Endangered and Threatened Wildlife and Plants; Final Rule To Amend the Listing for the Preble's Meadow Jumping Mouse (Zapus hudsonius preblei) To Specify Over What Portion of Its Range the Subspecies Is Threatened

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R9-ES-2007-0003; 92220-1113-0000; C6]

RIN 1018-AV64

Endangered and Threatened Wildlife and Plants; Final Rule To Amend the Listing for the Preble's Meadow Jumping Mouse (Zapus hudsonius preblei) To Specify Over What Portion of Its Range the Subspecies Is Threatened

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Final rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service/USFWS), under the authority of the Endangered Species Act of 1973, as amended (Act), amend the listing for the Preble's meadow jumping mouse (

Zapus hudsonius preblei

) (Prebles) to specify over what portion of its range the subspecies is threatened. Based on the best scientific and commercial data available, we have determined that the Prebles is a valid subspecies and should not be delisted based upon taxonomic revision; the subspecies is not threatened throughout all of its range; and the portion of the subspecies' current range located in Colorado represents a significant portion of the current range where the subspecies should retain its threatened status. This determination is based on a thorough review of all available information, which indicates that Prebles' populations in Wyoming are more widespread and threats to the subspecies less severe than those known at the time of listing, but that in Colorado the Prebles is likely to become endangered within the foreseeable future.

DATES:

This rule is effective August 11, 2008.

FOR FURTHER INFORMATION CONTACT:

Susan Linner, Field Supervisor, U.S. Fish and Wildlife Service, Colorado Field Office at 134 Union Blvd., Suite 670, Lakewood, CO 80228; telephone (303) 236-4773. Individuals who are hearing-impaired or speech-impaired may call the Federal Relay Service at 1-800-877-8339 for TTY assistance.

SUPPLEMENTARY INFORMATION:

General Information

Meadow jumping mice (

Zapus hudsonius

) are small rodents with long tails, large hind feet, and long hind legs. Total length of an adult is approximately 187 to 255 millimeters (7 to 10 inches), with the tail comprising 108 to 155 millimeters (4 to 6 inches) of that length (Krutzsch 1954, p. 420; Fitzgerald

et al

. 1994, p. 291).

Typical habitat for Prebles is comprised of well-developed riparian vegetation with adjacent, relatively undisturbed grassland communities and a nearby water source (Bakeman 1997, pp. 22-31). Prebles are typically captured in areas with multi-storied cover with an understory of grasses or forbs or a mixture thereof (Bakeman 1997, pp. 22-31; Bakeman and Deans 1997, pp. 28-30; Meaney

et al

. 1997a, pp. 15-16; Meaney

et al

. 1997b, pp. 47-48; Shenk and Eussen 1998, pp. 9-11; Schorr 2001, pp. 23-24). The shrub canopy is often willow (Salix spp.), although other shrub species may occur (Shenk and Eussen 1998, pp. 9-11). Trainor

et al.

(2007, pp. 471-472) found that high-use areas for Prebles tended to be close to creeks and were positively associated with the percentage of shrubs, grasses, and woody debris. Hydrologic regimes that support Prebles' habitat range from large perennial rivers such as the South Platte River to small drainages only 1 to 3 meters (m) (3 to 10 feet (ft)) in width.

Meadow jumping mice are primarily nocturnal or crepuscular (active during twilight), but also may be active during the day. The Prebles uses uplands at least as far out as 100 m (330 ft) beyond the 100-year floodplain (Shenk and Sivert 1999a, p. 11; Ryon 1999, p. 12; Schorr 2001, p. 14; Shenk 2004; USFWS 2003b, p. 26). While the Prebles' dispersal capabilities are thought to be limited, in one instance a Prebles was documented moving as far as 1.1 kilometers (km) (0.7 mile (mi)) in 24 hours (Ryon 1999, p. 12). The Prebles typically enters hibernation in September or October and emerges the following May (Whitaker 1963, p. 5; Meaney

et al

. 2003).

For additional information on the biology of this subspecies, see the May 13, 1998, final rule to list the Prebles as threatened (63 FR 26517) and the June 23, 2003, final rule designating critical habitat (68 FR 37275).

Previous Federal Actions

We listed the Prebles as threatened under the Act on May 13, 1998 (63 FR 26517). On May 22, 2001 (66 FR 28125), we adopted a final section 4(d) special rule for the Prebles that provides exemptions from section 9 take prohibitions for certain rodent control activities, ongoing agricultural activities, maintenance and replacement of existing landscaping, and existing uses of water. On October 1, 2002 (67 FR 61531), we amended this rule to provide exemptions for certain noxious weed control and ditch maintenance activities. The special rule, as amended, was scheduled to end May 22, 2004, but was made permanent on May 20, 2004 (69 FR 29101). On June 23, 2003, we designated critical habitat for the Prebles in portions of Colorado and Wyoming (68 FR 37275).

In June 2000, the Service established the Preble's Meadow Jumping Mouse Recovery Team (Recovery Team) composed of scientists and stakeholders. In June 2003, the Recovery Team provided their recommendations to the Service in the form of a draft recovery plan. The Service revised this technical working draft in November 2003. This document (hereafter referred to as the Preliminary Draft Recovery Plan) suggests the long-term protection of populations spread throughout the current range of the subspecies in order to lessen or eliminate threats. In particular, the documents suggest long-term protection of 1 large population (with June abundances of 2,500 or more individuals), 2 medium populations (with June abundances of 500-2,499 individuals), and 6 small populations (with evidence of occupancy; possibly 150 mice) within the North Platte River basin; 2 large, 3 medium, and 18 small populations within the South Platte River basin; and 1 large population, and 6 small populations within the Arkansas River basin (USFWS 2003b, pp. 19-23). Recovery planning efforts were halted in December 2003 after new information became available questioning the taxonomic validity of the subspecies. While the availability of the Preliminary Draft Recovery Plan (USFWS 2003b) has not yet been announced in the

Federal Register

, it represents the best scientific information available to us concerning recovery needs of the Prebles.

On December 23, 2003, we received two nearly identical petitions, from the State of Wyoming's Office of the Governor and Coloradans for Water Conservation and Development, seeking to remove the Prebles from the Federal List of Endangered and Threatened Wildlife (Freudenthal 2003; Sonnenberg 2003). The petitions maintained that the Prebles should be delisted based on the taxonomic revision suggested by Ramey

et al.

(2003) and new distribution, abundance, and trends data that suggested the subspecies was no longer threatened or endangered (Freudenthal 2003, p. 1; Sonnenberg 2003, p. 1).

On March 31, 2004, we published a notice announcing a 90-day finding that the petitions presented substantial information indicating that the

petitioned action may be warranted (69 FR 16944). On February 2, 2005, we published a 12-month finding that the petitioned action was warranted and a proposed rule to remove Prebles from the Federal List of Endangered and Threatened Wildlife (70 FR 5404). This notice also opened a 90-day public comment period. The proposed delisting was based upon a taxonomic revision suggested by Ramey

et al.

(2004a (a revision of Ramey

et al.

2003)), which concluded that Prebles should be synonymized with a neighboring subspecies (Ramey

et al.

2004a, pp. 1, 13). Although this report remained unpublished and had received mixed peer reviews, we concluded that a lack of distinct genetic and morphologic differences suggested that Prebles was likely not a valid subspecies of meadow jumping mouse (

Zapus hudsonius

). Considering the weight that the findings of Ramey

et al.

(2004a) had in the proposed delisting, verifying these results prior to making a final decision on the proposal was a high priority of the Service (Williams 2004; Morgenweck 2005). As such, we contracted with the U.S. Geological Survey (USGS) to conduct additional genetic analysis of Prebles and four neighboring subspecies of meadow jumping mice (USGS 2005, pp. 1-4).

On January 25, 2006, the USGS released its report concluding that the Prebles should not be synonymized with neighboring subspecies of meadow jumping mice (King

et al

. 2006a, pp. 2, 29). On February 17, 2006, the Service extended the rulemaking process an additional 6 months as allowed under section 4(b)(6)(B)(i) of the Act (71 FR 8556). This USGS study indicated that there was substantial disagreement regarding the sufficiency or accuracy of the available data relevant to the determination contained in our proposed rule. We reopened the comment period for an additional 60 days and announced that we intended to assemble a panel of experts to carefully review and assess the two studies.

On March 30, 2006, we published a notice of availability of the King

et al.

(2006a) and Ramey

et al.

(2005) data and extended the comment period on the proposed delisting rule an additional 30 days (71 FR 16090). We then contracted with Sustainable Ecosystems Institute (SEI) to organize a scientific review panel to analyze, assess, and weigh the reasons why the data, findings, and conclusions of King

et al.

differed from the data, findings, and conclusions of Ramey

et al.

(as written in this sentence, and hereafter, “Ramey

et al.

” or “King

et al.

” without a modifying date refers to the overall work of these authors instead of a specific publication) (USFWS 2006, p. 14). On July 21, 2006, SEI delivered a final report to the Service (SEI 2006a).

On September 26, 2006, the State of Wyoming submitted a 60-day notice of intent to sue over our failure to publish a final determination on our 2005 proposed delisting rule within the timeframes allowed by the Act. On January 24, 2007, the State of Wyoming filed a petition for review with the court. On June 22, 2007, the Service and the State of Wyoming reached a settlement agreement which required that, by October 31, 2007, we submit to the

Federal Register

for publication either (1) a withdrawal of our 2005 proposed delisting regulation; or (2) a new proposed regulation considering the Prebles' taxonomy and the subspecies' threatened status in light of all current distribution, abundance, and trends data (

State of Wyoming

v.

U.S. Department of the Interior

, No. 07CV025J (District of Wyoming 2007)). On November 7, 2007, we published a revised proposed rule to amend the listing of the Prebles to specify over what portion of its range the subspecies is threatened and opened a 75-day public comment period (72 FR 62992). Under the settlement agreement with the State of Wyoming, the Service agreed to submit a final determination on the revised proposed rule to the

Federal Register

no later than June 30, 2008.

Public Comments Solicited

Comments on this rulemaking were accepted from February 2 to May 3, 2005 (70 FR 5404, February 2, 2005), from February 17 to April 18, 2006 (71 FR 8556, February 17, 2006; 71 FR 16090, March 30, 2006), and from November 7, 2007 to January 22, 2008 (72 FR 62992, November 7, 2007). Open houses and public hearings were held on December 10, 2007, in Lakewood, Colorado, and on December 12, 2007, in Wheatland Wyoming (72 FR 62992, November 7, 2007). These opportunities to comment were publicized via the

Federal Register

, press releases, public notices in area newspapers, postings on our Web site, and direct contact with Federal and State agencies, county governments, scientific organizations, and other interested parties. In addition, the media provided substantial coverage of the proposals. Comments could be hand delivered to us, submitted to us via e-mail, mail, the Federal e-Rulemaking Portal, fax, or provided during public hearing testimony.

Comments were submitted by a variety of parties including the general public, business interests, environmental organizations, and Federal, State, and local governments. We received 122 written, faxed, or e-mailed comments during public comment periods (excluding peer reviewers' comments discussed below). An additional eight comments were provided during two public hearings. On March 24, 2006, the Service received a Data Quality Act challenge on behalf of Coloradans for Water Conservation and Development and the Colorado Farm Bureau. While this challenge was handled separately from this rulemaking, all of the relevant issues raised also were considered public comments and considered in this final determination. All of the public comments available prior to the July 2006 SEI panel were made available to the panelists.

Peer Review

In accordance with our Interagency Policy for Peer Review in Act Activities (59 FR 34270, July 1, 1994) and the Office of Management and Budget's (OMB) Final Information Quality Bulletin for Peer Review (70 FR 2664, January 14, 2005), we sought the expert opinions of appropriate and independent specialists regarding this rulemaking. First, we contacted five reviewers with expertise in genetics, systematics, and small mammals to review the taxonomic portions of this document. Four of those solicited provided comments during one or more of the comment periods (Gore 2008; Hoekstra 2005; Kelt 2005, 2006, 2008; Spencer 2005, 2006a, 2008). All of the peer reviews submitted prior to the July 2006 SEI panel meeting were made available to the expert panelists (Hoekstra 2005; Kelt 2005, 2006; Spencer 2005, 2006a). Second, we contacted an additional five reviewers with expertise in small-mammal biology, riparian-community ecology and status, population dynamics and extinction risk, and/or development trends and land-use conflicts to review the remainder of the 2007 revised proposal. All five of these reviewers provided comments (Anderson 2008; Beauvais 2008; Buskirk 2008; Nupp 2008; Travis 2008).

Given the information now available, all of the experts who commented on taxonomic portion of the rule were supportive of our discussion, analysis, and/or conclusions. No reviewers expressed significant concerns over our analysis of the Prebles' taxonomy.

Reviews that focused on the remainder of the 2007 revised proposed rule were generally supportive of Service efforts, but provided criticism

and suggestions regarding various aspects of the revised proposed rule. Six reviewers provided comments on whether evidence we presented in the revised proposed rule sufficiently supported our removal of the Act's protections for the Wyoming populations. Three reviewers supported our proposal as being reasonable based on evidence presented. Two reviewers questioned the proposal based largely on adequacy of existing knowledge regarding Prebles' populations in Wyoming. One reviewer opposed the proposal, calling it weakly supported. Two reviewers suggested that the revised proposed rule should have made better use of geographic information systems (GIS) to depict and analyze trapping efforts, documented occurrence, appropriate habitat, and projected threats.

Reviewer opinions also varied on use of the Wyoming—Colorado State line to delineate a significant portion of Prebles' range. While reviewers generally considered a division based on the North Platte River basin and the South Platte River basin more appropriate from an ecological or mouse population perspective, three concluded that the use of the State line was supported by the differing levels of threats described. Two reviewers called for more detailed analysis of threats as related to both sides of the State line. One reviewer discounted significant differences in threats across the State line. Three reviewers mentioned the administrative or practical convenience of using the State line.

Summary of Public Comments

We reviewed all comments from peer reviewers and the public for substantive issues and new information regarding this rulemaking. Substantive comments received during the comment periods have been addressed below or incorporated directly into this final rule. Comments of a similar nature have been grouped together under subject headings in a series of issues and responses.

Technical and Editorial Comments

Issue:

Several technical and editorial comments were provided by respondents. In addition, peer reviewers and other commenters provided or suggested additional literature to consider in our final rule.

Response:

We corrected inaccuracies in the revised proposed rule wherever appropriate. We also edited portions of the text to make it clearer. We reviewed and incorporated relevant additional literature and information when appropriate. The list of literature cited in this rule will be posted online (

http://www.fws.gov/mountain-prairie/species/mammals/preble/

).

Defining a “Listable Entity” under section 4 of the Act.

Issue:

We received numerous comments on taxonomic data quality and quantity. Many questioned the amount of data necessary to make such taxonomic determinations. Some commenters questioned the basis for the initial listing of the subspecies. Other commenters discussed whether the available data relied upon in our 2005 proposed rule was sufficient or insufficient. Some commenters suggested we should employ the precautionary principle when making a call on delisting. Other commenters questioned our apparent reliance upon the peer reviewer “majority vote” as a justification for our 2005 proposed delisting. Still other commenters noted or questioned evidence of political interference in this rulemaking process.

Response:

The Act requires that we base our determinations upon the best scientific and commercial information available. As a result, we evaluate all of the available information, its adequacy and reliability, and determine what the weight of evidence suggests. This final rule meets this standard. These issues and the available data are discussed below in the sections titled: Taxonomy; Other Taxonomic Information Available Prior to Listing; Taxonomic Information Solicited After Listing; and Taxonomic Conclusions.

Issue:

Many questioned the standards used to test what is a valid subspecies. Some commenters suggested philosophical differences played a role in shaping the hypothesis of each researcher and what each researcher considered a valid subspecies. Other commenters suggested that the Service is inconsistent in applying subspecies standards in its section 4 determinations. Some commenters noted that there are no quantitative standards in use by the scientific community or the Service with which to objectively describe subspecies. Some commenters suggested that acceptance by the scientific community is often nothing more than opinion.

Response:

As defined by the Act, a species includes any subspecies of fish or wildlife or plant, and any distinct population segment (DPS) of any species of vertebrate fish or wildlife which interbreeds when mature. The Act does not further define subspecies. Service regulations (50 CFR 424.11) state that “In determining whether a particular taxon or population is a species for the purposes of the Act, the Secretary shall rely on standard taxonomic distinctions and the biological expertise of the Department and the scientific community concerning the relevant taxonomic group.” This regulatory standard is consistent with the Act's requirement that we make such determinations solely on the basis of the best scientific and commercial data available. The Service consistently applies this standard.

In this case, we determine that the best scientific and commercial data available support the conclusion that the Prebles is a valid subspecies. While philosophical differences among researchers may play a role in what a particular researcher considers a biologically meaningful difference, we conclude that the weight of evidence supports the Prebles as a valid subspecies.

Specifically, the Prebles' geographic isolation from other subspecies of meadow jumping mice (Krutzsch 1954, pp. 452-453; Long 1965, pp. 664-665; Beauvais 2001, p. 6; Beauvais 2004; SEI 2006a, p. 34) has resulted in the accretion of considerable genetic differentiation (King

et al.

2006b, pp. 4336-4348; SEI 2006a, pp. 41-43). The available data suggest that the Prebles meets or exceeds numerous, widely accepted subspecies definitions (Mayr and Ashlock 1991, pp. 43-45; Patten and Unitt 2002, pp. 26-34; SEI 2006a, p. 44).

In terms of quantitative standards, the 75 percent rule (Amadon 1949; Patten and Unitt 2002) is one of the only widely employed quantitative subspecies definitions (Haig

et al.

2006, pp. 1584-1594). This definition suggests a subspecies is valid if 75 percent or more of a population is separable from all (or > 99 percent of) members of the overlapping population. As noted by SEI (2006a, p. 44), the Prebles exceeds this quantitative standard.

Issue:

We received numerous comments regarding the status of the Prebles relative to the requirements of the Interagency Policy Regarding the Recognition of Distinct Vertebrate Population Segments Under the ESA (DPS policy) (61 FR 4722, February 7, 1996) including the suggestion that the Prebles should or could be split into multiple DPSs based on significant genetic differences observed between populations north and south of Denver (Ramey

et al.

2005, pp. 334-341; King

et al.

2006a, pp. 28-29).

Response:

The available data supports the taxonomic status of the Prebles as a valid subspecies making most comments about potential application of the DPS policy moot. We do not believe splitting the subspecies into multiple DPSs would be prudent or beneficial

from a conservation perspective. In this case, we do not foresee any significant benefit to recovering multiple DPSs instead of a single listed entity.

Issue:

Some commenters suggested that the Service's revised proposed rule (72 FR 62992, November 7, 2007) displayed bias in our presentation of the available information. Specifically, some commenters suggested we highlighted flaws in reports questioning the taxonomic validity of the Prebles, while not offering similar critiques of information supporting the subspecies' taxonomic validity.

Response:

To the maximum extent possible, we attempted to objectively portray the available information regardless of the position it articulated. All information was held to a similar level of critical review. However, we have reviewed the final rule relative to the specific objections and made minor revisions where appropriate.

Ramey

et al.

and King

et al.

Issue:

Some commenters suggested the Ramey

et al.

(2003, 2004a, 2004b, 2005) studies exhibited bias. Some commenters questioned whether the studies could be relied upon because the studies were largely funded by the State of Wyoming, one of the petitioners. Other commenters noted that the conclusions strayed beyond genetics and taxonomy into policy considerations.

Response:

Ramey

et al.

(2004a, 2004b, 2005) were subjected to extensive peer and public review, were reviewed and approved by a peer-reviewed journal, and were reviewed by the SEI expert panel. All of this information has been taken into consideration in this final determination.

Issue:

Some commenters suggested the King

et al.

(2006a, 2006b) studies exhibited bias. It was suggested that Dr. King has a history of designating unwarranted or questionable subspecies. Some commenters questioned Dr. King's qualifications. Other commenters suggested that USGS was inherently biased because the Service and USGS are sister agencies under the Department of the Interior.

Response:

King

et al.

(2006a, 2006b) were the subject of extensive peer review and public review, were reviewed and approved by a peer-reviewed journal, and were reviewed by the SEI expert panel. All of this information has been taken into consideration in this final determination.

We believe the USGS research team was well qualified to conduct the analysis. For example, their previous work concerning Atlantic salmon (

Salmo salar

) was upheld by a National Research Council (2002b, p. 4) review. This validation provided us with confidence that these researchers' expertise could meet our scientific needs. We do not believe that USGS' research conclusions were biased by the fact that it is a sister agency to the Service.

Issue:

Some commenters questioned the critiques raised by peer reviewers and the scientific community. Rebuttals were offered for each criticism of Ramey

et al.

(2005) listed in the proposed rule. It was suggested that we failed to explain that many of these issues were relevant to the draft they evaluated (Ramey

et al.

2004a, 2004b), but resolved in the publication (Ramey

et al.

2005). Finally, it was suggested that many of these same issues plague the King

et al.

(2006b) report.

Response:

We have revised this section (see the Taxonomic Information Solicited After Listing section below) so as to clearly explain that many of the issues raised by peer reviewers of Ramey

et al.

(2004a, 2004b) were rectified in the 2005 publication (Ramey

et al.

2005). Each of these critiques was carefully considered. All of the issues remaining in this section of this final rule continue to remain relevant and may have contributed, at least in part, to the conclusions of Ramey

et al.

(2005).

For example, while the comment defended the use of museum specimens, we remain concerned that Ramey

et al.

's (2004a, 2004b, 2005) reliance upon museum specimens may have contributed to contamination of numerous key samples. As noted by Douglas (2004), the quality of DNA extracted from museum specimens is often inferior, fragmented, and low quantity. As a result, amplification can be difficult and cross-contamination with other high-quality DNA can occur. Ramey

et al.

(2004a, p. 6) confirmed “some DNA extracts, most notably those of older museum specimens (prior to 1980), did not amplify well or at all.” King

et al.

(2006b, pp. 4355-4357) demonstrated that numerous key DNA sequences were not repeatable. Most importantly, SEI (2006a, pp. 21-30) confirmed evidence of contamination of key Ramey

et al.

samples after reviewing the original supporting data. While other explanations are possible (King

et al.

2006, p. 4345; Ramey

et al.

2007, p. 3519), we have concluded that the Ramey

et al.

(2005) data demonstrates sufficient evidence of contamination to warrant inclusion on this list of concerns.

Similarly, results can be meaningfully altered if a museum specimen's tag (marking locality and subspecies) is incorrect. This appears to be the case with museum specimens KU115895, KU115896, and KU115897 (Anderson & Jones 1971 as cited in King

et al.

2006b, p. 4357). That said, museum specimens remain a valuable resource in providing specimens from a large geographic area and often allow a study to be executed in relatively short time. As recommended by the literature, proper precautions are required (Cooper and Poinar 2000).

Most of the other critiques of Ramey

et al.

centered on study design and the thoroughness of the evaluation. We continue to list these issues because each of these factors may have influenced the study's results and conclusions. We also have tried to clarify when a similar issue may have influenced the results and conclusions of King

et al.

The relative importance of many of these issues is discussed in the SEI report (SEI 2006, pp. 20-43).

Issue:

Numerous commenters suggested that the sampling regime was a critical difference between the two studies (Ramey

et al.

2004a, 2004b, 2005; King

et al.

2006a, 2006b). Several commenters suggested that Crandall and Marshall (2006) represented the best scientific and commercial information available in that their report combined the Ramey

et al.

(2005) and King

et al.

(2006a) data into a single, comprehensive analysis.

Response:

We think that an ideal sampling strategy, with unlimited resources, would sample many individuals from many populations across the range of all 12 recognized meadow jumping mouse subspecies. Instead, Ramey

et al.

sampled a few individuals from many sites, while King

et al.

sampled many individuals from a few sites. Each approach has its strengths and weaknesses.

The Ramey

et al.

approach likely captures variation across the range of the subspecies (Ramey

et al.

2005, p. 332), but may underestimate the level of within-population variation, inflate within-subspecies variance, and potentially lower the between-subspecies differentiation (King

et al.

2006b, p. 4346). The King

et al.

population-oriented approach likely denotes the diversity within a population (King

et al.

2006b, p. 4346), but may not capture variance along past or present contact zones between the subspecies (SEI 2006a, pp. 31-43) and may predispose the results to an exaggeration of genetic distances among subspecies (Ramey

et al.

2007, p. 3519). We considered each of these potential sources of bias in our evaluation of the available data. Overall, we concluded that sampling played only a minor role

in shaping differences between the two studies. Instead, we believe apparent contamination among a number of key samples was likely the primary reason the Ramey

et al.

(2005) and King

et al.

(2006b) mtDNA data differed. While Crandall and Marshall (2006) employed a hybrid approach reevaluating both the Ramey

et al.

and King

et al.

mtDNA sequences, this unpublished study has a number of important weaknesses (see Spencer 2006b) including the inclusion of these same questionable samples. As Crandall and Marshall (2006, p. 5) put it, “much is dependent on these few samples.” We have concluded that inclusion of these apparently contaminated samples makes the mtDNA results and conclusions of Ramey

et al.

(2005) and Crandall and Marshall (2006) unreliable.

Issue:

Several commenters suggested that even if the apparently contaminated samples are removed from the analysis, the data still supports the conclusions of Ramey

et al.

(2005).

Response:

No data or analysis were presented to support the assertion that Ramey

et al.

's key conclusions would not differ if the suspect samples were removed. Ramey

et al.

(2007, p. 3520) state that “With the samples in question excluded, analysis of molecular variance results just exceed our threshold, but the Prebles is still not even close to being reciprocally monophyletic.” This suggests the mtDNA results would satisfy Ramey

et al.

's (2005, p. 332) a priori mtDNA hypothesis for a valid subspecies where there was greater molecular variance among than within subspecies. Overall, we feel the available data is compelling in its support of the validity of this taxon.

Issue:

A few commenters suggested that Ramey

et al.

set up subspecies standards in advance of data collection, while King

et al.

relied upon post-hoc interpretations of the data.

Response:

Our evaluation of Ramey

et al.

(2003, p. 4; 2004a, p. 4; 2005, pp. 331-334), USGS (2005, p. 3) and King

et al.

(2006a, p. 5; 2006b, p. 4332) revealed that both research teams developed their hypotheses in advance of data collection which they consistently applied throughout the process.

Issue:

A few commenters questioned whether hybridization between the Prebles and the western jumping mouse could have impacted each study's results.

Response:

Genetic distance between the Prebles and the western jumping mouse is significant (King

et al.

2006b, p. 4341), and the available genetic studies experienced no difficulty differentiating between the two species (Riggs

et al.

1997, pp. 6-11; Ramey

et al.

2005, p. 332; King

et al.

2006b, p. 4341). Wunder and Harrington (1996, section 6.0) also ruled out hybridization based on a small sampling of random amplification of polymorphic DNA (RAPD) (an amplification of random segments of DNA with single primer of arbitrary nucleotide sequence). Based upon the best scientific and commercial information available, we do not believe hybridization is occurring between these two distinct species.

Issue:

Several commenters suggested King

et al.

examined too much data. Specifically, it was suggested that the statistically significant differences observed by King

et al.

were the result of the large number of microsatellite loci (the specific position of a gene or other chromosomal marker) examined and not reflective of any meaningful biological difference.

Response:

We find no support for the position that significant differences detected by King

et al.

were an artifact of an excessively large sample size. The Ramey

et al.

and King

et al.

microsatellite results do not appear dependent upon the number of loci examined (5 and 21 loci, respectively) as both data sets support a statistically significant independent cluster that corresponds to the Prebles (Crandall and Marshall 2006, pp. 26-27; SEI 2006a, p. 43). This, in combination with other available data, supports continued recognition of the subspecies as a valid taxon.

Information Quality and Peer Review for Taxonomy

Issue:

Numerous commenters suggested we should not rely upon unpublished literature that has not been subjected to a scientific journal's peer review process. They felt that using Ramey

et al.

or King

et al.

violated the Data Quality Act (44 U.S.C. 3516

et seq.

) and Service policy. Several commenters thought we should reopen the comment period once these documents were accepted for publication or published.

Response:

The Act requires that our actions be based upon the best scientific and commercial information available. Occasionally, relevant scientific and commercial information is not, or has not yet been, published. In these cases, peer review may assist us in our evaluation of the available science. At this point, most of the key literature relevant to the subspecies' taxonomy has been subjected to extensive peer review, reviewed and published by peer-reviewed journals, and reviewed by the SEI expert panel. Additionally, the public has had an opportunity to review and comment on all of the relevant literature (70 FR 5404, February 2, 2005; 71 FR 8556, February 17, 2006; 71 FR 16090, March 30, 2006; 72 FR 62992, November 7, 2007). Finally, we have conducted numerous peer reviews of our regulatory proposals (70 FR 5404, February 2, 2005; 71 FR 8556, February 17, 2006; 71 FR 16090, March 30, 2006; 72 FR 62992, November 7, 2007) in compliance with the Interagency Cooperative Policy for Peer Review in Act Activities (59 FR 34270, July 1, 1994) and the Office of Management and Budget's “Final Information Quality Bulletin for Peer Review” (Office of Management and Budget 2004). We have evaluated all of the available information, its adequacy and reliability, and determined what the weight of evidence suggests. Given the above, we feel we have exceeded all Federal requirements for information quality and peer review.

Issue:

Several commenters questioned the independence, impartiality, political motivation, and appropriate expertise of select local peer reviewers. Some commenters questioned the independence and impartiality of the Colorado Division of Wildlife (CDOW) in soliciting these peer reviews.

Response:

The CDOW solicited and received nine peer reviews of Ramey

et al.

(2004a) from regional scientists with a variety of expertise relevant to the questions at hand. These reviews were transmitted to us on April 24, 2004. We believe that the CDOW acted independently and impartially in selecting qualified reviewers of the subject study. During the summer of 2004, we solicited reviews from seven additional scientists selected for expertise in genetics and systematics. Reviewers were targeted from a wide variety of areas to geographically balance the CDOW review. Collectively, this diverse group of experts provided a balanced and objective review. To maintain consistency, we later contacted the same 16 experts to peer review Ramey

et al.

(2004b) and King

et al.

(2006a). It should be noted that some reviewers declined to participate in subsequent rounds of review (Ramey

et al.

2004b; King

et al.

2006a) because of these accusations of bias.

Issue:

Some commenters questioned why the Service asked non-geneticists to review King

et al.

(2006a).

Response:

As noted above, we solicited peer reviews of King

et al.

(2006a) from the same 16 reviewers asked to review Ramey

et al.

(2004a, 2004b). While we recognized this group included some non-geneticists, we felt consistency among reviewers was critical. We note that most of the non-

geneticists voluntarily declined to participate in the review of King

et al.

(2006a). The one exception, Armstrong (2006), is a respected academic with considerable expertise on the Prebles. His review was useful.

Expert Panel

Issue:

Several commenters questioned the Service's decision to organize a scientific panel to review the available information on the species' taxonomic and conservation status.

Response:

Recognizing the controversial nature of this determination, the Service decided not to organize and convene an expert panel ourselves. Instead, we contracted with an independent organization to assemble and manage the scientific review panel.

Issue:

Numerous parties had issue with the SEI expert panel. Some commenters opined that the SEI panel was tainted because the composition of the panel and the time allotted to participants was altered to favor a particular outcome. Some commenters questioned the objectivity and qualifications of SEI and the panelists.

Response:

We stand by the process used in the SEI review panel. Following an open and competitive bid process, SEI was selected as the contractor in June 2006. Once selected, SEI ran all aspects of this process within the bounds of the contract. The selection and retention of panelists as well as the agenda was entirely within SEI's purview. SEI also determined that the public could attend. In addition, Drs. Ramey, Crandall, and King addressed the panel in person. Other scientists participated over the phone. Questions from the audience were also presented for the panel's consideration. The panel also had access to published literature, unpublished reports, third-party critiques, public comments, and other materials suggested by interested parties (SEI 2006a, pp. 48-55). Overall, we think that the process was fair, open, and unbiased.

Furthermore, we believe SEI and the panelists were well qualified to conduct the contracted review. SEI regularly conducts such scientific reviews including panels on northern spotted owl, pallid sturgeon, and Everglades restoration (see:

http://www.sei.org/

). The panelists' qualifications are well established. As illustrated in appendix 1 of the SEI (2006a, pp. 56-82) report, each panelist has an extensive background in the genetic and systematic issues relevant to the Prebles' review.

Issue:

Some commenters suggested that the SEI report went beyond the original scope of their contract. Specifically, commenters suggested the SEI report should have abstained from offering reviewers' taxonomic conclusions.

Response:

We contracted with SEI to analyze, assess, and weigh the reasons why the data, findings, and conclusions of the two studies differed (USFWS 2006, p. 14). Incorporation of the panelists' taxonomic conclusions was a natural outgrowth of the contract's stated purpose. The final report fully satisfied SEI's contractual obligations.

Availability of Taxonomic Information

Issue:

Several commenters raised a concern that we relied on a paper (King

et al.

in review) for this rulemaking that we did not possess and thus was not available for public review during the comment period. Since this report was not available, some commenters requested an extension of the comment period.

Response:

The revised proposed rule referenced a document by USGS cited as “King

et al.

(in review).” This article was not the primary jumping mouse study by King

et al.

The primary study and its supporting data were released to the public in early 2006 (King

et al.

2006a; 71 FR 8556, February 17, 2006; 71 FR 16090, March 30, 2006) and published in

Molecular Ecology

in late 2006 (King

et al.

2006b).

Instead, King

et al.

(in review) was a comment article that

Molecular Ecology

intended to publish in the News and Views section of the journal, in response to Ramey

et al.

(2007) (another comment article). These comment articles were cited once in the revised proposed rule in a sentence that read: “Other evaluations of the available literature and data include Ramey

et al.

(in press), King

et al.

(in review), Crandall and Marshall (2006), Spencer (2006b), and Cronin (2007).” This sentence cited King

et al.

(in review), among other documents, to inform the public we were aware of its existence. However, our determination that the Prebles is a valid subspecies did not use or rely on this document.

The comment was correct that we did not have this document in our files. By citing the document as “in review,” we intended to convey that the document had been drafted and submitted for publication, but not yet accepted as it was still undergoing peer review. The USGS typically does not release documents unless they have been accepted for publication or otherwise peer reviewed. As the peer review process for this document remains incomplete, the article is solely in the possession of USGS and the reviewing journal.

Given the context of this citation and its inconsequentiality to our determination, we do not think that this document was critical to the public's review or understanding of our proposal. Therefore, we did not grant an extension of the comment period.

Distribution, Status, Population Size, and Population Trends

Issue:

Some commenters contended that our 2005, 12-month finding and proposed rule should have evaluated the distribution, abundance, trends, and threats information from the delisting petitions.

Response:

On February 2, 2005, we issued a 12-month finding on a petition to delist the Prebles and proposed to remove the mouse from the Federal list of endangered and threatened species (70 FR 5404, February 2, 2005). The basis for the proposed action was that the Prebles was “likely not a valid subspecies of meadow jumping mouse.” It was not necessary or appropriate to consider distribution, abundance, trends, or threats until it was determined that the Prebles qualified as a listable entity under the Act. Once we determined that the Prebles was a valid subspecies, we considered all relevant information on Prebles' distribution, abundance, trends, and threats in our revised proposed rule (72 FR 62992, November 7, 2007) and in this final rule.

Issue:

Some commenters suggested that Figure 1 could have been more clear or more informative. Specific suggestions put forth were to: Include more detail; depict all jumping mouse captures noting the species; and provide a better explanation of the data depicted in the key and text. One reviewer commented that the database from which Figure 1 was derived should be available to the public.

Response:

Figure 1 was too busy and difficult to read in the

Federal Register

. As a result, we have split this graphic representation of occupancy into a Wyoming (Figure 1) and a Colorado figure (Figure 2). We also revised the corresponding text. This final rule more clearly depicts known Prebles' distribution and results of other trapping efforts. The supporting data (Service 2008) is available upon request.

Issue:

Reviewers commented that distribution of available habitat and threats to the Prebles could be mapped, quantified, and better visualized through use of GIS. One reviewer suggested that we clearly map all threats or confirm that project constraints make these measures impractical.

Response:

The Service has mapped potential Prebles' habitat (67 FR 47154, July 17, 2002; 68 FR 37276, June 23, 2003), as has the Wyoming Natural Diversity Database (WNDD) (Beauvais 2001, 2004), the CDOW, and some Colorado counties. The Center for the West produced a series of GIS maps predicting growth through 2040 for the west including the Colorado Front Range and Wyoming (Travis

et al.

2005, pp. 2-7). These models represent a good approximation of projected development pressures. We also worked with the CDOW to examine protection status of designated critical habitat units and other selected areas supporting the Prebles. These results are summarized in the 5-factor analysis below.

Issue:

We received numerous comments on data quality and quantity relative to the subspecies' status. Many noted limited available information or data on historical and current range, current abundance, population trends, threats, and ecological relationships. Some commenters suggested this illustrated the weakness of our original listing and, therefore, suggested we should delist range-wide. Other commenters suggested a change in listing status in any portion of the subspecies' range should be precluded until better data is available.

Response:

The Act requires our determinations be based upon the best scientific and commercial information available. As a result, we evaluate all of the available information, its adequacy and reliability, and determine what the weight of evidence suggests. This final rule meets this standard.

Issue:

One reviewer suggested that we quantify relative abundance of the Prebles and compare abundance estimates to habitat features to better define quality habitat. This reviewer thought we could estimate relative abundance by calculating and comparing Prebles captured per trap night (number of traps employed times number of nights of trapping) for all trapping efforts throughout Prebles' range.

Response:

Where we have abundance information, we present it in this final rule. Data available is not adequate to quantify and compare the relative abundance of the Prebles across its range with any reasonable degree of confidence (i.e., much of the trapping was on small sites and over short periods with inconsistent timing and conditions).

Issue:

One commenter claimed our analysis is flawed because the Prebles cannot be differentiated from the western jumping mouse.

Response:

Genetic markers are effective in differentiating meadow jumping mice and western jumping mice (Riggs

et al.

1997, pp. 2-8; Ramey

et al.

2005, pp. 344-346; King

et al.

2006b, pp. 4341, 4344). Additionally, Discriminant Function Analysis (DFA) (analysis of cranial measurements and an anterior medial toothfold characteristic) appears to be a reliable technique for differentiating the two species (Conner and Shenk 2003a). We acknowledge that, for a number of historical and recent capture sites, mice were tentatively identified in the field based on capture location, size, and external features, but definitive identification to species was never attempted. In many of these cases, genetic samples were not obtained nor were voucher specimens taken; therefore, the specimen's species identity remains inconclusive. As noted below, positive identification to species is only an issue in areas of overlapping range (i.e., high-elevation sites in Colorado and most of Wyoming). We have addressed potential shortcomings for species identification in our analysis, and we have reviewed and modified the text for added clarity.

Issue:

Several commenters noted that Prebles are now known from more drainages and a greater number of sites than at the time of listing. These commenters suggested this was evidence that Prebles' populations are secure. One commenter requested that we state the specific number of sites where the Prebles is known to occur.

Response:

We have acknowledged an increase in our knowledge of distribution of Prebles, especially in the Wyoming portion of its range. We have summarized areas of known or potential occurrence by river basin, drainage (8-digit USGS hydrologic units), and river or stream. We also have emphasized instances where confirmed captures have extended our knowledge of Prebles' range and occurrence. We think that the number of individual capture sites is less meaningful. Documentation of multiple capture sites within portions of drainages or along streams where Prebles' populations occur is largely a function of trapping effort. When multiple sites are within close proximity of each other, counting each occurrence instead of a single population exaggerates abundance. Further, as one peer reviewer correctly cautioned, trends cannot be established from the number of documented sites alone, and that an increase in documented sites resulting from increased trapping efforts could mask a decreasing population trend.

Issue:

One commenter stated that the Prebles' range has not declined significantly. This commenter suggested the subspecies is now known to be present in virtually all historically documented locations except those in the greater Denver area.

Response:

The subspecies' declines within Colorado are fully explained in Factor A below. This analysis includes the apparent extirpation of the subspecies from approximately 420 km (260 mi) in and downstream of areas with concentrated human development. In terms of historically documented locations (i.e., sites from which we have specimens prior to 1980), we are aware of 17 such sites in Colorado. Of these, only one of these sites is currently thought to support the Prebles. The majority of historical records of Prebles in Colorado come from what is now widely known as the Front Range urban corridor, which extends well beyond the Denver area. In Wyoming, with the possible exception of Cheyenne, the Prebles is likely present at the few sites where it was historically documented.

Issue:

One commenter concluded that the high number of section 7 consultations conducted in Colorado as compared to Wyoming was evidence of “expansive range and increasing populations” in Colorado.

Response:

A more reasonable explanation for the number of section 7 consultations is that human development is expanding into areas of Prebles' occurrence. In Wyoming, far less development is occurring in areas where the Prebles is present.

Issue:

Some commenters questioned how we established that over 80 percent of trapping efforts in Colorado since listing have failed to capture Prebles. They questioned whether western jumping mice were included in the results and questioned the expertise of the trappers conducting the studies. Some commenters requested comparative trapping success rates from Wyoming trapping.

Response:

From 1998 to 2007, 27 percent of 1,350 data points associated with trapping efforts targeting Prebles in Colorado have resulted in captures of jumping mice (USFWS 2008). When we controlled for repeated trapping at single sites, such as established research sites, jumping mouse capture rates drop to less than 20 percent. Even this estimate may be high as some of these jumping mice were likely western jumping mice, particularly those from high-elevation trapping efforts.

From 1998 to 2007, 74 percent of 219 data points associated with trapping efforts in Wyoming have resulted in captures of jumping mice (USFWS

2008). The overlapping range of Prebles and western jumping mouse in Wyoming must be considered when comparing Preble's capture success between the two States. Based on individual mice confirmed to species, it is likely that more of the successful trapping efforts in Wyoming captured only western jumping mice. Of positive jumping mouse capture sites, 29 percent of the sites included only Prebles, 55 percent of the sites included only western jumping mice, 5 percent of the sites had both species present, and specimens from 11 percent of the successful sites were never positively identified to species.

All jumping mouse trapping efforts since listing have been carried out by researchers holding Service and State permits. While experience of individual biologists may vary, we believe all individuals permitted to trap Prebles are qualified to conduct such surveys.

Foreseeable Future

Issue:

One commenter stated that foreseeable future as defined in the revised proposed rule was too short, citing climate change projections to 100 years and Service HCPs issued for 50 years.

Response:

The term foreseeable future is not defined by the Act or in the implementing regulations at 50 CFR part 424. Merriam-Webster's Law Dictionary (1996) defines “foreseeable” as such as that which reasonably can or should be anticipated such that a person of ordinary prudence would expect it to occur or exist under the circumstances (Merriam-Webster's Dictionary of Law 1996;

Western Watershed Project

v.

Foss

(D. Idaho 2005; CV 04-168-MHW). Determination of foreseeable future is typically based on the timeframe over which the best available scientific data allows us to reasonably assess the threats and the species' response to those threats, and is supported by species-specific factors, including the species' life history characteristics (e.g., generation time) and population dynamics. From a scientific perspective, it would be inappropriate to set foreseeable future timeframes so short that natural variability in the ecosystem of the species, short-term population dynamics, or the expression of life history traits of the species through generational-scale variation in reproductive success or recruitment cannot be accounted for in the longer-term examination of factors impacting the species. Typically, threats tend to operate through their effects on survival and productivity over multiple generations, with one to two generations being insufficient to separate natural variability from directional effects of threats. Whenever possible, we will determine the “foreseeable future” based on a detailed assessment of threats and species-specific biological information.

For the Prebles, we defined foreseeable future based upon a threat-projection timeframe because future development intensity and patterns are likely to be the single greatest factor contributing to the subspecies' future conservation status. The foreseeable future for the Prebles, based on the currently available data, extends to approximately 2040. While it is likely human population growth and development projections could be extrapolated out into the more distant future, growth and development projections beyond this point are of increasingly lower value as uncertainty escalates. However, we agree that not all threat factors are necessarily foreseeable over the same time horizon and that for some threat factors a longer time horizon may be appropriate. Thus, this rule considers the range of climatic conditions predicted by the Intergovernmental Panel on Climate Change (IPCC) for the 21st century. While climate projections routinely go out past this 2040 time horizon (IPCC 2007, p. 7), climate change forecasts, like human development projections, become less certain as they are extended into the future (Hall 2008; Meyers 2008). The IPCC acknowledged this uncertainty in their most recent report when they stated that projections beyond the next two decades depend on specific emission scenarios (IPCC 2007, p. 7). The duration of section 10 permits, issued in support of approved Habitat Conservation Plans, have no bearing on what is foreseeable for this subspecies.

Impacts From Increased Human Population and Development

Issue:

Some commenters stated that local extirpations of Prebles in the Front Range urban corridor cannot be used to speculate about future threats in other portions of its range. They suggested that development threats are localized and do not affect most Prebles' populations.

Response:

While threats do vary across the range of the subspecies, we believe that the rule adequately captures and presents the severity of the issue across all portions of the subspecies' range. The direct and indirect effects of human development have resulted in substantial habitat alteration across large parts of the Colorado range. While habitat alteration has been most severe in the expanding Front Range urban corridor, projected future human growth will substantially extend this area of impact. Additional threats exist outside of areas of intense human development. For example, linear projects such as roads and pipelines may impact multiple counties and can affect rural habitat as well as that in urbanizing areas, and potential impacts from overgrazing are more likely to affect Prebles' habitat in rural areas than in areas of high residential density.

Issue:

Some commenters suggested that population growth forecasts can be unreliable. They pointed to the current housing slump and suggest that population growth within the Prebles' range will be less than predicted. One commenter stated that the Center for the American West models' depiction of development patterns in the future have limited utility since they assume that all private land is technically buildable and available for development.

Response:

Any future predictions include a degree of uncertainty. That said, we consider projections and related models to be the best information available on this subject. Economic downturns, that are relatively short-lived, are unlikely to significantly alter long-term forecasts.

The Center for the American West models (Travis

et al.

2005, pp. 2-7) predict development patterns on a sub-regional basis. The fate of individual parcels could be determined by a number of factors not addressed by the models, and the model developers have noted that the projections should not be applied to individual properties. We have cited these models in evaluating threats related to likely patterns of future human growth, not the presumed fate of individual properties. We have expanded our discussion of the models and their use in the text.

Issue:

One reviewer noted that while human development in Wyoming is likely to be far less than in Colorado, Wyoming does not “lack” development and much of it will be in rural areas. A few commenters addressed current and modeled future human population growth in Wyoming centered near Cheyenne. One reviewer questioned whether the absence of the Prebles in Cheyenne area was the result of development. Another reviewer concluded that projected growth in the Cheyenne area would not result in impacts to the Prebles because it would not overlap areas known to support the subspecies.

Response:

We acknowledge that human development is likely to occur in portions of Wyoming now supporting the Prebles. However, we believe that expansion of human presence and

related threats will be localized and relatively minor, and will not threaten the continued persistence of the Prebles in those areas.

Known occurrence records suggest that the Prebles is not common or widely present in the South Platte River basin in Wyoming. The cause of this rarity is unknown. The continued existence of the Prebles in the Cheyenne area also is unknown. Sites of recent confirmation of the Prebles in the South Platte River basin of Wyoming have been well upstream from Cheyenne. Development could impact Prebles' populations in the Cheyenne area, should they exist. However, the long-term viability of populations in these drainages is more likely to depend on persistence in upstream portions of the drainages rather than the Cheyenne area.

Issue:

Some commenters predicted that secondary impacts associated with human development in Colorado would impact Prebles' habitat in southern Wyoming. Particular issues raised included vacation homes, human recreational activities, water resource development and storage, and aggregate mining.

Response:

As human populations in Colorado, particularly northern Colorado, continue to grow, secondary impacts may spill over into southeastern Wyoming. Regarding vacation homes, the Center for the West models of human population growth take into account urban, suburban, ex-urban, and rural development (

http://www.centerwest.org/futures/west/2040.html; http://www.centerwest.org/futures/archive/development/development_wy.html

). These projections suggest ex-urban development could link Cheyenne and Fort Collins by mid-century, but indicate little development in the documented range of the Prebles in Wyoming. While some development will undoubtedly occur, we do not have data to indicate meaningful impacts are likely anywhere in the Wyoming portion of the subspecies' range, except around Cheyenne where the subspecies has not been recently documented to occur.

While increasing population may result in increased recreation, new water development, or additional aggregate mining, we are not aware of any specific proposals that would increase the effects of these types of activities on Prebles' populations. These issues are evaluated further in our 5-Factor analysis below.

Impacts From Agriculture

Issue:

Some commenters stated that grazing is not a significant threat, as evidenced by the special 4(d) rule allowing continued agricultural activities. One commenter stated that chronic violations of grazing regulations on public grazing lands impact Prebles' habitat. One commenter provided a Bureau of Land Management (BLM) (2004) report on public range in Wyoming, to demonstrate that range improvements have occurred over time. The report stated that range conditions have improved over time; efforts are under way to stop invasive weeds; and wildlife populations have increased.

Response:

Our special rule provides exemption from take prohibitions under section 9 of the Act for certain land uses including continued agriculture. While overgrazing can and does impact Prebles' habitat, and in some cases can be a threat, the 4(d) rule (66 FR 28125, May 22, 2001; 67 FR 61531, October 1, 2002; 69 FR 29101, May 20, 2004) was instituted to acknowledge that those ongoing agricultural operations maintaining habitat that supports the Prebles are an asset to conservation and recovery. Through this special rule, we anticipated increased opportunity to partner with agricultural interests toward conservation of the Prebles.

While we are aware of instances where operators have violated provisions of their grazing permits, we have concluded that this is not a widespread threat within the Prebles' range. We solicited and received data and information on livestock grazing from the U.S. Forest Service (USFS) regarding three National Forests that support Prebles' populations. Allotment inspection records or monitoring reports were received from the Laramie Ranger District, Medicine Bow National Forest in Wyoming (Florich 2008); the Canyon Lakes Ranger District, Arapahoe National Forest (Hodges 2008); and the South Park Ranger District, Pike National Forest (Branch 2008). While the records include instances of non-compliance and note grazing impacts to habitat, more often they reflect livestock grazing conducted in accordance with grazing plans that are consistent with maintenance of Prebles' habitat. Federal agencies, including the USFS and BLM, work cooperatively with the Service to fulfill their responsibilities under the Act. For example, we recently coordinated with the USFS regarding permittee non-compliance issues on the Arapahoe National Forest's Greyrock allotment. In that area, riparian habitat along the North Fork, Cache La Poudre River is recovering following remedial measures to counteract overgrazing.

We reviewed BLM (2004). While not specific to the Prebles' range, we are encouraged by its conclusions that conditions on BLM grazing lands in Wyoming are improving.

Issue:

One commenter stated that the Service inappropriately cited the Taylor (1999) trapping study as evidence of Prebles' compatibility with grazing. This comment indicated that: The properties on which the trapping was conducted are not representative of most grazing operations; the report documents grazing impacts on riparian habitat; and Prebles' populations may have decreased since this study because of drought.

Response:

The study at issue is by far the most extensive effort conducted on private lands in Wyoming. Jumping mice were captured at 18 of 21 survey sites representing diverse habitat conditions. Genetic testing confirmed Prebles at 11 sites, western jumping mice at 3 sites, both species at 3 sites, and one site was never identified to species (it is also worth noting that although many sites had multiple captures, not all specimens were preserved for species identification). Capture sites included both ideal habitat, such as riparian habitat or sub-irrigated hayfields, and sites where grazing or other factors had impacted habitat quality. While Prebles' habitat and populations are likely affected by periodic droughts, results of this trapping effort demonstrate a broad, long-term ability of the subspecies to coexist with traditional agricultural operations in Wyoming.

Issue:

Some commenters recommended that we explore additional threats to the Prebles in Wyoming from agricultural conversion to biofuels.

Response:

As discussed in the revised proposed rule, the conversion of native habitat to row crops has become increasingly rare in both Colorado and Wyoming (U.S. Department of Agriculture 2000, Tables 2, 3, & 9). This trend likely reflects that riparian habitats (and other areas) that could be feasibly converted to crop production have already been converted. Although pressures to increase agricultural production may result from the demand to produce biofuels, we are not aware of information that indicates this would result in meaningful decreases in the Prebles' riparian habitat in Wyoming. We explored whether former cropland removed from production through the Conservation Reserve Program (CRP) is now being returned to production and concluded that this scenario is likely to

have a negligible impact on the Prebles and its habitat. The issue is further discussed in Factor A below.

Other Potential Threat Factors

Issue:

One commenter noted that if the Prebles was delisted, forestry operations including thinning and prescribed burns could be a significant threat.

Response:

The role of fire, a natural part of the ecosystem, is discussed under Factor E below. Thinning of trees increases sunlight at ground level and prescribed burns release nutrients, both of which can promote increased vegetative growth at ground level. While these forest management activities can result in adverse impacts to Prebles' habitat, the impacts are generally temporary and offset by long-term benefits. In general, we conclude that management designed to improve forest health or prevent catastrophic fire will contribute to the long-term conservation of the Prebles and its habitat.

Issue:

Some commenters highlighted threats that occur range-wide including: Lack of adequate regulatory mechanisms in the absence of the Act's protections; invasive weeds; hydrologic changes brought on by climate change; and catastrophic fire. We also received some comments supporting our conclusion that only minor threats occur in Wyoming, but substantial threats related to human development occur in Colorado.

Response:

This rule summarizes the magnitude, immediacy, and likelihood of foreseeable threats in both States and as well as at the county or drainage level where supporting data are available. While some threats are relatively similar across portions of the two States, these non-development-related threats are not substantial factors driving the subspecies' conservation status. We believe small, fragmented populations are likely at greatest risk from these secondary threat factors. Across most of the subspecies' Colorado range, development actions will increasingly cause populations to become small and fragmented, thus, susceptible to these factors. The available data suggest that few Wyoming Prebles' populations suffer from small population size and fragmentation, and no foreseeable threats are likely to substantially increase this inherent vulnerability. Thus, despite a continued risk from some potential threats in both Wyoming and Colorado, these factors are not likely to threaten or endanger the subspecies in all of its range.

Issue:

Some commenters recommended that we explore additional threats to the Prebles in Wyoming from energy development, especially coalbed methane and natural gas.

Response:

Information on coalbed methane targets in Wyoming (Jones and DeBruin 1990, p. 10) indicates that coalfields and the range of the Prebles have little overlap in Wyoming. Furthermore, the coalfields that are nearest the subspecies' range are believed to have low coalbed methane development potential (DeBruin 2004, p. 6). Similarly, only a small portion of the Wyoming range of the Prebles may overlap with oil and gas producing formations (e.g., cretaceous and early tertiary rocks). A much larger portion of the subspecies' range overlaps with exposed undifferentiated precambian rocks or other non oil and gas producing formations (DeBruin 2002). Based on the limited potential for development of these resources within the Wyoming range of Prebles, we conclude that these activities (directly or indirectly) would not meaningfully affect the conservation status of the Prebles in Wyoming now or in the foreseeable future.

Issue:

Some commenters believe there is a lack of understanding regarding the relationship between the two jumping mouse species in all Wyoming drainages.

Response:

We do know that the Prebles and the western jumping mouse coexist in multiple drainages in both Wyoming and Colorado. In absence of evidence to the contrary, we conclude that this coexistence is not a recent occurrence. Because information is lacking as to whether, or to what degree, populations of Prebles and western jumping mice impact one another, we cannot conclude that western jumping mouse presence is a threat to the Prebles. However, further research may be valuable to identify the relationship between the two species where they co-occur.

Issue:

We received several comments on the potential threat to the Prebles from climate change. These commenters suggested that we had not given sufficient attention to future threats caused or compounded by climate change; that it could affect future demand and competition for water resources and influence water resource development; and that a warming climate could cause shifts in the subspecies' range and increase the importance of high-latitude, high-altitude Prebles' populations in Wyoming to the subspecies' survival. In contrast, we received a comment that future precipitation changes were too uncertain to be used in an analysis of future threats.

Response:

According to the IPCC (2007, p. 2) “warming of the climate system is unequivocal, as it is now evident from observations of increases in global air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.” In general, a trend of warming in the mountains of western North America is expected to decrease snowpack, hasten spring runoff, and reduce summer flows (IPCC 2007, p. 11). While this change could affect the Prebles and its habitat, to date, a negative impact has not been documented. A significant degree of uncertainty exists as to how projected climate changes, alone and in concert with other threats, will affect the Prebles over the foreseeable future. This issue is discussion in greater detail in Factor E below.

Issue:

One reviewer noted that our analysis struggles to weigh cumulative effects, and that threats to the Prebles were likely larger than a simple account of individual effects.

Response:

In the biological sense, cumulative effects include effects of stressors imposed by more than one mechanism, that when taken together can have different or more dramatic effects than those recognized from any one alone. In the context of threats to the Prebles, a combination of identifiable threats may have more impact than what would be expected for each individually. Cumulative effects are difficult to predict. Based on the best information available, we have considered the potential for cumulative effects of threats in our analysis. In many instances, we cite that small or fragmented populations may be more vulnerable to specific threats; this outcome also is likely the case with regard to vulnerability to cumulative effects.

Issue:

One commenter cited a report by Cryan (2004) that indicates that habitat for meadow jumping mice is increasing in the West.

Response:

Cryan (2004, p. 7) reviewed and synthesized existing information on meadow jumping mice in the northern Great Plains (North Dakota, South Dakota, Nebraska, Montana, and Wyoming). While he attributed a likely increase in meadow jumping mouse habitat in the western parts of the Great Plains to westward expansion of riparian forests and mixed-grass prairie, this assertion was not specific to the range of the Prebles nor do we see this habitat trend occurring within the subspecies' range.

Existing Protections

Issue:

Several commenters stated that we failed to properly consider Federal,

State, and local efforts to conserve the Prebles. One commenter thought that we did not differentiate between Federal and other lands in terms of future development threats. Some commenters suggested that States and counties will continue to protect the Prebles regardless of delisting. One commenter stated that extensive local regulations prohibit development in riparian habitat. Other commenters suggested that conservation measures by State and local governments are widespread and that lands set aside as open space or under conservation easements protect Prebles' habitat. The CDOW (Nesler 2008) commented that our recognition of ongoing efforts in Colorado is incomplete. The CDOW provided an estimate that, as of spring 2007, 45 percent of occupied Prebles' habitat in Colorado was protected in public lands, land trusts, or through conservation easements.

Response:

Both the revised proposed rule and this final rule considered the differential level of threat facing Prebles' populations and their habitat on Federal and other lands. In general, private lands face the greatest threat from direct development pressures. However, Federal and other public lands are not immune from development threats. Roads, trails, recreational facilities including campgrounds, and other human development is likely to affect habitat present on public lands. Indirect effects of upstream development also can meaningfully impact Prebles' populations on protected lands.

Effectiveness of local regulations in maintaining naturally functioning riparian corridors varies greatly depending on how these apparently flexible regulations are implemented. While certain local regulations are designed to conserve wetlands or floodplains on private lands, their effectiveness in conserving Prebles is uncertain. It is also unlikely they would effectively control land uses (grazing, mowing, cutting, and burning) that may affect the hydrology, vegetation, and hibernacula sites on which the Prebles depends. Importantly, most local regulations are flexible and provide little assurance. It is not clear what level of interest in Prebles' conservation would continue following delisting.

We have worked with the CDOW to further understand, document, map, and analyze the lands in public ownership in Colorado. This rule appropriately weighs existing and likely future conservation efforts. All of these factors are discussed below in Factor D and considered in the Conclusion of the 5-Factor Analysis.

Issue:

Some commenters stated that there is no proof that existing HCPs are working to protect the Prebles.

Response:

HCPs developed for the Prebles are designed to support its conservation and recovery. Permit conditions and monitoring requirements help insure that conservation benefits ensue. Some individual HCPs are complete and have met their planned objectives while other HCPs are in the implementation or monitoring phase.

Issue:

One commenter stated that the CWA is the “cornerstone of surface water quality protection,” and requires mitigation of all wetland and riparian habitats impacted. Thus, security of the Prebles' habitat is assured under the CWA.

Response:

The primary purpose of the CWA is to protect water quality. To achieve this goal, the CWA seeks to avoid and minimize impacts to jurisdictional wetlands. Human impacts to many habitats utilized by the Prebles (including riparian and floodplain habitats outside of jurisdictional wetlands, and adjacent upland habitats) are not directly addressed by the CWA.

Issue:

Some commenters suggested that we had not followed section 4(b)(1)(A) of the Act and our Policy for Evaluation of Conservation Efforts (PECE Policy) (68 FR 15100, March 28, 2003) when addressing beneficial measures to conserve the Prebles.

Response:

Section 4(b)(1)(A) of the Act requires that we make listing determinations solely on the basis of the best scientific and commercial data available after conducting a review of the species' status and after taking into account those efforts being made by State and local governments. This rulemaking meets this standard, including consideration of efforts being made by State and local governments.

The PECE policy was developed to ensure consistent and adequate evaluation of current and future conservation efforts when considering species for addition to the Federal list of endangered and threatened species. This policy does not apply to delisting determinations. Nevertheless, we have appropriately weighed existing and likely future conservation efforts. This evaluation, included in Factor D below, considered Federal, State, and local regulations; land ownership, use, and management; and relevant programs and initiatives of conservation significance to the Prebles.

Issue:

Several commenters suggested the subspecies was threatened in Wyoming by a lack of adequate regulatory mechanisms.

Response:

Under the Act, listing can be justified in cases where the entity suffers from the inadequacy of existing regulatory mechanisms. In order to meet this standard, the lack of adequate protections, typically in combination with other threat factors, must result in the species being in danger of extinction throughout all or a significant portion of its range (i.e., endangered) or likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range (i.e., threatened). The Wyoming population of Preble's do not appear, at present or within the foreseeable future, dependent upon regulatory mechanisms to maintain their conservation status. As such, the lack of regulatory mechanisms does not appear to threaten or endanger this portion of the range and, thus, the Act's protections are not warranted in Wyoming because of inadequate regulatory mechanisms.

Prebles Status Under the Act, Service Conclusions, and Our Use of Significant Portion of Range

Issue:

One commenter suggested that we would be in violation of the Interagency Policy Regarding the Role of the State Agencies in Act Activities and Executive Order 13352 if we failed to delist the Prebles, since both the States of Wyoming and Colorado supported delisting.

Response:

Neither the Interagency Policy Regarding the Role of the State Agencies in Act Activities (59 FR 34275, July 1, 1994) nor Executive Order 13352 (69 FR 52989, August 30, 2004) delegates Act listing decisions to the States. Such delegation would violate the Act. Instead, the Interagency Policy Regarding the Role of the State Agencies in Act Activities requires that we solicit and utilize the expertise of and information possessed by State agencies. Similarly, Executive Order 13352 promotes cooperative conservation, with an emphasis on appropriate inclusion of local participation in Federal decision making, in accordance with their representative agency missions, policies, and regulations. We have worked, and will continue to work cooperatively in seeking and utilizing all relevant information in possession of both the Wyoming Game and Fish Department (WGFD) and the CDOW as required for decisions made under section 4 of the Act. Thus, we have met or exceeded the requirements of the Interagency Policy Regarding the Role of the State Agencies in Act Activities and Executive Order No. 13352.

Issue:

Several commenters suggested that the Service should delist the Prebles because of the economic impact of the listing or the expense of conservation efforts relative to the

conservation benefits realized. Some commenters suggested that the Final Listing Priority Guidance for Fiscal Year 2000 (Listing Priority Guidance) (57 FR 57114, October 22, 1999) requires that we focus our efforts on listing actions that provide the greatest conservation benefits.

Response:

Any determination on whether a species is threatened or endangered must be based solely on the basis of the species conservation status using the best scientific and commercial information available. Spending on a species or economic impacts cannot be considered in such a determination.

The Final Listing Priority Guidance for Fiscal Year 2000 (57 FR 57114, October 22, 1999) does not apply to this rulemaking. The Listing Priority Guidance provides guidance for assigning relative priorities to listing actions conducted by the Service's Listing Program under section 4 of the Act. The guidance clearly articulates that delisting activities are not part of the listing program. Delisting activities have been undertaken by the Service's Recovery Program since fiscal year 1999.

Issue:

One commenter was concerned that the revised proposed rule was inconsistent with Prebles’ status as classified by the WNDD.

Response:

The WNDD (2003, p. A-12) lists the Prebles among 1 of 35 mammal species or subspecies of concern in Wyoming (specific ranking and ranking criteria available at:

http://uwadmnweb.uwyo.edu/wyndd/SOC/2003_WYNDD_Soc.pdf

). In making our determination we considered the best scientific and commercial information available including information available from the WNDD. However, our evaluation and determination of status under the Act is not dictated by the WNDD classification of the Prebles.

Issue:

Several commenters stated that the 2007 Department of the Interior Solicitor’s opinion (U.S. Department of the Interior 2007) was an incorrect interpretation of the Act. These commenters argued that we have authority to list or delist only whole species, subspecies, and DPSs—in other words, if we find a species to be in danger of extinction in only a significant portion of its range, we must list it and apply all of the protections of the Act to its entire range, even to portions of the range that are not at risk. These commenters opined that the “partial-listing” approach represents a dramatic departure from thirty years of listing practice.

In particular, some commenters suggested the Prebles should be protected rangewide because it is threatened over a significant portion of its range. They suggested “partial-listings” would lead to a limitless series of petitions and lawsuits over the status of taxa in portions of their ranges.

Others suggested the subspecies should be delisted throughout its entire range, unless the threats are so severe in the Colorado portion of the range that it puts the subspecies' “future * * * in doubt.” This commenter suggested the Service's new listing approach inappropriately allows “partial-listings” when the loss of a portion of range results in a decrease, no matter how small, in the ability to conserve a species, subspecies, or DPS.

Response:

We agree with the interpretation of the Act set forth in the Solicitor's opinion, and disagree with these comments for the reasons given in that opinion. It is true that the Act only allows the listing and delisting of species, subspecies, or DPSs. As such, this action lists the Preble's because the subspecies is likely to become endangered within the foreseeable future in a significant portion of its range. However, once we determine listing is appropriate, section 4(c) of the Act requires we “specify with respect to each such species over what portion of its range it is threatened.” In this case, we are specifying that the subspecies is threatened in Colorado. Thus, the protections of the Act are only necessary and shall only apply in the Colorado portion of its range.

The interpretation of the Act advocated by these commenters fails to give sufficient consideration to the import of section 4(c), is inconsistent with legislative history of the Act that strongly supports the view that Congress intended to give the Secretary broad discretion to tailor the protections of the Act with the needs of the species, and would lead to absurd results.

Moreover, even before the 2007 Solicitors opinion, we have applied differential levels of protections for species facing differential levels of threats in different parts of their range. For example, in 1978, the gray wolf (

Canis lupus

) was protected as endangered in the lower-48 States, except in Minnesota, where it was protected as threatened (a lower level of protection is often provided to threatened species than to endangered species) (43 FR 9607, March 9, 1978). Nor is the listing determination for Prebles the only listing determination applying the Solicitor's opinion. In our 2008 Gunnison prairie dog 12-month finding (73 FR 6660, February 5, 2008), we determined that the Gunnison's prairie dog does not warrant the Act's protections throughout its range, but that the significant portion of the species' range located in central and south-central Colorado and north-central New Mexico does warrant protection under the Act.

According to the Solicitor's opinion, we have broad discretion in defining what portion of a range is “significant,” but this discretion is not unlimited. Specifically, we may not define “significant” to require that a species is endangered only if the threats faced by a species in a portion of its range are so severe as to threaten the viability of the species as a whole. The suggestion by one of the commenters that a portion of the range of a species can be significant only if its loss would put the “future [of the species] in doubt” rests on a single quote from hearing testimony on a bill that was a precursor to the Act. If by the future of the species being in doubt the commenter means that the threat to the portion of the range must threaten the entire species, such an interpretation would read the “significant portion or its range” language from the Act. Unlike the Solicitor's opinion, the commenter did not address this issue, or the relevant case law.

For this determination, we used an analysis similar to that we have used in other recent listing determinations: A portion of a species' range is significant if it is part of the current range of the species and it contributes substantially to the representation, resiliency, or redundancy of the species. The contribution must be at a level such that its loss would result in a decrease in the ability to conserve the species. In other words, in considering significance, the Service asks whether the loss of this portion likely would eventually move the species toward extinction, but not to the point where the species should be listed as threatened or endangered throughout all of its range.

To determine if a portion of the species' range contributes substantially to the resiliency of the species, the Service considered in this instance: (1) To what extent does this portion of the range contribute to the total of large blocks of high-quality habitat? (2) To what extent do the population size and characteristics within this portion of the range contribute to the ability of the species to recover from periodic disturbances? (3) To what extent does this portion of the range act as a refugium of the species? (4) To what extent does this portion contain an important concentration of habitats necessary for certain life history functions?

To determine if a portion of the species' range contributes substantially

to the redundancy of the species, the Service considered in this instance: (5) To what extent does this portion of the range contribute to the total [gross area] range of the species? (6) To what extent does this portion of the range contribute to the total population of the species? (7) To what extent does this portion of the range contribute to the total suitable habitat? (8) To what extent does this portion of the range contribute to the geographical distribution of the species?

To determine if a portion of the species' range contributes substantially to the representation of the species, the Service considered in this instance: (9) To what extent does this portion of the range contribute to the genetic diversity of the species? (10) To what extent does this portion of the range contribute to the morphological/physiological diversity of the species? (11) To what extent does this portion of the range contribute to the behavioral diversity of the species? (12) To what extent does this portion of the range contribute to the diversity of ecological settings in which the species is found?

These questions provide for a relative ranking (high, medium, and low) of the level of the portion's contribution to the listable entity's (species, subspecies or DPSs) representation, resiliency, or redundancy. Because the questions may not be independent of each other or equivalent in value, it is inappropriate to “sum” the high, medium, and low rankings across questions or arrive at a total “score.” Rather, the questions are tools to identify those factors that are important in considering a portion's contribution to resiliency, redundancy, and representation, and whether it is significant. The Service then reviews the results and the justifications to decide whether the portion contributes substantially to the representation, redundancy and resiliency of the listable entity (species, subspecies or DPS). In general, if the contribution to the representation, resiliency, or redundancy of all the questions is low, the portion likely does not contribute substantially to representation, resiliency, or redundancy; if the contribution to the representation, resiliency, or redundancy of most or multiple questions are high, the portion likely contributes substantially to representation, resiliency, or redundancy.

Issue:

Several commenters suggested the “partial-listing” approach allowed by the Solicitor's opinion undoes the effect of the 1978 DPS amendments to the Act.

Response:

We do not believe this approach undoes the 1978 amendments to the Act, instead it compliments the 1978 amendments. A DPS of a vertebrate species which interbreeds when mature is considered and treated as a species (i.e., a listable entity) under the Act. A significant portion of the range is a portion of the range of the listed entity (whether a full species, subspecies, or DPS of a vertebrate) that contributes meaningfully to the conservation of the species. Therefore, we may apply the protections of the Act in a significant portion of a DPS. In addition, we may apply the protections of the Act in a significant portion of a species or subspecies of non-vertebrate.

According to our DPS policy (61 FR 4722, February 7, 1996), a DPS must be discrete and must be significant to the taxon to which it belongs (species or subspecies) as a whole. The term “significant” in the Act's definitions of endangered and threatened species should not be considered entirely equivalent to the “significance” element of the DPS policy. We recognize, however, that many of the attributes (described below) we have identified as important for evaluating whether a portion of a species' range is significant are similar to the attributes identified in the DPS policy as being appropriate for evaluating the significance of a potential DPS. There is no requirement that a significant portion of the range be discrete, but similar to DPSs, a significant portion of the range must be significant. As explained in detail previously, the significance of a significant portion of the range is based on an evaluation of its contribution to the conservation of the listable entity being considered. The DPS policy lists four possible factors to consider when determining significance, but does not limit consideration of significance to only those four factors. The considerations we made in this instance for determining whether a portion is significant encompass and expand on some of the concepts in the DPS policy.

Issue:

One commenter suggested we use a 4(d) rule to reduce regulatory restrictions in more secure portions of its range instead of this “partial-listing” approach.

Response:

Special rules under section 4(d) of the Act apply only where the protections of the Act are in place. Thus, once we determined the subspecies was not threatened in the Wyoming portion of its range, use of section 4(d) was no longer an option for Prebles populations in Wyoming. While a 4(d) rule allows us to tailor the Act's taking provisions as necessary and advisable to provide for the conservation of the species, the approach utilized here also eliminates the need for critical habitat and consultation under section 7 of the Act. We believe this approach is more consistent with the intention of Congress as expressed in the legislative history concerning the phrase “significant portion of its range.”

Issue:

Some commenters questioned our analysis and conclusion regarding the status of the Prebles in Wyoming as compared to our analysis and conclusion regarding Colorado. They stated that, like Colorado, the Wyoming portion of the range is necessary for resiliency, redundancy, and representation of the Prebles, and that loss of populations in Wyoming would result in a decrease in our ability to conserve the Prebles. Some commenters stated that Preble's populations in Wyoming should be protected because, even with the protections of the Act, the subspecies continues to decline in Colorado. These commenters suggested Wyoming Preble's populations will likely be essential to conserving the subspecies.

Response:

The Wyoming portion of its range is necessary for resiliency, redundancy, and representation of the Prebles. The basis for amending the listing of the Prebles in the Wyoming portion of its range is not the lack of significance of Wyoming populations to the survival of the subspecies, but rather that Wyoming populations appear secure into the foreseeable future without protections of the Act. Overall, in the absence of the Act's protective measures, we believe the subspecies will likely remain secure and well distributed across Wyoming into the foreseeable future. We have concluded that the lack of present or threatened impacts to the Prebles in these areas indicates that this subspecies is neither in danger of extinction, nor likely to become endangered within the foreseeable future, throughout all of its range. Thus, the Prebles does not merit continued listing as threatened throughout all of its range. In Colorado, where we have determined the Prebles remains threatened, the Act will provide for the subspecies' protection and, with the assistance of our partners, eventual recovery.

Issue:

Some commenters suggested a “partial delisting” would not improve the conservation status of the subspecies and would treat different communities inequitably with regards to the level of protection required and costs associated with them over different geographic areas.

Response:

We believe this approach allows for a more surgical application of the Act, as envisioned by Congress when it wrote the “significant portion of its range” language. The Act does not

allow us to consider in this listing decision whether there would be higher costs in Colorado than in Wyoming. On the whole, we believe this targeted approach provides for the necessary and appropriate needs of the species, while avoiding unnecessary regulatory burdens.

Issue:

Two reviewers suggested that our proposal, which would result in the removal of the Act's protections for the Prebles in Wyoming, but not in the Colorado portion of its range, may limit human activities in Colorado and thereby encourage the transfer of those same activities and impacts to the Prebles' habitats in Wyoming.

Response:

We have concluded that this outcome is unlikely. For example, we cannot envision prohibitions of the Act limiting residential development in Colorado to the extent that development options in Wyoming are pursued that would otherwise not be pursued. Much more likely, human development activities planned in Colorado that could adversely impact the Prebles would be modified. Prebles' occurrence is largely limited to riparian corridors and adjacent uplands that make up a small portion of the Colorado Front Range. Most activities that could prove harmful to the subspecies and its habitat can be feasibly modified to avoid impacts, or adverse effects can be addressed through section 7 consultations or HCPs. If relocation of projects occurs, in most cases we think that viable project alternatives are likely to be near the originally proposed site.

Issue:

A few commenters stated that a change in listing status could preclude further investigation, monitoring, and assessing of the Prebles in Wyoming. Other commenters argued that we did not explain how maintenance of populations in Wyoming would be assured without monitoring. Some commented that a 5-year monitoring plan should be developed to monitor State and county commitments to conserve the Prebles and its habitat. One suggested a “special rule” be developed to assure such monitoring.

Response:

As discussed previously, according to 50 CFR 424.11(d) of our regulations, we may delist a species if the best available scientific and commercial data indicate that the species is neither endangered nor threatened for the following reasons: (1) The species is extinct; (2) the species has recovered and is no longer endangered or threatened; and/or (3) the original scientific data used at the time the species was classified were in error. Section 4(g)(1) of the Act requires us to monitor a species for at least 5 years after it is delisted based on recovery. In this case, we are amending the status of the Prebles based on new information that was not available at the time of listing. Of the three options laid out in 50 CFR 424.11(d) of our regulations and identified above, we have determined that this case most appropriately falls under option (3) the original scientific data used at the time the species was classified were in error. The Act does not require us to monitor a species in such cases. However, we intend to work with the State and other interested parties in Wyoming to continue monitoring efforts for the subspecies.

The State of Wyoming has committed to conducting ongoing monitoring efforts for the Prebles and to ensuring its long-term viability (Freudenthal 2008). The State has expressed an interest in working with the Service in developing monitoring protocols. The State is working with the WNDD to determine relative connectivity of Prebles' populations in Wyoming. In addition, the WNDD (Griscom

et al.

2007) is engaged in a 5-year to 7-year study with the USFS to inventory and monitor Prebles' populations, correlate populations with habitat conditions, and measure effects of fire and livestock grazing.

Issue:

Several commenters stated that any delisting rule for the Prebles must provide evidence that the subspecies has met the recovery criteria cited in the Preliminary Draft Recovery Plan.

Response:

Because this action is based upon error (i.e., “the original scientific data used at the time the species was classified were in error”) and not recovery, satisfying the Preliminary Draft Recovery Plan is not necessary. Additionally, recovery plans are not regulatory documents and are instead intended to provide guidance to the Service, States, and other partners on methods of minimizing threats to listed species and on criteria that may be used to determine when recovery is achieved. In short, recovery of a species is a dynamic process requiring adaptive management that may, or may not, fully follow the guidance provided in a recovery plan. Finally, the Preliminary Draft Recovery Plan is a draft and has not been approved by either the Service or the Recovery Team.

That said, we believe that our determinations regarding the conservation status of Prebles in Wyoming and Colorado are largely consistent with the recovery concepts described in the Preliminary Draft Recovery Plan. In Wyoming, the Preliminary Draft Recovery Plan focuses on maintaining 1 large population and 2 medium populations. The availability of large, connected areas of suitable habitat with confirmed Prebles occurrence records suggests these populations currently exist (USFWS 2003b, pp. iv, 29; Beauvais 2004; USFWS 2008). Because these populations face no meaningful threats over the foreseeable future, we believe these populations will be maintained well into the foreseeable future. Thus, the protections of the Act are no longer necessary or appropriate in this portion of range. The same is not true for Prebles' populations in Colorado where the protections of the Act remain necessary.

Issue:

One commenter questioned our conclusions and stated that there was no indication that habitat conditions for the Prebles have improved since the time of listing and that the same threats persist.

Response:

Our determination that the Prebles should remain listed in the Colorado portion of its range recognizes the continuation of the main threats identified at the time of listing. Our determination regarding Prebles populations in Wyoming is based on expanded knowledge of populations present and subsequent evaluation of foreseeable threats in relation to areas supporting these populations.

Issue:

One commenter noted that, based on extrapolated estimates of the Prebles per mile and extent of apparently occupied habitat, more Prebles exist in Colorado than are needed for recovery as proposed in the Preliminary Draft Recovery Plan.

Response:

Extrapolation of Prebles' numbers based on limited distribution and population data must be made with caution. Habitat varies greatly across the known range of the subspecies and the actual extent of occupied habitat is largely unknown. In addition, the Preliminary Draft Recovery Plan does not emphasize total numbers of Prebles throughout the subspecies' range, but rather the documentation of existing populations of specified size and distribution, establishing stability of these populations over time, and the elimination of threats. We cannot, based on the best available information, conclude that Prebles' populations in Colorado meet these criteria or warrant removal of the protections of the Act.

Use of State Line To Delimit the Colorado Significant Portion of Range

Issue:

Some commenters questioned the use of the State line to delineate the Colorado significant portion of range. They were concerned that the State border does not represent a biological divide between Prebles' populations. Furthermore, they contend that southern Wyoming and northern Colorado are ecologically similar, as are

the dominant agricultural land uses. Some suggested the use of the State line to delineate the Colorado significant portion of range appeared to be a political compromise. Some commenters suggested that we should study Prebles' interactions across the State line. One reviewer questioned whether a metapopulation or source-sink structure existed with populations in one State, dependent on populations in the other. Other commenters stated that management practicality favors use of the State line. One respondent commented that landowners are used to and better understand regulations based on governmental lines (rather than watershed lines) and that regulation based on State or county lines best corresponds to local zoning and development-related permitting.

Response:

The State line is not a strict ecological divide. However, this rule incorporates this geopolitical boundary because it appropriately divides differential threats to the north and south. As such, it is relevant biologically to the subspecies' status.

Furthermore, the available data suggests use of the State line will not split any Prebles' populations into federally protected and unprotected segments. Prebles' populations in the Upper Lodgepole, Upper Laramie, Crow Creek, and Lone Tree Creek drainages are not known in Colorado, and Prebles' populations in the Cache La Poudre drainage are not known to occur in Wyoming. While such populations may exist, we see little potential for Prebles' populations in any drainage to have a significant component in the immediate area of the Wyoming-Colorado State line. Based on known dispersal abilities of the Prebles and proximity of known populations in Wyoming and Colorado, interaction across the State line is not known or likely to occur. Even if such interactions exist, they are likely infrequent or unimportant to populations on either side. Further, if such dependency exists, we do not anticipate it would be disrupted by the action in this final rule. Threats north of the border that would disrupt any metapopulation dynamic are minimal, while populations in Colorado remain protected.

As we have described, there also is a practical consideration supporting use of the State line to delineate the significant portion of range where the Act's protections are still necessary.

Issue:

One commenter thought that political boundaries may be supportable in the assessment of listing status in cases where State regulations vary, but noted that there are no such differences between Wyoming and Colorado.

Response:

Differential protection under State regulations could render a State line an important boundary of differing threats. In this case, we have concluded that levels of threats differ largely because of differing levels of projected human population growth. Rationale for using the State line is the same (i.e., differential threats) though the reason for the threats differs.

Modification of the Boundaries for the Colorado Significant Portion of Range

Issue:

We received numerous comments regarding our delineations of the southern, eastern, and western boundaries of the Colorado significant portion of range. Some supported the boundaries as proposed. One feared that altering the proposed lines of protection could detract from recovery activities. Another commenter suggested that boundaries were adequately delineated, and that block clearances and site exclusions are viable regulatory options to address concerns at sites within the significant portion of range where the Prebles was not likely present. One commenter stated that attempts to fine tune boundaries by drainages or counties were inappropriate and supported the proposed latitude-longitude boundaries. This commenter concluded that “simplest is best.” In contrast, we also received comments that we should remove areas where appropriate habitat for Prebles was not present.

Response:

We have considered these comments and continue to conclude that a broad delineation of the Colorado significant portion of range is appropriate. Such a delineation is likely to encompass all Prebles' populations, maximizing conservation potential within Colorado. Fine-scale delineation of habitat is more akin to a critical habitat designation and not appropriate for a significant portion of the range designation of where the Act's protections apply. Elimination of all non-habitat would require determinations of habitat suitability for each individual stream reach creating an unwieldy task. Furthermore, only listing the subspecies in these stream reaches would require lengthy legal descriptions of all habitat boundaries including possible UTM delineations (a standardized coordinate system based on the metric system and a division of the earth into sixty 6-degree-wide zones). This would be difficult for the public, other Federal agencies, State agencies, local governments and other interested parties to interpret and implement.

We also considered an intermediate approach. This approach would apply the Act's protections to all riparian areas and their associated wetlands, their 100-year floodplain and an additional 100 m (330 ft) within the portion of Colorado west of 103 degrees 40 minutes West, north of 38 degrees 30 minutes North, and east of 105 degrees 50 minutes West. One difficulty with this approach is that 100-year flood plains have not been designated by Federal Emergency Management Agency throughout the range of the subspecies. Because these designations have not been defined across the range, the actual table at 50 CFR 17.11 would require lengthy legal descriptions including possible UTM delineations. Alternatively, we considered applying the Act's protections to all riparian areas and their associated wetlands plus a defined buffer (such as 1,000 m (3,300 ft)) within the portion of Colorado west of 103 degrees 40 minutes West, north of 38 degrees 30 minutes North, and east of 105 degrees 50 minutes West. This approach would likely be inaccurate as actual utilized habitat varies across streams and within streams based on topography of that particular reach. An additional complication with this approach is defining “riparian areas and their associated wetlands.” Generally, these terms lack a regulatory definition. Perhaps the closest regulatory definition is Clean Water Act's (CWA) area of authority described as “navigable waters of the United States.” Unfortunately, many areas utilized by Prebles fall outside these jurisdictional wetlands. As such, the actual table at 50 CFR 17.11 would again require lengthy legal descriptions including possible UTM delineations. As such, we believe these intermediate approaches would also be difficult for the public, other Federal agencies, State agencies, local governments and other interested parties to interpret and implement.

Instead, we will continue to determine potential for habitat at a particular site to support the Prebles on a case-by-case basis. All block clearances and site exclusions will continue to be subject to individual review, amendment, and expansion/contraction as more information becomes available on Prebles' presence.

Issue:

Some commenters opined that Prebles' populations in particular drainages, counties, or stream reaches in Colorado should be removed from protection under the Act based on considerations similar to those we cited for removing protections in Wyoming. One commenter suggested that all areas where threats were less severe should be excluded from protections in Colorado. The State of Wyoming suggested that we remove protections of the Act for

Prebles' populations in Lone Tree-Owl, Crow Creek, and Upper Laramie drainages in Colorado.

Response:

We have considered these comments and continue to conclude that existing Prebles' populations in Colorado represent a single significant portion of range that should not be further subdivided. While we also considered splitting the subspecies into significant portions of the range based on river basins (i.e., only removing the Act's protections in the North Platte River basin), we concluded that this would be more difficult to administer with little conservation benefit to the subspecies.

Given expected development patterns in the Colorado portions of these drainages, we do not believe the available data support Wyoming's proposal to remove the Act's protections for Prebles' populations in Lone Tree-Owl, Crow Creek, and Upper Laramie drainages in Colorado. While we recognize that information is currently lacking to confirm the presence of existing Prebles' populations in the Colorado portion of Lone Tree-Owl and Crow Creek drainages, we believe that, based on the availability of suitable habitat (Pague and Granau 2000, pp. 2-3, 5-3, 7-3), portions of these drainages may be occupied.

Issue:

One reviewer suggested that we extend the limits of the Colorado significant portion of range protection further east to include lower basins and the confluence of occupied rivers and streams. This reviewer thought that such protection might be critical to habitat connectivity and dispersal.

Response:

In cases where lower portions of drainages and basins are thought to be outside of the current range of the Prebles, we doubt that dispersal via these routes would occur as suitable habitat no longer exists and is not viewed as likely recoverable. Therefore, we do not see any reason to extend protection to these areas that are unlikely to support the subspecies. Connectivity among populations in separate drainages may be occurring overland where drainages have closely adjacent headwater streams or by way of water conveyance ditches.

Other Issues

Issue:

One commenter suggested that our final rule should address Prebles' status in Wyoming by June 30, 2008, consistent with our settlement agreement with the State of Wyoming, but allow for additional time to consider status of the Prebles in Colorado.

Response:

Our revised proposed rule addressed the status of the Prebles throughout its range. It would be inconsistent with our draft guidance on the application of a significant portion of range analysis and settlement agreement to delay our final determination for any part of the Prebles' range. Status of the Prebles in Colorado will be further evaluated during future 5-year reviews.

Issue:

Several commenters requested that the final rule clarify how the removal of the Act's protections in Wyoming impacts existing HCPs and previous section 7 consultations including mitigation, monitoring, and reporting requirements.

Response:

No HCPs are in effect in Wyoming so this portion of the issue is moot. Previous commitments made through the section 7 process with respect to an action area in Wyoming will no longer be binding as of the effective date of this listing determination; however, coordination with lead Federal agencies should be pursued to substantiate their jurisdiction over other aspects of previously approved projects. For example, commitments specific to the Prebles and to conservation of wetlands and adjacent buffers under CWA permits may overlap.

Issue:

Some commenters questioned how the proposed action might impact section 9 take prohibitions and the section 7 consultation process, including jeopardy determinations.

Response:

The prohibitions under section 9 of the Act and requirements under section 7 of the Act apply to the portion of the subspecies' range where it remains threatened. Our jeopardy analysis will be conducted on the significant portion of range which remains listed (i.e., Colorado), rather than the subspecies' range as a whole. The question we will ask with regard to the jeopardy analysis is, “does the proposed action appreciably reduce the likelihood of survival and recovery of the species within the significant portion of range where the prohibitions of the Act apply?”

Taxonomy

The Prebles is a member of the family

Dipodidae

(jumping mice) (Wilson and Reeder 1993, p. 499), which contains four extant genera. Two of these,

Zapus

(jumping mice) and

Napaeozapus

(woodland jumping mice), are found in North America (Hall 1981, p. 841; Wilson and Ruff 1999, pp. 665-667).

In his 1899 study of North American jumping mice, Edward A. Preble concluded the

Zapus

genus consisted of 10 species (Preble 1899, pp. 13-41). According to Preble (1899, pp. 14-21),

Z. hudsonius

(the meadow jumping mouse) included five subspecies. Preble (1899, pp. 20-21) classified all specimens of the meadow jumping mouse from North Dakota, Montana, South Dakota, Wyoming, Nebraska, Colorado, and Missouri as a single subspecies,

Z. h. campestris

. Cockrum and Baker (1950, pp. 1-4) later designated specimens from Nebraska, Kansas, and Missouri as a separate subspecies,

Z. h. pallidus

.

Krutzsch (1954, pp. 352-355) revised the taxonomy of the

Zapus

genus after studying morphological characteristics of 3,600 specimens. This revision reduced the number of species within this genus from 10 to 3, including

Z. hudsonius

(the meadow jumping mouse),

Z. princeps

(the western jumping mouse), and

Z. trinotatus

(the Pacific jumping mouse). According to Krutzsch (1954, pp. 385-453), the meadow jumping mouse included 11 subspecies.

Krutzsch (1954, pp. 452-453) described and named the subspecies Prebles (

Zapus hudsonius preblei

) based on geographic separation and morphological (physical form and structure of an organism) differences. Krutzsch (1954, pp. 452-453) discussed the presence of physical habitat barriers and the lack of known intergradation (merging gradually through a continuous series of intermediate forms or populations) between the Prebles, known only from eastern Colorado and southeastern Wyoming, and other identified subspecies of meadow jumping mice ranging to the east and north. Additionally, Krutzsch (1954, pp. 452-453) examined the morphometric characteristics of 4 adult and 7 non-adult specimens. Krutzsch (1954, pp. 452-453) reported 7 distinguishing traits, but only published quantitative results (9 measurements) on two of these traits (n=3) (Krutzsch 1954, p. 465). Acknowledging the small number of samples upon which his conclusion was based, Krutzsch (1954, p. 453) nonetheless concluded that the differences between Prebles and neighboring meadow jumping mice was considerable and enough to warrant a subspecific designation.

In Krutzsch's analysis, subspecies neighboring Prebles included

Zapus hudsonius campestris

in northeastern Wyoming, southwestern South Dakota, and southeastern Montana;

Z. h. intermedius

in North Dakota, and northwestern, central, and eastern South Dakota; and

Z. h. pallidus

(Cockrum and Baker 1950) in Nebraska, Kansas, and Missouri (Krutzsch 1954, pp. 441-442, 447-452). In 1981, Hafner

et al.

(1981, p. 501) identified

Z. h. luteus

from Arizona and New Mexico as another neighboring subspecies of meadow

jumping mouse. This population had previously been assumed a subspecies of western jumping mouse (Krutzsch 1954, pp. 406-407; Hall and Kelson 1959, pp. 774-776; Jones 1981, p. iv). Among recognized subspecies, Krutzsch (1954, p. 452) found that Prebles most closely resembled

Z. h. campestris

from northeastern Wyoming, but documented differences in coloration and skull characteristics.

Krutzsch's description (1954), as modified by Hafner

et al.

(1981, p. 501), with 12 subspecies of meadow jumping mice, has been generally accepted by most small mammal taxonomists for the past half-century (Hall and Kelson 1959, pp. 771-774; Long 1965, pp. 664-665; Armstrong 1972, pp. 248-249; Whitaker 1972, pp. 1-2; Hall 1981, pp. 841-844; Jones

et al.

1983, pp. 238-239; Clark and Stromberg 1987, p. 184; Wilson and Reeder 1993, p. 499; Hafner

et al.

1998, pp. 120-121; Wilson and Ruff 1999, pp. 666-667).

Other Taxonomic Information Available Prior to Listing

As part of a doctoral dissertation, Jones (1981, pp. 4-29, 229-303, 386-394, 472) analyzed the morphology of 9,900 specimens within the

Zapus

genus from across North America, including 39 Prebles' specimens. Jones' dissertation (1981, p. 144) concluded that the Pacific jumping mouse was not a valid taxon and suggested reducing the number of species in the genus to two (the western jumping mouse and the meadow jumping mouse). At the subspecific level, Jones (1981, pp. V, 303) concluded that no population of meadow jumping mouse was sufficiently isolated or distinct to warrant subspecific status. Regarding the Prebles, Jones (1981, pp. 288-289) wrote that “No named subspecies is geographically restricted by a barrier, with the possible exception of

Z. h. preblei

[Preble's meadow jumping mouse]” which “appears to be isolated,” but that “no characteristics indicate that these populations have evolved into a separate taxon.” Jones' taxonomic conclusions regarding the Prebles are difficult to evaluate as he did not compare the Prebles to

Z. h. campestris

, the closest neighboring subspecies, nor did he conduct statistical tests of morphological differences between the Prebles and any other subspecies. This dissertation was approved by Jones' doctoral committee and the Indiana State University's School of Graduate Studies in 1981 (Jones 1981, p. ii). Jones' (1981) findings were not published in a peer-reviewed journal and were not incorporated into the formal jumping mouse taxonomy.

Prior to listing, the CDOW contracted for a genetic analysis of the Prebles (Riggs

et al.

1997). Riggs

et al.

(1997, p. 1) examined 433 base-pairs in 1 region of the mitochondrial deoxyribonucleic acid (mtDNA) (maternally inherited genetic material) across 5 subspecies of meadow jumping mouse (92 specimens). This study concluded that the Prebles' specimens formed a homogenous group recognizably distinct from other nearby populations of meadow jumping mice (Riggs

et al.

1997, p. 12). At the request of the Service, Hafner (1997, p. 3) reviewed the Riggs study, inspected Riggs' original sequence data, and agreed with its conclusions. The supporting data for this report remain privately held (Ramey

et al.

2003, p. 3). The Riggs

et al.

(1997) results were not published in a peer-reviewed journal. Prior to listing, this study was the only available information concerning the genetic uniqueness of the Prebles relative to neighboring subspecies.

Our original listing determined that Krutzsch's (1954) revision of the meadow jumping mouse species, including the description of the Prebles, was widely supported by the scientific community as indicated by the available published literature (63 FR 26517, May 13, 1998). Our 1998 determination weighed the information in unpublished reports, such as Jones (1981), and public comments on the rule and found that they did not contain enough scientifically compelling information to suggest that revising the existing taxonomy was appropriate (63 FR 26517, May 13, 1998). Our 1998 conclusion was consistent with Service regulations that require us to rely on standard taxonomic distinctions and the biological expertise of the Department and the scientific community concerning the relevant taxonomic group (50 CFR 424.11).

Taxonomic Information Solicited After Listing

In 2003, the Service, the State of Wyoming, and the Denver Museum of Nature and Science funded a study to resolve ongoing taxonomic questions about the relationship between the Prebles and neighboring mouse taxa (USFWS 2003a, pp. 1-2). In December 2003, we received a draft report from the Denver Museum of Nature and Science examining the uniqueness of the Prebles relative to other nearby subspecies of meadow jumping mice (Ramey

et al.

2003). In 2004, the Service and other partner agencies provided additional funding to expand the scope of the original study (USFWS 2004). In August 2005, an expanded version of this original report was published in the journal

Animal Conservation

(Ramey

et al.

2005). This publication included an examination of morphometric differences, mtDNA, and microsatellite DNA (a short, noncoding DNA sequence, usually two to five base-pairs, that is repeated many times within the genome of an organism). Ramey

et al.

(2005, pp. 339-341) also examined the literature for evidence of ecological exchangeability among subspecies (a test of whether individuals can be moved between populations and can occupy the same ecological niche).

Ramey

et al.

's morphometric analysis tested 9 skull measurements of 40 Prebles, 40

Zapus hudsonius campestris

, and 37

Z. h. intermedius

specimens (Ramey

et al.

2005, p. 331). Their results did not support Krutzsch's (1954, p. 452) original description of the Prebles as “averaging smaller in most cranial measurements” (Ramey

et al.

2005, p. 334). Ramey

et al.

(2005, p. 334) found that only one cranial measurement was significantly smaller, while two cranial measurements were significantly larger.

Ramey

et al.

examined 346 base-pairs in 1 region of the mtDNA across 5 subspecies of meadow jumping mice (205 specimens) (Ramey

et al.

2005, pp. 331-332, 335). Ramey

et al.

(2005, p. 335, 338) found low levels of difference between the Prebles and neighboring subspecies. The subspecies failed Ramey

et al.

's tests of uniqueness in that the subspecies did not show greater molecular variance among than within subspecies or did not demonstrate nearly complete reciprocal monophyly with respect to other subspecies. The data demonstrated that all of the mtDNA haplotypes (alternate forms of a particular DNA sequence or gene) found in the Prebles also were found in

Zapus hudsonius campestris

. The mtDNA data demonstrated evidence of recent gene flow between the Prebles and neighboring subspecies (Ramey

et al.

2005, p. 338).

Ramey

et al.

(2005, pp. 333-334, 338) analyzed 5 microsatellite loci across 5 subspecies of meadow jumping mice (195 specimens). The subspecies failed Ramey

et al.

's tests of uniqueness in that the subspecies did not show greater molecular variance between than within subspecies and that multiple private alleles were not at a higher frequency than shared alleles at the majority of loci (Ramey

et al.

2005, p. 333). Ramey

et al.

(2005, p. 340) concluded that these results were consistent with their morphometric and mtDNA results.

Finally, a review of the literature found no published evidence of adaptive or ecological differences

between Prebles and other subspecies of jumping mouse. Ramey

et al.

(2005, pp. 339-341) conclude that the lack of morphological difference supported the proposition of no adaptive or ecological difference.

Based on hypothesis testing using four lines of evidence—morphometrics, mtDNA, microsatellites, and a lack of recognized adaptive differences—Ramey

et al.

(2005, p. 340) concluded that Prebles and

Zapus hudsonius intermedius

should be synonymized with

Z. h. campestris

.

Prior to publication of Ramey

et al.

(2005) in

Animal Conservation

, the CDOW and the Service solicited 16 peer reviews of the 2004 draft report provided to the Service (Ramey

et al.

2004a). Fourteen of these reviewers provided comments (Armstrong 2004; Ashley 2004; Bradley 2004; Conner 2004; Crandall 2004; Douglas 2004; Hafner 2004; Meaney 2004; Mitton 2004; Oyler-McCance 2004; Riddle 2004; Sites 2004; Waits 2004; White 2004). In 2005, the Service approached the same 16 experts to review Ramey

et al.

2004b (an expansion of Ramey

et al.

2004a). Eleven of these reviewers provided comments (Ashley 2005; Baker and Larsen 2005; Bradley 2005; Crandall 2005; Douglas 2005; Hafner 2005; Maldonado 2005; Mitton 2005; Oyler-McCance 2005; Waits 2005; White 2005). In 2006, some of these reviewers provided comments on Ramey

et al.

(2005) as part of their review of King

et al.

(2006a). Krutzsch (2004) also reviewed Ramey

et al.

(2004a). In August 2006,

Animal Conservation

published two critiques of Ramey

et al.

(2005) (Martin 2006; Vignieri

et al.

2006) and two responses (Crandall 2006b; Ramey

et al.

2006a).

Many of the reviewers generally supported the findings of Ramey

et al.

(Baker and Larsen 2005; Bradley 2004, 2005; Crandall 2004, 2005; Hafner 2004; Krutzsch 2004; Maldonado 2005; Meaney 2004; Mitton 2004, 2005; Riddle 2004; Sites 2004; Waits 2004, 2005). However, the reviewers raised a number of important issues. Because these experts reviewed the unpublished reports (Ramey

et al.

2004a, 2004b), many of the criticisms were addressed prior to publication in

Animal Conservation

(Ramey

et al.

2005). For example, reviewers recommended that the study be augmented to include microsatellite data; this information was added to the published version (Ramey

et al.

2005). Some of the most significant unresolved issues identified included:

(1) Reliance upon museum specimens which can be prone to contamination (Douglas 2004, 2005, 2006; Hafner 2006; Maldonado 2005);

(2) The reliability of, and failure to validate, specimens' museum identification tag (Ashley 2005; Douglas 2004, 2005; Hafner 2004; Oyler-McCance 2004, 2005, 2006);

(3) The sampling regime and its impact on the analysis (Ashley 2006; Crandall 2006a; Douglas 2006; Hafner 2006; Maldonado 2005, 2006; Oyler-McCance 2004, 2006);

(4) Reliance upon a small portion (346 base-pairs) of mtDNA (Ashley 2004, 2005; Baker and Larsen 2005; Crandall 2004, 2005, 2006a; Douglas 2004, 2005, 2006; Hafner 2005, 2006; Maldonado 2005; Oyler-McCance 2004, 2005, 2006; Riddle 2004; Sites 2004; Waits 2004, 2005);

(5) The small number of microsatellite DNA loci examined (five) (Crandall 2006a; Oyler-McCance 2006; Hafner 2006; Vignieri

et al.

2006, p. 241);

(6) The statistical tests employed (Crandall 2004; Douglas 2004, 2005; Hafner 2006; Maldonado 2005; Mitton 2005; Oyler-McCance 2005, 2006);

(7) The criteria used and factors considered to test taxonomic validity as well as alternative interpretations of the data (Ashley 2004; Conner 2004; Douglas 2004, 2005, 2006; Hafner 2005, 2006; Oyler-McCance 2004, 2005; Vignieri

et al.

2006, pp. 241-242; White 2004);

(8) Whether the western jumping mouse was an appropriate outgroup (a closely related group that is used as a rooting point of a phylogenetic tree) (Douglas 2004);

(9) Failure to measure all of the morphological traits examined by Krutzsch (1954) (Vignieri

et al.

2006, p. 238); and

(10) An inadequate evaluation of ecological exchangeability and habitat differences among subspecies (Ashley 2004; Conner 2004; Douglas 2004; Meaney 2004; Mitton 2004; Oyler-McCance 2004, 2005; Sites 2004; Vignieri

et al.

2006, p. 238; Waits 2004, 2005). Collectively, these critiques indicated that delisting based on the conclusions of Ramey

et al.

alone might be premature.

Because the proposed rule to delist the Prebles relied solely upon an unpublished report (Ramey

et al.

2004a) that had received mixed peer reviews (see above), verifying these results was a high priority of the Service (Morgenweck 2005; Williams 2004). Thus, in 2006, the Service contracted with USGS to conduct an independent genetic analysis of several meadow jumping mouse subspecies (USGS 2005, pp. 1-4). The USGS study concluded that the Prebles should not be synonymized with neighboring subspecies (King

et al.

2006a, pp. 2, 29). An expanded version of this report was published in the journal

Molecular Ecology

(King

et al.

2006b). This study included an examination of microsatellite DNA, 2 regions of mtDNA, and 15 specimens critical to the conclusions of Ramey

et al.

(2005).

King

et al.

's (2006b, p. 4336) microsatellite analysis examined approximately 4 times the number of microsatellite loci (21) and more than 1.75 times more specimens (348 specimens) than Ramey

et al.

(2005) across the same 5 subspecies of meadow jumping mice. King

et al.

(2006b, p. 4337) concluded that their microsatellite data demonstrated a strong pattern of genetic differentiation between the Prebles and neighboring subspecies. King

et al.

(2006b, pp. 4336-4341) also reported that multiple statistical tests of the microsatellite data verified this differentiation.

In their evaluation of mtDNA, King

et al.

(2006b, p. 4341) examined approximately 4 times the number of base-pairs across 2 regions (374 control region and 1,006 cytochrome-B region base-pairs) and more than 1.5 times more specimens (320 specimens for the control region analysis and 348 for the cytochrome-B analysis) than Ramey

et al.

(2005) across the same 5 subspecies of meadow jumping mice. King

et al.

(2006b, p. 4341) concluded that these data suggested strong, significant genetic differentiation among the five subspecies of meadow jumping mice surveyed.

Additionally, their mtDNA results indicated that the Prebles did not share haplotypes with any neighboring subspecies (King

et al.

2006b, p. 4341). Such haplotype sharing contributed to Ramey

et al.

's (2004a, pp. 1, 9; 2005, p. 335) conclusion that the Prebles was not unique and that the Prebles was a less genetically variable population of

Zapus hudsonius campestris

. Because of these conflicting results, King

et al.

(2006b, pp. 4355-4357) reexamined 15 specimens from the University of Kansas Museum collection that were key in Ramey

et al.

's determination that neighboring subspecies shared haplotypes. King

et al.

(2006b, p. 4357) could not duplicate the mtDNA sequences reported by Ramey

et al.

for these specimens. If these specimens were removed from the analysis, neither study would illustrate haplotype sharing between the Prebles and neighboring subspecies. King

et al.

(2006b, p. 4357) concluded that “these findings have identified the presence of a systemic error in the control region data reported by Ramey

et al.

(2005)” and “calls into question all of the results of Ramey

et al.

(2005) based on the

mtDNA genome and prevents analysis of the combined data.” King

et al.

(2006, p. 4357) noted that possible reasons for the difference in sequences included contamination, mislabeling of samples, or other procedural incongruity. Ramey

et al.

(2007, pp. 3519-3520) proposed a number of alternative explanations for these contradictory results including nuclear paralogs (copies of mtDNA sequence that have been incorporated into the nuclear genome and are now pseudogenes, that is, they are no longer functional), heteroplasmy (the existence of more than one mitochondrial type in the cells of an individual), different amplification primers and conditions, and template quality.

Overall, King

et al.

(2006b, p. 19) concluded that considerable genetic differentiation occurred among all five subspecies and found no evidence to support the proposal to synonymize the Prebles,

Zapus hudsonius campestris

, and

Z. h. intermedius

.

Prior to its release, King

et al.

(2006a) underwent an internal peer review per USGS policy (USGS 2003, pp. 3, 6, 12, 28-33). In an effort to provide consistent, comparable reviews, we solicited peer reviews from the same 16 reviewers asked to review Ramey

et al.

(2004a, 2004b). Nine of the experts provided comments (Armstrong 2006; Ashley 2006; Bradley 2006; Crandall 2006a; Douglas 2006; Hafner 2006; Maldonado 2006; Oyler-McCance 2006; Riddle 2006). Ramey

et al.

(2006b, 2007) also critiqued King

et al.

(2006a, 2006b).

Most of the reviewers supported the findings of King

et al.

(Armstrong 2006; Ashley 2006; Douglas 2006; Hafner 2006; Maldonado 2006; Oyler-McCance 2006; Riddle 2006). These reviews offered a number of issues and possible explanations why the results differed from Ramey

et al.

Because reviewers were asked to review the unpublished report (King

et al.

2006a), some of the issues were addressed in the

Molecular Ecology

publication (King

et al.

2006b). For example, numerous reviews suggested expanding the geographic range of the study by adding a Prebles' population in Wyoming; this issue was addressed in the published version (King

et al.

2006b). Similarly, the publication incorporated the suggestion to retest the museum specimens Ramey

et al.

(2005) identified as having shared haplotypes for signs of cross contamination. Some of the other issues raised included:

(1) The sampling regime and its impact on the analysis (Armstrong 2006; Ashley 2006; Crandall 2006a; Douglas 2006; Oyler-McCance 2006; Ramey

et al.

2007, p. 3519; Riddle 2006);

(2) Failure to evaluate morphometrics and ecological exchangeability (Crandall 2006a);

(3) Reliance upon a small portion of control region mtDNA (Riddle 2006);

(4) The number of loci examined (i.e., too many), the programs used to analyze the data, and the resulting sensitivity in detecting difference (Crandall 2006a; Ramey

et al.

2006b; Ramey

et al.

2007, p. 3519);

(5) a specimen collection methodology which could cause contamination (Ramey

et al.

2007, p. 3519);

(6) The statistical tests employed (Crandall 2006a; Douglas 2006; Maldonado 2006; Riddle 2006); and

(7) The criteria used and factors considered to test taxonomic validity and alternative interpretations of the data (Bradley 2006; Crandall 2006a).

Given the discrepancies between the Ramey

et al.

and King

et al.

reports, we contracted for a scientific review to analyze, assess, and weigh the reasons why the data, findings, and conclusions of the two studies differed (USFWS 2006, p. 14). Following an open and competitive bid process, we selected SEI as the contractor (USFWS 2006).

SEI assembled a panel of experts with the necessary scientific expertise in genetics and systematics (SEI 2006a, pp. 7, 56-82). The panelists reviewed, discussed, and evaluated all of the literature relevant to this issue including published literature, unpublished reports, third-party critiques, public comments, and other materials suggested by interested parties (SEI 2006a, pp. 48-55). Additionally, the panel examined and reanalyzed the raw data (SEI 2006a, pp. 8, 21) used by Ramey

et al.

and King

et al.

, including the mtDNA data, microsatellite DNA data, and original sequence chromatograms (automated DNA sequence data output recordings) (SEI 2006a, pp. 8, 23). The scientific review panel was open to the public and allowed for interactions among panel members, Dr. King, Dr. Ramey, other scientists, and the public.

In July 2006, SEI delivered a report outlining its conclusions to the Service (SEI 2006a). Although the panelists were not obligated to reach a consensus, they did not disagree on any substantive or stylistic issues (SEI 2006a, p. 9). Thus, the report represented the consensus of all three panelists, as well as the individual opinions of each panelist. The panel organized its evaluation into four sections corresponding with the different types of scientific evaluations performed, including morphology, ecological exchangeability, mtDNA, and microsatellite DNA. The panel's findings with regard to each are summarized briefly below. The full report is available for review at

http://www.fws.gov/mountain-prairie/species/mammals/preble/Prebles_SEI_report.pdf.

Morphology:

The panel found that all seven of the morphological characters examined by Krutzsch (1954, pp. 452-453) should have been reexamined in order to support Ramey

et al.

's proposed taxonomic revision. The panel also concluded that the type specimen (the original specimen from which the description of a new species is made) of each taxon should have been included in the analysis. The panel's conclusion was that an insufficient test of the morphological definition of the Prebles had been conducted to support the synonymy of the Prebles with other subspecies (SEI 2006a, p. 41).

Ecological Exchangeability:

The panel concluded that no persuasive evidence was presented regarding ecological exchangeability, and that the ecological exchangeability of the subspecies remains unknown (SEI 2006a, p. 41).

MtDNA:

The panel noted that data provided by Ramey

et al.

(2005) and King

et al.

(2006b) differed in geographic sampling strategy, amount of sequence data examined, aspects of the analysis, and quality (SEI 2006a, p. 41). All of these could help explain why the two studies came to differing conclusions. However, the panel noted that the most significant difference between the two studies in terms of mtDNA was whether the Prebles shared any mtDNA haplotypes with other subspecies of meadow jumping mice. Upon review of the raw data, the panel found evidence of contamination within some of the key sequences reported by Ramey

et al.

and that the supporting data for the samples in question was of poor quality and/or quantity (SEI 2006a, pp. 23-32). The panel concluded that no reliable evidence existed of any haplotype sharing between the Prebles and neighboring subspecies (SEI 2006a, p. 42). The panel determined that if the conflicting mtDNA sequences were removed from consideration, the two studies' mtDNA data would largely agree (SEI 2006a, p. 32). The panel also suggested that because the western jumping mouse and the meadow jumping mouse are distantly related, western jumping mouse may perform poorly as an outgroup, leading to poor resolution of relationships among meadow jumping mouse subspecies. While both Ramey

et al.

and King

et al.

used western jumping mice as their outgroup, an unrooted analysis lacking these genetic points of reference showed

clearer phylogenetic structuring between the subspecies (SEI 2006a, p. 42).

Microsatellite DNA:

The panel found that the two microsatellite datasets contain similar information. The panel pointed out that both the Ramey

et al.

(2005) and King

et al.

(2006b) microsatellite data, as well as Crandall and Marshall's (2006) reanalysis of these data, strongly support a statistically significant independent cluster that corresponds to the Prebles, providing support for a distinct subspecies (SEI 2006a, pp. 42-43). The panel indicated that while the microsatellite data alone did not make a strong case for evolutionary significance, in concert with the mtDNA data (discussed above), the two datasets corroborate the distinctness of the Prebles (SEI 2006a, p. 43).

The panel's overall conclusion was that the available data are broadly consistent with the current taxonomic status of the Prebles as a valid subspecies and that no evidence was presented that critically challenged its status (SEI 2006a, p. 4). In August 2006, Ramey

et al.

(2006c) submitted a statement to the Service disputing the approach and conclusions of the SEI report. Some of the most significant issues raised included: (1) Objection to the deference given to Krutzsch (1954); (2) disagreement with the suggestion that all seven morphometric characters examined by Krutzsch (1954) and the type specimen should be reexamined; (3) dispute with the assertion that Ramey

et al.

's (2005) evaluation of ecological significance was inadequate; (4) the contention that the Prebles and neighboring subspecies remain weakly genetically differentiated; and (5) SEI's failure to develop objective standards for testing the validity of suspect subspecies. No new data or analyses were presented in this statement, and the panel previously considered most of these contentions (Ramey

et al.

2003, 2004a, 2004b, 2005, 2006a, 2006b; SEI 2006a, 2006b, 2006c). Other evaluations of the available literature and data include Ramey

et al.

(2007), Crandall and Marshall (2006), Spencer (2006b), and Cronin (2007).

Taxonomic Conclusions

When listed in 1998, the Prebles was widely recognized as a valid subspecies by the scientific community (Hall and Kelson 1959, pp. 771-774; Long 1965, pp. 664-665; Armstrong 1972, pp. 248-249; Whitaker 1972, pp. 1-2; Hall 1981, pp. 841-844; Jones

et al.

1983, pp. 238-239; Clark and Stromberg 1987, p. 184; Wilson and Reeder 1993, p. 499; Hafner

et al.

1998, pp. 120-121; Wilson and Ruff 1999, pp. 666-667). At the time of listing, Krutzsch (1954) represented the best available information on the taxonomy of the Prebles (63 FR 26517, May 13, 1998). Our 1998 conclusion was consistent with Service regulations that require us to rely on standard taxonomic distinctions and the biological expertise of the Department and the scientific community concerning the relevant taxonomic group (50 CFR 424.11). However, when the best available science indicates that the generally accepted taxonomy may be in error, the Service must rely on the best available science (

Center for Biological Diversity,

et al.

, v. Robert Lohn,

et al.

, 296 F. Supp. 2d. 1223 W.D. Wash. 2003). Such considerations led to our February 2, 2005, proposal to delist the Prebles based upon information that questioned the subspecies' taxonomic validity (70 FR 5404).

We now determine that the best scientific and commercial data available support the conclusion that the Prebles is a valid subspecies. Specifically, the Prebles' geographic isolation from other subspecies of meadow jumping mice (Krutzsch 1954, pp. 452-453; Long 1965, pp. 664-665; Beauvais 2001, p. 6; Beauvais 2004; SEI 2006a, p. 34) has resulted in the accretion of considerable genetic differentiation (King

et al.

2006b, pp. 4336-4348; SEI 2006a, pp. 41-43). The available data suggest that the Prebles meets or exceeds numerous, widely accepted subspecies definitions (Mayr and Ashlock 1991, pp. 43-45; Patten and Unitt 2002, pp. 26-34; SEI 2006a, p. 44). In reaching this conclusion, we have not used a presumption that we must rely on the established taxonomy in the absence of conclusive data to the contrary (see SEI report at p. 39). After a review of all available information, we have determined that the taxonomic revision for the Prebles suggested in our proposed delisting rule (70 FR 5404, February 2, 2005) is no longer appropriate.

Historical Range and Recently Documented Distribution

Generally, the Prebles' range includes portions of the North Platte, the South Platte, and the Arkansas river basins (Long 1965, p. 665; Armstrong 1972, pp. 248-249; Clark and Stromberg 1987, p. 184; Fitzgerald

et al.

1994, p. 293; Clippinger 2002, p. 20).

At the time of listing, we described the historical range in Wyoming as including five counties (Albany, Laramie, Platte, Goshen, and Converse), but cited only two sites with recent reports of jumping mice likely to be the Prebles. We cited a study by Compton and Hugie (1993, p. 6) suggesting the subspecies might be extirpated in Wyoming and comments by the WGFD that the Prebles had likely been extirpated from most or all of its historical range in Wyoming (Wichers 1997).

At the time of listing, we assumed that most of the subspecies' current range was in Colorado. Within Colorado, the final listing rule described a presumed historical range including portions of 10 counties (Adams, Arapahoe, Boulder, Denver, Douglas, El Paso, Elbert, Jefferson, Larimer, and Weld) and cited recent documentation of the subspecies in 7 of these 10 counties (Boulder, Douglas, El Paso, Elbert, Jefferson, Larimer, and Weld).

Since we listed the Prebles in 1998, our knowledge about distribution of the subspecies has grown substantially. Numerous trapping surveys conducted during the last 9 years in Wyoming and Colorado have documented the subspecies' presence or likely absence at locations of suitable habitat. While many recent trapping efforts have been at locations with no record of historical surveys, most have been within the presumed historical range of the Prebles or in adjacent drainages where habitat and elevation appeared suitable. Thus, the recent increase in sites of Prebles' occurrence likely represents an improvement in our understanding of the subspecies' range as a result of increased trapping effort rather than any actual expansion of the range of the Prebles.

In Wyoming, recent captures and confirmed identification have expanded our knowledge of the distribution of the Prebles to include over two dozen new plains, foothills, and montane sites, including presence west of the Laramie Mountains in the North Platte River basin and in the Upper Laramie River drainage in Albany County (Taylor 1999; USFWS 2008). Post-listing activities have identified many additional sites occupied by the subspecies. Since listing, trapping efforts in Wyoming targeting Prebles have captured jumping mice at 72 percent of sites (124 of 173 sites) (USFWS 2008). Of positive jumping mouse capture sites, 29 percent of the sites included only Prebles, 55 percent of the sites included only western jumping mice, 5 percent of the sites had both species present, and specimens from 11 percent of the successful sites were never positively identified to species. These data also reveal that the Prebles occurs in four of the five counties that we described as the likely historical range at the time of listing including Albany, Laramie, Platte, and

Converse counties. While generalized range maps (Long 1965, p. 665, Armstrong 1972, pp. 248-249, Clark and Stromberg 1987, p. 184) depicted Prebles' range extending east into Goshen County, we have no evidence that the subspecies was ever present there.

At the time of listing, we discussed how increased trapping efforts in Colorado had recently documented distribution in Elbert, Larimer, and Weld counties. We also suggested other sites where trapping should occur to determine if Prebles were present. Additional trapping since listing has expanded the documented distribution of the Prebles in Colorado to include: (1) Additional foothill and montane sites along the Front Range in Larimer, Boulder, Jefferson, and Douglas counties; (2) previously untrapped rural prairie and foothill streams in southern Douglas County and adjacent portions of Elbert County; and (3) additional prairie and foothill streams in northwestern El Paso County. Although we have identified some additional sites occupied by the Prebles, since listing over 80 percent of Colorado trapping efforts targeting Prebles have failed to capture jumping mice (as illustrated in Figure 2 below) (USFWS 2008). In 2007, 2 of 31 trapping efforts targeting new sites in Colorado resulted in captures of jumping mice. These negative trapping results suggest that the subspecies is rare or extirpated from many portions of the subspecies' historical range in Colorado. Areas where the subspecies is presumed extirpated are discussed in the Factor A discussion below.

BILLING CODE 4310-55-P

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BILLING CODE 4310-55-C

The Prebles has now been recently documented in portions of Albany, Laramie, Platte, and Converse counties in Wyoming; and in portions of Boulder,

Douglas, El Paso, Elbert, Jefferson, Larimer, and Weld counties in Colorado (Figures 1 and 2). The North Platte River at Douglas, Wyoming, marks the northernmost confirmed location for the Prebles. Specimens from Colorado Springs, Colorado, mark the southernmost documented location of the Prebles.

The Prebles is generally found at elevations between 1,420 m (4,650 ft) and 2,300 m (7,600 ft). At the lower end of this elevation gradient, the semi-arid climate of southeastern Wyoming and eastern Colorado limits the extent of riparian corridors and restricts the range of the Prebles (Beauvais 2001, p. 3). The Prebles is likely an Ice Age relict; once the glaciers receded from the Front Range of Colorado and the foothills of Wyoming and the climate became drier, the Prebles was confined to riparian systems where moisture was more plentiful (Fitzgerald

et al.

1994, p. 1994; Smith

et al.

2004, p. 293). The eastern boundary for the subspecies is likely defined by the dry shortgrass prairie, which may present a barrier to eastward expansion (Beauvais 2001, p. 3). In Wyoming, the Prebles has not been found east of Cheyenne, Laramie County (Beauvais 2001, p. 3). Habitat modeling and trapping suggest the subspecies does not occur in Wyoming's Goshen, Niobrara, and eastern Laramie counties (Keinath 2001, p. 7). In Colorado, the Prebles has not been found on the extreme eastern plains (Clippinger 2002, pp. 20-21).

At the higher elevations, discerning the status of the Prebles is complicated by the overlap in the ranges of the Prebles and the western jumping mouse (Long 1965, pp. 665-666; Clark and Stromberg 1987, pp. 184-187; Schorr 1999, p. 3; Bohon

et al.

2005; Schorr

et al.

2007, p. 5). Field differentiation between the Prebles and the western jumping mouse is difficult (Conner and Shenk 2003a, p. 1456). Generally, the western jumping mouse occurs in the montane and subalpine zones and the Prebles occurs lower, in the plains and foothills (Smith

et al.

2004, p. 10). Using this information as a guide, many jumping mice were trapped and released without being conclusively identified as either a Prebles or a western jumping mouse. Western jumping mice have been verified at elevations well below the upper elevation limit of the Prebles (Smith

et al.

2004, p. 11), leading to difficulty in making assumptions regarding identification based on elevation. Drainages where overlapping ranges have been verified include: The Glendo Reservoir, Lower Laramie, Upper Laramie, and Horse Creek drainages in Wyoming (Conner and Shenk 2003b, pp. 26-27, 34-37; Meaney 2003; King 2006a; King 2006b; King

et al.

2006b, pp. 4351-4353); and the Cache La Poudre, Big Thompson, and Upper South Platte River drainages in Colorado (Bohon

et al.

2005; King 2005; King 2006a; King

et al.

2006b, pp. 4351-4353; Schorr

et al.

2007).

Size, external morphology, dentition, skull measurements, and genetic analysis can all be used to differentiate meadow jumping mice from western jumping mice (Krutzsch 1954, pp. 351-384; Klingenger 1963, p. 252; Riggs

et al.

1997, pp. 6-11; Conner and Shenk 2003a; Ramey

et al.

2005, p. 332; King

et al.

2006b, p. 4341). The following description of the Prebles' current distribution and status emphasizes locations where individual mice have been positively identified through genetic analysis or DFA (Conner and Shenk 2003a). Information regarding individual mice and capture locations can be found in Riggs

et al.

(1997, pp. 7-11, A1-A4), Conner and Shenk (2003b, pp. 31-35), and King

et al.

(2006b, pp. 4351-4353). Positive identification of individual mice is most important in areas where both the Prebles and the western jumping mouse occur. Overlap appears to occur in most of Wyoming's occupied drainages (as described further below). In Colorado, with few exceptions, jumping mice positively identified below 2,050 m (6,700 ft) have been Prebles. Between 2,050 m (6,700 ft) and 2,320 m (7,600 ft) in Colorado, Prebles and western jumping mice are known to have an overlapping distribution in the Cache La Poudre, Big Thompson, and Upper South Platte River drainages.

Below is a summary of recent (since 1980) trapping data by drainage (as defined by 8-digit USGS hydrologic units), within both Wyoming (e.g., the North and South Platte River basins) and Colorado (e.g., the South Platte River and Arkansas River basins). Although trapping data is important because it absolutely confirms the occurrence of jumping mice at particular locations, trapping data is only one of several lines of evidence we use to estimate the actual range of the subspecies. Records have been compiled by the Service (2008) in coordination with the WNDD, State of Wyoming, and CDOW. Figure 1 above illustrates all recently confirmed Prebles' capture locations in Wyoming. Figure 2 above illustrates all recent Prebles' capture locations in Colorado. Given wide areas of overlapping range in Wyoming, we require all Wyoming specimens to be confirmed as Prebles in order to be considered in our discussion below (and in Figure 1). In Colorado, jumping mice are considered Prebles in our discussion below (and in Figure 2) when identification is confirmed or, if they occur in areas below 2,050 m (6,700 ft), where western jumping mice have not been documented.

North Platte River Basin, Wyoming—In the North Platte River basin, occurrence of the Prebles has been confirmed in four Wyoming counties (Converse, Platte, Albany, and Laramie) as reported by drainage below.

The Middle North Platte drainage represents the northern extent of the reported Prebles' historic range. Jones (1981) examined one Prebles' specimen from within this drainage, trapped at Boxelder Creek, Converse County. Recent trapping surveys have been quite limited and generally at high elevations. Although several other recent jumping mice have been trapped in this drainage, these specimens have not been confirmed as Prebles.

In the Glendo Reservoir drainage, the Prebles is known from several locations, including along the North Platte River at Douglas (King 2006b), and Cottonwood Creek and its tributaries (Meaney 2003; King 2006a; King 2006b; King

et al.

2006b, pp. 4351-4353). While the western jumping mouse also has been confirmed from the Glendo Reservoir drainage, trapping records to date suggest that the Prebles is more common.

In the Lower Laramie drainage, the Prebles has been confirmed from the Laramie River and its tributaries, including the North Laramie River, and Sturgeon, Wyman, Rabbit, and Luman creeks; as well as several locations along Chugwater Creek and its tributaries (King 2006b; King

et al.

2006b, pp. 4351-4353). Both Prebles and western jumping mice occur in the Sybille Creek, Friend Creek and the Friend Park areas (Conner and Shenk 2003b, pp. 26-27, 34-37; King 2006a; King 2006b; King

et al.

2006b, pp. 4351-4353). The Lower Laramie drainage appears to support coexisting Prebles and western jumping mice in multiple locations.

In the Horse Creek drainage, the Prebles has been widely documented west of Interstate Highway 25 (I-25) and at one site east of I-25. The majority of these recent captures have been made in Bear Creek and its tributaries, and in headwaters of Horse Creek and its tributaries. Both Prebles and western jumping mice inhabit multiple sites on both creeks (Conner and Shenk 2003b, pp. 26-27, 34-37; Meaney 2003; King 2006b; King

et al.

2006b, pp. 4351-4353).

In the Upper Laramie drainage, the Prebles has been confirmed at Hutton

Lake National Wildlife Refuge (NWR) and from a site north of Laramie (Meaney 2003). Other specimens at these same sites have been confirmed as western jumping mice (Meaney 2003; King 2006a). Therefore, it appears likely that both Prebles and western jumping mice are present at multiple sites in this drainage. Based on positive identification of

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