[Federal Register Volume 71, Number 30 (Tuesday, February 14, 2006)]
[Proposed Rules]
[Pages 7715-7720]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-1288]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17


Endangered and Threatened Wildlife and Plants; Petition To List 
the Douglas County Pocket Gopher as Threatened or Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
90-day finding on a petition to list the Douglas County pocket gopher 
(Thomomys talpoides macrotis) as threatened or endangered under the 
Endangered Species Act of 1973, as amended (Act). We find that the 
petition does not present substantial scientific or commercial 
information indicating that listing the Douglas County pocket gopher 
may be warranted. This finding is based on our determination that the 
Douglas County pocket gopher is more widespread than indicated in the 
petition, that substantially more sites are currently occupied, and 
that many of these occupied sites are protected from development by 
being part of county-administered open space, Lowry Military 
Reservation lands, or various

[[Page 7716]]

State-owned lands in Douglas, Arapahoe, and Elbert Counties, Colorado. 
Therefore, we will not initiate a status review in response to this 
petition. However, the public may submit to us new information 
concerning the status of or threats to the Douglas County pocket gopher 
at any time.

DATES: The finding announced in this document was made on February 14, 
2006.

ADDRESSES: The complete file for this finding is available for public 
inspection, by appointment, during normal business hours at U.S. Fish 
and Wildlife Service, 134 Union Boulevard, Suite 645, Lakewood, 
Colorado 80228. Submit new information, materials, comments or 
questions regarding the status of or threats to this taxon at the above 
address.

FOR FURTHER INFORMATION CONTACT: Bob Dach, U.S. Fish and Wildlife 
Service, Region 6 (see ADDRESSES) (telephone 303-236-4264; facsimile 
303-236-0027).

SUPPLEMENTARY INFORMATION:

Background

    Section 4(b)(3)(A) of the Act (16 U.S.C. 1531 et seq.) requires 
that we make a finding as to whether the Petitioners (Center for Native 
Ecosystems [CNE], Forest Guardians, Michael C. McGowan, and Jacob 
Smith) presented substantial scientific or commercial information 
indicating that listing the Douglas County pocket gopher as threatened 
or endangered may be warranted. Our regulations require that we make 
this finding, to the maximum extent practicable, within 90 days of our 
receipt of the petition and then promptly publish it in the Federal 
Register. Although this notice has been delayed, it represents our 90-
day finding.
    This 90-day finding is not intended to determine whether the 
Douglas County pocket gopher should be listed. It is only intended to 
determine whether substantial scientific or commercial information 
indicates that listing may be appropriate. ``Substantial scientific or 
commercial information'' is ``that amount of information that would 
lead a reasonable person to believe that the measure proposed in the 
petition may be warranted'' (50 CFR 424.14(b)(1)). If we find that 
substantial scientific or commercial information exists, we are 
required to promptly commence a status review of the species. The 
status review would ultimately lead to a listing determination.
    In accordance with the Act's requirement that we use the best 
available information to support our finding, we reviewed additional 
information readily available in our files to clarify certain points 
raised in the petition, including preliminary information regarding the 
genetic distinctness of the Douglas County pocket gopher. Also, 
although we did not conduct research or subject the petition to 
rigorous critical review, we did consider additional information in our 
files concerning more recent field observations. In total, the 
information available to us indicates that the Douglas County pocket 
gopher is more widespread than indicated in the petition, substantially 
more sites are currently occupied, and many of these occupied sites are 
protected from development by being part of county-administered open 
space, Lowry Military Reservation lands, or various State-owned lands 
in Douglas, Arapahoe, and Elbert Counties, Colorado.

Previous Federal Action

    On March 27, 2003, we received a formal petition from the CNE, 
Forest Guardians, Michael C. McGowan, and Jacob Smith to list the 
Douglas County pocket gopher as a threatened or endangered species 
pursuant to section 4 of the Act and to designate critical habitat. The 
petition cited threats from rapid commercial and residential 
development, exotic species, herbicide use, modifications to natural 
water runoff patterns, predation, lack of regulatory mechanisms, 
poisoning, and environmental and genetic stochasticity. The petition 
also requested an emergency rule based on immediate threats from 
development.
    In a letter dated May 20, 2003, we denied emergency listing 
because, after reviewing available data and risks to the subspecies, we 
determined that there was not a significant and immediate risk to its 
continued existence. On May 5, 2003, and April 1, 2004, the Petitioners 
sent notices of intent to sue for our failure to make 90-day and 12-
month findings, respectively, and on February 2, 2005, we received a 
Complaint for Declaratory and Injunctive Relief. In light of these 
legal actions, we discussed various options with the plaintiffs and 
agreed to submit a completed 90-day finding to the Federal Register by 
February 3, 2006.

Species Information

    The pocket gopher is a fossorial (adapted to digging) rodent 
measuring 225-230 millimeters (8.9-9 inches). It is 1 of 58 northern 
pocket gopher (Thomomys talpoides) subspecies, 9 of which are located 
within Colorado (Hall 1981). Pocket gophers have a small, flattened 
head, short neck, and muscular shoulders and forearms. Fur-lined cheek 
pouches (pockets), which open externally, distinguish them from other 
rodents. Adult pocket gophers are solitary, territorial, and have very 
small home ranges. The northern pocket gopher is short-lived, with a 
maximum lifespan of approximately 5 years.

Distribution and Population Status

    The northern pocket gopher has the widest distribution of all 
pocket gophers--from Manitoba to Colorado, and from the Cascade and 
Sierra Nevada mountain ranges eastward to Minnesota. Disjunct 
populations occur in Arizona, New Mexico, and Utah. Local populations 
are separated by unsuitable habitat, usually attributed to soil type, 
and by major geographic barriers (Culver and Mitton, in litt., 2004). 
The northern pocket gopher inhabits a variety of habitat types, 
including deep, tractable soils, heavily compacted soils, and shallow 
gravels (CNE et al. 2003). The Douglas County pocket gopher in 
particular seems able to tolerate a variety of soil types, utilizing 
areas not preferred by adjacent northern pocket gopher subspecies.
    Douglas County pocket gopher life history characteristics 
(including their strong territoriality and solitary nature) and their 
discontinuous distributions (based on local habitat characteristics) 
lead to small population sizes. The historic distribution of the 
Douglas County pocket gopher is limited to parts of southwestern 
Arapaho, northern Douglas, and northwestern Elbert Counties in Colorado 
(CNE et al. 2003). The Petitioners identified five sites where the 
Douglas County pocket gopher had recently been known to occur, all in 
Douglas County. Their petition was based largely on threats to these 
remaining colonies.
    The petition estimated the current global population of the Douglas 
County pocket gopher at 501 to 1,000 individuals or ``unknown, but 
thought to be small.'' This estimate was taken from the Colorado 
Division of Wildlife (CDOW) Vertebrate Ranking System--a proactive tool 
to help identify potential wildlife conservation needs in the State. 
However, the Vertebrate Ranking System is not intended to provide 
accurate population estimates of individual species or subspecies (Gary 
Skiba, CDOW, pers. comm., 2003). Although CDOW is aware of potential 
conservation concerns, they emphasize that population size is 
``unknown'' (Skiba 2003).
    Field studies conducted by the Colorado Natural Heritage Program

[[Page 7717]]

(CNHP) in 2002 identified 5 additional northern pocket gopher colonies 
in southern Douglas, eastern Elbert, and southern Arapahoe Counties 
that were not identified in the petition, extending the known range of 
the gopher to the east and south of the type locality (Jeremy Siemers, 
CNHP, pers. comm. April 4, 2003). Although these populations have not 
been positively identified to the subspecific level, they were within 
or near the Douglas County pocket gopher's range as delimited by 
Armstrong (1972) (Siemers 2003). In addition, field observations 
conducted in 2003 by the Service, CDOW, Douglas County, David Armstrong 
(mammalogist, University of Colorado), and Chris Pague (The Nature 
Conservancy) identified Douglas County pocket gopher spoil mounds, soil 
casts, and eskers in an additional 36 locations, at least six of which 
are currently protected as open space, are on State park lands, or are 
currently being held in trust (that is, Lowry Military Reservation) 
(Elliott Sutta, Service, in litt., May 20, 2003). The location and soil 
type of these colonies supports their assignment to Thomomys talpoides 
macrotis. The 2003 observations were very limited in duration and 
scope, indicating that a more thorough analysis of the gopher's range 
is necessary to fully understand its current distribution. No other 
subspecies of pocket gopher has been reported in the area of these 
additional colony sites. Based on the proximity of these additional 
locations to known Douglas County pocket gopher populations, as well as 
the distance from other pocket gopher subspecies populations, there is 
no reason to believe these additional colonies may be other than 
Thomomys talpoides macrotis. The best available scientific and 
commercial information suggests that there are at least 41 more 
colonies than identified in the petition.

Classification

    The taxonomy of the northern pocket gopher has not been revised 
since 1915, and only recently have genetic data been collected to 
evaluate the phylogenetic relationships among the subspecies (Culver 
and Mitton, in litt. 2004). Thomomys talpoides macrotis was named by 
F.W. Miller in 1930 and characterized by its larger body and paler, 
more grayish color (when compared to adjacent populations of T. t. 
rostralis and T. t. retrorsus). Existing taxonomy, based on pelage 
color and morphology alone, suggests that variation between subspecies 
of northern pocket gophers is often less than variation seen within a 
single subspecies (Culver and Mitton, in litt., 2004). Available 
information further suggests that the taxon includes more than one 
species (Culver and Mitton, in litt., 2004). Based on this information, 
we concur with assertions made by Culver and Mitton (in litt., 2004) 
that the available information brings into question the species' 
current subspecific taxonomy.
    The Petitioners provided some information regarding the Douglas 
County pocket gopher's subspecific status, but their justification 
relied largely on its existing, widely accepted taxonomy as described 
by Miller (1930) and the lack of compelling evidence to suggest 
otherwise. However, a recent mitochondrial DNA analysis found no 
diagnostic differences among the three contiguous subspecies of the 
northern pocket gopher in the Douglas County area (Thomomys talpoides 
macrotis, T. t. rostralis, and T. t. retrorsus) (Culver and Mitton 2005 
in litt., 2004). Although this study calls into question the species' 
current taxonomy, we consider the findings preliminary given certain 
methodology limitations (for example, limited number of specimens 
sampled [115], small amount of genome sampled [305 basepairs], reliance 
on museum specimens [including skin and liver tissue]). Also, the study 
has not been peer-reviewed and published.

Discussion

    In the following discussion, we respond to each of the major 
assertions made in the petition, organized by the Act's listing 
factors. According to section 4(a)(1) of the Act and its implementing 
regulations (50 CFR 424), a species may be added to the Federal list of 
endangered and threatened species due to one or more of the following 
five factors--(1) The present or threatened destruction, modification 
or curtailment of its habitat or range; (2) overutilization for 
commercial, recreational, scientific, or educational purposes; (3) 
disease or predation; (4) the inadequacy of existing regulatory 
mechanisms; and (5) other natural or manmade factors affecting its 
continued existence. The Petitioners provided information regarding 
these 5 factors, but they only addressed 5 of 46 known sites (that is, 
there was no information provided on 41 sites and no information 
provided in the petition, or readily available in our files, to assume 
that the threats identified in the petition are consistent throughout 
the Douglas County pocket gopher's range).
    Fundamental to the threats discussion is the need for substantial 
scientific or commercial information indicating that a reduction in 
range and/or population size has been, or is likely, occurring. We have 
reviewed the information provided in the petition and did not find 
substantial scientific or commercial information indicating that 
limited range and small population size were a threat to this species. 
Although the Douglas County pocket gopher has a comparatively small 
range (with respect to other northern pocket gopher subspecies), there 
is no indication that its geographic range is becoming smaller. When 
comparing field studies and observations from 2002 and 2003 with its 
historic range, range size may be stable--although as indicated above, 
a more thorough analysis of the gopher's geographic range is necessary 
to fully understand its current distribution. We do not have 
information concerning historical or current population abundance at 
any sites to address the question of whether the overall population has 
experienced a decline.

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

Information Provided in the Petition
    The petition stated that the limited range and small population 
size of the Douglas County pocket gopher makes it vulnerable to 
disturbance; rapid commercial and residential development are resulting 
in habitat loss and fragmentation; habitat is being degraded from 
exotic species and herbicide use; and modifications to natural water 
runoff patterns are altering soil moisture content and limiting habitat 
availability (related to both site-specific development and climate 
change). The Petitioners further state that Douglas County pocket 
gophers are currently limited to five sites in Douglas County, 
Colorado--the Willow Creek, Lincoln Avenue, McArthur Ranch, Newlin 
Gulch, and Grandview Estates sites (CNE et al. 2003). These sites were 
surveyed in 1993 and 1994 by CNHP, and subsequently visited in January 
2003 (CNE et al. 2003).
    In 1993, the Willow Creek site was heavily disturbed and fragmented 
by Interstate C-470 and County Line Road, ephemeral streams and ravines 
had been cut off, streams had been channelized, bike paths had been 
built through the site, and there were many exotic plant species (CNE 
et al. 2003). By 2003, colonies north of C-470 had been lost to 
construction of a strip mall and car dealerships, and habitat to the 
south had been severely fragmented from other development (that is, the 
land had been graded and seeded with nonnative grasses) (CNE et al. 
2003). Although some gopher habitat remained, the Petitioners stated 
that it was currently

[[Page 7718]]

being managed for recreational cyclists. Threats to this site included 
commercial development, altered hydrology, noxious weeds, habitat 
fragmentation, loss of native forage species, and recreational 
disturbances from the adjacent bike path (CNE et al. 2003).
    The Lincoln Avenue site is located approximately 2 miles (3 
kilometers) south of the Willow Creek site and could possibly have been 
part of the Willow Creek colony (CNE et al. 2003). In 1993 and 1994, 
the Lincoln Avenue site showed signs of two gopher concentrations, 
although by 2003 one concentration had been completely lost to 
development and the other had been severely isolated. Threats to this 
site included development, fragmentation, rodenticides, herbicides 
(associated with a neighboring golf course), other pesticides, loss of 
native forage, altered hydrology, and recreational disturbance (CNE et 
al. 2003).
    In 1993, the McArthur Ranch site had abundant signs of Douglas 
County pocket gopher use, but by 2003 all areas previously described by 
CNHP had been developed, were undergoing development, or had been 
reserved for future housing, schools, and recreational facilities (CNE 
et al. 2003). The petition stated that threats to this site included 
loss of native forage, fragmentation, road disturbance, and 
development.
    The Newlin Gulch site was largely open prairie used for cattle 
grazing in 1994 (when CNE last observed the site). Four groups of 
mounds, each likely representing one or two individual Douglas County 
pocket gophers, were reported in the area (CNE et al. 2003). The land 
has since been sold to the Parker Water and Sanitation District, where 
a 205,622,616-hectoliter (16,670-acre-foot) reservoir is under 
construction with a planned expansion of 670,154,574 hectoliters 
(54,330 acre-feet). At least one set of mounds observed in 1994 would 
be destroyed from this development (CNE et al. 2003). The petition 
stated that threats to this site also included changes in hydrology, 
disturbance associated with the construction and maintenance of the 
reservoir, disturbance associated with recreational opportunities 
around the reservoir, habitat fragmentation, noxious weeds, and soil 
removal.
    The Grandview Estates site consisted largely of disturbed 
grasslands where only sporadic gopher mounds had been observed. There 
has been no development on this site, but the area has been zoned for 
commercial development (CNE et al. 2003). Therefore, the petition 
identified development, loss of native forage, and habitat 
fragmentation as threats.
    In general, the petition stated that habitat destruction was the 
primary threat to the Douglas County pocket gopher. Douglas County 
pocket gopher concentrations at three of the five sites reviewed in the 
petition had already been destroyed, and development of the Rueter-Hess 
Project and commercial development proposed for Grandview Estates 
threatened the remaining two sites. In addition, the petition 
identified habitat fragmentation (leading to inbreeding and loss of 
gene flow) and degradation (noxious weeds and an increase in fire 
frequency) as significant threats for the remaining isolated colonies. 
The Petitioners included some information on the effects of herbicides 
and suggested that disruptions in natural runoff patterns may alter 
soil moisture content.
Evaluation of Information in the Petition Regarding Factor A
    The petition presented compelling information regarding habitat 
loss as a result of commercial and residential development, and 
specific colonies have undoubtedly been lost. We found this discussion 
undeniable for those sites completely covered by concrete and asphalt, 
where they may have been lost due to the construction of recreational 
facilities (for example, baseball diamonds, football or soccer fields, 
golf courses), or covered by water (as may be for the Reuter-Hess 
Project). However, we were unable to conclude that these threats were 
common throughout a significant portion of the pocket gopher's range or 
a significant factor at the subspecific level based upon the new 
information we have about additional occupied sites. We did not find 
substantial scientific or commercial information indicating that bike 
path construction posed a risk to the subspecies. Also, the petition 
presented information indicating that certain sites had been heavily 
impacted by exotic plant species. However, it also identified pocket 
gopher populations occurring within these disturbed areas, and it did 
not include information demonstrating an effect on the pocket gopher.
    The petition also provided information regarding the effects of 
herbicide applications on pocket gophers in general but did not provide 
substantial scientific or commercial information regarding the actual 
use of herbicides on Douglas County pocket gopher habitats (that is, 
although the petition stated that herbicides were bad for pocket 
gophers, it did not provide substantial scientific or commercial 
information regarding whether, where, or how they were being applied). 
Without this information, we cannot determine whether threats from the 
application of herbicides are significant. With respect to runoff 
patterns and soil moisture content, the petition recognized the lack of 
available information regarding potential effects to the Douglas County 
pocket gopher and provided no substantial scientific or commercial 
information to support possible effects from flooding in urban areas 
caused by disrupted runoff patterns. No information was presented to 
demonstrate, for example, possible effects from urban runoff on any 
pocket gopher species, which are generally adapted to avoiding seasonal 
runoff (Chapman and Feldhamer 1982). Although not provided in the 
petition, information enabling review of local hydrology, frequency of 
high water events, or effects on specific colonies (for example, 
proximity of pocket gopher colonies to streambanks or number of 
locations potentially affected) may help to support this claim.

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

Information Provided in the Petition
    Regarding Listing Factor B, the petition restated commercial and 
residential development as threats and stated that pocket gophers were 
killed for agricultural purposes, and destroyed to make way for 
recreational facilities (for example, baseball fields, bike paths, golf 
courses). The Petitioners provided information to show that pocket 
gophers were widely regarded as agricultural pests and that a division 
under the U.S. Department of Agriculture manufactured and disseminated 
toxicants to control pocket gopher populations in areas used for 
agriculture and silviculture. The petition stated that these toxicants 
were available to area landowners and managers.
Evaluation of Information in the Petition Regarding Factor B
    Commercial and residential development, including baseball fields, 
bike paths, and golf courses was considered under Listing Factor A, 
above, and as stated, there was not substantial scientific or 
commercial information presented to warrant further status review. In 
addition, the petition did not provide substantial scientific or 
commercial information to indicate that poisoning is a threat to the 
subspecies--only that pocket gopher control has occurred and that 
toxicants are readily available. Control is largely related to

[[Page 7719]]

agricultural areas, which are not representative of currently known 
pocket gopher localities. No information was provided to support 
widespread (or even limited) use of poisons on pocket gopher colonies 
by State, city, or local officials or suggestions that eradication 
programs are under way in certain areas.
    The petition did not present any information indicating that the 
Douglas County pocket gopher is being overutilized (pursuant to the 
intent of this listing factor) and we are not aware of any organized 
use of the subspecies for commercial, recreational, scientific, or 
educational purposes (that is, they are not a game species, provide no 
commercial value, are not prone to target shooting, and we have no 
information to suggest that scientific or educational collections are 
widespread).

C. Disease or Predation

Information Provided in the Petition
    Predation has not been documented as limiting Douglas County pocket 
gopher numbers or range (CNE et al. 2003). However, the petition 
suggested that population growth may modify traditional predator-prey 
relationships with a deleterious effect to Douglas County pocket 
gophers. The Petitioners suggested that construction would lead to 
additional raptor perches, referencing a Bureau of Land Management 
Environmental Impact Statement (EIS) for oil and gas development in the 
Powder River basin, Wyoming, and that residential development would 
increase predation from domestic dogs and cats. The petition also 
suggested that coyote control would lead to an increase in smaller 
predator populations (such as bobcats, badgers, foxes, and skunks) that 
could have an increased effect on Douglas County pocket gophers.
Evaluation of Information in the Petition Regarding Factor C
    The petition did not provide substantial scientific or commercial 
information that would allow an objective review of its hypotheses. We 
are unaware of any studies that demonstrate an increase in raptor 
densities corresponding to increased residential and commercial 
construction in urban areas, and information contained in the 
referenced EIS is largely inapplicable given the substantially 
different ecosystems being discussed (that is, large expanses of open 
prairie with intermittent raptor perches versus urban development and 
the associated negative effects to raptor colonization and use). No 
information was provided to assess the likelihood or potential 
magnitude of the effects from domestic dogs and cats and, although 
coyote control efforts and other factors would likely have an effect on 
the prevalence of smaller predators, there was no information presented 
that would enable an assessment of the impact of these factors across 
the pocket gopher's range. Disease was not identified as a potential 
threat in the petition.

D. Inadequacy of Existing Regulatory Mechanisms

Information Provided in the Petition
    The petition stated that there are no specific regulatory 
mechanisms in place to protect the Douglas County pocket gopher and 
that only one site, Willow Creek, is being managed as open space. Even 
at the Willow Creek site, the South Suburban Parks and Recreation 
District is not actively managing for pocket gophers, but focuses their 
efforts on recreational use (CNE et al. 2003).
Evaluation of Information in the Petition Regarding Factor D
    Recent surveys have identified at least six additional pocket 
gopher sites that are either managed as open space, on State park 
lands, or currently being held in trust (that is, Lowry Military 
Reservation). It is not clear from the information presented in the 
petition or readily available to us, what threats may be pertinent to 
these populations, or if specific regulatory protections are needed.

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

Information Provided in the Petition
    The petition identified global climate change, demographic, 
environmental and genetic stochasticity, stress, and population growth 
as threats under this listing factor. Regarding climate change, the 
petition stated that human-caused climate change may lead to increases 
in the frequency and intensity of drought and flooding and stated that 
winter and spring precipitation in Colorado may increase by as much as 
70 percent. These changes would affect Douglas County pocket gophers by 
increasing soil moisture content.
    Regarding demographic stochasticity, the petition stated that the 
extremely short lifespan of the Douglas County pocket gopher, its 
vulnerability upon dispersal, and its relatively low rate of 
reproduction all exacerbate its susceptibility to extinction, given its 
very small population size (CNE et al. 2003). Because all five of the 
populations identified in the petition are threatened by development, 
the Petitioners stated that the potential for demographic bottlenecks 
and consequent extinction is great.
    Issues pertinent to environmental stochasticity, as presented in 
the petition, generally include fire, disease, resource availability, 
and predation--factors more pertinent to smaller geographic 
distributions (less important to population size because entire 
populations are usually affected). The petition specifically stated 
that drought, excessive levels of water in snow pack, and atypical snow 
melts contribute to declines in Douglas County pocket gophers. The 
Petitioners also identified inbreeding depression and a resulting loss 
of fitness as potential genetic stochastic events.
    The petition also stated that many of the factors previously 
discussed could lead to increased stress levels, subsequently leading 
to reduced reproduction and survival rates, and the petition provided 
various census data demonstrating high levels of population growth in 
Arapahoe and Douglas Counties.
Evaluation of Information in the Petition Regarding Factor E
    The Petitioners discussed the effects of climate change on survival 
and recruitment, but presented information largely inapplicable to the 
Douglas County pocket gopher. It was not clear based on the information 
presented in the petition how climate change has affected the pocket 
gopher's habitat. Climate change has been linked to a number of 
conservation issues and observed changes in animal populations and 
ranges. However, direct evidence that climate change is the cause of 
these alterations is often lacking (McCarty 2001). To our knowledge, 
specific analysis regarding potential effects of climate change on the 
Douglas County pocket gopher has not been conducted. The information 
provided in the petition is speculative in nature and does not provide 
substantial scientific or commercial information of threats to the 
pocket gopher from climate change.
    Stochastic, or random, changes in a wild population's demography or 
genetics can threaten its persistence (Pimm et al. 1988). A stochastic 
demographic change, such as a skewed age or sex ratio (such as a sudden 
loss of adult females) could negatively affect reproduction, especially 
in small populations (that is, Allee effects; Allee 1931). Northern 
pocket gophers are subject to intermittent fluctuations in population 
size (Chapman and Feldhamer 1982), and the impacts could be more 
pronounced in the Douglas County pocket gopher given its

[[Page 7720]]

comparatively smaller historic range and population.
    However, we did not find substantial scientific or commercial 
information in the petition to indicate whether the factors necessary 
for such stochastic events are present (decreasing population 
densities, decreasing reproduction rates, unreliable sources of 
immigration). Information related to these metrics is vital for 
determining whether demographic or genetic stochastic events are likely 
to occur given threats to the subspecies. In all cases, the Petitioners 
supported their claims with 2 fundamental assertions, that there are 
less than 5 remaining colonies of Douglas County pocket gophers and 
that the subspecies' population size is between 501 and 1,000 
individuals and declining. As we have noted previously, there appear to 
be many more colonies than those identified in the petition and there 
has not been substantial scientific or commercial information provided 
to support estimates of the subspecies population size or status. 
Because information pertaining to the 41 colonies not recognized in the 
petition was unavailable to us, we could not conclude that ``all of the 
remaining populations are threatened by development'' as stated in the 
petition. In addition, the Petitioners presented no information to 
support their claims that environmental stochasticity presents a threat 
to pocket gophers; there was no information provided to demonstrate 
that fire would be more likely to occur as a result of development, 
disease is not considered a threat to this subspecies, and there was 
not substantial scientific or commercial information presented to 
support weather fluctuations or predation as threats.
    The Petitioners relied on the fact that the Douglas County pocket 
gopher was only known from five sites to show that stochastic events 
threaten the species. Given what is now known about the additional 41 
populations, we do not think that stochastic events would threaten the 
species throughout all or a significant portion of its range.
    The petition did not provide substantial scientific or commercial 
information to demonstrate that a reduction in reproduction and 
survival had occurred, was occurring, or was a threat at the 
subspecific level. This information could be used to support the claim 
that stress was a significant threat. Also, we do believe that 
development could pose a long-term threat to this species, but there 
was not substantial scientific or commercial information indicating 
that development would be a threat across the Douglas County pocket 
gopher's range in the foreseeable future.
Summary
    The Petitioners presented information on potential threats that 
could be affecting the Douglas County pocket gopher. However, there was 
insufficient information presented to determine whether these threats 
were substantially occurring or what degree of impact they may be 
having at the subspecific level, largely because the Petitioners' 
assessment was limited to only five populations. Also, there was 
insufficient information demonstrating a declining range or population 
trend. Most limiting was a necessary consideration of how the potential 
threats recognized by the Petitioners applied to the 41 additional 
sites identified through field observations and studies in 2002 and 
2003. Based on the limited information presented in the petition and 
readily available in our files, we were unable to extrapolate the 
Petitioners' claims to those populations.
Finding
    On the basis of our review, we find that the petition does not 
present substantial scientific or commercial information indicating 
that listing the Douglas County pocket gopher may be warranted. This 
finding is based on our determination that the pocket gopher is more 
widespread than indicated in the petition, that substantially more 
sites are currently occupied, and that many of these occupied sites are 
protected from development by being part of county-administered open 
space, Lowry Military Reservation lands, or various State-owned lands 
in Douglas, Arapahoe, and Elbert Counties, Colorado. Therefore, we will 
not initiate a status review in response to this petition. However, we 
will continue to monitor the taxon's population status and trends, 
potential threats, and ongoing management actions that might be 
important with regard to the conservation of the Douglas County pocket 
gopher across its range. We encourage interested parties to continue to 
gather data that will assist with these conservation efforts. New 
information should be submitted to U.S. Fish and Wildlife Service (see 
ADDRESSES).

References Cited

    A complete list of all references cited herein is available, upon 
request, from the U.S. Fish and Wildlife Service (see ADDRESSES).

Author

    The primary author of this notice is Bob Dach, Region 6 Office, 
U.S. Fish and Wildlife Service (see ADDRESSES).

Authority

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

    Dated: February 3, 2006.
Marshall P. Jones,
Deputy Director, Fish and Wildlife Service.
[FR Doc. 06-1288 Filed 2-13-06; 8:45 am]
BILLING CODE 4310-55-P