing and roads associated
with grazing may cause habitat fragmentation and may directly or
indirectly cause increased mortality of prairie dogs by increasing
prairie dog-vehicle collisions, creating perch sites for raptors, and
providing access corridors for predators (Call and Maser 1985, p. 3;
Connelly et al. 2000, p. 974; Connelly et al. 2004, pp. 1-2).
``Overgrazing'' refers to continued heavy grazing beyond the
recovery capacity of the forage plants (Vallentine 1990, p. 329).
Overgrazing causes the palatable and preferred herbaceous vegetation of
prairie dogs to be preferentially removed, allowing shrubs and
unpalatable plants to flourish. Overgrazing can facilitate the
establishment of invasive species such as cheatgrass (Bromus tectorum)
(Masters and Sheley 2001, p. 503) (see below for more information). The
intensity, duration, and distribution of livestock grazing are more
influential on rangeland condition than livestock density (Aldridge et
al. 2008, p. 990). Grazing impacts to rangeland are determined by the
type of animal, stocking rate, duration of grazing, season of use, and
current habitat conditions (Vallentine 1990, entire).
Impacts of livestock grazing on white-tailed prairie dogs are not
known largely because of our lack of historical species distribution
information and the lack of ungrazed habitats as a baseline (Seglund et
al. 2006, p. 49). Overgrazing may impact prairie dogs by degrading the
quality and quantity of forage; decreasing forage availability during
important breeding, rearing, and pre-hibernation periods; and
decreasing white-tailed prairie dog reproductive success and over-
wintering survival (Seglund et al. 2006, p. 49). However, the potential
for impacts is likely to be site-specific. For example, removing
livestock from shrub-steppe habitat can result in either an increase of
species richness (Anderson and Inouye 2001, pp. 538, 544-545, 549-550),
or a decrease in species richness (Manier and Hobbs 2007, p. 743),
depending on site variables.
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Grazing effects to other prairie dog species are known to some
degree. Livestock grazing can have positive effects on black-tailed
prairie dog colonies because of grazing's effect of converting mid-
height and tall grasses to short grasses improves predator surveillance
visibility (Uresk et al. 1981, p. 200; Cable and Timm 1987, p. 46).
Overgrazing was shown to negatively affect Utah prairie dog growth
rates, foraging ability, and survivorship (Cheng and Ritchie 2006, p.
550). Utah prairie dog colony extinction rates increased as plant
species richness declined due to overgrazing (Ritchie 1999, p. 12).
Heavy grazing also can contribute to an increase in shrubs in Utah
prairie dog habitat (Crocker-Bedford 1976, p. 88). However, over time,
Utah prairie dogs prefer areas with moderate grazing intensities over
ungrazed areas, because sufficient forage remained available in the
grazed plots (Cheng and Ritchie 2006, p. 554); cattle cannot eat plants
below 2 centimeters (0.879 in), limiting the impacts of moderate
grazing on prairie dogs. Results from the Utah prairie dog studies are
most applicable to white-tailed prairie dogs due to similarities in
habitat preferences. Both species use arid shrub-steppe habitats, and
white-tailed prairie dogs can utilize shrub cover for hiding (Gadd
2000, pp. 24-26). Therefore, we assume that white-tailed prairie dogs
react to grazing in a similar manner to Utah prairie dogs. However,
reactions to overgrazing may not be as extreme in the white-tailed
species due to their higher shrub tolerance.
We do not have information regarding site-specific range conditions
on Federal or non-Federal allotments that overlap white-tailed prairie
dog habitats. Range condition data is not collected in a manner that is
biologically meaningful for small mammals. White-tailed prairie dogs,
being a diet generalist living in arid environments, can persist with
limited forage. It is unknown how far range condition must deteriorate
before a habitat becomes incapable of supporting a colony. Therefore,
we do not know how much of the habitat is overgrazed versus moderately
grazed. It is likely that overgrazing impacts white-tailed prairie dog
colonies in localized portions across the species' range. However, the
available literature indicates that prairie dogs can coexist with some
level of grazing, and in some cases, benefit from grazing. White-tailed
prairie dogs have persisted during higher historical grazing pressures
and livestock stocking rates have declined substantially. Therefore, we
do not consider grazing to be a significant threat to the species now
or in the foreseeable future.
Fire Occurrence and Suppression
The shrub-steppe habitat occupied by the white-tailed prairie dog
evolved with infrequent fire frequency intervals of 100 to 450 years
depending on the dominant species of sagebrush (Baker 2006, pp. 180-
181). Fire suppression activities also were infrequent (Baker 2006, p.
182) and probably had little effect on sagebrush landscapes (Baker in
press, p. 22).
Fire ecology of sagebrush habitats has changed since European
settlement of the West. In general, fire frequencies have increased in
lower elevation sagebrush habitats due to (and resulting in further)
invasion of nonnative annual grasses, such as cheatgrass (Baker 2006,
p. 178; Crawford et al. 2004, p. 8). Fire frequencies also have
increased due in part to human activities and presence (Miller et al.
in press p. 38). Fire frequencies have declined in higher elevation
sagebrush habitats, resulting in the expansion of shrubs and trees
(Miller and Rose 1999, p. 557; Baker 2006, p. 178; Crawford et al.
2004, p. 8). The number of fires and total area burned increased from
1980-2007 in sage-grouse habitat (Miller et al. in press, p. 39); this
overlaps much of the white-tailed prairie dog's gross range in Wyoming
and Colorado. However, the habitat mosaics and effects to wildlife
resulting from fires are not well understood and vary across the
landscape (Baker 2006, pp. 178, 183).
We do not have information specific to the effects of fire or fire
suppression on white-tailed prairie dogs. White-tailed prairie dogs are
adapted to a shrub-steppe grass mosaic. They use shrubs as forage and
cover from predators (Tileston and Lechleitner 1966, pp. 31, 302;
Hoogland 1981, pp. 266-268; Gadd 2000, pp. 24-26). They feed on forbs
and grasses, and these can be increased by fire in shrubland habitat
(Pyle and Crawford 1996, p. 323; Davies et al. 2007, p. 518).
We anticipate that the impacts of fire to white-tailed prairie dogs
will vary locally across the species' gross range. In some places where
fire has occurred, shrub or pinyon-juniper invasions are likely to
occur and may reduce available sagebrush communities for the species
(Miller and Rose 1999, p. 557). In other cases, cheatgrass may become
the dominant plant species (Baker 2006, p. 178; Crawford et al., p. 8),
reducing preferred forage quantity and quality for the white-tailed
prairie dog. However, the white-tailed prairie dog is able to use the
mosaic of habitats created by fire and fire suppression activities, and
thus we do not believe that fire occurrence or suppression is a
significant threat to the white-tailed prairie dog now or in the
foreseeable future.
Invasive Plant Species
Invasive plant species are promoted by intense levels of
disturbance to the environment (Masters and Shelley 2001, p. 504), such
as oil and gas development, agriculture, and urbanization. Invasive
plant species alter ecological processes by displacing native species,
increasing the vulnerability of communities to more invaders, and
reducing wildlife habitat quality (Masters and Sheley 2001, p. 503).
They can be particularly damaging in areas of low moisture, including
shrub-steppe habitats, because they reduce water infiltration of the
soil and possess deeper roots than native species, allowing them to use
more water and reduce nutrient availability over time (DiTomaso 2000,
p. 257). The proliferation of exotic annual weeds over native perennial
grasses and forbs may impact the ability of white-tailed prairie dogs
to meet their dietary needs, especially during drought years. Utah
prairie dog colony extinction rates were found to increase as the
number of locally occurring plant species declined (Ritchie 1999, p.
12). Cheatgrass in particular is widely distributed across the gross
range of the white-tailed prairie dog. Cheatgrass creates an altered
fire regime, increasing the amount of fire and reducing native grasses
and shrubs (Masters and Sheley 2001, p. 503). Juniper species have
invaded sagebrush habitat beginning with European settlement (Miller
and Rose 1999, pp. 551, 555), and may result in decreased habitat if
forestation progresses.
The main effect of invasive species is the decrease in habitat
quality and forage. Some habitat may be lost due to pine-juniper
invasion. It is likely that invasive species will have localized
impacts to individual white-tailed prairie dog habitat. Presumably, a
certain amount of invasive species is tolerable. Despite localized
impacts, no data indicate that invasive species are threatening the
species on a rangewide scale. At this point, the available information
does not indicate that invasive species, although present within the
gross range, are a significant threat to the white-tailed prairie dog
now or in the foreseeable future.
Climate Change
Global surface temperatures rose (with regional variations) during
the past 157 years, with the largest increases occurring since the
1970s (Trenberth et
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al. 2007, p. 252). Globally, average surface temperatures rose by 0.074
degrees Celsius ([deg]C) plus or minus 0.018 [deg]C (0.13 degrees
Fahrenheit ([deg]F) plus or minus 0.03 [deg]F) per decade during the
past century (1906 through 2005) and by 0.177 [deg]C plus or minus
0.052 [deg]C (0.32 [deg]F plus or minus 0.09 [deg]F) per decade during
the past quarter-century (1981 through 2005) (Trenberth et al. 2007, p.
253).
Similar surface temperature increases occurred across the gross
range of the white-tailed prairie dog. The Southwest region, including
the Colorado and Utah portion of the species' gross range, observed a
0.83 [deg]C (1.5 [deg]F) increase in average temperatures when compared
to a 1960 to 1979 baseline (Karl et al. 2009, p. 129). The Great Plains
region (including the Wyoming and Montana portion of the gross range)
experienced a 0.83 [deg]C (1.5 [deg]F) increase over average
temperatures, compared to the same baseline (Karl et al. 2009, p. 123).
Drought conditions across the species' gross range were moderate to
extreme (Marshall et al. 2008, p. 274).
The timeframe over which the best available scientific information
allows us to reliably assess the effects of climate change is an
important consideration. Until about 2050, greenhouse gas emissions
scenarios (reviewed in the Intergovernmental Panel on Climate Change
Special Report on Emission Scenarios in 2000, as cited in Ray et al.
2009, p. 8), which are an essential component of any climate change
assessment, result in a similar range of projections of global and
regional climate change (Ray et al. 2009, p. 8). Temperature increases
over the next 30 to 50 years are relatively insensitive to the
emissions scenarios used to model the projected change. Some warming,
as projected in the greenhouse gas emissions scenarios, is anticipated
as a result of greenhouse gases already in the atmosphere that will
influence future climate, more so for mid-century versus late century
(Meehl et al. 2007, p. 749; Mote and Salathe 2009, p. 30). The range in
the spread of the models is due both to details in the formulation
(which includes emission scenarios) of each individual model, and
natural variability in climate. Because increases of greenhouse gas
emissions have lag effects on climate, and because projections of
greenhouse gas emissions can be interpreted with greater confidence
until approximately mid-century, model projections for the next 30 to
50 years (centered on 2050) have greater credibility than results
projected further into future. On the basis of available information,
we have determined that predicted climate changes for 2025 and 2050 are
more reliable than projections for the second half (up until 2100) of
the 21st century and as such, we consider 2050 to represent the
foreseeable future.
One scenario predicts an average increase in annual temperature in
western North America (covering the entire gross range of the species)
of between 1.1 to 3.4 [deg]C (2 to 4 [deg]F) by 2050, compared to a
1961 to 1979 baseline in the western United States (Smith et al. 2000,
p. 29). Other predictions range from an annual mean warming of about
1.4 to 3 [deg]C (2.5 to 5.5 [deg]F) by 2050 as part of a continent-wide
pattern of warming (Ray et al. 2009 p. 15). The projections show
summers warming more (1.7 to 3.9 [deg]C (3 to 7[deg]F)) than winters
(1.1 to 2.7 [deg]C (2 to 5 [deg]F)) (Ray et al. 2009 p. 15)
Climate change will affect precipitation. Generally, a reduction of
depth, duration, and distribution of snowpack is expected (Solomon et
al. 2007, pp. 770-772; Marshall et al. 2008, p. 276). Precipitation is
predicted to decrease in the Southwest region (Karl et al. 2009, p.
129), and increase in the Great Plains region (Karl et al. 2009, p.
123). Climate change also will affect plague ecology (please see Factor
C. Disease and Predation, below).
Recent climatic changes, including increased temperatures and
freeze-free periods, and changes in precipitation, are important
driving forces on ecosystems and have affected a wide variety of
organisms with diverse geographic distributions (Walther et al. 2002,
pp. 391-392; Parmesan and Yohe 2003, p. 41). Many plant and animal
species have advanced the timing of spring events (e.g., plant
flowering or bird migration) to occur earlier in the year and
experienced a shift in latitudinal and altitudinal range (i.e.,
movement to higher latitudes or higher altitude) (Walther et al. 2002,
pp. 391-392).
The white-tailed prairie dog and its habitat will likely be
affected in some manner by climate change. Climate change could impact
habitat quality, which may in turn affect prairie dog productivity. For
example, higher quality habitats promote higher weaning success of
adult and yearling female white-tailed prairie dogs (Cooke 1993, in
Seglund et al. 2006, p. 7). We would expect higher quality habitats to
occur in areas where rainfall is predicted to increase. Alternatively,
increased drought in the southwestern portion of the gross range could
reduce vegetation quality and quantity, resulting in lowered nutrition
for the white-tailed prairie dog (Collier and Spillet 1975, p. 153;
Seglund et al. 2006, p. 64). Drought may result in more time spent in
burrows and less time spent foraging, as well as water-stress from lack
of succulent forage (Collier and Spillet 1975, p. 153).
Population fluctuations of white-tailed prairie dog colonies at the
Coyote Basin Subcomplex, Kennedy Wash Subcomplex, and Snake John
Subcomplex in Uintah County, Utah, were likely the result of drought
(Maxfield 2009, pers. comm.). The 2002 drought resulted in a decrease
in available forage for white-tailed prairie dogs at a time when
populations had peaked. This resulted in little or no reproduction in
2003, and a population crash in 2004 (Maxfield 2010, pers. comm.).
Habitat conditions improved and the colonies rebounded to pre-drought
population levels by 2008-2009 (Seglund et al. 2006, p. 101; Maxfield
2010, pers. comm.), indicating a level of resiliency of this species to
withstand at least short-term climatic variations.
Life-history characteristics of the white-tailed prairie dog may be
responsible for its resiliency and may provide protection from effects
of climate change. The burrowing and hibernating behaviors of prairie
dogs provide protection in times of low resource availability and
unfavorable conditions, including those associated with climate change
(Liow et al. 2009, pp. 264, 270). Overwinter survival and reproductive
success is linked to habitat quality (Rayor 1985, p. 2839), so lack of
adequate food resources during drought leads to a decrease in
reproductive output as seen above. Individual animals also may adapt by
becoming mostly inactive during times of drought (Liow et al. 2009, p.
270).
Shifts in the geographic ranges of wildlife have occurred as an
effect of climate change (Walther et al. 2002, pp. 390-391), and may
thus be anticipated for the white-tailed prairie dog. Due to the large
gross range of the species (from the Southwest to the Great Plains,
which are projected to have much different impacts from climate change,
as discussed above), we expect the effects of climate change to vary
throughout the species' gross range, both in nature of the impact and
the timing of these effects. In addition, the species' gross range is
contained within a region that already witnesses climatic variability
as climate varies considerably between years (Smith et al. 2000, p.
224). Therefore we expect the effects of climate change to vary
temporally (year-to-year) as well. This variation in effects will
buffer the cumulative effects of climate change on the species as a
whole because only a
[[Page 30353]]
portion of the gross range will be impacted at a given time.
Although the white-tailed prairie dog will likely be affected by
climate change, it is not apparent that a net loss in occupied habitat
will result. Variation in conditions across the gross range and a
possible gross range shift could maintain sufficient habitat for the
species. The species is adaptable to a wide array of climes, as
evidenced by a geographic range that includes four States, as well as a
wide elevational distribution (see Ecology and Life History, above).
Unlike more vulnerable species in polar, coastal, and alpine
ecosystems, habitat space exists to accommodate shifts in range.
Therefore, we do not believe that climate change poses a threat to the
species now or in the foreseeable future. The relationship between
climate change and plague is discussed in more detail below (see Factor
C. Disease or Predation).
Summary of Factor A
Energy development, urbanization, agricultural conversion, grazing,
fire suppression, introduction of invasive plant species, and climate
change within the gross range of the white-tailed prairie dog have
occurred and will continue to occur in the future. We do not expect oil
shale, tar sands, coal, and other mineral extraction activities to
impact a large portion of the species' gross range. Urbanization will
have an effect on some local populations, particularly in Colorado, but
is not considered a rangewide threat. Grazing is likely impacting some
areas of habitat, but no evidence indicates it is a significant threat.
A net loss of habitat is not expected to result from climate change.
Oil and gas development has the most potential to impact the species
due to its widespread distribution and magnitude, yet the intensity of
these activities varies greatly across the range due to differences in
well density and spacing. Robust colonies and complexes exist even in
the most developed areas. The majority of the gross range has not been
subject to the intensity of development witnessed around robust
colonies of Coyote Basin and Wolf Creek. While further development will
occur, we expect the majority to occur in areas with high potential for
productivity. Therefore, we do not consider oil and gas to be a
significant threat to the species. We have no indication that invasive
plant species are a significant threat to the white-tailed prairie dog
now or in the foreseeable future.
We conclude that the best scientific and commercial information
available indicates that the white-tailed prairie dog is not now, or in
the foreseeable future, threatened by the present or threatened
destruction, modification, or curtailment of its habitat or range to
the extent that listing under the Act as an endangered or threatened
species is warranted at this time.
Factor B. Overutilization for commercial, recreational, scientific, or
educational purposes.
White-tailed prairie dogs were historically subjected to
recreational hunting and shooting as a form of pest management on ranch
and agricultural land; these practices continue under State regulations
(see Factor D. Inadequacy of Existing Regulatory Mechanisms).
The effects of recreational shooting on white-tailed prairie dogs
have not been examined. We do have limited information on how shooting
affects black-tailed prairie dog populations. Black-tailed prairie dogs
in colonies subject to hunting spent more time in alert behaviors and
less time foraging, although this effect decreased a year after
shooting (Pauli and Buskirk 2007, p. 1223). Recreational shooting
reduced black-tailed prairie dog density at specific sites (Vosburgh
and Irby 1998, pp. 366-367; Knowles 2002, p. 14) and may negatively
affect reproductive rates (Pauli and Buskirk 2007, p. 1228). However,
recovery of black-tailed prairie dog populations following shooting
occurs (Knowles 1988, p. 54). No research has evaluated long-term
impacts from recreational shooting, although population viability
monitoring suggests it is unlikely to lead to extinctions of even small
populations (Seglund and Schnurr 2009, p. 167).
Life-history traits and species distribution are likely to mediate
the effects of shooting on white-tailed prairie dogs. The majority of
black-tailed prairie dogs do not reproduce until 2 years of age
(Hoogland 2001, p. 920). White-tailed prairie dogs, as previously
stated, reach maturity at 1 year of age. Thus, we believe that white-
tailed prairie dog populations may be able to recover from the effects
of shooting more quickly than black-tailed prairie dogs.
Human recreationists may prefer targeting black-tailed prairie dogs
because they live in larger, denser, more identifiable colonies and
their mounds are more conspicuous (Seglund et al. 2006. p. 55). White-
tailed prairie dogs are more dispersed on the landscape and use
shrubland habitat for cover from predators. As a consequence, they may
be more difficult to find and successfully shoot (Grenier 2009, pers.
comm.), limiting the number of recreationists targeting white-tailed
prairie dog colonies.
Recreational hunting is permitted rangewide, but it is unlikely
that all colonies are exposed to equal risk. Recreational hunting is
concentrated on colonies with reasonably easy access (Gordon et al.
2003, p. 12). Colonies at higher elevations or in remote areas may
never receive hunting pressure due to the difficulty in gaining access.
Colonies in close proximity to urban areas and agricultural fields
likely receive the greatest shooting pressure (Gordon et al. 2003, p.
12; Seglund et al. 2006, p. 33). Urban and agricultural land uses
affect a small part of the species' gross range (see Factor A).
The reproductive cycle of prairie dogs may influence impacts of
recreational shooting. Lactating females spend the most time above
ground, and lactation occurs during the months of April through July
(Tileston and Lechleitner 1966, p. 301). During this time, adult male
activity decreases. Recreational hunting in April, May, and June may
have the greatest population level impacts because pregnant and
lactating females and young of the year are the most vulnerable
(Vosburgh and Irby 1998, p. 369; Keffer et al. 2000, p. 7).
Recreational shooting could remove more offspring than adults or
artificially skew the population sex ratio. Thus, seasonal restrictions
may be important to reduce the effects of shooting at localized sites.
Seasonal white-tailed prairie dog hunting regulations are
implemented in Utah and Colorado. In Utah, shooting is not permitted on
white-tailed prairie dog towns between April 1 and June 15 (Utah
Division of Wildlife Resources (UDWR) 2007, p. 4). In Colorado,
shooting is not permitted on public land between March 1 and June 15
(Colorado Division of Wildlife (CDOW) 2009, p. 10). These closures may
reduce impacts to the demographic structure and are expected to provide
protection to white-tailed prairie dog populations (Seglund and Schnurr
2009, p. 165).
Recreational and pest removal shooting of white-tailed prairie dogs
is allowed without a permit across much of the species' gross range;
only Colorado requires a license. Because permits are not required,
quantifying the number of prairie dogs killed by shooting is difficult.
The only data available are from Colorado's Harvest Information Program
(CDOW 2001-2005). In this program, a random survey of registered
hunters was performed and an estimated take extrapolated from the
survey results. This program does not differentiate between species of
prairie dog, so estimates include Gunnison's,
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black-tailed, and white-tailed prairie dogs.
According to the data in Colorado's 2000-2005 Small Game Harvest
Reports, prairie dogs are not a common target among hunters. Only 4.6
to 7.4 percent of hunters reported shooting prairie dogs (CDOW 2001-
2005). In addition, as previously discussed, the majority of hunted
prairie dogs are likely to be black-tailed and Gunnison's prairie dogs,
not white-tailed prairie dogs. Therefore, we do not believe this
represents high hunting pressure on white-tailed prairie dogs.
Summary of Factor B
White-tailed prairie dogs, due to their distribution and life-
history characteristics, are likely less affected by shooting than
other species of prairie dogs. Effects of recreational shooting may be
high on specific, easily accessible, localized colonies. However we do
not expect that these effects will occur equally across the species'
gross range or significantly threaten the species as a whole.
There are no other known threats due to commercial, scientific, or
educational uses of this species. We conclude that the best scientific
and commercial information available indicates that the white-tailed
prairie dog is not now, or in the foreseeable future, significantly
threatened by the overutilization for commercial, recreational,
scientific, or educational purposes.
Factor C. Disease or predation.
Sylvatic Plague
Sylvatic plague (plague) is an exotic disease foreign to the
evolutionary history of North American prairie dogs. Plague was first
observed in wild rodents in North America near San Francisco,
California, in 1903 (Eskey and Haas 1940, p. 1), and was first
confirmed in white-tailed prairie dogs in 1936 (Eskey and Haas 1940, p.
14). It now occurs throughout the entire species' gross range (Biggins
and Kosoy 2001, p. 906; Pauli et al. 2006, p. 3).
Plague is caused by a bacterium (Yersinia pestis), which fleas
acquire by biting infected animals and subsequently transmit via a bite
to other animals (Gage and Kosoy 2005, pp. 516-517). The disease also
can be transmitted through pneumonic (airborne) or septicemic (blood)
pathways from infected to disease-free animals (Barnes 1993, p. 28; Ray
and Collinge 2005, p. 203; Cully et al. 2006, p. 158; Rocke et al.
2006, p. 243; Webb et al. 2006, p. 6236).
Plague occurs in prairie dog colonies as enzootic and epizootic
events. Enzootic plague is an infection maintained in the population
over time and causes a low rate of mortality within the colony. Not all
individuals are affected because the low density within a colony
results in less contact between individuals and a reduced transmission
rate. Epizootic plague occurs when the disease spreads from enzootic
hosts to more susceptible animals, resulting in a rapidly spreading
die-off cycle (Barnes 1993, p. 29; Biggins and Kosoy 2001, p. 909;
Cully and Williams 2001, p. 900; Gage and Kosoy 2005, pp. 506-508).
Large numbers of animals can die within a few days (Lechleitner et al.
1962, pp. 190-192; Cully 1993, pp. 40-42).
The factors that cause a change from an enzootic to epizootic cycle
are still being researched, but may include host density, flea density,
and climatic conditions (Cully 1989, p. 49; Parmenter et al. 1999, p.
814; Cully and Williams 2001, pp. 899-903; Enscore et al. 2002, p. 186;
Lomolino et al. 2003, pp. 118-119; Stapp et al. 2004, p. 237; Gage and
Kosoy 2005, p. 509; Ray and Collinge 2005, p. 204; Stenseth et al.
2006, p. 13110; Adjemian et al. 2007, p. 372; Snall et al. 2008, p.
246). Plague cycles (e.g., epizootic, recovery, enzootic) may result in
successive population peaks that are progressively lower than the
previous peak and that with each new epizootic, the loss of colonies
from plague will exceed the rate of establishment of new colonies
(Knowles 2002, p. 13). However, this pattern of progressively lower
peaks has not been consistently observed throughout significant
portions of the species' gross range.
White-tailed prairie dogs are extremely susceptible to plague
(Williams 1986, p. 4). Individual colony population declines of 85 to
96 percent were reported throughout the species' gross range following
epizootic plague events (Anderson and Williams 1997, pp. 702, 729).
Recovery of white-tailed prairie dog colonies post-plague has occurred
within as little as 1 to 2 years (Anderson and Williams 1997, p. 728;
Menkens and Anderson 1991, p. 330; Anderson and Williams 1997, p. 728;
Seglund et al. 2006, p. 69), or can take greater than 10 years (see
site discussions below, particularly Little Snake). Epizootic plague
frequently recurs in colonies (Barnes 1993, p. 29; Cully 1993, p. 39).
Plague likely persists in prairie dog colonies as an enzootic even
when an epizootic outbreak subsides. In the absence of epizootic
events, plague was found in fleas, plague antibodies were found in
prairie dog and carnivore blood serum samples, and dead plague-positive
prairie dogs were found (Biggins et al. in press, p. 7). More evidence
of enzootic plague acting in populations of prairie dogs and of black-
footed ferrets is an increase in survivorship when treated with
experimental vaccines and flea control, even in the absence of
epizootic plague outbreaks (Matchett et al. 2009 in Biggins et al. in
press, p. 7). Increased survival with these treatments compared with
untreated areas is indicative that enzootic plague is frequently
present and suppressing population levels in untreated areas.
Possible reasons for maintenance of plague as an enzootic in the
environment include survival of the bacterium in the soil, persistence
of the bacterium in fleas, and the continued slow transmission of the
bacterium within the prairie dog community (Gage and Kosoy 2006 in
Biggins et al. in press, p. 2). Infected fleas exist in burrows for up
to 13 months following a plague event (Fitzgerald 1993, p. 57).
Impacts of long-term enzootic plague infection may include local
extirpation of colonies, extreme fluctuations in densities and occupied
habitat, and inbreeding (Seglund et al. 2006, p. 58). Enzootic plague
also may alter ecological processes (Biggins 2003, p. 7), such as
population dynamics and dispersal. For example, if plague results in
higher mortality of adults than juveniles, the remaining juveniles
would be less likely to disperse away from their native colonies; they
would instead replace the adults in the native colony, resulting in a
younger population (Biggins et al. in press, pp. 2, 7).
We lack an understanding of how plague is impacting the white-
tailed prairie dog on a rangewide basis. Plague monitoring is not
performed rangewide. To assess the effects of plague, we evaluated
available population and trend data on colonies and complexes known or
suspected to be affected by plague. Sharp declines in abundance are
generally attributed to epizootic plague outbreaks in the absence of
testing. No data was available before the 1980s; all available data
were collected after introduction of plague, in what we consider to be
a post-plague environment. Therefore, recovery is defined as a return
to observed population highs and not a return to pre-plague (prior to
1936 when it was first observed) abundance. We previously defined
persistence as the long-term continuance of white-tailed prairie dog
colonies, at a high enough level to exist in the long-term with minimal
management assistance (i.e., dusting, the application of insecticides
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to control flea populations, to reduce the spread of plague), in a
variety of locations across the species' gross range. We recognize that
different methodologies were used at different times and in different
locales to derive the various historical estimates we obtained for
review. These estimates contribute to the best available information,
and we consider them comparable for determining long-term population
trends, while acknowledging potential error margins.
Evaluating the data is difficult due to differences in survey
methodologies. Information available for various colonies is
alternately presented as surveys of active burrows, occupied habitat,
population estimates, or prairie dog counts. For this reason,
comparison between colonies is not appropriate, and we review each
colony individually to derive a general understanding of plague
effects. Available data for several colonies includes estimated prairie
dog populations and prairie dog counts for different years; these
figures are not directly comparable but still describe general trends.
Much of the available data is for sites that were considered for
black-footed ferret management areas, which often, but not always,
represent the most robust of the known white-tailed prairie dog
colonies. Data collected at many of these sites was intended to
determine suitability for black-footed ferret reintroduction, and not
specifically designed to measure prairie dog abundance. The following
is a discussion of some examples of white-tailed prairie dog complexes
that have been impacted by plague. Some have declined and maintain
lower numbers (appear to still be in a period of decline), while other
complexes have declined but either partially or fully recovered. We
believe population numbers in colonies or portions of colonies will
continue to fluctuate widely, but retain the capacity to return to pre-
epizootic numbers.
Little Snake Complex, Moffat County, Colorado
Plague was documented at this complex in 1994 and 1995, following
notable declines in populations in 1983-1987 and again in 1993 (USFWS
1995, p. 11). In 1995, white-tailed prairie dog populations were
estimated to equal 60 percent of levels prior to the 1983 epizootic
(USFWS 1995, p. 11). Mapped occupied habitat declined by 92 percent
between 1994 and 1999 (Seglund et al. 2006, p. iii). A portion of the
complex representing 20 percent of the total area was remapped in 2009.
Occupied habitat in that area was 11 percent of the area mapped in 1989
(Ausmus 2010, pers. comm.). Population trends in the remaining 80
percent of the complex were not yet assessed. No dusting (for flea
control) is performed at this site. In summary, dramatic declines have
occurred at the Little Snake Complex. We cannot document any recovery
of the colony to date based on this limited information. The amount of
occupied habitat has declined since the detection of plague in the mid-
1990s.
Wolf Creek Complex, Moffat and Rio Blanco Counties, Colorado
Plague was suspected in 1985, due to white-tailed prairie dog
declines. By 1994, the prairie dog population rebounded to pre-1985
levels (Seglund et al. 2006, p. 20). In 2001, population numbers at the
Wolf Creek ferret management area were 52 percent lower than in 1993-
1994. Populations remained stable through 2002 and 2003 (Seglund et al.
2006, p. 93), and densities increased from 2004 to 2006 (Seglund and
Schnurr 2009, p. 72).
Wolf Creek was again heavily affected by plague in 2008, and the
colony was treated with an insecticide for flea control in fall of 2008
and 2009 (Holmes 2010a, pers. comm.). Active colonies remain in the
complex. Quantitative population estimates will not be available until
fall 2010 (Rustand 2010, pers. comm.). In summary, white-tailed prairie
dog populations at the Wolf Creek Complex have shown dramatic declines
followed by recoveries. Fluctuations are likely related to climatic
conditions, disease, or a combination of both (Holmes 2008 in Seglund
and Schnurr 2009, p. 72).
Dinosaur National Monument, Moffat County, Colorado
A large white-tailed prairie dog colony occurred at the National
Monument. No prairie dogs were observed on the colony in 2009. The
colony is near Wolf Creek and may be affected by the same epizootic
plague outbreak (Holmes 2010a, pers. comm.; Holmes 2010b, pers. comm.)
Montana
Montana Fish, Wildlife and Parks (MFWP) has records of 31 white-
tailed prairie dog colonies historically occurring in the State (Begley
2010b, pers. comm.). In 1997, only two colonies remained (FaunaWest
1998 in Knowles 2002, p. 15). Three of these colonies were permanently
lost to urbanization (Begley 2010b, pers. comm.). The cause behind the
loss of the remaining 26 is unknown, although poisoning and plague are
potential causes (Begley 2010c, pers. comm.). In 2006, the total number
of colonies had increased to 10. In 2009, there were eight known active
colonies (MFWP 2009a, p. 1; Hanebury 2009, pers. comm.). Plague was
suspected by State biologists in the disappearance of one colony from
2006-2009. We do not have population numbers or trend information for
any of the Montana colonies.
Shiner Subcomplex, Uintah County, Utah
White-tailed prairie dog population estimates in Shiner Basin were
15,065 in 1997; 47,551 in 1998; 5,383 in 1999, and 13,707 in 2000
(Seglund et al. 2006, p. 101). Total animals were counted on transects
(not extrapolated for the area) between 2002 and 2007, and estimates
were 5,475 animals in 2002; 4,284 in 2004; and 6,124 in 2007 (Maxfield
2009, pers. comm.). In summary, white-tailed prairie dog populations in
this area have fluctuated since 1997. The population appears to be
lower than occurred in 1998, but has stabilized since 2002. Plague was
suspected in this decline (Maxfield 2010, pers. comm.).
Cisco Desert, Southeastern Utah
Mapping and burrow density estimates were conducted for white-
tailed prairie dogs from 1985 to 1986. The area was resurveyed using
counts of individuals in 1991 and 1992, because of concerns that
prairie dog colonies may be declining (Seglund et al. 2006, p. 30).
Substantially more prairie dogs were counted during 1992 than in 1991
(Seglund et al. 2006, p. 30). The population was estimated to be 50,000
animals in 1997 followed by apparent declines in burrow activity in
2001 (Wright 2006, p. 3). Between 1985 and 2006, burrows detected on
transects dropped from 48.8 per ha (120.6 per ac) to 37.1 per ha (91.8
per ac). Of the individual complexes, 14 increased in density while 31
decreased (Wright 2006, p. 7).
We interpret this to represent an overall decline in this area
between 1985-2006, with marked fluctuations during this period. Plague
is suspected in these declines, although drought also contributed
(Wright 2006, p. 3). The white-tailed prairie dog is still considered
widespread and abundant in this area (Wright 2006, p. 3).
Meeteetsee Complex, Park County, Wyoming
Plague was first documented at Meeteetsee in 1985 (Biggins 2003, p.
7). Large fluctuations in population estimates and active burrows occur
at this complex. For example, total active burrows counted were 12,481
in 1985; 7,644 in 1989; 6,782 in 1997; 12,428 in
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1990; and 16,736 in 1998 (Biggins 2003, p. 11). This complex was
resampled in 2008, and numbers were higher than 1997, but still below
1980s values (Biggins 2010, pers. comm.). In summary, individual
colonies within the complex appear to suffer local, large population
collapses followed by subsequent recoveries (Biggins et al. in press,
p. 2). White-tailed prairie dogs continue to occupy the Meeteetsee
Complex.
Shirley Basin/Medicine Bow Complex, Wyoming
Population estimates for the complex are available, based on
partial surveys. Therefore, numbers presented represent trends but are
not directly comparable. Numbers in parenthesis are the percent of
complex transected during that year. Population estimates were 30,389
(31) in 1991; 14,551 (22) in 1993; 5,916 (6) in 1994; 19,876 (19) in
1996; 6,547 (16) in 1998; 6,669 (16) in 2000; and 34,698 (8) in 2001
(Seglund et al. 2006, p. 107). An additional 38,756 white-tailed
prairie dogs also were recorded in 2001, in an area of the complex not
surveyed in the previous years (Grenier et al. 2002, p. 23). Mapped
occupied habitat increased 25 percent between 1991 and 2006 (Grenier et
al. 2007, p. 133). Similar to other complexes, white-tailed prairie dog
populations at Shirley Basin fluctuate dramatically, although direct
comparisons are not appropriate due to yearly variation in transect
sites. Plague was first documented at Shirley Basin in 1987 (Seglund et
al. 2006, p. 36). In summary, plague likely impacted populations at
Shirley Basin (Seglund et al. 2006, p. 36) and may be responsible for
the fluctuating populations.
The examples above clearly show that plague is present within
white-tailed prairie dog colonies across the species' gross range, and
is likely responsible for large population fluctuations and significant
declines in complexes or portions of complexes. However, the colonies
and complexes also show a capacity to recover after plague events. Some
colonies decline and maintain lower numbers, perhaps due to enzootic
plague (Little Snake, Montrose County, and Shiner Basin). Other
complexes decline but either partially recover (Montana colonies, Wolf
Creek, Cisco Desert) or fully recover (Shirley Basin/Medicine Bow).
We do not know if the colonies and complexes recovered to
population numbers that existed before plague was introduced because we
do not have historical population information. We also do not know if
the colonies and complexes exhibit pre-plague life-history patterns of
mortality, reproduction, dispersal, and colonization. The available
data indicates that white-tailed prairie dogs can continue to persist
in the presence of plague. Population numbers in colonies or portions
of colonies will continue to fluctuate widely, but retain the capacity
to return to pre-epizootic numbers. Plague is demonstrated to cause
this pattern in rodent species in Asia, where plague is native (Biggins
and Kosoy 2001, p. 64).
Continued persistence of colonies rangewide is impacted by many
factors. The separation of colonies within complexes and distance
between colonies may mediate the spread of plague. For example, the
slow population decline witnessed at Meeteetsee between 1989 and 1997
is likely the impact of plague affecting only a portion of the complex
at a time (Biggins et al. in press, p. 2). Similarly, only a portion of
Wolf Creek was affected by plague while the nearby Crooked Wash did not
experience a concurrent decline (Holmes 2010b, pers. comm.). Finally, a
population at the Arapaho National Wildlife Refuge in north-central
Colorado did not decline concurrent with the decline at Wolf Creek
(Hoogland 2010, pers. comm.).
The ability for white-tailed prairie dogs to migrate may promote
recolonization of colonies impacted by plague (Seglund et al. 2006, p.
10). The ability to repopulate colonies depends on a mosaic of
interconnected colonies; isolated colonies are less likely to support
sufficient immigration for long-term persistence of plague-affected
colonies (Seglund et al. 2006, p. 60). The complexes of Little Snake,
Wolf Creek, Coyote Basin, Kennedy Wash, Snake John, and Shiner are
considered separate but are all located in adjacent Uintah and Moffat
Counties, and a reasonable amount of connectivity exists between them.
Size also may be an important factor regulating persistence of
individual colonies. Most of the sites discussed above are considered
large complexes. In black-tailed prairie dogs, introduction of plague
has resulted in colonies being consistently smaller than before first
exposure to plague (Cully and Johnson 2008, p. 12). White-tailed
prairie dog colonies may overall be smaller now when compared to pre-
plague levels. Small colonies not part of a large complex may be
affected by plague at a higher intensity and may not have enough source
individuals to recover. Smaller populations are generally accepted to
be more vulnerable than larger populations (Shaffer 1981, p. 131).
Larger groups of black-tailed prairie dogs had a higher survival
probability after translocation than small groups (Robinette et al.
1995, p. 872). We do not have data to assess specifically how plague
operates in smaller, more isolated colonies. However, population
viability modeling in black-tailed prairie dogs demonstrated continued
persistence in small, fragmented colonies, assuming connectivity
between populations (George et al. 2008, p. 1).
The temporal nature of plague is an important factor when
considering rangewide impacts (Seglund et al. 2006, p. 59). Plague does
not impact all populations rangewide at the same time, with a
predictable reoccurrence rate, or to the same intensity. Large plague-
related population declines were witnessed across the gross range, but
in different years: Montana in 1997; Shirley Basin/Medicine Bow,
Wyoming, in 1994 and 1998; Wolf Creek, Colorado, in 2001/2002 and 2008;
and Uintah Basin in 1999 and 2003/2004.
Some social and behavioral traits of white-tailed prairie dogs
appear to favor their long-term persistence in a plague environment.
White-tailed prairie dog colonies are less dense and more widely
dispersed than black-tailed or Gunnison's prairie dog colonies, which
may slow transmission rates (Cully 1993, pp. 40-41; Cully and Williams
2001, pp. 898-899). White-tailed prairie dogs are less social when
compared to other species; this trait may reduce transmission among
individual animals (Hoogland 1981, pp. 252-253; Cully 1993, p. 40).
Hibernation also contributes to slower transmission rates, although
this may simply delay the onset of symptoms throughout all the colonies
(Barnes 1993, p. 35).
Some tools are available to control plague. Deltamethrin and
pyraperm are two insecticides used to successfully control fleas on
colonies of different prairie dog species (Seery et al. 2003, entire;
Hoogland et al. 2004, entire). Use of these insecticides has increased
the number of juvenile Utah prairie dogs weaned (Hoogland et al. 2004,
p. 379) and resulted in higher survival rates for black-tailed, white-
tailed, and Utah prairie dogs (Biggins et al. in press, p. 5).
Currently, insecticide use on white-tailed prairie dog colonies is
limited to experimental use and when plague appears to be impacting
colonies that support black-footed ferret reintroduction sites. Wolf
Creek was treated in the summer and fall of 2009, in conjunction with
that outbreak, and likely will be treated again in 2010. Other sites
with black-footed ferrets include Coyote Basin, Snake John, Shirley
Basin/ Medicine Bow, and Meeteetsee. Due to the expense of
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applying insecticide and the effects to non-target species, this method
is only used when plague has already been detected.
Experimental vaccine-laden baits are in development to immunize
prairie dogs against plague. Black-tailed prairie dogs exposed to
plague in a lab setting and fed vaccine baits experienced a high rate
of survival (Mencher et al. 2004, pp. 5503-5504, Rocke et al. 2008, pp.
933, 936). The effectiveness of the vaccine is scheduled for field
testing over the next year. A systemic flea control bait also is under
development (Poche et al. 2008, entire). The flea control bait reduces
flea loads on animals, the primary vector in spreading plague in
prairie dogs (Jachowski 2009, entire). While use of any of the above
techniques, or combinations thereof, to manage plague has not been
tested at the landscape level, these techniques show promise in the
ability to manage plague.
The occurrence of plague may be affected by climate change. As
discussed in Factor A, Wyoming and Montana's yearly precipitation will
become more variable while temperatures are expected to increase
rangewide over the next 40 years. Plague outbreaks are significantly
correlated with increased rainfall, particularly spring rainfall (Stapp
et al. 2004, p. 237; Snall et al. 2008, pp. 245-246). However, plague
outbreaks are negatively correlated with the yearly total number of hot
days and overall increased temperatures (Stapp et al. 2004, p. 238;
Snall et al. 2008, p. 245).
Because climate change will likely produce variation in annual
rainfall (Stapp et al. 2004, pp. 504-505), plague outbreaks may
oscillate as these factors interact. Warmer winters in particular can
result in increased plague transmission (Stapp et al. 2004, p. 236;
Salkeld and Stapp 2008, p. 620). This effect is probably due to a range
of factors including reduced hibernation (Rayor 1985, p. 195), better
over-winter flea survival, and increased habitat productivity (Stapp et
al. 2004, pp. 237-238). In the Colorado and Utah portions of the gross
range, winter precipitation is expected to vary greatly from year to
year, with some winters being very dry while others experience intense
precipitation and flooding (Karl et al. 2009, p. 130). This variation
may result in pulses of winter or early spring plague outbreaks during
wetter years that are reduced in intensity over several years as hotter
summer temperatures reduce plague in the environment. Plague
occurrences are likely to decrease in black-tailed prairie dogs due to
climate change effects (Sna ll et al. 2009, p. 505). Because it is
believed that changing environmental conditions resulting from climate
change is directly impacting plague transmission, we also may expect
that plague will eventually decrease in white-tailed prairie dog
habitats, concurrent with rising temperatures. Climate change may have
less of an impact on plague levels if white-tailed prairie dogs exhibit
a range shift as witnessed in some other species.
Tularemia and Monkeypox
Tularemia (Francisella tularensis) and monkeypox (Orthopoxvirus
spp.) are diseases that have had impacts on captive black-tailed
prairie dogs associated with the pet trade, and a wild black-tailed
prairie dog was reported as having fallen victim to West Nile virus
(Seglund et al. 2006, p. 58). We have no information to indicate that
any of these diseases are a concern for white-tailed prairie dogs at
the population or species level.
Predation
Many species prey upon the white-tailed prairie dog including
black-footed ferrets (Mustela nigripes), hawks (Accipiter, Micronisus,
Melierax, Urotriorchis and Megatriorchis spp.), eagles (Haliaeetus
spp.), badgers (Taxidea taxus), and coyotes (Canus lupis) (Seglund et
al. 2006, p. 58). However, predation is a natural occurrence for white-
tailed prairie dogs, and we have no information to indicate that
predation is a threat to the species.
Summary of Factor C
Plague occurs throughout the gross range of the white-tailed
prairie dog. The rangewide and long-term effects of plague on prairie
dog populations are not well understood. There is evidence of epizootic
outbreaks of the disease and enzootic maintenance of the disease in
prairie dog colonies. We acknowledge that populations are probably
reduced from historic levels, and some colony behavioral functions,
including migration and social interactions, may be impaired by plague.
However, we have no evidence that demonstrates that plague has
eliminated white-tailed prairie dogs from large portions of its gross
range after over 70 years of exposure to the disease. Affected colonies
have shown partial or complete recovery after plague events, and
complexes continue to persist at the landscape level. Available
information indicates that plague events are to some extent localized
temporally and spatially, which may help mediate the species-level
effects. Management actions are underway to research and implement
plague control mechanisms, such as dusting, vaccines, and flea control,
which should help alleviate colony population fluctuations and declines
due to plague in the foreseeable future. As a result, we have
determined that while plague is affecting the white-tailed prairie dog,
it is not a significant threat that is now causing or projected to
cause the species to be at risk of extinction.
The available evidence does not indicate that other diseases or
predation are sufficiently acting on the species to threaten the
species with possible extinction now or in the foreseeable future. We
conclude that the best scientific and commercial information available
indicates that the white-tailed prairie dog is not now, or in the
foreseeable future, threatened by disease or predation to the extent
that listing under the Act as an endangered or threatened species is
warranted at this time. Continued plague monitoring and research will
be important for us to continue to assess the level of impact this
disease plays in the long-term conservation of white-tailed prairie
dogs. The development of a vaccine to protect prairie dog populations
may help decrease future effects of plague.
Factor D. The inadequacy of existing regulatory mechanisms.
State Regulations and Private Land Management
Rangewide
State laws and regulations may impact white-tailed prairie dog
conservation by providing specific authority for white-tailed prairie
dog conservation over lands which are directly owned by the State;
providing broad authority to regulate and protect wildlife on all lands
within their borders; and providing a mechanism for indirect
conservation through regulation of threats to the species (e.g.,
noxious weeds). In general, States have broad authority to regulate and
protect wildlife within their borders. All of the States within the
range of the white-tailed prairie dog have State school trust lands
that they manage for income to support their schools. We are unaware of
any specific regulations to ensure that the management of the State
trust lands is consistent with the needs of white-tailed prairie dog.
Thus there are currently no regulatory mechanisms on State trust lands
to ensure conservation of the species.
Environmental planning regulations establish environmental quality
as an essential component of land use and project planning and provide
a structured, analytical frame work to make decisions that balance
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environmental and economic factors (Council on Environmental Quality
(CEQ) 1997, p.11). The implementation of the National Environmental
Policy Act (NEPA, 42 U.S.C. 4321 et seq.) has improved the quality of
projects and reduced impacts to the environment in the Federal planning
process (CEQ 1997, p. 17). Within the range of the white-tailed prairie
dog, only Montana has NEPA-like environmental planning regulations (CEQ
2009, entire). Because activities on private and State lands in
Colorado, Utah, and Wyoming are not subject to environmental review,
they may have a greater impact to white-tailed prairie dogs than
similar activities on Federal lands.
Potential impacts to the species that can be managed by State or
private entities include recreational shooting, shooting to protect
agricultural interests, and oil and gas development on non-Federal
mineral estates. In addition, the 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 white-tailed prairie dog and
other species among the western States. The WAFWA prepared a Rangewide
Conservation Agreement for the White-Tailed Prairie Dog in 2006
(Seglund et al. 2006, entire). The objectives of the conservation
agreement include identification and monitoring of the species' status
and distribution, public education, identification and implementation
of priority research needs, and creation of State management plans
(Seglund et al. 2006, p. 3). The conservation agreement provides
expertise, recommendations, and coordination of funding for the
conservation of the species, but does not provide regulatory
protection.
Private lands comprise a large portion of the predicted range of
the species. Private landowners can control prairie dogs on their land
as necessary in all States. However, general public access and hunting
on private lands throughout the gross range are limited by trespass
laws. We have no evidence that the control activities or policies of
individual private landowners are threatening the species.
Oil and gas development occurs across the gross range of the
species, including on lands managed by the States. We are unaware of
any regulations or protection measures for white-tailed prairie dogs on
these lands. However, based on available information, we do not
consider oil and gas development a factor that significantly threatens
the white-tailed prairie dog (see Factor A. Oil and Gas Exploration and
Development, above).
Colorado
The Colorado Department of Wildlife (CDOW) released a Statewide
Conservation Strategy outlining the management of white-tailed and
Gunnison's prairie dogs in fall 2009 (Seglund and Schnurr 2009,
entire). This document guides the development of conservation
strategies for the three white-tailed prairie dog Individual Population
Areas (IPAs) (see Distribution and Abundance). Local action plans with
individual goals and objectives are under development for each IPA. The
Statewide Conservation Strategy provides management priorities and
guidance for the species, but does not provide regulatory protection.
All prairie dog species are classified as small game in Colorado. A
small game license is required for shooting prairie dogs, with the
exception of private landowners and their immediate family members or
designees, who may kill prairie dogs causing damage on their lands
(CDOW 2009, p. 10). Shooting of prairie dog species is not permitted on
public land between March 1 and June 15 (CDOW 2009, p. 10), providing
protection during the sensitive breeding and rearing time periods.
The Colorado Oil and Gas Conservation Commission (COGCC) had a
policy encouraging voluntary cooperation among oil and gas operators in
preventing and mitigating potential impacts to wildlife (COGCC 1996,
entire). In 2009 the state legislature passed rules requiring oil and
gas companies to consult with state wildlife officials regarding the
impacts of their proposed development to wildlife. The rules promote
best management practices and allow the state to set reasonable
conditions of development in sensitive wildlife areas (COGCC 2009,
entire). Application of these rules to white-tailed prairie dogs in
particular is then up to state wildlife officials. Given the recent
passing of these rules, it is unknown if they will be applied to
prairie dog species.
Montana
White-tailed prairie dogs are identified as a Species of Greatest
Conservation Need (Tier 1) in Montana's Comprehensive Fish and Wildlife
Conservation Strategy (MFWP 2009a, p. 1). The State defines this as a
species whose needs must be specifically addressed, whether through
focus areas, community types, or individually (MFWP 2005, p. 188). This
designation gives the State statutory authority to manage the species.
For example, under this authority, MFWP translocates white-tailed
prairie dogs in an effort to establish new colonies. Translocations
began in 2007, and are expected to continue until at least 2011.
White-tailed prairie dogs in Montana were once protected from all
shooting, but the regulation protecting them has lapsed, and they are
currently unprotected. A license is not required to hunt prairie dogs
in Montana.
Utah
The white-tailed prairie dog is listed as a Species of Concern in
Utah, defined by the State as a wildlife species for which there is
credible scientific evidence to suggest a threat to continued
population viability within the State (UDWR 2007, p. 1). Species are
provided this designation in order to encourage management actions and
prevent the species from declining to the point where listing is
necessary. Utah completed a conservation agreement and Strategy for
white-tailed and Gunnison's prairie dogs in 2007. Under the
conservation agreement, the State committed to conduct occupancy
surveys in an effort to detect population declines and respond with
appropriate management actions (Lupis et al. 2007, pp. 22-23). The
Statewide conservation strategy provides management priorities and
guidance for the species, but does not provide regulatory protection.
No license is required to hunt prairie dogs in Utah (UDWR 2009, p.
1). However, prairie dog shooting is not allowed between April 1 and
June 15 (UDWR 2009, p. 4), providing the species with protection during
sensitive breeding and rearing periods. In addition, a year-round
shooting closure is implemented in the Coyote Basin black-footed ferret
reintroduction area (7,604 ha (18,789 ac)).
Wyoming
White-tailed prairie dogs are considered a Species of Greatest
Conservation Need: Native Species Status 4 in Wyoming. Species are
given this designation when habitat is restricted or threatened, or
population numbers are declining and unknown. The species was given a
status level of 4 due to unknown population trends and restricted or
vulnerable but not declining habitat (Wyoming Game and Fish Commission
1998, p. 238). No conservation agreement is in place for the species in
Wyoming. State biologists participate in prairie dog surveys and
management under the guidance of WAFWA.
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Shooting of white-tailed prairie dogs is permitted in Wyoming
without a license (WGFC 1998, pp. 52-54), and there are no seasonal
closures. State biologists have witnessed no negative effects from
removing a seasonal closure on the Shirley Basin population (Grenier
2009, pers. comm.); therefore, it seems unlikely that lack of closures
is having a population-level effect.
In summary, the States are actively involved in prairie dog
research and monitoring efforts under direction of the WAFWA
Conservation Agreement and State-specific species management plans. The
information obtained through these efforts will be valuable for future
efforts to conserve the species and avoid threats. Recreational
shooting of prairie dogs is not considered a threat to the species (see
Factor B. Overutilization, above). However, seasonal shooting closures
are implemented on a site-specific basis in Colorado and Utah. The lack
of environmental planning and protection for the species from all land
use activities on non-Federal land, including non-Federal oil and gas
leases, may impact the species in the future. However, at this time the
information we do have does not indicate that threats from land use
activities are sufficient to require regulatory mechanisms now or in
the foreseeable future (see Factor A., above).
Federal Management Authority
Potential impacts to the species that could be managed by the
Federal land management agencies include oil and gas development,
grazing, fire suppression, 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.) is the primary Federal law governing most land
uses on BLM lands. Section 102(a)(8) of FLPMA specifically recognizes
wildlife and fish resources as being among the uses for which these
lands are to be managed. The BLM considers the needs of wildlife,
including the white-tailed prairie dog, when conducting activities in
their habitat. Typically, this means the impacts to these species are
considered during project planning stages and conservation measures may
be included at the discretion of the agency biologists. In addition,
the BLM is required to meet environmental planning requirements under
NEPA (73 FR 61292), which requires reviewing the effects of actions on
the environment (including wildlife) before implementation.
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(k)). These plans provide a framework
and programmatic guidance for site-specific activity plans. In
addition, BLM management plans may include conservation measures to
protect the species. These measures vary between State and field
offices.
Site-specific plans likely to affect white-tailed prairie dogs
typically include livestock grazing, oil and gas field development,
wildlife habitat management, and other land use activities. The
potential effects of these activities on the species' habitat are
addressed under Factor A, above.
In Colorado's Grand Valley/Uncompahgre IPA, BLM lands have special
designations offering protections, such as a yearly closure to
motorized and non-motorized travel restrictions to designated routes
only, and withdrawal from all forms of mineral entry, including oil and
gas leasing (Seglund and Schnurr 2009, p. 55). The BLM-owned portion of
the Northwest IPA's white-tailed prairie dog's gross range is
considered high or medium potential for oil and gas development. The
RMPs stipulating activities in this IPA are undergoing revisions to
address oil and gas development and associated impacts (Seglund and
Schnurr 2009, p. 61). We do not know if the RMP revisions will include
conservation measures to minimize the effects of oil and gas
development to white-tailed prairie dogs. At this time, we do not
believe oil and gas development to be a significant threat to the
species (see Factor A. Oil and Gas Exploration and Development, above).
However, the ability to adequately monitor the species in energy
development areas will be important for our long-term ability to
minimize impacts.
In Utah, the BLM updated several field office RMPs in 2007. These
updated RMPs included a stipulation to avoid surface-disturbing
activities within 201 m (660 ft) of white-tailed prairie dog colonies
in known prairie dog habitat (BLM 2008a, p. K:13). An exception may be
granted if impacts can be mitigated or if there is no other reasonable
location to develop the lease. This stipulation is included in the
management plans that apply to white-tailed prairie dog colonies near
Vernal, Richfield, Price, and Moab. No exceptions to this stipulation
have yet been made in the Moab or Price field offices. Vernal field
office staff report four exceptions to this stipulation. In all
examples, disturbance was limited to the edge of a colony because no
other alternatives were available (McDonald 2010, pers. comm.). The RMP
governing activities in Rich County has not been amended to include a
stipulation to protect white-tailed prairie dog habitat (Madsen 2009,
pers. comm.). However, this area comprises a very small amount of
occupied habitat in Utah, and any impacts to this area are unlikely to
produce population-level effects.
In Wyoming, no extra protections are extended to white-tailed
prairie dogs on BLM land, although control efforts (described below in
Factor E) are not permitted except in the case of extensive resource
damage or a threat to human health and safety (Keefe 2009, pers.
comm.). Given the extent of oil and gas development in this State, lack
of regulations on BLM land could be detrimental to the species, but the
available evidence does not suggest that impacts are rising to a
significant population-level threat (see Factor A. Oil and Gas
Exploration and Development, above).
U.S. Forest Service (USFS)
The USFS considers the white-tailed prairie dog to be a Region 2
sensitive species, which requires USFS to consider the presence of the
species and recommend mitigation when planning projects that may affect
the species (Seglund and Schnurr 2009, p. 55). Controlling prairie dogs
with toxicants is banned or closely controlled on USFS lands (Seglund
et al. 2006, p. 62). The USFS manages less than 1 percent of the total
species' gross range, so their management strategies are unlikely to
impact the species rangewide significantly.
U.S. Fish and Wildlife Service
The Service manages over 500 National Wildlife Refuges and their
satellites, but only about 7,975 ha (19,706 ac) fall within the white-
tailed prairie dog's predicted range (Seglund et al. 2006 pp. 98, 104,
109). Management of this species is not addressed on these lands
(Seglund et al. 2006, p. 62). Control of prairie dogs through toxicants
on these lands is banned or closely controlled (Seglund et al. 2006, p.
62). Given the small amount (less than 1 percent) of predicted habitat
managed by us, the available information does not suggest that our
management practices are having a significant impact on the species.
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National Park Service
The NPS preserves unimpaired the natural and cultural resources and
values of the national park system for the enjoyment, education, and
inspiration of this and future generations. This agency manages 13,393
ha (33,096 ac) of the white-tailed prairie dog's predicted range
(Seglund et al. 2006, pp. 98, 104, 109). Management of this species is
not addressed on these lands (Seglund et al. 2006, p. 62). Control of
prairie dogs through toxicants on these lands is banned or closely
controlled (Seglund et al. 2006, p. 62). Given the small amount (less
than 1 percent) of predicted habitat managed by this agency, the
available information does not suggest that NPS management practices
are having a significant impact on the species.
Tribal Lands
The Bureau of Indian Affairs (BIA) administers 135,376 ha (334,523
ac) of land within the white-tailed prairie dog's predicted range
(Seglund et al. 2006, pp. 98, 104, 109). Additional land owned by
Tribes or Tribal members may have been included under the calculations
for private land. We are unaware of any official policies from the BIA
or Tribal councils regarding protection of white-tailed prairie dogs on
BIA-administered or Tribally owned lands. Given the small amount (less
than 1 percent) of predicted habitat managed by Tribes, the available
informationdoes not suggest that BIA management practices are having a
significant impact on the species.
In summary, Federal agencies have very few regulations for the
protection of this species. The oil and gas surface use restrictions in
the State of Utah likely help minimize the impacts of oil and gas
development to white-tailed prairie dogs. The lack of protection
measures for the species elsewhere may impact the species in the
future; however, at this time the available information does not
indicate that factor significantly threatens the species in the
foreseeable future (see Factor A. Oil and Gas Exploration and
Development, above). Poisoning also is banned or closely controlled on
Federal lands (see Factor E. Poisoning, below, for further discussion).
Summary of Factor D
All States are involved in active management of the species. The
States' conservation agreements and strategies, while not regulatory
documents, contain direction to help mitigate threats to the species.
Potential threats for which regulatory mechanisms may play a role
include oil and gas development, grazing, fire suppression, poisoning,
and recreational shooting. We have determined that these factors do not
rise to the level of a significant threat to the white-tailed prairie
dog or its habitat rangewide.
Our evaluation determined that these land uses may impact white-
tailed prairie dogs on a localized basis. Existing regulatory
mechanisms are adequate to reduce impacts at these localized levels.
For example, seasonal shooting closures in Colorado and Utah are
protecting white-tailed prairie dog populations in some areas during
sensitive breeding and rearing time periods. The BLM's RMPs in Utah
contain recommendations to avoid surface disturbance during oil and gas
development, although this does not mediate the impact of habitat
fragmentation from this threat. In addition, the historical threat of
poisoning was curtailed when Federal regulation of pesticides was
enacted, and is generally not permitted on Federal lands.
Further coordination between State and Federal agencies would be of
benefit to this species, particularly in managing habitat
fragmentation. More management would be of benefit to the species, but
the available evidence does not indicate that limited management
strategies are a significant threat to the species.
We conclude that the best scientific and commercial information
available indicates that the white-tailed prairie dog is not now, or in
the foreseeable future, threatened by inadequate regulatory mechanisms
to the extent that listing under the Act as an endangered or threatened
species is warranted at this time.
Factor E. Other natural or manmade factors affecting its continued
existence.
The following potential natural or manmade factors may affect the
white-tailed prairie dog: (1) Poisoning, and (2) competition with
Wyoming ground squirrels. These factors are further discussed below.
Poisoning
Poisoning of white-tailed prairie dogs has historically occurred
throughout the species' gross range (Seglund et. al 2006, p. 63). The
USDA Biological Survey and the Agriculture Appropriations Act of 1915
(38 Stat. 1111) planned and authorized a Westside Plan to eliminate
prairie dogs across western rangelands (Oakes 2000 in Seglund and
Schnurr 2009, p. 140). Prairie dog poisoning campaigns began in all
States across the gross range of the white-tailed prairie dogs by 1919
(Seglund and Schnurr 2009, p. 140).
The population-level impact of this practice is difficult to
quantify due to our lack of knowledge of the species' historical
distribution and our lack of information on the exact locations of
poisoning efforts (Seglund and Schnurr 2009, p. 140). However, the
extent of poisoning for all prairie dog species was extensive. For
example, from 1915 to 1964, Colorado poisoned an area of 9,380,191 ha
(23,178,959 ac), which was occupied by the Gunnison, black-tailed, and
white-tailed species of prairie dogs (Forrest 2002 in Seglund and
Schnurr 2009, p. 141). Black-tailed prairie dogs were the main target
of eradication campaigns due to their visibility on the landscape, but
Gunnison and white-tailed prairie dogs also were poisoned (Seglund and
Schnurr 2009, p. 140).
Poisoning in all States became less common after Federal regulation
of pesticides was enacted (Seglund et al. 2006, p. iv). State and
Federal agencies are rarely involved in control efforts unless human
health and safety are at risk. The BLM, in particular, has a
restriction against poisoning prairie dogs unless required for human
health and safety or if resource damage meets specified requirements.
Control of white-tailed prairie dogs in this manner is rare, with the
agency only reporting one small area currently under control (Keefe
2009, pers. comm.). Individual landowners may still control prairie
dogs on their private property.
Poison applications can be an effective means to control prairie
dog population size. Baited poisons can result in 75 to 85 percent
mortality, and fumigants can result in 95-percent mortality of prairie
dog populations when properly applied (Seglund and Schnurr 2009,
p.141). Although poisoning was historically widespread, there is no
information available to indicate that poisoning occurs at more than a
localized scale today. We were unable to quantify amount of toxicants
sold for white-tailed prairie dog control. The States within the gross
range of the white-tailed prairie dog do not compile records of
pesticide sales. There are 103 licensed dealers of restricted use
toxicants in Utah and 288 licensed dealers in Colorado. The WGFD staff
surveyed Wyoming dealers in 2003, and determined that toxicant sales
were too small to warrant tracking, with a total less than would be
required to treat 400 ha (1,000 ac) per year (Grenier 2009, pers.
comm.).
White-tailed prairie dog biology may provide some protection from
poisoning. Because they inhabit less dense, widely distributed
colonies, they
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do not attract the amount of negative attention associated with black-
tailed prairie dogs (Knowles 2002, p. 2; Grenier 2009, pers. comm.). In
addition, the widespread nature of white-tailed prairie dog colonies
makes control through the use of toxicants very labor intensive and
unsuitable for widespread control. Black-tailed prairie dogs are known
to rebound rapidly after control efforts (Seglund and Schnurr 2009, p.
140). White-tailed prairie dogs may have this capability as well
(Seglund and Schnurr 2009, p. 140), particularly because they reproduce
at a younger age than black-tailed prairie dogs.
In summary, today, poisoning generally occurs only on private land
for site-specific control purposes rather than wide-spread population
eliminations (Seglund et al. 2006, p. 65). White-tailed prairie dogs
may have the capability to rebound from control efforts. Their
scattered distribution and behavioral mechanisms may provide them with
some protection from poisoning efforts. Therefore, we do not believe
poisoning to be a significant threat to the species now or in the
foreseeable future.
Competition
Competition may occur between Wyoming ground squirrels and white-
tailed prairie dogs (Seglund and Schnurr 2009, p. 100). Their diets
overlap and their burrows are often interspersed. Wyoming ground
squirrels are found in some areas where plague has decimated Gunnison's
prairie dogs (Seglund and Schnurr 2009, p. 100). However, white-tailed
prairie dogs were observed to chase and kill Wyoming ground squirrels
(Cooke 1990, p. 275). Given their size advantage and aggression, it
seems unlikely that prairie dogs would be excluded by Wyoming ground
squirrels (Hoogland 2009, pers. comm.). In addition, ground squirrels
are vulnerable to plague, and epidemics reduce their numbers alongside
prairie dogs. At this time there is no evidence to suggest that there
may be other competitors or that competition is a threat to the white-
tailed prairie dog.
Summary of Factor E
Available evidence does not suggest that control of prairie dogs
through poisoning is a major or increasing threat to the while-tailed
prairie dog. It seems unlikely that competition with Wyoming ground
squirrels would threaten the species' persistence.
We conclude that the best scientific and commercial information
available indicates that the white-tailed prairie dog is not now, or in
the foreseeable future, threatened by other natural or manmade factors
affecting its continued existence, to the extent that listing under the
Act as an endangered or threatened species is warranted at this time.
Finding
As required by the Act, we considered the five factors in assessing
whether the white-tailed prairie dog is endangered or threatened
throughout all of its range. We have carefully examined the best
scientific and commercial information available regarding the past,
present, and future threats faced by the white-tailed prairie dog. We
reviewed the petition, information available in our files, and other
available published and unpublished information, and we consulted with
recognized white-tailed prairie dog experts and other Federal, State,
and tribal agencies.
In considering what factors might constitute threats, we must look
beyond the mere exposure of the species 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 endangered or threatened
under the Act.
We identified and evaluated the risks of the present or threatened
destruction, modification, or curtailment of the habitat or range of
the white-tailed prairie dog: (1) Oil and gas exploration and
development; (2) oil shale, tar sands, and other minerals, (3)
renewable energy development--wind and solar; (4) urbanization; (5)
agricultural land conversion; (6) grazing; (7) fire occurrence and
suppression; (8) invasive plant species; and (9) climate change. While
oil and gas development is impacting the species, we have no evidence
that it will significantly threaten the species in the foreseeable
future. We concluded that oil shale, tar sands, and other minerals;
renewable energy development; urbanization; agricultural land
conversion; grazing; fire suppression; invasive plant species; and
climate change are not significant threats to the species now or in the
foreseeable future. Based on our review of the best available
information, we find that the present or threatened destruction,
modification, or curtailment of the white-tailed prairie dog habitat or
range is not a significant threat now or in the foreseeable future.
We identified and evaluated the risks from overutilization for
commercial, recreational, scientific, or educational purposes. While
shooting results in some individual mortality and may affect easily
accessible colonies, available evidence does not indicate that the
magnitude or intensity is enough to significantly threaten the species
rangewide. Therefore, we conclude that the white-tailed prairie dog is
not significantly threatened by overutilization for commercial,
recreational, scientific, or educational purposes now or in the
foreseeable future.
We found that plague impacts populations throughout the species'
range. We determined that colonies and complexes persist in the post-
plague environment, which demonstrates a rangewide resiliency to the
disease. We determined that the species' life-history characteristics
provide some protection from the spread of plague and that epizootic
plague only affects a small portion of the range at one time. The
threat of plague may decrease across the range with the impacts of
management and climate change. Tularemia, monkey-pox, and West Nile
virus are not considered threats to the species. Additionally, we note
that while white-tailed prairie dogs are prey for numerous species,
available information does not indicate that predation has an overall
adverse effect on the species. Therefore, we find that neither disease
nor predation is a significant threat to the species now or in the
foreseeable future.
Based on our analysis of the existing regulatory mechanisms, we
determined the States are actively involved in managing the species
through conservation agreements and strategies. Although these
agreements are not regulatory, they provide an important mechanism for
conservation, monitoring, and research efforts. The existing regulatory
mechanisms in place on State and Federal lands are limited. However, we
determined in the evaluation that other threats would not adversely
affect the white-tailed prairie
[[Page 30362]]
dog now or within the foreseeable future. Additionally, the white-
tailed prairie dog receives some protection from shooting under State
laws in Colorado and Utah, and from oil and gas development in Utah.
Therefore, based on our review of the best available scientific
information, we conclude that inadequacy of existing regulatory
mechanisms is not a significant threat to the species now or in the
foreseeable future.
We also assessed the potential risks to white-tailed prairie dogs
from poisoning and interspecific competition, and we find that there is
no evidence that indicates these factors significantly threaten the
continued existence of white-tailed prairie dog now or in the
foreseeable future.
We determined that energy development, urbanization, grazing, fire
suppression, agricultural conversion, recreational shooting, poisoning,
invasive plant species, and plague may impact the species in at least
localized areas. White-tailed prairie dogs were impacted throughout
history by each of these factors. We believe that, collectively, these
activities have resulted in the presumed reduced abundance of white-
tailed prairie dog from historical levels. We also believe that the
ecological function of this species within western landscapes has been
altered from its historical function. Many of these factors (grazing,
urbanization, fire suppression, agricultural land use conversion, and
poisoning) were at much greater magnitude in the past and are not
currently impacting species with the same intensity. Other threats (oil
and gas development, climate change, shooting, plague, and invasive
plant species) can be expected to continue into the future. Of these,
we consider plague and oil and gas development to have the greatest
potential for cumulative impacts. Yet some of the most robust and
resilient colonies exist in areas where both of these potential threats
occur. Therefore, we do not believe these factors will cumulatively
threaten the continued existence of white-tailed prairie dog now or in
the foreseeable future.
Our review of the information pertaining to the five threat factors
does not support a conclusion that there are independent or cumulative
threats of sufficient imminence, intensity, or magnitude that would
cause substantial losses of population distribution or viability of the
white-tailed prairie dog that would result in the species being at risk
of extinction. Therefore, we do not find that the white-tailed prairie
dog is currently in danger of extinction (endangered), nor do we find
it is likely to become endangered within the foreseeable future
(threatened), throughout its range. Therefore, listing the species as
endangered or threatened under the Act is not warranted at this time.
Distinct Vertebrate Population Segments
After assessing whether the species is endangered or threatened
throughout its range, we next consider whether any distinct vertebrate
population segment (DPS) exists and meets the definition of endangered
or is likely to become endangered in the foreseeable future
(threatened).
Under the Service's Policy Regarding the Recognition of Distinct
Vertebrate Population Segments Under the Endangered Species Act (61 FR
4722, February 7, 1996), three elements are considered in the decision
concerning the establishment and classification of a possible DPS.
These are applied similarly for additions to or removal from the
Federal List of Endangered and Threatened Wildlife. These elements
include:
(1) The discreteness 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 (removal from the list), or
reclassification (i.e., is the population segment endangered or
threatened).
Discreteness
Under the DPS policy, a population segment of a vertebrate taxon
may be considered discrete if it satisfies either one of the following
conditions:
(1) It is markedly separated from other populations of the same
taxon as a consequence of physical, physiological, ecological, or
behavioral factors. Quantitative measures of genetic or morphological
discontinuity may provide evidence of this separation.
(2) It is delimited by international governmental boundaries within
which differences in control of exploitation, management of habitat,
conservation status, or regulatory mechanisms exist that are
significant in light of section 4(a)(1)(D) of the Act.
The predicted range of the white-tailed prairie dog encompasses
13,066,887 ha (32,288,981 ac) (Seglund et al. 2006, p. 91). We do not
consider any population segment of white-tailed prairie dog to be
markedly separated from other populations of the same taxon as a
consequence of physical, physiological, ecological, or behavioral
factors. As a colonial species, white-tailed prairie dogs are naturally
distributed across the landscape in a discontinuous fashion. Occupied
habitat changes rapidly, shifting on a landscape scale (Seglund et al.
2006, p. iii). The species spans Colorado, Utah, Wyoming, and Montana.
Available information suggests while population areas within Colorado
and Utah are not continuous with other populations areas within the
same State, they are continuous between these States and with
populations in Wyoming. Therefore, we do not consider any of these
areas to be physically discrete. Because discontinuous distribution is
the ``baseline'' condition for the species, for us to consider any
geographic discontinuity as being evidence of marked separation (i.e.,
discreteness) under the DPS policy, we would need the best available
information to indicate that the amount of discontinuity is over and
above what is considered to be normal for the species.
We do not have detailed mapping of occupied habitat throughout the
range of the species. We recognize the likely occurrence of some small,
isolated white-tailed prairie dog colonies, but have very limited
information available that identifies their locations. Therefore, we
looked for other measures of discontinuity, such as measures of genetic
or morphological differences as guided by the DPS policy, to determine
whether any populations showed evidence of marked separation. The
information available does not indicate that any ecological or physical
factors have produced population segments that express any genetic or
morphological discontinuity due to separation from other prairie dog
populations. Gene flow via dispersal and migration may maintain genetic
diversity in prairie dog species or help restore genetic diversity in
prairie dog populations following plague epizootics (Trudeau et al.
2004, p. 206). The available information does not suggest that
populations differ genetically or morphologically.
We determine, based on a review of the best available information,
that no population segment of the white-tailed prairie dog meets the
discreteness conditions of the 1996 DPS policy. Therefore, no
population segment qualifies as a DPS under our policy and is not a
listable entity under the Act.
The DPS policy is clear that significance is analyzed only when a
population segment has been identified as discrete. Since we found that
no population segment met the
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discreteness element and, therefore, no population segments qualify as
a DPS under the Service's DPS policy, we will not conduct an evaluation
of significance.
Significant Portion of the Range Analysis
We evaluated the white-tailed prairie dog's predicted range in the
context of whether any potential threats are concentrated in one or
more areas of the projected range, such that if there were concentrated
impacts, those white-tailed prairie dog populations might be
threatened, and further, whether any such population or complex might
constitute a significant portion of the range. The potential threat
factors we evaluated for possible geographic concentration were the
most substantial factor(s) affecting the species (in this case, plague
and habitat fragmentation due to oil and gas development).
Plague
We regard sylvatic plague as the most substantial factor affecting
the white-tailed prairie dog. The disease is present throughout the
species' range. We consider the entire range of the species to be
operating in a post-plague environment. We documented variation between
colonies and complexes in their ability to maintain observed peaks of
abundance. However, this variation occurred in every portion of the
range, and was not concentrated in any geographic location. At this
time, there is no evidence to suggest that plague affects portions of
the range differently, or will in the foreseeable future.
Oil and Gas Development
Oil and gas development is a widespread land use within the
species' range. Our analysis indicated a concentration of oil and gas
activity in Uintah County, Utah, and the Northwest IPA, located in
adjacent Moffat, Mesa, and Rio Blanco Counties in Colorado. A similar
concentration can be visually observed in Sweetwater County, Wyoming
(Hotze 2010, p. 11). However, some of the most robust and resilient
colonies are found within these areas of concentrated development. The
available evidence does not indicate that oil and gas development
activities are negatively impacting the species (see Factor A. Oil and
Gas Exploration and Development). Given these factors, we do not
believe the regional concentration of oil and gas development is
threatening the species in these portions of its range.
On the basis of this review, we have determined that the magnitude
and imminence of threats do not indicate that the white-tailed prairie
dog is in danger of extinction, or likely to become endangered,
throughout all or a significant portion of its range, within the
foreseeable future. The species also does not meet the elements of our
1996 DPS Policy that would result in a DPS designation for any segment
of the population. We conclude that no Significant Portion of the Range
(SPR) exists for the white-tailed prairie dog. We do not find that the
species is in danger of extinction now, nor is it likely to become
endangered within the foreseeable future, throughout all or a
significant portion of its range. Therefore, listing the white-tailed
prairie dog as endangered or threatened under the Act is not warranted
at this time.
We request that you submit any new information concerning the
status of, or threats to, the white-tailed prairie dog to our Utah Fish
and Wildlife Office (see ADDRESSES) whenever it becomes available. New
information will help us monitor the white-tailed prairie dog and
encourage its conservation. If an emergency situation develops for the
white-tailed prairie dog or any other species, we will act to provide
immediate protection.
References Cited
A complete list of references cited is available on the Internet at
http://www.regulations.gov and upon request from the Utah Field Office
(see ADDRESSES).
Authors
The primary authors of this document are the staff members of the
Utah Field Office, West Valley City, Utah.
Authority
The authority for this section is section 4 of the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: May 14, 2010
Daniel M. Ashe,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2010-12599 Filed 5-28-10; 8:45 am]
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