# Endangered and Threatened Wildlife and Plants; Revised Proposed 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

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URL: https://www.frixlaw.com/law-library/documents/fr%3A07-5486

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** November 7, 2007
- **Citation:** 72 FR 62992

## Text

DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AV64

Endangered and Threatened Wildlife and Plants; Revised Proposed 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:

Revised proposed rule.

SUMMARY:

Under the authority of the Endangered Species Act of 1973, as amended (Act), we, the U.S. Fish and Wildlife Service (Service), revise our February 2, 2005 (70 FR 5404), proposed rule to remove the Preble's meadow jumping mouse (
Zapus hudsonius preblei
) (Preble's) from the List of Endangered and Threatened Wildlife. We now propose to amend the listing for the Preble's meadow jumping mouse to specify over what portion of its range the subspecies is threatened. The best scientific and commercial data available demonstrates that: The Preble's meadow jumping mouse 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 current range of the subspecies located in Colorado represents a significant portion of the current range where the Preble's meadow jumping mouse is likely to become endangered within the foreseeable future, and the subspecies in that portion of its range should retain its threatened status. We seek comments from the public regarding this revised proposal. Comments previously submitted need not be resubmitted as they have already been incorporated into the public record and will be fully considered in the final determination.

DATES:

Written Comments:
We will consider comments on this revised proposed rule that we receive by the close of business on January 22, 2008. Any comments we receive after the closing date may not be considered in our final decision on the proposal.

Open House and Public Hearing:
We will hold an open house and public hearing on this revised proposed rule in Colorado on December 10, 2007 and in Wyoming on December 12, 2007. Each open house will run from 4 p.m. to 5 p.m., with brief presentations about this revised proposed rule given at 4 p.m., and each public hearing will run from 6 p.m. to 8 p.m.

ADDRESSES:

Written Comments:
If you wish to comment on this revised proposed rule, you may submit your comments and materials by any one of several methods:

(1)
By mail to:
Susan Linner, Field Supervisor, Colorado Field Office, Ecological Services, P.O. Box 25486, MS-65412, Denver Federal Center, Denver, CO 80225.

(2)
By hand-delivery to:
Susan Linner, Colorado Field Office at 134 Union Blvd., Suite 670, Lakewood, CO 80228.

(3)
By fax to:
(303) 236-4005.

(4)
By electronic mail (e-mail) to: FW6_PMJM@fws.gov
. Please see the Public Comments Solicited section below for other information about electronic filing.

(5)
By the Federal eRulemaking Portal at: http://www.regulations.gov
. Follow the instructions on that Web site for submitting comments.

Open House and Public Hearing:
We will hold an open house and public hearing at the Colorado Field Office, 134 Union Boulevard, Room 100A—Eagle Conference Room, Lakewood, CO 80228 and at the First State Bank Conference Center, 1405 16th Street, Wheatland, WY 82201.

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; facsimile (303) 236-4005. If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at (800) 877-8339.

SUPPLEMENTARY INFORMATION:

Public Comments Solicited

We intend that any final action resulting from this proposal will be as accurate and as effective as possible. Therefore, we solicit data, comments, new information, or suggestions from the public, other concerned governmental agencies, the scientific community, industry, or any other interested party concerning this revised proposed rule. Generally, we seek information, data, and comments concerning:

(1) Survey results for Preble's meadow jumping mouse, as well as any studies that may show distribution, status, population size, or population trends;

(2) Pertinent aspects of life history, ecology, and habitat use of Preble's meadow jumping mouse, especially those pertaining to its relationship to the western jumping mouse
(Zapus princeps)
;

(3) Current and foreseeable threats faced by the Preble's meadow jumping mouse in relation to the five factors (as defined in section 4(a)(1) of the Act (16 U.S.C. 1531 et seq.));

(4) Effects of current and foreseeable land management practices on Preble's meadow jumping mouse status, including conservation efforts;

(5) Our analysis and conclusions regarding the conservation status of the Preble's meadow jumping mouse throughout all of its range, in particular information relative to the long-term security of existing populations of the subspecies in Wyoming.

(6) Our analysis and conclusions regarding “significant portion of its range” in light of the March 14, 2007, Department of the Interior, Solicitor Memorandum opinion available at
http://www.doi.gov/solicitor/M37013.pdf;

(7) The contribution of both the Wyoming and Colorado portions of the range to the status of the subspecies;

(8) The range of the subspecies as defined in this proposal and the areas where the protections of the Act should remain in place (see “
Significant Portion of the Range Where the Subspecies is Threatened” for specific information solicited
) and

(9) The Sustainable Ecosystems Institute (SEI) report “Evaluation of scientific information regarding Preble's meadow jumping mouse” (available at
http://www.fws.gov/mountain-prairie/species/mammals/preble/
) and other information concerning the taxonomic status of Preble's meadow jumping mouse.

You may submit your comments and materials concerning this revised proposed rule by one of several methods (see
ADDRESSES
). If you use e-mail to submit your comments, please submit them in ASCII file format and avoid the use of special characters and encryption. Please include “Attn: Preble's meadow jumping mouse” in your e-mail subject header, preferably with your name and return address in the body of your message. If you do not receive a confirmation from the system that we have received your e-mail, contact us directly by calling our Colorado Field Office at (303) 236-4773. Please note that we must receive comments by the date specified in the
DATES
section in order to consider them in our final determination and that we will close out the e-mail address
FW6_PMJM@fws.gov
at the termination of the public comment period.

Before including your address, phone number, e-mail address, or other personal identifying information in your comment, you should be aware that

your entire comment—including your personal identifying information—may be made publicly available at any time. While you can ask us in your comment to withhold your personal identifying information from public review, we cannot guarantee that we will be able to do so. We will always make submissions from organizations and businesses, and from individuals identifying themselves as representatives or officials of organizations and businesses, available for public inspection in their entirety.

Comments and materials we receive, as well as supporting documentation we used in preparing this revised proposed rule, will be available for public inspection, by appointment, during normal business hours at the U.S. Fish and Wildlife Service Colorado Field Office, 134 Union Blvd., Suite 670, Lakewood, CO 80228, (telephone (303) 236-4773) . We will take into consideration all substantive comments and any pertinent information we receive during the comment period on this revised proposed rule during the preparation of a final rulemaking. Accordingly, the final decision may differ from this proposal.

Open Houses and Public Hearings

We will hold open houses and public hearings on the dates listed in the
DATES
section, and at the addresses listed in the
ADDRESSES
section, of this document. Anyone wishing to make an oral statement for the record at either of the public hearing is encouraged to provide a written copy of his or her statement and present it to us at the hearing. Persons wishing to make an oral statement at the public hearing may sign up only at the open house or at the public hearing; we will not reserve speaking time in advance of the open house. In the event that there is a large attendance, the time allotted for oral statements may be limited. Oral and written statements receive equal consideration. There are no limits on the length of written comments submitted to us. If you have any questions concerning the open house or public hearing, please contact Sharon Rose at (303) 236-4580. Persons needing reasonable accommodations in order to attend and participate in the open house or public hearing should contact Sharon Rose as soon as possible in order to allow sufficient time to process requests. Please call no later than 1 week before the hearing date. Information regarding this revised proposal is available in alternative formats upon request.

Previous Federal Actions

We listed Preble's meadow jumping mouse as threatened under the Act on May 13, 1998 (63 FR 26517). We designated critical habitat for Preble's meadow jumping mouse on June 23, 2003 (68 FR 37275). On May 22, 2001 (66 FR 28125), we adopted a final section 4(d) special rule for the Preble's meadow jumping mouse 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 sunset May 22, 2004, but was made permanent on May 20, 2004 (69 FR 29101).

In June 2000, the Service established the Preble's Meadow Jumping Mouse 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. This technical working draft was revised by the Service in November 2003. The Preliminary Draft Recovery Plan suggested long-term protection of: One large population (with June abundances of 2,500 or more individuals), two medium populations (with June abundances of 500-2,499 individuals), and six small populations (with evidence of occupancy; possibly 150 mice) within the North Platte River basin two large, three medium, and eighteen small populations within the South Platte River basin and one large population, and six small populations within the Arkansas River basin (Service 2003b, p. 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 this document (hereafter referred to as the Preliminary Draft Recovery Plan (Service 2003b)) has not yet been announced in the
Federal Register
, it represents the best available information on the recovery needs of the subspecies.

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 Preble's meadow jumping mouse from the Federal List of Endangered and Threatened Wildlife (Freudenthal 2003; Sonnenberg 2003). The petitions maintained that Preble's meadow jumping mouse should be delisted based on the taxonomic revision suggested by Ramey
et al.
(2003) and new distribution, abundance, and trends data which 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 Preble's meadow jumping mouse from the Federal List of Endangered and Threatened Wildlife, and opened a 90-day public comment period (70 FR 5404). 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 Preble's meadow jumping mouse 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 Preble's meadow jumping mouse was likely not a valid subspecies of meadow jumping mouse (
Zapus hudsonius
). Considering the weight that we gave Ramey
et al.
(2004a) in the proposed delisting, verifying the results of this study 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 Preble's meadow jumping mouse and four neighboring subspecies of meadow jumping mice (U.S. Geological Survey 2005, pp. 1-4).

On January 25, 2006, USGS released its report concluding that Preble's meadow jumping mouse 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 because 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 (71 FR 8556). 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.
differ 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) (Service 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 Preble's meadow jumping mouse's 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)). If a new proposed regulation is deemed necessary, the Service is required to submit a final determination to the
Federal Register
no later than June 30, 2008.

Public Comments on the 2005 Proposed Rule

From February 2, 2005, through May 3, 2005 (70 FR 5404, February 2, 2005), and from February 17, 2006, through May 18, 2006 (71 FR 8556, February 17, 2006; 71 FR 16090, March 30, 2006), we solicited, from all interested parties, comments and information that might contribute to the final delisting determination for the Preble's meadow jumping mouse. We received a total of 67 written comments, including 28 comments during the initial comment period and 39 during the reopened comment period. These included comments from: The Governor of the State of Wyoming; the Attorney General of the State of Wyoming; the Colorado Department of Natural Resources; U.S. Forest Service, Rocky Mountain Region; 6 comments from local governments; and 57 comments from individuals or groups. During the reopened comment period we also received a challenge under the Information Quality Act (44 U.S.C. 3516) to influential information disseminated by the Service during this rulemaking process. This challenge and our response are available at
http://www.fws.gov/informationquality/.
This response has been appealed and the appeal is currently under review by the Service. Because we received the original challenge during the open public comment period, these issues are considered public comments on our proposed rule.

In accordance with our July 1, 1994, Interagency Cooperative Policy for Peer Review in Endangered Species Act Activities (59 FR 34270), we solicited five expert peer reviews of our proposed rule (70 FR 5404, February 2, 2005). We selected peer reviewers for expertise in genetics, systematics (the science of dealing with the diversity of organisms), and small mammals. We excluded previous peer reviewers of Ramey et al. and King et al. from this solicitation. Three of the experts approached provided comments (Hoekstra 2005; Kelt 2005; Spencer 2005). After reopening the public comment period on February 17, 2006 (71 FR 8556), we contacted the same five experts and invited them to provide additional comments given the availability of new information (i.e., King et al. 2006a). Two of these reviewers provided comments (Kelt 2006; Spencer 2006a).

All previously submitted comments have been included in the public record and will be considered in the final determination regarding this proposal. Comments previously submitted need not be resubmitted. Additionally, all of the previously submitted comments and reviews relevant to the taxonomy discussion were made available to the SEI panel for its consideration. Substantive comments will be addressed in a series of issues and responses in our final determination.

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).

Across their range, meadow jumping mice typically occur in moist habitats, including low undergrowth consisting of grasses, forbs, or both, in open wet meadows and riparian corridors, or where tall shrubs and low trees provide adequate cover (Krutzsch 1954, p. 351; Armstrong 1972, p. 248; Jones et al. 1983, p. 238). Trainor et al. (2007, pp. 471-472) found that high use areas for Preble's meadow jumping mouse tended to be close to creeks and were positively associated with the percentage of shrubs, grasses, and woody debris. Hydrologic regimes that support Preble's meadow jumping mouse 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 Preble's meadow jumping mouse 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; Service 2003b, p. 26). While the Preble's meadow jumping mouse dispersal capabilities are thought to be limited, in one instance a Preble's meadow jumping mouse was documented moving as far as 1.1 kilometers (km) (0.7 mile (mi)) in 24 hours (Ryon 1999, p. 12). The Preble's meadow jumping mouse typically enters hibernation between September and 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 Preble's meadow jumping mouse as threatened (63 FR 26517) and the June 23, 2003, final rule designating critical habitat (68 FR 37275).

Taxonomy

The Preble's meadow jumping mouse 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. hudsonius 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 Preble's meadow jumping mouse (
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 Preble's meadow jumping mouse, 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) evaluated the morphometric characteristics of 4 adult and 7 non-adult specimens. Acknowledging the small number of samples upon which his conclusion was based, Krutzsch (1954, p. 453) nonetheless concluded that the differences between Preble's meadow jumping mouse and neighboring meadow jumping mice was considerable and enough to warrant a subspecific designation.

In Krutzsch's analysis, the subspecies neighboring Preble's meadow jumping mouse included
Z. h. campestris
in northwestern 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). Among recognized subspecies, Krutzsch (1954, p. 452) found that Preble's meadow jumping mouse most closely resembled
Z. h. campestris
from northeastern Wyoming, but documented differences in coloration and skull characteristics.

In 1981, Hafner et al. (1981, p. 501) identified
Zapus hudsonius luteus
from Arizona and New Mexico as the 12th subspecies of meadow jumping mouse. This population had previously been assumed to be a subspecies of western jumping mouse (Krutzsch 1954, pp. 406-407; Hall and Kelson 1959, pp. 774-776; Jones 1981, p. iv).

Krutzsch's description (1954) as modified by Hafner et al. (1981, p. 501), with 12 subspecies of meadow jumping mice, was 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 Preble's meadow jumping mouse specimens. Jones's 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 Preble's meadow jumping mouse, 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 did not compare the Preble's meadow jumping mouse to
Z. h. campestris
, a neighboring subspecies, nor did he conduct statistical tests of morphology between the Preble's meadow jumping mouse and any other subspecies. Jones's (1981) findings were not published in a peer-reviewed journal and were not incorporated into the formal jumping mouse taxonomy, leaving his conclusions difficult to evaluate.

Prior to listing, the Colorado Division of Wildlife (CDOW) contracted for a genetic analysis of the Preble's meadow jumping mouse (Riggs et al. 1997). Riggs et al. (1997, p. 1) examined a small number of base-pairs (433) in one 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 Preble's meadow jumping mouse 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 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 Preble's meadow jumping mouse.

Our original listing determined that Krutzsch's (1954) revision of the meadow jumping mouse species, including the description of the Preble's meadow jumping mouse, 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 July 2003, we entered into a cooperative agreement with the Denver Museum of Natural Science (DMNS) to determine if the Preble's meadow jumping mouse was a unique subspecies relative to other nearby subspecies of meadow jumping mice (Service 2003a, pp. 1-2). This task was a priority of the Recovery Team (Service 2003a, pp. 1-2; Service 2003b, pp. iv, 38, 43, 76). In December 2003, we received a draft report from the DMNS examining the uniqueness of the Preble's meadow jumping mouse relative to other nearby subspecies of meadow jumping mice (Ramey et al. 2003). 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 2 to 5 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 Preble's meadow jumping mice, 40
Z. h. 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 Preble's meadow jumping mouse 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 a small number of base-pairs (346) 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 Preble's meadow jumping mouse and neighboring subspecies. Their data demonstrated that all of the mtDNA haplotypes (alternate forms of a particular DNA sequence or gene) found in the Preble's meadow jumping mouse were also found in
Z. h. campestris.
The mtDNA data demonstrated evidence of recent gene flow between the Preble's meadow jumping mouse and neighboring subspecies (Ramey et al. 2005, p. 338).

Ramey et al. (2005, pp. 333-334, 338) analyzed a small number (5) of microsatellite loci (the specific position of a gene or other chromosomal marker) across 5 subspecies of meadow jumping mice (195 specimens). Ramey et al. (2005, p. 340) concluded that these results were consistent with morphometric and mtDNA results.

Based on morphometrics, mtDNA, and microsatellites data, and a lack of recognized adaptive differences, Ramey et al. (2005, p. 340) suggested synonymizing the Preble's meadow jumping mouse and
Z. h. intermedius
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 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).

While many of the reviewers supported the findings of Ramey et al. (Baker and Larsen 2005; Bradley 2004, 2005; Crandall 2004, 2005; Hafner 2004; Maldonado 2005; Meaney 2004; Mitton 2004, 2005; Riddle 2004; Sites 2004; Waits 2004, 2005), the reviews raised a number of important issues. Some of the most significant issues identified included: (1) Reliance upon museum specimens which can be prone to contamination (Douglas 2004, 2005; Maldonado 2005); (2) the reliability of, and failure to validate, specimens' museum tag locality (and thus subspecies) identification (Ashley 2005; Douglas 2004, 2005; Hafner 2004; Oyler McCance 2004, 2005); (3) reliance upon a small portion of mtDNA (Ashley 2004, 2005; Baker and Larsen 2005; Crandall 2004, 2005; Douglas 2004, 2005; Hafner 2005; Maldonado 2005; Oyler-McCance 2004, 2005; Riddle 2004; Sites 2004; Waits 2004, 2005); (4) the small number of microsatellite DNA loci examined (Vignieri et al. 2006, p. 241); (5) 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; Hafner 2005; Oyler-McCance 2004, 2005; Vignieri et al. 2006, pp. 241-242; White 2004); (6) whether the authors used an appropriate outgroup (a closely related group that is used as a rooting point of a phylogenetic tree) (Douglas 2004); (7) the sampling regime and its impact on the analysis (Maldonado 2005; Oyler-McCance 2004); (8) failure to test all of the morphological characters examined by Krutzsch (1954) (Vignieri et al. 2006, p. 238); (9) 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); and (10) failure to consider the Preble's meadow jumping mouse's geographic isolation (Vignieri et al. 2006, pp. 237-238). 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 Preble's meadow jumping mouse 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 (U.S. Geological Survey 2005, pp. 1-4). The USGS study concluded that the Preble's meadow jumping mouse 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 publication 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 1
1/2
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 Preble's meadow jumping mouse 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 1
1/2
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 results indicated that the Preble's meadow jumping mouse did not share haplotypes with any neighboring subspecies (King et al. 2006b, p. 4341). Such haplotype sharing had led Ramey et al. to previously conclude that the Preble's meadow jumping mouse was not unique; specifically, Ramey et al. concluded that because all of the Preble's meadow jumping mouse haplotypes were found in
Z. h. campestris
, the Preble's meadow jumping mouse was a less genetically variable population of
Z. h. campestris

(Ramey et al. 2004a, pp. 1, 9; 2005, p. 335). Because of these conflicting results, King et al. (2006b, pp. 4355-4357) reexamined 15 specimens from the University of Kansas Museum collection relied upon by Ramey et al. in determining that neighboring subspecies shared haplotypes. Among the specimens reported to contain the Preble's meadow jumping mouse's haplotypes by Ramey et al. (2005, pp. 335-336), King et al. (2006b, p. 4357) found that the results could not be repeated. If these specimens were removed from the analysis, neither study would illustrate haplotype sharing between the Preble's meadow jumping mouse 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.

Overall, King et al. (2006b, p. 19) concluded that there was considerable genetic differentiation among all five subspecies and found no evidence to support the proposal to synonymize the Preble's meadow jumping mouse,
Z. h. campestris
, and
Z. h. intermedius
.

Prior to its release, King et al. (2006a) underwent an internal peer review per USGS policy (U.S. Geological Survey 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). Some of the most significant issues raised included the sampling regime and its impact on the analysis (Armstrong 2006; Ashley 2006; Crandall 2006a; Douglas 2006; Oyler-McCance 2006; Riddle 2006); and 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 (Service 2006, p. 14). Following an open and competitive bid process, we selected SEI as the contractor (Service 2006).

SEI assembled a panel of experts with the necessary scientific expertise in genetics and systematics (SEI 2006a, p. 7). The panelists reviewed, discussed, and evaluated all of the literature relevant to this issue, including published literature, unpublished reports, third-party critiques, 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 their 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:
Although Ramey et al. (2005) examined two of the seven morphological characters identified by Krutzsch (1954, pp. 452-453), the panel found that all seven of these characters should have been reexamined in order to support the proposed taxonomic revision. The panel also concluded that the type specimen (a single specimen designated as the type by the original author at the time of publication of the original description of a taxon) 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 Preble's meadow jumping mouse had been conducted to support the synonymy of the Preble's meadow jumping mouse 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 Preble's meadow jumping mouse 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. The panel concluded that there was no reliable evidence of any haplotype sharing (SEI 2006a, p. 42). The panel further determined that if these 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 this outgroup, unrooted analysis showed clearer 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. (2006) 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 Preble's meadow jumping mouse, 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 Preble's meadow jumping mouse (SEI 2006a, pp. 43).

The panel's overall conclusion was that the available data are broadly consistent with the current taxonomic status of the Preble's meadow jumping mouse 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 findings and conclusions

of the SEI report. No new data or analyses were presented in this statement, and the panel previously considered most of the 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. (in press), King et al. (in review), Crandall and Marshall (2006), Spencer (2006b), and Cronin (2007).

Taxonomic Conclusions

When listed in 1998, the Preble's meadow jumping mouse 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 Preble's meadow jumping mouse (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 Preble's based upon information which questioned the subspecies' taxonomic validity (70 FR 5404).

We now determine the best scientific and commercial data available support the conclusion that the Preble's meadow jumping mouse is a valid subspecies. Specifically, the Preble's meadow jumping mouse's geographic isolation from other subspecies of meadow jumping mice (Krutzsch 1954, pp. 452-453; Long 1965, pp. 664-665; 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 Preble's meadow jumping mouse 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 do not use 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). In Therefore, after a review of all available information, we have determined that the taxonomic revision for the Preble's meadow jumping mouse suggested in our proposed delisting rule (70 FR 5404, February 2, 2005) is no longer appropriate.

Historical Range and Recently Documented Distribution

Generally, the Preble's meadow jumping mouse 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 Preble's meadow jumping mouse. We cited a study by Compton and Hugie (1993, p. 6) suggesting the subspecies might be extirpated in Wyoming and comments by the Wyoming Game and Fish Commission that the Preble's meadow jumping mouse 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 ten counties (Adams, Arapahoe, Boulder, Denver, Douglas, El Paso, Elbert, Jefferson, Larimer, and Weld) and cited recent trapping efforts that documented the subspecies in seven of these ten counties (Boulder, Douglas, El Paso, Elbert, Jefferson, Larimer, and Weld).

Since we listed the Preble's meadow jumping mouse in 1998, 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 Preble's meadow jumping mouse or in adjacent drainages where habitat and elevation appeared suitable. Thus, the recent increase in sites of Preble's meadow jumping mouse 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 Preble's meadow jumping mouse.

In Wyoming, recent captures and confirmed identification have expanded our knowledge of the distribution of the Preble's meadow jumping mouse from the two sites documented at the time of listing to include over two dozen new plains, foothills, and montane sites east of the Laramie Mountains in the North Platte River basin, and presence in the Upper Laramie River drainage in Albany County (Taylor 1999; Service 2007). Post-listing activities have identified many additional sites occupied by the subspecies. These data also reveal that the Preble's meadow jumping mouse occurs in four of the five counties described as the likely historical range at the time of listing including Albany, Laramie, Platte, and Converse Counties.

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 the Preble's meadow jumping mouse were present. Additional trapping since listing has expanded the documented distribution of the Preble's meadow jumping mouse in Colorado to include: additional foothill and montane sites along the Front Range in Larimer, Boulder, Jefferson, and Douglas Counties; previously untrapped rural prairie and foothill streams in southern Douglas County and adjacent portions of Elbert County; and additional prairie and foothill streams in northwestern El Paso County. Although we have identified some additional sites occupied by the Preble's meadow jumping mouse, over 80 percent of such trapping efforts throughout Colorado have failed to capture Preble's meadow jumping mice (as illustrated in Figure 1 below) (Service 2007).

BILLING CODE 4310-55-P

EP07NO07.000

BILLING CODE 4310-55-C

These negative trap results suggest that the subspecies is rare or possibly extirpated from many portions of the subspecies' historical range in Colorado.

Areas where the subspecies is presumed extirpated is discussed in the Factor A discussion below.

The Preble's meadow jumping mouse 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 (Figure 1). The North Platte River at Douglas, Wyoming, marks the northernmost confirmed location for the Preble's meadow jumping mouse. Specimens from Colorado Springs, Colorado, mark the southernmost documented location of the Preble's meadow jumping mouse.

The Preble's meadow jumping mouse is generally found at elevations between 1,420 m (4,650 ft) and 2,300 m (7,600 ft), although elevations vary across the range of the subspecies. 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 Preble's meadow jumping mouse (Beauvais 2001, p. 3). The Preble's meadow jumping mouse is likely an Ice Age relic; once the glaciers receded from the Front Range of Colorado and the foothills of Wyoming and the climate became drier, the Preble's meadow jumping mouse 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 Preble's meadow jumping mouse has not been found east of Cheyenne, Laramie County (Beauvais 2001, p. 3). Habitat modeling and trapping suggest the subspecies may not occur in Wyoming's Goshen, Niobrara, and eastern Laramie Counties (Keinath 2001, p. 7). In Colorado, the Preble's meadow jumping mouse has not been found on the extreme eastern plains (Clippinger 2002, pp. 20-21).

At the higher elevations, discerning the status of the Preble's meadow jumping mouse is complicated by the overlap in the ranges of the Preble's meadow jumping mouse 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 Preble's meadow jumping mouse 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 Preble's meadow jumping mouse occurs lower, in the plains and foothills (Smith
et al.
2004, p. 10). Using this as a guide, many jumping mice were trapped and released without being conclusively identified as either a Preble's meadow jumping mouse or a western jumping mouse. Because western jumping mice have been verified at elevations well below the upper elevation limit of the Preble's meadow jumping mouse (Smith
et al.
2004, p. 11), this leads 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. 31-35; 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 drainage 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 (including the Preble's meadow jumping mouse) from western jumping mice (Krutzsch 1954, pp. 351-384; Klingenger 1963, p. 252; Riggs
et al.
1997, pp. 2-8; Conner and Shenk 2003a; Ramey
et al.
; King
et al.
). The following description of the Preble's meadow jumping mouse's current documented distribution and status is based primarily on individuals positively identified as Preble's meadow jumping mice, with emphasis on locations where individual mice have been identified by genetic analysis or discriminant function analysis (DFA) (analysis of cranial measurements and an anterior medial toothfold characteristic) (Conner and Shenk 2003a). Information regarding individual mice and capture locations can be found in Riggs
et al.
(1997, pp. 8-11, A2-A5), 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 Preble's meadow jumping mouse and the western jumping mouse occur. Overlap appears to occur in most of Wyoming's occupied drainages. In Colorado, with few exceptions, jumping mice below 2,050 m (6,700 ft) have been positively identified as Preble's meadow jumping mice. Above 2,050 m (6,700 ft) in Colorado, Preble's meadow jumping mice 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, as discussed in detail below, trapping data is one of several lines of evidence we use to estimate the actual current range of the subspecies. Records have been compiled by the Service (2007) in coordination with the Wyoming Natural Diversity Database, State of Wyoming, and CDOW. In addition, Figure 1 above illustrates all recent Preble's meadow jumping mouse specimens, historical (pre-1980) locations no longer believed to be occupied, and recent negative trapping efforts. Given wide areas of overlapping range in Wyoming, we require all Wyoming specimens to be confirmed as Preble's meadow jumping mice in order to be considered below. In Colorado, jumping mice are considered Preble's meadow jumping mice when identification is confirmed or if they occur in areas where western jumping mice are not known.

North Platte River Basin, Wyoming.
In the North Platte River basin, occurrence of the Preble's meadow jumping mouse 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 Preble's meadow jumping mouse range; however, trapping surveys have been quite limited and generally at high elevations. Although several jumping mice have been trapped in this drainage, these specimens have not been confirmed as Preble's meadow jumping mice.

In the Glendo Reservoir drainage, the Preble's meadow jumping mouse is known from several locations, including along the North Platte River at Douglas (King 2006b), Cottonwood Creek and its tributaries (Meaney 2003; King 2006a; King 2006b; King et al. 2006b), and the Horseshoe Creek area (Krutzsch 1954, p. 453). While the western jumping mouse has also been confirmed from the Glendo Reservoir drainage, the Preble's meadow jumping mouse appears more common.

In the Lower Laramie drainage, the Preble's meadow jumping mouse 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). Both Preble's meadow jumping mice and western jumping mice occur in the Sybille Creek, Friend Creek and the Friend Park areas (Conner and Shenk 2003b; King 2006a; King 2006b; King et al. 2006b). The Lower Laramie drainage appears to support coexisting Preble's meadow jumping mice and western jumping mice in multiple locations.

In the Horse Creek drainage, the Preble's meadow jumping mouse 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 Preble's meadow jumping mice and western jumping mice inhabit multiple sites on both creeks (Conner and Shenk 2003b; Meaney 2003; King 2006b; King et al. 2006b).

In the Upper Laramie drainage, the Preble's meadow jumping mouse 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 both Preble's meadow jumping mice and western jumping mice are present in this drainage. Based on positive identification of the Preble's meadow jumping mouse from the sites mentioned above, Smith et al. (2004, p. 12) suggested the range of the Preble's meadow jumping mouse may extend into the Upper Laramie River, Little Laramie River, Rock Creek, and possibly the Medicine Bow River.

South Platte River Basin, Wyoming.
Within the Wyoming portion of the South Platte River basin, trapping efforts have confirmed Preble's meadow jumping mouse occurrence, albeit possibly in low numbers, within two drainages in Laramie and Albany Counties.

In the Upper Lodgepole drainage, jumping mice have been found from several locations at and upstream of Highway 211. While at least one Preble's meadow jumping mouse has been confirmed (Riggs et al. 1997), most of the captured mice have been identified as western jumping mice (Meaney 2003; King 2006a). Therefore, while this drainage supports the Preble's meadow jumping mouse, its distribution may be limited.

Although historically reported from the Crow Creek drainage at Cheyenne, Preble's meadow jumping mouse occurrence in this drainage remains uncertain. Specimens from Warren Air Force Base were assumed to be Preble's meadow jumping mice based on the elevation of 1,900 m (6,150 ft), but subsequent analyses identified only western jumping mice (Riggs et al. 1997; Conner and Shenk 2003b; King 2006a). The only trapping evidence confirming Preble's meadow jumping mouse occurrence in this drainage comes from a specimen from the South Crow Creek Reservoir area originally identified as a western jumping mouse by the DMNS and then re-identified as a Preble's meadow jumping mouse based on a DFA analysis considering dental characteristics (Meaney 2003). Additional specimens have only verified western jumping mice from Middle Crow Creek, the South Fork of Middle Crow Creek, and South Crow Creek Reservoir (Meaney 2003; King 2006a). No jumping mice have been reported trapped downstream of Cheyenne.

The Lone Tree Creek drainage was previously assumed to be inhabited by the Preble's meadow jumping mouse based on the field identification of low elevation captures of jumping mice (1,900 m (6,200 ft)). However, DFA analysis of existing museum specimens (Conner and Shenk 2003b) and genetic analysis of specimens obtained from trapping efforts (Riggs et al. 1997; King 2006a), have only confirmed presence of western jumping mice in this drainage.

South Platte River Basin, Colorado.
Recent presence of the Preble's meadow jumping mouse in Colorado has been documented within the South Platte River basin in seven counties: Larimer, Weld, Boulder, Jefferson, Douglas, Elbert, and El Paso. From the Wyoming State line south through the Denver area, little recent documentation of the Preble's meadow jumping mouse exists from sites east of the foothills where most of the subspecies' historical recordings occurred. This area largely corresponds to the Front Range urban corridor, an area experiencing continued human population growth and development (Clippenger 2002, pp. 22-26; Colorado Demography Office 2007). At higher elevation plains and foothills sites south of the Denver area, the Preble's meadow jumping mouse has been documented at a number of locations where riparian habitats are still largely intact. With rare exception, all jumping mouse records verified below 2,050 m (6,700 ft) in the South Platte River drainage of Colorado have been Preble's meadow jumping mice.

In the Cache La Poudre River drainage, jumping mice have been documented on sites upstream of Fort Collins, Larimer County, at elevations consistent with known Preble's meadow jumping mouse distribution. These sites include the main stem Cache La Poudre River and its tributaries, including Young Gulch and Stove Prairie Creek, and the North Fork Cache La Poudre River and its tributaries, including Stonewall, Rabbit, and Lone Pine Creeks. Shenk and Eussen (1999, pp. 11-12) cautioned that both Preble's meadow jumping mice and western jumping mice were likely present in some of these areas. Subsequent genetic analysis confirmed both Preble's and the western jumping mouse in Cherokee Park at 2,260 m. (7,480 ft) (King 2005, 2006b), but only Preble's meadow jumping mice have been confirmed from lower elevations, including Rabbit and Lone Pine Creeks, the Livermore Mountain area, and the North Fork of the Cache La Poudre River (Riggs et al. 1997; King et al. 2006b). Despite a number of trapping efforts, no jumping mice have been recently documented within the Fort Collins, Larimer County, area or downstream on the Cache La Poudre River to its confluence with the South Platte River at Greeley, Weld County (Service 2007).

Within the Big Thompson drainage, the Preble's meadow jumping mouse has been documented in foothills sites along Buckhorn Creek and certain of its tributaries, and on Dry Creek, in Larimer County. Genetic analysis of mice from three tributaries of Buckhorn Creek up to 2,240 m (7,360 ft) support identifications as Preble's meadow jumping mice; however, both Preble's meadow jumping mice and western jumping mice were confirmed from the Lakey Canyon site at 2,170 m (7,120 ft) and a mouse from the North Fork of the Big Thompson River at 2,170 m (7,120 ft) was identified as a western jumping mouse (King 2006a). Despite a number of trapping efforts, the Preble's meadow jumping mouse has not been documented on the Big Thompson and Little Thompson Rivers through the Front Range urban corridor, but has been found on both rivers east of I-25, in Weld County.

In the Saint Vrain drainage, the Preble's meadow jumping mouse has been documented along the Saint Vrain River, its tributaries and water conveyance ditches upstream of the town of Hygiene, on two tributaries of Boulder Creek west of the City of Boulder, and along South Boulder Creek, all in Boulder County; and on upper reaches of Coal and Rock Creeks, Jefferson County. On Rocky Flats NWR, Jefferson County, the Preble's meadow jumping mouse has been documented on Rock Creek as well on nearby Walnut

and Woman Creeks (within the Middle South Platte-Cherry Creek drainage). Several of these locations include mice confirmed as Preble's meadow jumping mice by genetic analysis or DFA (Riggs et al. 1997; Conner and Shenk 2003b). The Preble's meadow jumping mouse occurrence has not been confirmed by trapping efforts along eastern parts of the drainage, the Saint Vrain River from Hygiene, Boulder County, downstream to its confluence with the South Platte River, along Boulder Creek from the City of Boulder east to its confluence with the Saint Vrain River, or downstream of Rocky Flats NWR on Walnut, Woman, or Dry Creeks.

In the Clear Creek drainage, the Preble's meadow jumping mouse has been verified in the foothills on Ralston Creek (Riggs et al. 1997), and unidentified jumping mice have been captured on two tributaries of Clear Creek at elevations of potential Preble's meadow jumping mouse occurrence (below 2,300 m (7,600 ft)). No jumping mice have been captured on either creek downstream through the urban corridor to the South Platte River.

In the Upper South Platte drainage, the Preble's meadow jumping mouse has been documented immediately upstream of Chatfield Reservoir on the South Platte River, and also well upstream on the South Platte River and its tributaries in Jefferson and Douglas Counties to near the Teller County-Douglas County line. The U.S. Forest Service provided a summary of Preble's meadow jumping mouse trapping efforts at 15 sites in the Upper South Platte drainage in the Pike National Forest. Based on examination of voucher specimens, Preble's meadow jumping mice were confirmed at six sites up to 2,300 m (7,600 ft) and western jumping mice were confirmed from six sites, the lowest of which, at 2,030 m (6,660 ft), was lower than five Preble's meadow jumping mouse sites (Bohon et al. 2005). Schorr et al. (2007) also summarized co-occurrence of Preble's and the western jumping mouse in the same area. Also in the Upper South Platte drainage, the Preble's meadow jumping mouse has been widely documented upstream of Chatfield Reservoir on Plum Creek, including occurrences on East Plum Creek, West Plum Creek, and various tributaries, all in Douglas County (Riggs et al. 1997; Conner and Shenk 2003b; King et al. 2006b). Western jumping mice have also been identified in this drainage at 1,800 m (5,900 ft) and 1,950 m (6,400 ft) (Conner and Shenk 2003b). Pague and Schuerman (1998, p. 5) assessed Preble's meadow jumping mouse habitat throughout the Plum Creek watershed, randomly trapped suitable habitat, and estimated 64 km (40 mi) of streams occupied by the Preble's meadow jumping mouse. On the downstream portion of this drainage, below Chatfield Reservoir, there is no recent documentation of Preble's meadow jumping mouse's presence on the South Platte River through Denver.

In the Middle South Platte, Cherry Creek drainage, Preble's meadow jumping mice have been found on Cherry Creek and its tributaries from approximately the Arapahoe County-Douglas County line, upstream to the headwaters of East and West Cherry Creeks near the Palmer Divide in El Paso County. Also within Middle South Platte-Cherry Creek drainage, limited trapping efforts have documented the Preble's meadow jumping mouse on Running Creek and a tributary, Hay Creek, in Elbert County. Based on limited genetic analysis and DFA, western jumping mice have not been confirmed from this drainage. The Preble's meadow jumping mouse occurrence has not been confirmed by trapping downstream along Cherry Creek through Arapahoe County and Denver to the South Platte River. Because of numerous negative trapping efforts and lack of contiguous suitable habitat, we no longer consider the greater Denver area (including most of Denver County and portions of Adams, Arapahoe, Boulder, Broomfield, Douglas, and Jefferson Counties) to be occupied. On the South Platte River downstream from the Denver area, a single Preble's meadow jumping mouse was recently captured from near the South Platte River in Milliken, Weld County, not far from the confluence of the Big Thompson River and South Platte River (Savage and Savage 2001).

Farther east, there are two records of a Preble's meadow jumping mice on Kiowa Creek, Elbert County. Additional trapping in Elbert County would be useful to document whether the Preble's meadow jumping mouse is present along significant reaches of the Middle South Platte-Cherry Creek and Kiowa Creek drainages, and on the Bijou Creek drainage, Elbert County, which has not been trapped.

Arkansas River Basin, Colorado.
In the Arkansas River basin, confirmed current occurrence of the Preble's meadow jumping mouse is limited largely to the Fountain Creek drainage and specifically to Monument Creek and its tributaries north of Colorado Springs. Genetic analysis and DFA have thus far confirmed no western jumping mice from within the Preble's meadow jumping mouse's range in this drainage (Conner and Shenk 2003b; King et al. 2006b). The Preble's meadow jumping mouse has been well studied at the U.S. Air Force Academy (Academy) on Monument Creek and its tributaries, and has been documented farther upstream on Monument Creek and on tributaries to the east and north toward the Palmer Divide. Numerous records of Preble's meadow jumping mouse captures on streams in northwestern El Paso County are the result of extensive trapping that has taken place in conjunction with proposed development projects. Downstream of the Academy, numerous trapping surveys indicate that the Preble's meadow jumping mouse has little likelihood of occurrence along Monument Creek through the downtown portions of Colorado Springs. Similarly, extensive trapping surveys suggest that the Preble's meadow jumping mouse may be extirpated from Cottonwood Creek and its tributaries.

In the Chico Creek drainage, jumping mice (assumed to be Preble's meadow jumping mice as explained above) have been documented on the upper reaches of Black Squirrel Creek and on a tributary, both in El Paso County. Limited trapping efforts in potential Preble's meadow jumping mouse habitat farther to the east in the Chico Creek drainage and in the Big Sandy Creek drainage have not confirmed Preble's meadow jumping mouse occurrence. Downstream, to the east and south, these drainages appear to have little habitat suitable for the Preble's meadow jumping mouse.

Within the Arkansas River basin south of the documented Preble's meadow jumping mouse locations, trapping efforts targeting the Preble's meadow jumping mouse conducted in southern El Paso County, Pueblo County, and Fremont County, including surveys funded and carried out by the Department of the Army at Fort Carson, have not resulted in capture of jumping mice (Bunn et al. 1995; Werner 2003).

In conclusion, the Preble's meadow jumping mouse appears to be widespread in the North Platte River basin were trapping efforts confirm the subspecies' distribution across at least four drainages. The Preble's meadow jumping mouse appears scarce within the Wyoming portion of the South Platte River basin, where trapping efforts to date provide few confirmed occurrences of the subspecies and suggest that the western jumping mouse is much more widespread. Trapping efforts within the Colorado portion of the South Platte River Basin indicate the Preble's meadow jumping mouse has little likelihood of occurrence in portions of some drainages that coincide with the

Front Range development corridor (areas around I-25 from Fort Collins south through the Denver metropolitan area), is more widespread in foothills and some montane areas within these same drainages, and generally present in rural portions of drainages south of Denver. In the Arkansas River basin in Colorado, Preble's meadow jumping mouse distribution appears very limited, with trapping efforts confirming occurrence largely in upper Monument Creek and some headwater tributaries.

Data limitations, such as limited trapping data, do not allow us to equate documented distribution with range. For example, the subspecies has been documented in several places along Hay Creek in Elbert County, and it is reasonably likely to occur further downstream in Arapahoe County, but no trapping has occurred to confirm or deny this assertion (See figure 1). Similarly, on Trout Creek a Preble's meadow jumping mouse was found in Douglas County near the Teller County line and it is reasonable to assume the subspecies may also occur in Teller County. Given the data limitations, “range” (relative to the March 14, 2007, Department of the Interior, Solicitor Memorandum opinion) is defined in the Conclusion of the 5-Factor Analysis section of this rule below.

Abundance

Intensive trapping studies designed to estimate populations of the Preble's meadow jumping mouse have occurred on only a few sites. Because not all appropriate habitat has been surveyed for Preble's meadow jumping mouse occurrence and because population estimates are available for only a few selected sites, no regional, Statewide, or rangewide population estimates for the Preble's meadow jumping mouse have been developed. Population density and trends are not well known in Wyoming (Wyoming Game and Fish Department 2005, p. 36). There are a few population estimates but little trend information for Preble's meadow jumping mouse populations in Colorado. In addition, because jumping mouse populations in a given area vary significantly from year to year (Quimby 1951, pp. 91-93; Whitaker 1972, p. 4), short-term studies may not accurately characterize abundance. In an ongoing trapping study, population highs of 24 Preble's meadow jumping mice per site were estimated for two control sites in 1998 and 1999; subsequent trapping in 2002, during regional drought conditions, estimated no Preble's meadow jumping mice present at either site (Bakeman 2006, p. 11). Meaney et al. (2003, p. 620) estimated Preble's meadow jumping mouse populations on study sites over 4 years, noted absence of the Preble's meadow jumping mouse at certain sites during some seasons, and suggested that 10 or more years of study might be necessary to assess the full extent of population variation.

White and Shenk (2000, p. 9) summarized abundance estimates from nine sites in Colorado for field work conducted during 1998 and 1999 (Meaney et al. 2000; Kaiser-Hill 2000; Ensight Technical Services 1999, 2000, 2001; Shenk and Sivert 1999b; Schorr 2001). Since Preble's meadow jumping mice are found in linear riparian communities, abundances were estimated in number of individuals per km (or mi) of stream corridor. Estimates of linear abundance ranged widely, from 4 to 67 mice/km (6 to 107 mice/mi) with a mean of 33 +/−5 mice/km (53 +/−8 mice/mi) (White and Shenk 2000, p. 9). The subsequent addition of new sites and 2 more years of data (2000-2001) provided a range of 2 to 67 mice/km (3 to 107 mice/mi) and a mean of 27 +/−4 mice/km (44 +/−6 mice/mi) (Shenk 2004).

The above estimates, coupled with sufficient knowledge of occupied stream miles, can provide a rough indicator of Preble's meadow jumping mouse numbers within a stream reach or drainage. For example, the Preble's meadow jumping mouse Recovery Team used the above estimate (Shenk 2004) to approximate stream miles required to support varying sized populations of the Preble's meadow jumping mouse (Service 2003b, p. 25). Hayward (2002) cautioned that reliance on an average number of mice per length of stream to predict population sizes would result in the overestimation of actual population size for about half of all sites. Of additional concern in any assessment of Preble's meadow jumping mouse population size is the potential for including western jumping mice in the estimate (Bohon et al. 2005; Schorr et al. 2007, p. 4). This is of particular importance in areas where both Preble's meadow jumping mice and western jumping mice are known to occur, including higher elevation Colorado sites and at most sites in Wyoming.

Another potential source of error is that the Preble's meadow jumping mouse population estimates above do not include estimates for riparian corridors along mountain streams or any sites in Wyoming. In Pike National Forest, Colorado, site inspection of many streams previously mapped as Preble's meadow jumping mouse habitat revealed poorly developed or intermittent riparian vegetation surrounded by sparse uplands dominated by pine forest (Bohon et al. 2005). Poor trapping success even in suitable habitat suggested low population densities in Pike National Forest compared to those at lower elevations (Bohon et al. 2005; Hansen 2006, p. 168). In studies targeting the Preble's meadow jumping mouse at 11 higher elevations (1,890 to 2,420 m (6,200 to 7,940 ft)) riparian sites in Douglas, Jefferson, and Teller Counties, Schorr et al. (2007, p. 4) reported a 0.6 percent capture rate of jumping mice over 19,500 trap nights. Since coexistence of both the Preble's meadow jumping mouse and the western jumping mouse was confirmed in these studies, the capture rate of the Preble's meadow jumping mouse was probably much lower. In comparable trapping effort in high quality habitat at lower elevations, Schorr (2001, p.18) reported a 3.5 percent capture rate of Preble's meadow jumping mice over 14,700 trap nights at the Academy, and Meaney et al. (2003, p. 616) reported a 3.4 percent capture rate of Preble's meadow jumping mice over 21,174 trap nights along South Boulder Creek, Boulder County. We believe that more research is needed before conclusions can be drawn regarding Preble's meadow jumping mouse abundance and security along montane streams and headwaters.

Trends

Without comprehensive population estimates for the subspecies, the only basis for trend assessment is presence or absence surveys in historical habitat (Smith et al. 2004, p. 29). This presence/absence information paints a very different picture for Wyoming compared to Colorado.

In Wyoming, we now have much more information regarding Preble's meadow jumping mouse distribution than we had at time of listing, when we described only two occupied sites. Much of what we noted in the listing to be historical range of the Preble's meadow jumping mouse in Wyoming has now been definitively found to support Preble's. But, while many jumping mice have been confirmed as Preble's meadow jumping mice in the North Platte River basin, the subspecies appears uncommon in the South Platte River basin, with only western jumping mice previously confirmed at several locations believed to be within Preble's meadow jumping mouse range.

In Colorado, historical trapping records establish that the Preble's meadow jumping mouse was present in a range that included major plains streams from the base of the Colorado Front Range east to at least Greeley, Weld County (Armstrong 1972, p. 249;

Fitzgerald et al. 1994, p. 293, Clippenger 2002, p. 18). Recent trapping efforts have documented that the Preble's meadow jumping mouse is rare or, perhaps, absent from these same areas today (Ryon 1996, p. 2; Clippinger 2002, p. 22; Service, 2007). This pattern is especially apparent along prairie riparian corridors directly or indirectly impacted by human development. This issue is discussed further in Factor A below.

Summary of Factors Affecting the Subspecies

Section 4 of the Act and its implementing regulations (50 CFR part 424) set forth the procedures for listing, reclassifying, or removing species from listed status. “Species” is defined by the Act as including any species or subspecies of fish or wildlife or plants, and any distinct vertebrate population segment of fish or wildlife that interbreeds when mature (16 U.S.C. 1532(16)). Once the “species” is determined we then evaluate whether that species may be endangered or threatened because of one or more of the five factors described in section 4(a)(1) of the Act. We must consider these same five factors in delisting determinations. Under 50 CFR 424.11(d), we may remove the protections of the Act if the best available scientific and commercial data substantiate 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; or (3) the original scientific data used at the time the species was classified were in error. Data error only applies when subsequent investigations show that the best scientific or commercial data available when the species was listed, or the interpretation of such data, were in error.

We may delist a species for any of the above reasons only if such data substantiate that the species is neither endangered nor threatened. Determining whether a species meets these definitions requires consideration of the same five categories of threats specified in section 4(a)(1) of the Act. For species that are already listed as endangered or threatened, this analysis of threats is an evaluation of both the threats currently facing the species and the threats that are reasonably likely to affect the species in the foreseeable future following the delisting or downlisting and the removal or reduction of the Act's protections.

Under section 3 of the Act, a species is “endangered” if it is in danger of extinction throughout all or a “significant portion of its range” and is “threatened” if it is likely to become endangered within the foreseeable future throughout all or a “significant portion of its range.” The word “range” in the phrase “significant portion of its range” refers to the range in which the species currently exists. Range is discussed further in the Conclusion of the 5-Factor Analysis section of this proposal below.

For the purposes of this analysis, we will evaluate whether the currently listed subspecies is threatened or endangered. This determination is a multiple-step analysis. If we determine that the subspecies is endangered throughout all of its range, we list it as endangered throughout its range and no further analysis is necessary. If not, we then evaluate if the subspecies meets the definition of threatened throughout all of its range. If the subspecies is threatened in all of its range, we list as threatened and consider if any significant portions of the range warrants consideration as endangered. If we determine that the subspecies is not threatened or endangered in all of its range, we consider whether any significant portions of the subspecies' range warrant consideration as threatened or endangered. We would then only list that significant portion of its range as threatened or endangered and not list the remaining portion of its range.

Foreseeable future is determined by the Service on a case-by-case basis, taking into account a variety of species-specific factors such as lifespan, genetics, breeding behavior, demography, threat-projection timeframes, and environmental variability. For the purposes of this proposal, we define 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. As described in more detail below, human-population-growth projections extend out to 2035 in Colorado and 2036 in Wyoming. Similarly, water requirements are estimated through 2030 in Colorado and 2035 in Wyoming. A Center for the West model predicting future land-use patterns projects development changes within the range of Preble's through 2040. Such projections frame our analysis as they help us understand what factors can reasonably be anticipated to meaningfully affect the subspecies' future conservation status. In our view, the foreseeable future for this subspecies, based on the currently available data, does not extend beyond 2040. While it is likely some of the above estimates could be extrapolated out into the more distant future, development projections beyond this point are of increasingly lower value as uncertainty escalates.

The following analysis examines all five factors currently affecting, or that are likely to affect, the Preble's meadow jumping mouse within the foreseeable future.

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

Introduction.
Decline in the extent and quality of Preble's meadow jumping mouse habitat has been considered the primary factor threatening the subspecies (Bakeman 1997, p. 78; Hafner et al. 1998, p. 122; Pague and Grunau 2000). In our 1998 final rule to list Preble's meadow jumping mouse as threatened (63 FR 26517, May 13, 1998), we stated that Colorado east of the Front Range and adjacent areas of southeastern Wyoming had changed, over time, from predominantly prairie habitat intermixed with perennial and intermittent streams and associated riparian habitats to an agricultural and increasingly urban setting.

In our listing decision, we stated that Preble's meadow jumping mouse populations had experienced a decline and faced continued threats linked to widespread loss and fragmentation of the subspecies' required riparian habitat from human land uses including: urban, suburban, and recreational development; highway and bridge construction; water development; instream changes associated with increased runoff and flood control efforts; aggregate (sand and gravel) mining; and overgrazing (63 FR 26517, May 13, 1998). These human land-use activities affect the Preble's meadow jumping mouse by directly destroying its protective cover, nests, food resources, and hibernation sites; disrupting behavior; or acting as a barrier to movement. We noted that such impacts reduced, altered, fragmented, and isolated habitat to the point where Preble's meadow jumping mouse populations may no longer persist. We also noted that patterns of capture suggested that Preble's meadow jumping mouse populations fluctuate greatly over time at occupied sites, raising questions regarding security of the many currently documented populations which are isolated and affected by human development.

Historical records in Colorado (pre-1980) illustrate areas of Preble's meadow jumping mouse occupancy along the Front Range within both foothill and prairie riparian corridors

(Armstrong 1972, p. 249; Fitzgerald et al. 1994, p. 293). Between 1980 and 2005, the human population of Colorado counties within the Preble's meadow jumping mouse range increased by nearly 60 percent, from 1.7 million to 2.7 million (Colorado Demography Office, 2007). As explained further below, the apparent absence of the Preble's meadow jumping mouse in areas of substantial development, where trapping had previously confirmed subspecies presence, supports the conclusion that human land uses adversely affect Preble's meadow jumping mouse populations.

Ryon (1996) evaluated the condition of eight historical Preble's meadow jumping mouse capture sites in six Colorado counties based on vegetation structure, dominant plant species, and trapping results. Ryon reported no Preble's meadow jumping mouse captures at any of the seven sites trapped (one site no longer contained suitable habitat) (1996, p. 25). In addition, he reported that the historical sites contained fewer native species in plant communities and were lacking the multi-strata vegetation structure he observed at sites where trapping had recently confirmed Preble's meadow jumping mouse presence (Ryon 1996, p. 30). Investigations into land-use changes at the historical sites suggested that most had been directly altered in terms of habitat or had been influenced by habitat fragmentation (Ryon, 1996, p. 30). Clippinger (2002, pp. 14-29) mapped and compared past (through 1972) and current (post-1972) distribution records of the Preble's meadow jumping mouse in central Colorado and southeastern Wyoming based on museum specimens, published accounts, and unpublished reports. Clippinger reported that his distribution maps illustrated a loss of Preble's populations in expanding urban and suburban areas, especially around Cheyenne, Denver, and Colorado Springs, and in general along the eastern extent of historical range (Clippinger 2002, p. 22). Note that Clippinger's reference to historical range is based on the few existing records (through 1972) documenting Preble's meadow jumping mouse occurrence. These records are focused around what is now the I-25 urban corridor and based upon our current knowledge of the subspecies do not truly represent the extent of the range of the subspecies. The apparent loss of historically occupied sites (those sites where the subspecies was documented to occur prior to 1980) also provides some insight into this relationship. Based on Service records, consisting of intensive trapping efforts and assessments of habitat quality, only 1 of 17 of these documented historical sites of Preble's meadow jumping mouse occurrence in Colorado (Bear Creek, Boulder County) is thought to currently support the Preble's meadow jumping mouse.

Recent trapping records maintained by the Service indicate that Preble's meadow jumping mouse populations have little likelihood of occurrence along large portions of major river and stream reaches within the subspecies' historical described range in Colorado including:

• The Cache La Poudre River within Fort Collins and downstream to its confluence with the South Platte River at Greeley, 60 km (37 mi);

• The Big Thompson River and Little Thompson River through the Front Range urban corridor, approximately 50 km (32 mi);

• The Saint Vrain River from Hygiene to its confluence with the South Platte River, 35 km (22 mi);

• Boulder Creek from Boulder east to its confluence with the Saint Vrain River, approximately 35 km (22 mi);

• Walnut, Woman, and Dry Creeks downstream from Rocky Flats National Wildlife Refuge (NWR) to the confluence of Dry Creek and beyond to the South Platte River, 40 km (25 mi);

• Ralston Creek and Clear Creek through the urban corridor to the South Platte River, approximately 40 km (25 mi);

• The South Platte River downstream of Chatfield Reservoir through Denver to Brighton, 60 km (38 mi);

• The South Platte River downstream from Brighton to Greeley, approximately 55 km (34 mi) (one recent Preble's capture);

• Cherry Creek from the Arapahoe County-Douglas County line downstream through Denver to the South Platte River, 30 km (19 mi);

• Monument Creek downstream from its confluence with Cottonwood Creek through Colorado Springs, approximately 15 km (9 mi).

In total, Preble's meadow jumping mouse populations appear to have little likelihood of occurrence along 420 km (260 mi) in and downstream of areas with concentrated human development. However, despite apparent local extirpations, many of these streams continue to support Preble's meadow jumping mouse populations in their upstream reaches or tributaries.

Historical losses relative to ongoing threats are relevant in predicting whether the subspecies is likely to become endangered in all or a significant portion of its current range within the foreseeable future. It appears unlikely that the Preble's meadow jumping mouse can be returned to the historical localities within the Front Range urban corridor; however, we find that the subspecies' apparent local extirpation from areas of human development provides useful perspective about the potential impacts of future development within the remaining range of the Preble's meadow jumping mouse. If the protections of the Act are removed, we expect these threat factors, discussed in more detail below, would continue to affect the subspecies in large portions of its current range into the foreseeable future.

For the purposes of this revised proposed rule, we reviewed and considered the best available information regarding threats within the range of the Preble's meadow jumping mouse, including Ryon (1996), Shenk (1998), Bakeman (1997), Pague and Granau (2000), Clippinger (2002), and Service (2003b). We summarize these accounts below.

Following listing, The Nature Conservancy, under a contract with the Colorado Division of Natural Resources, formed a Preble's Meadow Jumping Mouse Science Team (Pague 1998). With guidance from the Science Team and following numerous meetings with scientists and stakeholders, Pague and Grunau (2000) developed a conservation planning handbook that addressed each of seven Colorado counties containing Preble's meadow jumping mouse populations. The document provided “issues and stresses” for all presumed threat factors operating in known or suspected Preble's meadow jumping mouse habitat, and assigned a qualitative risk assessment level to each of the identified issues. The work of Pague and Granau (2000) continues to provide important, science-based insight into threats to, and potential conservation strategies for, the Preble's meadow jumping mouse in Colorado on a county-by-county basis. Habitat-related “issues” identified as high or very high priority in one or more counties included habitat conversion through housing, commercial, and industrial construction; travel corridor (i.e., roadway) construction; travel corridor maintenance; fragmentation of habitat and corridors; hydrological flow impairment; habitat conversion to a reservoir; bank stabilization; high impact livestock management; rock and sand extraction; invasive weeds; and catastrophic fire (Pague and Granau 2000, pp. 1-15, 2-12, 3-13, 4-14, 5-14, 6-15, 7-14). Pague (2007) provided observations updating the 2000 report. No comparable document exists for the

four Wyoming counties where the subspecies occurs.

Colorado's Comprehensive Wildlife Conservation Strategy lists the meadow jumping mouse (including both the Preble's meadow jumping mouse and
Zapus hudsonius luteus
which occurs in extreme south-central Colorado) as a “Species of Greatest Conservation Need,” citing threats to habitat and range including habitat conversion (due to housing, urban, and exurban development) and habitat degradation (due to altered native vegetation and altered hydrological regime) (CDOW 2006, p. 102).

The Wyoming Comprehensive Wildlife Plan (WCWP) also lists meadow jumping mouse (including both the Preble's meadow jumping mouse and
Zapus hudsonius campestris
which occurs in northeastern Wyoming) as a “Species of Greatest Conservation Need.” This plan identifies ecoregions in the State and provides a summary of “mean habitat quality” scores for each ecological system (or habitat) within the ecoregion (WGFD 2005, pp. 19-25). Within the three Wyoming ecoregions that include Preble's meadow jumping mouse range (Central Shortgrass Prairie, Northern Great Plains Steppe, and Southern Rocky Mountains), the two ecological systems most likely to support the Preble's meadow jumping mouse (Rocky Mountain Lower Montane Foothill Riparian and Shrubland, Western Great Plains Riparian/Western Great Plains Floodplain) ranked in the lowest 20 percent in mean habitat quality relative to the State's other ecosystems (WGFD 2005, pp. 19-25). Among threats to habitat in these ecoregions are invasive plants, residential development radiating from the Cheyenne area, and recreation in the Southern Rocky Mountain region (WGFD 2005, pp. 53, 55, 56).

The direct impacts of development on the Preble's meadow jumping mouse and its habitat have likely slowed since our 1998 listing because of protection afforded to the Preble's meadow jumping mouse and its critical habitat rangewide under the Act. One indication of continuing impacts to the Preble's meadow jumping mouse and its habitat is the number of formal consultations performed to date under section 7 of the Act and the number of section 10 permits issued to date in conjunction with approved Habitat Conservation Plans (HCPs). Section 7 of the Act requires Federal agencies to consult with the Service to ensure that their actions do not jeopardize the continued existence of the subspecies or cause destruction or an adverse modification of critical habitat. Thus far, the section 7 process has been successful in avoiding adverse effects, from Federal actions, that would be likely to jeopardize the continued existence of the species or result in the destruction or adverse modification of critical habitat.

Section 10(a)(1)(B) of the Act authorizes the Service to issue permits for non-Federal actions that result in the incidental taking of listed wildlife. Incidental take permit applications must be supported by an HCP that identifies conservation measures that the permittee agrees to implement for the species to avoid, minimize, and mitigate the impacts of the requested incidental take.

As of August 2007, we have conducted 124 formal section 7 consultations (109 in Colorado, 15 in Wyoming) and issued 19 HCP related incidental take permits (all in Colorado) for projects affecting the Preble's meadow jumping mouse. We have authorized take for actions that did not result in jeopardy but nevertheless resulted in permanent impacts to over 320 hectares (ha) (800 acres (ac)) of Preble's meadow jumping mouse habitat, and temporary impacts to more than twice that amount of land. These projects have incorporated conservation measures or mitigation to avoid or minimize adverse impacts to the Preble's meadow jumping mouse.

However, even with the protections afforded to the species under section 7, habitat overall has continued to decline in quality and quantity, especially in Colorado. In the absence of listing, projects in Preble's meadow jumping mouse habitat would otherwise go forward with little Federal oversight. Other Federal, as well as State and local regulatory mechanisms, that may provide protection for the Preble's meadow jumping mouse and its habitat are evaluated under Factor D below.

Residential and Commercial Development.
Clippinger (2002) assessed the impacts of residential development on the Preble's meadow jumping mouse. He analyzed Colorado land-cover data compared to positive and negative trapping results for the Preble's meadow jumping mouse in a geographic information system analysis and concluded that the likelihood of successful trapping of Preble's meadow jumping mice was reduced by either low-or high-density residential developments when the developments were within 210 m (690 ft) of the trapping sites (Clippinger 2002, pp. iv, 94). Clippinger (2002, p. iv) noted that the Preble's meadow jumping mouse can be a useful indicator of environmental integrity in riparian areas and associated upland areas in the Colorado Piedmont. These data demonstrate that nearby development increases the risk of extirpation of Preble's meadow jumping mice from occupied sites.

Theobold et al. (1997) emphasized both housing density and spatial patterns in evaluating effects of residential development on wildlife habitat. They concluded that while clustered development can decrease habitat disturbance (Theobold et al. 1997, p. 34), much of the Rocky Mountain West is experiencing what has been termed “rural sprawl” where rural areas are growing at a faster rate than urban areas (Theobold et al. 2001, p. 4). In Colorado, residential demand and State law encourage developers to design subdivisions with lots of at least 14 ha (35 ac) each with one house, to avoid detailed county subdivision regulations (Riebsame et al., p. 420). The Larimer County Master Plan (Larimer County Planning Division 1997) cites a trend toward residential properties with relatively large lots, which leads to scattered development and more agricultural land taken out of production. Where public and private lands are intermingled, private land ownership typically follows valley bottoms (Theobald et al. 2001, p. 5), thus rural development is likely to disproportionately affect valley-bottom riparian areas (Riebsame et al., p. 402), the favored habitat of the Preble's meadow jumping mouse. Beyond direct impact to habitat, when ranches are subdivided, subsequent residential construction and associated disturbance can result in the disruption of wildlife movement along stream corridors (Riebsame et al., p. 402). Rural development disproportionately occurs around edges of undisturbed public lands and affects the conservation value of the undisturbed public lands (Hansen et al. 2005, p. 1900).

Human development often causes subtle effects on riparian habitat as well. Indirect effects of human settlement have resulted in declines in native trees and shrubs, greater canopy closure, and a more open understory with reduced ground cover within riparian habitat (Miller et al. 2003, p. 1055). An open understory does not favor the Preble's meadow jumping mouse, which prefers dense ground cover of grasses and shrubs and is less likely to use open areas where predation risks are assumed to be higher (Trainor et al. 2007, pp. 472-476; Clippinger 2002, pp. 69, 72).

Fragmentation is another indirect impact of development in proximity to Preble's meadow jumping mouse

habitat. The Preble's meadow jumping mouse is closely associated with narrow riparian systems that represent a small percentage of the landscape within the subspecies' range. Fragmentation of these linear habitats limits the extent and size of Preble's meadow jumping mouse populations. As populations become fragmented and isolated, it becomes more difficult for them to persist (Caughley and Gunn 1996, pp. 165-189). Major risks associated with small populations include—demographic stochasticity (an increased risk of decline in small populations due to variability in population growth rates arising from random differences among individuals in survival and reproduction within a season); environmental stochasticity (an increased risk of decline in small populations due to variation in birth and death rates from one season to the next in response to weather, disease, competition, predation, or other factors external to the population); and loss of genetic variation (a reduction in the amount of diversity retained within populations and an increased chance that deleterious recessive alleles may be expressed; the loss of diversity can limit a population's ability to respond adaptively to future environmental changes) (Caughley and Gunn 1996, pp. 165-189). These issues are discussed in greater detail in Factor E below. The Recovery Team determined that small, fragmented units of habitat will not be as successful in supporting the Preble's meadow jumping mouse in the long term as larger areas of habitat (Service 2003b, p. 21). On a landscape scale, maintenance of dispersal corridors linking patches of Preble's meadow jumping mouse habitat may be critical to the subspecies' conservation (Shenk 1998, p. 21).

One indicator of the level of development pressure since listing is the number of development-related section 7 consultations and HCPs completed by the Service. Of the 109 formal consultations and 19 HCPs completed in Colorado, 17 section 7 consultations and 10 HCPs were specifically for residential and commercial developments with direct adverse effects to the Preble's meadow jumping mouse or its habitat. Approved projects allowed for adverse impacts (permanent or temporary) in excess of 180 ha (450 ac) of Preble's habitat. While conservation measures or mitigation in various forms have been incorporated into all permitted projects, implementation of these habitat restoration and enhancement measures has been limited by factors such as droughts or floods. Recent development pressure has been most concentrated south of Denver, Colorado, in Douglas and El Paso Counties; eight section 7 consultations and three HCPs have occurred in the Middle South Platte-Cherry Creek drainage, all south of Denver, and six section 7 consultations and four HCPs have occurred in the Fountain Creek drainage. We have also worked with other Federal agencies and a substantial number of landowners and developers to avoid adverse impacts to Preble's meadow jumping mouse habitat, thus avoiding formal consultation. Additional planned residential and commercial development projects that would adversely affect Preble's meadow jumping mouse habitat in Colorado are continually being reviewed by the Service. Since listing, protections afforded under the Act have slowed, but not eliminated, the loss of Preble's meadow jumping mouse habitat due to residential and commercial development in Colorado. We believe that in the absence of the protections under the Act, Preble's meadow jumping mouse habitat in Colorado and the populations it supports would be lost at a greatly increased rate.

Continued rapid development is expected along Colorado's Front Range as the human population continues to grow. The State of Colorado expects the population of counties supporting the Preble's meadow jumping mouse to increase by an additional 1.5 million people by 2035, including: 99,000 in Boulder County; 272,000 in Douglas County; 42,000 in Elbert County; 369,000 in El Paso County; 143,000 in Jefferson County; 201,000 in Larimer County; and 323,000 in Weld County (Colorado Demography Office 2007). These expected increases support Pague and Grunau's (2000) conclusion that habitat conversion is a very high priority issue to the Preble's meadow jumping mouse in Larimer, Weld, and El Paso Counties, and a high priority issue for the remaining counties supporting the Preble's meadow jumping mouse in Colorado.

In contrast to the situation in Colorado, no formal section 7 consultations or HCPs have been sought for residential or commercial development in Wyoming. This reduced level of consultations reflects the general lack of development pressure within Preble's meadow jumping mouse habitat. This lack of development pressure is predicted to continue into the foreseeable future as described below.

Wyoming estimates that the population of the counties supporting the Preble's meadow jumping mouse will increase by about 11,000 people from 2005 to 2020, including: an increase of 800 in Albany County; an increase of 1,500 in Converse County; an increase of 9,100 in Laramie County; and a decrease of 400 in Platte County (Wyoming Department of Administration and Information 2007). Commercially available estimates suggest counties supporting the Preble's meadow jumping mouse will increase by about 18,400 people from 2006 through 2036, including: a decline of 3,700 in Albany County; an increase of 3,500 in Converse County; an increase of 18,300 in Laramie County; and an increase of 300 in Platte County (Economy.com 2007 as provided by Lui 2007).

While population growth rates provide valuable insight into development pressures, they may not provide a complete picture. For example, human population increases in Cheyenne, Fort Collins, Greeley, Longmont, the immediate Denver metropolitan area, and much of Colorado Springs are likely to have little direct impact on the Preble's meadow jumping mouse because the subspecies appears to have little likelihood of occurrence within and downstream from these cities. Conversely, substantial human population increases in the Laramie Foothills of Larimer County, Colorado, or southern portions of Douglas County, Colorado, are likely to have a high impact to the Preble's meadow jumping mouse. In Wyoming, given the small projected increases in the human population, we expect rural development will continue to have only small, localized impacts.

Modeling exercises can also provide some insights into future land-use development patterns. While these models have weaknesses, such as an inability to accurately predict economic upturns or downturns, uncertainty regarding investments in infrastructure that might drive development (such as roads, airports, or water projects), and an inability to predict open-space acquisitions, we nevertheless believe such models are useful in adding to our understanding of likely patterns. For example in 2005, Center for the West produced a series of maps predicting growth through 2040 for the west including the Colorado Front Range and Wyoming (Travis et al. 2005, pp. 2-7). The projections for the Colorado Front Range (available at:
http://www.centerwest.org/futures/frtrng/2040.html
) illustrate significant increases in urban/suburban, low-density suburban, and exurban land uses across virtually all private lands

within the Colorado portion of the Preble's meadow jumping mouse range. Only small isolated patches of Preble's meadow jumping mouse habitat in public ownership, including headwater areas in Federal ownership, would avoid the direct impacts of residential and associated commercial development. Although similar maps for Wyoming are less refined (available at:
http://www.centerwest.org/futures/west/2040.html
), they suggest only limited increases in development, primarily around Cheyenne.

Based upon known impacts to the Preble's meadow jumping mouse associated with development and best available projections for future development (as described above and in Factor D below), we conclude that residential and commercial development constitutes a substantial threat to the Preble's meadow jumping mouse in Colorado, now and into the foreseeable future. In Wyoming, residential and commercial development is likely to be limited with only small, localized impacts to the Preble's meadow jumping mouse expected. While some development is projected in the vicinity of Cheyenne, trapping efforts to date have not confirmed presence of Preble's meadow jumping mice in this area.

Transportation, Recreation, and Other Rights of Way Through Habitat.
At the time of listing, the Service concluded that roads, trails, or other linear development through the Preble's meadow jumping mouse's riparian habitat could act as partial or complete barriers to dispersal (63 FR 26517, May 13, 1998). These forms of development have continued to affect and fragment Preble's meadow jumping mouse habitat. Since listing, the Service has conducted 38 formal consultations under section 7 of the Act for road or bridge projects (32 in Colorado and 6 in Wyoming) resulting in permitted impacts to approximately 50 ha (125 ac) of Preble's meadow jumping mouse habitat. In addition, a formal 2005 programmatic section 7 consultation with the Federal Highway Administration for the Wyoming Statewide Transportation Improvement Program could result in 19 future highway projects with impacts to 42 ha (104 ac) of Preble's meadow jumping mouse habitat (Service 2005). Under the Douglas County (Colorado) Regional HCP for the Preble's meadow jumping mouse, completed in May 2006, 67 approved road and bridge construction projects by Douglas County, and the cities of Parker and Castle Rock, may affect up to 122 ha (302 ac) of Preble's meadow jumping mouse habitat over a 10-year period (Service 2006).

One of the largest road projects is a proposed improvement to I-25 in El Paso County, Colorado. The proposed construction would affect 10 of the 11 to 14 eastern tributaries of Monument Creek thought to support Preble's (Bakeman and Meaney 2001, p. 21). Impacts to Preble's would include habitat fragmentation and modification, change in population size, and behavioral impacts (Bakeman and Meaney 2001, pp. 18-20). While measures to avoid, minimize, and mitigate impacts were identified, the project would have significant cumulative effects on Preble's meadow jumping mice in the Monument Creek drainage, especially east of I-25 (Bakeman and Meaney 2001, pp. i, ii, 22-27).

With an increased human population, a high level of road construction and maintenance projects will occur; in the absence of the Act's protective measures, impacts to Preble's and its habitat would likely be substantial. While the Act rarely stops such projects, it does promote measures to avoid, minimize, or compensate for impacts and helps control the level of negative impacts to the Preble's meadow jumping mouse and its habitat. Pague and Grunau (2000) considered “travel corridor construction” to be a high priority issue to Preble's meadow jumping mouse populations in Weld, Douglas, Elbert, and El Paso Counties in Colorado.

Human-caused impacts associated with recreation include backcountry roads, trails, and campgrounds, which are often located along streams and near water (Wyoming Game and Fish Department 2005, p. 56). Recreational trail systems are frequently located within riparian corridors (Meaney et al. 2002, p. 116). The development of trail systems can affect the Preble's meadow jumping mouse by modifying its habitat, nesting sites, and food resources in both riparian and upland areas. Use of these trails by humans or pets can alter wildlife activity and feeding patterns (Theobold et al. 1997, p. 26). Meaney et al. (2002, pp. 131-132) suggest fewer Preble's meadow jumping mice were found on sites with trails than on sites without trails. While temporal and spatial variation in Preble's meadow jumping mouse numbers resulted in low precision of population estimates and weak statistical support for a negative trail effect, the authors considered the magnitude of the potential effect sufficient to encourage careful management and additional research (Meaney et al. 2002, pp. 115, 131-132). Since the listing of the Preble's meadow jumping mouse in 1998, a dozen recreational trail projects with proposed impacts to Preble's meadow jumping mouse habitat in Larimer, Boulder, Douglas, and El Paso Counties, Colorado, have been addressed through section 7 consultations or HCPs. An additional 24 trail projects have been permitted under the Douglas County Regional HCP. As human populations continue to increase (as discussed above), we anticipate increased demand for recreational development in public open space and on conservation properties. Without protections afforded by the Act, Preble's meadow jumping mouse populations on properties free from residential and commercial development threats will still be subject to widespread threats from future recreational development and increased human use.

Many utility lines (sewer, water, gas, communication, and electric lines, and municipal water ditches) cross Preble's meadow jumping mouse habitat. Current and future utility rights-of-way through these habitats will cause habitat destruction and fragmentation from periodic maintenance and new construction. Since the listing of the Preble's meadow jumping mouse, 18 utilities projects adversely affecting the Preble's meadow jumping mouse and its habitat have been evaluated through section 7 consultations (3 in Wyoming, 15 in Colorado). In addition, an approved HCP with Denver Water permits impacts to 34 ha (84 ac) of Preble's meadow jumping mouse habitat at multiple sites in Colorado. While often more costly than trenching, avoidance measures such as directional drilling under riparian crossings can reduce or avoid impacts to the Preble's meadow jumping mouse. If the Preble's meadow jumping mouse were to be delisted, we do not anticipate that project operators would voluntarily directionally drill to avoid Preble's meadow jumping mouse habitat.

Overall, we believe threats related to transportation, recreation, and other rights of way through habitat are directly related to human population pressures. Thus, we expect these issues will have substantial impacts to Preble's meadow jumping mouse populations in Colorado, but only minimal impacts to Preble's meadow jumping mouse populations in Wyoming.

Hydrologic Changes.
Establishment and maintenance of riparian plant communities are dependent on the interactions between surface-water dynamics, groundwater, and river-channel processes (Gregory et al. 1991, pp. 542-545). Changes in hydrology can

alter the channel structure, riparian vegetation, and valley-floor landforms (Gregory et al. 1991, pp. 541-542; Busch and Scott 1995, p. 287). Thus, changes in the timing and abundance of water can be detrimental to the persistence of the Preble's meadow jumping mouse in these riparian habitats due to resultant changes in vegetation (Bakeman 1997, p. 79). Changes in hydrology may occur in many ways, but two of the more prevalent are the excessively high and excessively low runoff cycles in watersheds with increased areas of paved or hardened surfaces, and disruption of natural flow regimes downstream of dams, diversions, and alluvial wells (Booth and Jackson 1997, pp. 3-5; Katz et al. 2005, pp. 1019-1020).

Urbanization can dramatically increase frequency and magnitude of flooding while decreasing base flows (the portion of stream flow that is not surface runoff and results from seepage of water from the ground into a channel slowly over time; base flow is the primary source of running water in a stream during dry weather) (Booth and Jackson 1997; pp. 8-10; National Research Council 2002, pp. 182-186). Infiltration of precipitation is greatly reduced by increases in impervious surfaces. The magnitude of peak flows increases in urban areas as water runs off as direct overland flow. Increased peak flows can exceed the capacity of natural channels to transport flows, trigger increased erosion, and degrade habitat (Booth and Jackson 1997, pp. 3-5). Changes in hydrology associated with urbanization can result in channel downcutting, lowering of the water table in the riparian zone, and creation of a “hydrologic drought,” which in turn alters vegetation, soil, and microbial processes (Groffman et al. 2003, p. 317). Meanwhile, reduced infiltration results in reduced groundwater recharge, reduced groundwater contributions to stream flow, and, ultimately, reduced base flows during dry seasons (National Research Council 2002, p. 182; Groffman et al. 2003, p. 317). Established methods of mitigating downstream impacts of urban development, such as detention basins, have only limited effectiveness; downstream impacts are probably inevitable without limiting the extent of watershed development (Booth and Jackson 1997, p. 17).

In response to altered hydrology, stormwater-management, flood-control, and erosion-control efforts occur along many streams within the former and current range of the Preble's meadow jumping mouse. The methods used include channelization; construction of detention basins, outfall structures, drop structures, riprap banks, impervious cement channels; and other structural stabilization. Structural stabilization methods designed to manage runoff and control erosion can increase the rate of stream flow, shorten

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A07-5486. Public record. Not legal advice.