Endangered and Threatened Wildlife and Plants; Endangered Status for Gunnison Sage-Grouse

Federal RegisterJan 11, 2013

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R6-ES-2012-0108; 4500030113]

RIN 1018-AZ20

Endangered and Threatened Wildlife and Plants; Endangered Status for Gunnison Sage-Grouse

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service, propose to list the Gunnison sage-grouse

(Centrocercus minimus)

as endangered under the Endangered Species Act of 1973, as amended (Act). The effect of this regulation would be to add the Gunnison sage-grouse to the Lists of Endangered and Threatened Wildlife under the Act.

DATES:

We will accept comments received or postmarked on or before March 12, 2013. Comments submitted electronically using the Federal eRulemaking Portal (see

ADDRESSES

section, below) must be received by 11:59 p.m. Eastern Time on the closing date. We must receive requests for public hearings, in writing, at the address shown in the

FOR FURTHER INFORMATION CONTACT

section by February 25, 2013.

ADDRESSES:

You may submit comments by one of the following methods:

(1)

Electronically:

Go to the Federal eRulemaking Portal:

http://www.regulations.gov.

In the Keyword box, enter Docket No. FWS-R6-ES-2012-0108, which is the docket number for this rulemaking. Then, in the Search panel on the left side of the screen, under the Document Type heading, check on the Proposed Rules link to locate this document. You may submit a comment by clicking on “Comment Now!”

(2)

By hard copy:

Submit by U.S. mail or hand-delivery to: Public Comments Processing, Attn: FWS-R6-ES-2012-0108; Division of Policy and Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, MS 2042-PDM; Arlington, VA 22203.

We request that you send comments only by the methods described above. We will post all comments on

http://www.regulations.gov.

This generally means that we will post any personal information you provide us (see the Information Requested section below for more information).

FOR FURTHER INFORMATION CONTACT:

Patty Gelatt, Western Colorado Supervisor, U.S. Fish and Wildlife Service, Western Colorado Field Office, 764 Horizon Drive, Building B, Grand Junction, CO 81506-3946; telephone 970-243-2778; facsimile 970-245-6933. If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule.

Under the Act, if a species is determined to be an endangered or threatened species throughout all or a significant portion of its range, we are required to promptly publish a proposal in the

Federal Register

and make a determination on our proposal within one year. Listing a species as an endangered or threatened species can only be completed by issuing a rule. In this case, we are required by a judicially approved settlement agreement to make a final determination on this proposal regarding the Gunnison sage-grouse by no later than September 30, 2013.

This rule proposes the listing of the Gunnison sage-grouse as endangered.

• We are proposing to list the Gunnison sage-grouse as endangered under the Endangered Species Act.

The basis for our action.

Under the Act, we can determine that a species is an endangered or threatened species based on one or more any of five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence.

Based on the best available scientific and commercial data, we have determined that the principal threat to Gunnison sage-grouse is habitat loss, degradation, and fragmentation due to residential, exurban, and commercial development and associated infrastructure such as roads and power lines. The human population is increasing throughout much of the range of Gunnison sage-grouse, and data indicate this trend will continue. With this growth, we expect an increase in human development, further contributing to loss and fragmentation of Gunnison sage-grouse habitats. Other threats to the species include improper grazing management; predation (often facilitated by human development or disturbance); genetic risks in the declining, smaller populations; and inadequate local, State, and Federal regulatory mechanisms (e.g., laws, regulations, zoning) to conserve the species. Other factors that may not individually threaten the continued existence of Gunnison sage-grouse but, collectively, have the potential to threaten the species, include invasive plants, fire, and climate change, and the interaction of these three factors; fences; renewable and non-renewable energy development; piñon-juniper encroachment; water development; disease;, drought; and recreation.

We will seek peer review.

We are seeking comments from knowledgeable individuals with scientific expertise to review our analysis of the best available science and application of that science and to provide any additional scientific information to improve this proposed rule. Because we will consider all comments and information received during the comment period, our final determination may differ from this proposal.

Information Requested

We intend that any final action resulting from this proposed rule will be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments or information from the public, other concerned governmental agencies, Native American tribes, the scientific community, industry, or any other interested parties concerning this proposed rule. We particularly seek comments concerning:

(1) The species' biology, range, and population trends, including:

(a) Habitat requirements for feeding, breeding, and sheltering;

(b) Genetics and taxonomy;

(d) Historical and current population levels, and current and projected trends; and

(e) Past and ongoing conservation measures for the species, its habitat, or both.

(2) The factors that are the basis for making a listing determination for a species under section 4(a) of the Act (16 U.S.C. 1531

et seq.

), which are:

(a) The present or threatened destruction, modification, or curtailment of its habitat or range;

(b) Overutilization for commercial, recreational, scientific, or educational purposes;

(d) The inadequacy of existing regulatory mechanisms; or

(e) Other natural or manmade factors affecting its continued existence.

(3) Biological, commercial trade, or other relevant data concerning any threats (or lack thereof) to this species and existing regulations that may be addressing those threats.

(4) Additional information concerning the historical and current status, range, distribution, and population size of this species, including the locations of any additional populations of this species.

(5) Any information on the biological or ecological requirements of the species and ongoing conservation measures for the species and its habitat.

Please include sufficient information with your submission (such as scientific journal articles or other publications) to allow us to verify any scientific or commercial information you include.

Please note that submissions merely stating support for or opposition to the action under consideration without providing supporting information, although noted, will not be considered in making a determination, as section 4(b)(1)(A) of the Act directs that determinations as to whether any species is a threatened or endangered species must be made “solely on the basis of the best scientific and commercial data available,”.

You may submit your comments and materials concerning this proposed rule by one of the methods listed in the

ADDRESSES

section. We request that you send comments only by the methods described in the

ADDRESSES

section.

If you submit information via

http://www.regulations.gov,

your entire submission—including any personal identifying information—will be posted on the Web site. If your submission is made via a hardcopy that includes personal identifying information, you may request at the top of your document that we withhold this information from public review. However, we cannot guarantee that we will be able to do so. We will post all hardcopy submissions on

http://www.regulations.gov.

Please include sufficient information with your comments to allow us to verify any scientific or commercial information you include.

Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on

http://www.regulations.gov,

or by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Western Colorado Field Office (see

FOR FURTHER INFORMATION CONTACT

Previous Federal Actions

On January 18, 2000, we designated the Gunnison sage-grouse as a candidate species under the Act, with a listing priority number of 5. However, a

Federal Register

notice regarding this decision was not published until December 28, 2000 (65 FR 82310). Candidate species are plants and animals for which the Service has sufficient information on their biological status and threats to propose them as endangered or threatened under the Act, but for which the development of a proposed listing regulation is precluded by other higher priority listing activities. A listing priority of 5 is assigned to species with high-magnitude threats that are nonimminent.

On January 26, 2000, American Lands Alliance, Biodiversity Legal Foundation, and others petitioned the Service to list the Gunnison sage-grouse (Webb 2000, pp. 94-95). In 2003, the U.S. District Court for the District of Columbia ruled that the species was designated as a candidate by the Service prior to receipt of the petition, and that the determination that a species should be on the candidate list is equivalent to a 12-month finding

(American Lands Alliance

Gale A. Norton,

C.A. No. 00-2339, D. DC). Therefore, we did not need to respond to the petition.

In annual documents that we call Candidate Notices of Review (CNOR), we summarize the status and threats that we evaluated in order to determine that species qualify as candidates and to assign a listing priority number (LPN) to each species or to determine that species should be removed from candidate status. In the 2003 Candidate Notice of Review (CNOR), we elevated the listing priority number for Gunnison sage-grouse from 5 to 2 (69 FR 24876; May 4, 2004), as the imminence of the threats had increased. In the subsequent CNOR (70 FR 24870; May 11, 2005), we maintained the LPN for Gunnison sage-grouse as a 2. A LPN of 2 is assigned to species with high-magnitude threats that are imminent.

Plaintiffs amended their complaint in the DC district court in May 2004, to allege that the Service's warranted-but-precluded finding and decision not to emergency list the Gunnison sage-grouse were in violation of the Act. The parties filed a stipulated settlement agreement with the court on November 14, 2005, which included a provision that the Service would make a proposed listing determination by March 31, 2006. On March 28, 2006, the plaintiffs agreed to a one-week extension (April 7, 2006) for this determination.

In April 2005, the Colorado Division of Wildlife (CDOW) (hereafter, Colorado Parks and Wildlife (CPW), pursuant to the agency's reorganization on July 1, 2011) applied to the Service for an Enhancement of Survival Permit for the Gunnison sage-grouse pursuant to section 10(a)(1)(A) of the Act. The permit application included a proposed Candidate Conservation Agreement with Assurances (CCAA) between CPW and the Service. The standard that a CCAA must meet is that the “benefits of the conservation measures implemented by a property owner under a CCAA, when combined with those benefits that would be achieved if it is assumed that conservation measures were also to be implemented on other necessary properties, would preclude or remove any need to list the species” (64 FR 32726, June 17, 1999). The CCAA, the permit application, and the environmental assessment were made available for public comment on July 6, 2005 (70 FR 38977). The CCAA and environmental assessment were finalized in October 2006, and the associated permit was issued on October 23, 2006. Landowners with eligible property in southwestern Colorado who wish to participate can voluntarily sign up under the CCAA and associated permit through a Certificate of Inclusion by providing habitat protection or enhancement measures on their lands. If the Gunnison sage-grouse is listed under the Act, the CCAA remains in place and the permit authorizes incidental take of Gunnison sage-grouse due to otherwise lawful activities specified in the CCAA, when performed in accordance with the terms of the CCAA (e.g., crop cultivation, crop harvesting, livestock grazing, farm equipment operation, commercial/residential development, etc.), as long as the participating landowner is performing conservation measures voluntarily agreed to in the Certificate of Inclusion. Fourteen Certificates of Inclusion have been issued by the CPW and Service to private landowners to date (CPW 2012b, p. 11).

On April 11, 2006, the Service determined that listing the Gunnison sage-grouse as an endangered or threatened species was not warranted and published the final listing determination in the

Federal Register

on April 18, 2006 (71 FR 19954). As a result of this determination, we also removed Gunnison sage-grouse from the candidate species list.

On November 14, 2006, the County of San Miguel, Colorado; Center for Biological Diversity; WildEarth Guardians; Public Employees for Environmental Responsibility; National Audubon Society; The Larch Company; Center for Native Ecosystems; Sinapu; Sagebrush Sea Campaign; Black Canyon Audubon Society; and Sheep Mountain

Alliance filed a complaint for declaratory and injunctive relief, pursuant to the Act, and on October 24, 2007, filed an amended complaint for declaratory and injunctive relief, alleging that our determination on the Gunnison sage-grouse violated the Act. On August 18, 2009, a stipulated settlement agreement and Order was filed with the court, with a June 30, 2010, date by which the Service was to submit to the

Federal Register

a 12-month finding, pursuant to 16 U.S.C. 1533(b)(3)(B), that listing the Gunnison sage-grouse under the Act is (a) Warranted; (b) not warranted; or (c) warranted but precluded by higher priority listing actions. We then published a notice of intent to conduct a status review of Gunnison sage-grouse on November 23, 2009 (74 FR 61100). Later, the Court approved an extension of the June 30, 2010, deadline for the 12-month finding to September 15, 2010.

On September 15, 2010, we determined that listing the Gunnison sage-grouse as an endangered or threatened species was warranted but precluded by higher priority actions to amend the Lists of Endangered and Threatened Wildlife and Plants. This finding was published in the

Federal Register

on September 28, 2010 (75 FR 59804). The finding also reported that the species was added to the candidate species list and assigned a listing priority of 2 based on the Service's determination that threats to the species were of high magnitude and immediacy, as well as the taxonomic classification of Gunnison sage-grouse as a full species.

On September 9, 2011, the U.S. District Court for the District of Columbia approved a settlement agreement laying out a multi-year listing work plan for addressing candidate species, including the Gunnison sage-grouse. As part of this agreement, the Service agreed to publish a proposed rule in the

Federal Register

on whether to list Gunnison sage-grouse and designate critical habitat by September 30, 2012. On August 13, 2012, in response to a motion from the Service, the U.S. District Court for the District of Columbia modified the settlement agreement to extend this original deadline by 3 months, to December 30, 2012. The deadline for the final rule did not change and remains September 30, 2013. The request for an extension was made to allow more time to complete the proposed rule and more opportunity to engage with State and local governments, landowner groups, and other entities to discuss the conservation needs of the species.

Background

Gunnison sage-grouse and greater sage-grouse (a similar, closely related species) have similar life histories and habitat requirements (Young 1994, p. 44). In this proposed rule, we use information specific to the Gunnison sage-grouse where available but still apply scientific management principles for greater sage-grouse (

C. urophasianus

) that are relevant to Gunnison sage-grouse management needs and strategies, a practice followed by the wildlife and land management agencies that have responsibility for management of both species and their habitat.

Species Information

A detailed discussion of Gunnison sage-grouse taxonomy, the species description, historical distribution, habitat, and life-history characteristics can be found in the 12-month finding published September 28, 2010 (75 FR 59804).

Current Distribution and Population Estimates

Gunnison sage-grouse currently occur in seven widely scattered and isolated populations in Colorado and Utah, occupying 3,795 square kilometers (km

) (1,511 square miles [mi

]) (Gunnison Sage-grouse Rangewide Steering Committee) [GSRSC] 2005, pp. 36-37; CDOW 2009a, p. 1). The seven populations are Gunnison Basin, San Miguel Basin, Monticello-Dove Creek, Piñon Mesa, Crawford, Cerro Summit-Cimarron-Sims Mesa, and Poncha Pass (Figure 1). A comparative summary of the land ownership and recent population estimates among these seven populations is presented in Table 1, and Figures 2 and 3, respectively. Population trends over the last 12 years indicate that six of the populations are in decline. The largest population, the Gunnison Basin population, while showing variation over the years, has been relatively stable through the period (CDOW 2010a, p. 2; CPW 2012a, pp.1-4). Six of the populations are very small and fragmented (all with less than 40,500 hectares (ha) (100,000 acres [ac]) of habitat likely used by grouse and, with the exception of the San Miguel population, less than 50 males counted on leks (communal breeding areas)) (CDOW 2009b, p. 5; CPW 2012a, p. 3). The San Miguel population, the second largest, comprises six fragmented subpopulations.

BILLING CODE 4310-55-P

EP11JA13.012

Table 1—Percent Surface Ownership of Gunnison Sage-Grouse Occupied

Habitat

[GSRSC

2005, pp. D-3-D-6; CDOW

2009a, p. 1]

Population

Hectares

Acres

Gunnison sage-grouse occupied habitat management and ownership

BLM

NPS

USFS

CPW

CO state land board

State of UT

Private

Gunnison Basin

239,953

592,936

San Miguel Basin

41,022

101,368

Monticello-Dove Creek (Combined)

45,275

111,877

Dove Creek

16,706

41,282

Monticello

28,569

70,595

Piñon Mesa

15,744

38,904

Cerro Summit-Cimarron-Sims Mesa

15,039

37,161

Crawford

14,170

35,015

Poncha Pass

8,262

20,415

Rangewide

379,464

937,676

Occupied Gunnison sage-grouse habitat is defined as areas of suitable habitat known to be used by Gunnison sage-grouse within the last 10 years from the date of mapping, and areas of suitable habitat contiguous with areas of known use, which have no barriers to grouse movement from known use areas (GSRSC 2005, p. 54).

Gunnison Sage-grouse Rangewide Steering Committee.

Colorado Parks and Wildlife.

Bureau of Land Management.

National Park Service.

United States Forest Service.

Estimates reported in San Miguel Basin Gunnison Sage-grouse Conservation Plan (San Miguel Basin Gunnison Sage-grouse Working Group (SMBGSWG) 2009, p. 28) vary by 2 percent in these categories from those reported here. We consider these differences insignificant.

EP11JA13.013

EP11JA13.014

BILLING CODE 4310-55-C

Gunnison Basin Population

—The Gunnison Basin is an intermontane (located between mountain ranges) basin that includes parts of Gunnison and Saguache Counties, Colorado. The current Gunnison Basin population is distributed across approximately 240,000 ha (593,000 ac), roughly centered on the town of Gunnison. Elevations in the area occupied by Gunnison sage-grouse range from 2,300 to 2,900 meters (m) (7,500 to 9,500 feet [ft]). Approximately 70 percent of the land area occupied by Gunnison sage-grouse in this population is managed by Federal agencies (67 percent) and CPW (3 percent), and the remaining 30 percent is primarily private lands. Wyoming big sagebrush (

Artemisia tridentata

ssp.

wyomingensis

) and mountain big sagebrush (

A. t.

ssp.

vaseyana

) dominate the upland vegetation and have highly variable growth form depending on local site conditions.

In 1961, Gunnison County was one of five counties containing the majority of all sage-grouse in Colorado (Rogers 1964, p. 20). The vast majority (87 percent) of Gunnison sage-grouse are now found only in the Gunnison Basin population. The 2012 population estimate for the Gunnison Basin was 4,082 (CPW 2012a, pp. 1-2). In 2011, 42 of 83 leks surveyed in the area were active (at least two males in attendance during at least two of four 10-day count periods), 6 were inactive (inactive for at least 5 consecutive years), 11 were deemed historic (inactive for at least 10 consecutive years), and 24 were of unknown status (variability in counts resulted in lek not meeting requirements for active, inactive, or historic) (CPW 2011b, pp. 27-29). Approximately 45 percent of leks in the Gunnison Basin occur on private land and 55 percent on public land, primarily land administered by the BLM (GSRSC 2005, p. 75).

San Miguel Basin Population

—The San Miguel Basin population is in Montrose and San Miguel Counties in Colorado, and is composed of six small subpopulations (Dry Creek Basin, Hamilton Mesa, Miramonte Reservoir, Gurley Reservoir, Beaver Mesa, and Iron Springs) occupying approximately 41,000 ha (101,000 ac). Gunnison sage-grouse use some of these areas year-round, while others are used seasonally. Gunnison sage-grouse in the San Miguel Basin move widely between the six subpopulation areas (Apa 2004, p. 29; Stiver and Gibson 2005, p. 12). The area encompassed by this population is believed to have once served as critical migration corridors between populations to the north (Cerro Summit-Cimarron-Sims Mesa) and to the south (Monticello-Dove Creek) (Oyler-McCance

et al.

2005, p. 636; SMBGSWG 2009, p. 9), but gene flow among these populations is currently very low (Oyler-McCance

et al.

2005, p. 635). Historically, Gunnison sage-grouse used all available big sagebrush plant communities in San Miguel and Montrose Counties (Rogers 1964, p. 9).

Habitat conditions vary among the six subpopulation areas of the San Miguel Basin population areas. The following discussion addresses conditions among the subpopulations beginning in the west and moving east. The majority of occupied acres in the San Miguel Basin population (approximately 25,130 ha (62,100 ac) or 62 percent of the total population area) occur in the Dry Creek Basin subpopulation (SMBGSWG) 2009, p. 28). However, the Dry Creek Basin contains some of the poorest habitat and the smallest individual grouse numbers in the San Miguel population (SMBGSWG) 2009, pp. 28, 36). Sagebrush habitat in the Dry Creek Basin area is patchily distributed. Where irrigation is possible, private lands in the southeastern portion of Dry Creek Basin are cultivated. Sagebrush habitat on private land has been heavily thinned or removed entirely (GSRSC 2005, p. 96). Elevations in the Hamilton Mesa subpopulation are approximately 610 m (2,000 ft.) higher than in the Dry Creek Basin, resulting in more mesic conditions. Agriculture is very limited on Hamilton Mesa and the majority of the vegetation consists of oakbrush and sagebrush. Gunnison sage-grouse use the Hamilton Mesa area (1,940 ha (4,800 ac)) in the summer, but use of Hamilton Mesa during other seasons is unknown.

Gunnison sage-grouse occupy approximately 4,700 ha (11,600 ac) around Miramonte Reservoir (GSRSC 2005, p. 96). Sagebrush stands there are generally contiguous with a mixed-grass and forb understory. Occupied habitat at the Gurley Reservoir area (3,305 ha (7,500 ac)) is heavily fragmented by human development, and the understory is a mixed-grass and forb community. Farming attempts in the Gurley Reservoir area in the early 20th century led to the removal of much of the sagebrush, although agricultural activities are now restricted primarily to the seasonally irrigated crops (hay meadows), and sagebrush has reestablished in most of the failed pastures. However, grazing pressure and competition from introduced grasses have kept the overall sagebrush representation low (GSRSC 2005, pp. 96-97). Sagebrush stands in the Iron Springs and Beaver Mesa areas (2,590 ha and 3,560 ha (6,400 ac and 8,800 ac respectively)) are contiguous with a mixed-grass understory. The Beaver Mesa area has numerous scattered patches of oakbrush

(Quercus gambelii).

In 2012, the entire San Miguel Basin population contained an estimated 172 individuals on nine leks (CPW 2012a, p. 3). CPW translocated Gunnison sage-grouse from the Gunnison Basin to Dry Creek Basin in 2006, 2007, and 2009. In the spring of 2006, six individuals were released and an additional two individuals were released in the fall of that year. Nine individuals were translocated in the spring of 2007. Another 30 individuals were translocated in the fall of 2009. A 40 to 50 percent mortality rate was observed within the first year after release, compared to an average annual mortality rate of approximately 20 percent for radiomarked adult sage-grouse (CDOW 2009b, p. 9; CPW 2012b, p. 4). For a more detailed discussion of translocation efforts, please refer to the

Scientific Research

section below.

Monticello-Dove Creek Population

—This population is divided into two disjunct subpopulations of Gunnison sage-grouse, the Monticello and Dove Creek subpopulations. Currently, the larger subpopulation is near the town of Monticello, in San Juan County, Utah. Gunnison sage-grouse in this subpopulation inhabit a broad plateau on the northeastern side of the Abajo Mountains, with fragmented patches of sagebrush interspersed with large grass pastures and agricultural fields. In 1972, the population was estimated at between 583 and 1,050 individuals; by 2002, the estimate decreased to between 178 and 308 individuals (UDWR 2011, p. 1). The 2012 population estimate for this subpopulation was 103 individuals with two active leks (CPW 2012a, p. 3). Gunnison sage-grouse currently occupy an estimated 28,570 ha (70,600 ac) in the Monticello area (GSRSC 2005, p. 81).

The Dove Creek subpopulation is located primarily in western Dolores County, Colorado, north and west of Dove Creek, although a small portion of occupied habitat extends north into San Miguel County. All sagebrush plant communities in Dolores and Montezuma Counties within Gunnison sage-grouse range in Colorado were historically used by Gunnison sage-grouse (Rogers 1964, p. 9). Habitat north of Dove Creek is characterized as mountain shrub habitat, dominated by oakbrush interspersed with sagebrush. The area west of Dove Creek is dominated by sagebrush, but the habitat is highly fragmented by agricultural fields. Lek counts in the Dove Creek area were more than 50 males in 1999,

suggesting a population of about 245 birds, but declined to 2 males in 2009 (CDOW 2009b, p. 71), suggesting a population of 10 birds. A new lek was found in 2010, and the 2011 population estimate was 59 individuals on 2 leks (CPW 2011a, p. 1). The 2012 population estimate was 44 individuals on the same two leks (CPW 2012a, p. 1). Low sagebrush canopy cover, as well as low grass height, exacerbated by drought, may have led to nest failure and subsequent population declines (Connelly

et al.

2000a, p. 974; Apa 2004, p. 30).

In the fall of 2010, 13 Gunnison sage-grouse were transplanted from the Gunnison Basin to the Dove Creek population area. Another 29 individuals were transplanted in 2011 (CPW 2012b, p. 4). For a more detailed discussion of translocation efforts, please refer to the

Scientific Research

section below.

Piñon Mesa Population—

The Piñon Mesa population occurs on the northwestern end of the Uncompahgre Plateau in Mesa County, about 35 km (22 mi) southwest of Grand Junction, Colorado. Gunnison sage-grouse likely occurred historically in all suitable sagebrush habitat in the Piñon Mesa area, including the Dominguez Canyon area of the Uncompaghre Plateau, southeast of Piñon Mesa proper (Rogers 1964, p. 114). Their current distribution is approximately 15,744 ha (38,904 ac) (GSRSC 2005, p. 87) which, based on a comparison of potential presettlement distribution, is approximately 6 percent of presettlement habitat on the northern portion of the Uncompahgre Plateau in Mesa County, Colorado, and Grand County, Utah. The 2012 population estimate for Piñon Mesa was 54 birds. Of the 10 known leks, only 3 were active in 2011. Two new possible leks were found in 2012 (CPW 2012a, pp. 2-3). The Piñon Mesa area may have additional leks, but the high percentage of private land, a lack of roads, and heavy snow cover during spring make locating additional leks difficult (CDOW 2009b, p. 109).

Between 2010 and 2012, 44 Gunnison sage-grouse were transplanted from the Gunnison Basin to the Piñon Mesa population. Over 50 percent of birds transplanted to date have not survived (CPW 2012b, p.5). For a more detailed discussion of translocation efforts, please refer to the

Scientific Research

section below.

Crawford Population

—The Crawford population of Gunnison sage-grouse is in Montrose County, Colorado, about 13 km (8 mi) southwest of the town of Crawford and north of the Gunnison River. Basin big sagebrush

(A. t.

ssp.

tridentata)

and black sagebrush

(A. nova)

dominate the mid-elevation uplands (GSRSC 2005, p. 62). The 2012 population estimate for Crawford was 98 individuals in 14,170 ha (35,015 ac) of occupied habitat. Three leks are currently active in the Crawford population (CPW 2012a, p. 1). All active leks are on BLM lands in sagebrush habitat near an 11 km (7 mi) stretch of road. This area represents the largest contiguous sagebrush plant community within the occupied area of the Crawford population (GSRSC 2005, p. 64).

In the spring of 2011, seven Gunnison sage-grouse were transplanted from the Gunnison Basin to the Crawford area population. Another 20 individuals were transplanted in 2011 (CPW 2012b, p. 4). For a more detailed discussion of translocation efforts, please refer to the

Scientific Research

section below.

Cerro Summit-Cimarron-Sims Mesa Population

—This population is divided into two geographically separated subpopulations, both in Montrose County, Colorado: the Cerro Summit-Cimarron and Sims Mesa subpopulations. We do not know if sage-grouse currently move between the Cerro Summit-Cimarron and Sims Mesa subpopulations.

The Cerro Summit-Cimarron subpopulation is centered about 24 km (15 mi) east of Montrose. Rogers (1964, p. 115) noted a small population of sage-grouse in the Cimarron River drainage, but did not report population numbers. He noted that lek counts at Cerro Summit in 1959 listed four individuals. The habitat consists of 15,039 ha (37,161 ac) of patches of sagebrush habitat fragmented by oakbrush and irrigated pastures. Five leks are currently known in the Cerro Summit-Cimarron group. Eleven individuals were observed on one lek in 2012, resulting in a population estimate of 54 individuals (CPW 2012a, p. 1).

The Sims Mesa area, about 11 km (7 mi) south of Montrose, consists of small patches of sagebrush that are heavily fragmented by piñon-juniper, residential and recreational development, and agriculture (CDOW 2009b, p. 43). Rogers (1964, p. 95) recorded eight males in a lek count at Sims Mesa in 1960. In 2000, the CPW translocated six Gunnison sage-grouse from the Gunnison Basin to Sims Mesa (Nehring and Apa 2000, p. 12). There is only one currently known lek in Sims Mesa and, since 2003, it has lacked Gunnison sage-grouse attendance. However, lek counts did not occur in 2011. A lek is designated historic when it is inactive for at least 10 consecutive years, according to CPW standards. Therefore, the current status of the Sims Mesa lek is unknown (CDOW 2009b, p. 7; CPW 2012a, p. 1).

Poncha Pass Population

—The Poncha Pass Gunnison sage-grouse population is located in Saguache County, approximately 16 km (10 mi) northwest of Villa Grove, Colorado. The known population distribution is in 8,262 ha (20,415 ac) of sagebrush habitat from the summit of Poncha Pass extending south for about 13 km (8 mi) on either side of U.S. Highway 285. Sagebrush in this area is continuous with little fragmentation; sagebrush habitat quality throughout the area is adequate to support a population of the species (Nehring and Apa 2000, p. 25). San Luis Creek runs through the area, providing a year-round water source and wet meadow riparian habitat for brood-rearing.

This population lies within potential presettlement habitat, but was extirpated prior to 1964 (Rogers 1964, p. 116). The reestablishment of this population is a result of 30 birds transplanted from the Gunnison Basin in 1971 and 1972, during efforts to reintroduce the species to the San Luis Valley (GSRSC 2005, p. 94). In 1992, a CPW effort to simplify hunting restrictions inadvertently opened the Poncha Pass area to sage-grouse hunting, and at least 30 grouse were harvested from this population. Due to declining population numbers since the 1992 hunt, in the spring of 2000, CPW translocated 24 additional birds from the Gunnison Basin (Nehring and Apa 2000, p. 11). In 2001 and 2002, an additional 20 and 7 birds, respectively, were moved to Poncha Pass by the CPW (GSRSC 2005, p. 94). Translocated females have bred successfully (Apa 2004, pers. comm.), and male display activity resumed on the historic lek in the spring of 2001. A high male count of 3 males occurred in 2012, resulting in an estimated population size of 15 for the Poncha Pass population. The only known lek is located on BLM-administered land (CPW 2011a, p. 1; CPW 2012a, p. 3).

Additional Special Status Considerations

The Gunnison sage-grouse has an International Union for Conservation of Nature (IUCN) Red List Category of “endangered” (Birdlife International 2009). NatureServe currently ranks the Gunnison sage-grouse as G1-Critically Imperiled (Nature Serve 2010, entire). The Gunnison sage-grouse is on the National Audubon Society's WatchList 2007 Red Category which is “for species that are declining rapidly or have very small populations or limited ranges, and face major conservation threats.”

Summary of Factors Affecting the Species

Section 4 of the Act (16 U.S.C. 1533), and its implementing regulations at 50 CFR part 424, set forth the procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of the Act, we may list a species based on any of the following five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; and (E) other natural or manmade factors affecting its continued existence. Listing actions may be warranted based on any of the above threat factors, singly or in combination. Each of these factors as applied to the Gunnison sage-grouse is discussed below. We rely on the status review and analysis reported in the September 28, 2010, 12-month finding (75 FR 59804), but have updated it as appropriate to incorporate new information.

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

The historic and current distribution of the Gunnison sage-grouse closely matches the distribution of sagebrush. Potential Gunnison sage-grouse range is estimated to have been 5,536,358 ha (13,680,640 ac) historically (GSRSC 2005, p. 32). Gunnison sage-grouse currently occupy approximately 379,464 ha (937,676 ac) in southwestern Colorado and southeastern Utah (CDOW 2009a, p. 1; GSRSC 2005, p. 81); an area that represents approximately 7 percent of the species' potential historic range. The following describes the factors affecting Gunnison sage-grouse and Gunnison sage-grouse habitat within the current range of the species.

The onset of EuroAmerican settlement in the late 1800s resulted in significant alterations to sagebrush ecosystems throughout North America (West and Young 2000, pp. 263-265; Miller

et al.

2011, p. 147) primarily as a result of urbanization, agricultural conversion, and irrigation projects. Areas that supported basin big sagebrush were among the first sagebrush community types converted to agriculture because their typical soils and topography are well suited for agriculture (Rogers 1964, p. 13).

In southwestern Colorado, between 1958 and 1993, 20 percent (155,673 ha (384,676 ac)) of sagebrush was lost, and 37 percent of sagebrush plots examined were fragmented (Oyler-McCance

et al.

2001, p. 326). In another analysis, it was estimated that approximately 342,000 ha (845,000 ac) of sagebrush, or 13 percent of the pre-EuroAmerican settlement sagebrush extent, were lost in Colorado, which includes both greater sage-grouse and Gunnison sage-grouse habitat (Boyle and Reeder 2005, p. 3-3). However, the authors noted that the estimate of historic sagebrush area used in their analyses was conservative, possibly resulting in a substantial underestimate of historic sagebrush losses (Boyle and Reeder 2005, p. 3-4). Within the range of Gunnison sage-grouse, the principal areas of sagebrush loss were in the Gunnison Basin, San Miguel Basin, and areas near Dove Creek, Colorado. The authors point out that the rate of loss in the Gunnison Basin was lower than other areas of sagebrush distribution in Colorado. The Gunnison Basin currently contains approximately 250,000 ha (617,000 ac) of sagebrush; this area partially comprises other habitat types such as riparian areas and patches of non-sagebrush vegetation types such as aspen forest, mixed-conifer forest, and oakbrush (Boyle and Reeder 2005, p. 3-3). Within the portion of the Gunnison Basin currently occupied by Gunnison sage-grouse, 170,000 ha (420,000 ac) is composed exclusively of sagebrush vegetation types, as derived from Southwest Regional Gap Analysis Project (SWReGAP) landcover data (multiseason satellite imagery acquired 1999-2001) (USGS 2004, entire).

Sagebrush habitats within the range of Gunnison sage-grouse are becoming increasingly fragmented as a result of various changes in land uses and the expansion in the density and distribution of invasive plant species (Oyler-McCance

et al.

2001, pp. 329-330; Schroeder

et al.

2004, p. 372). Habitat fragmentation is the separation or splitting apart of previously contiguous, functional habitat components of a species. Fragmentation can result from direct habitat losses that leave the remaining habitat in noncontiguous patches, or from alteration of habitat areas that render the altered patches unusable to a species (i.e., functional habitat loss). Functional habitat losses include disturbances that change a habitat's successional state or remove one or more habitat functions; physical barriers that preclude use of otherwise suitable areas; or activities that prevent animals from using suitable habitat patches due to behavioral avoidance.

A variety of human developments including roads, energy development, residential development, and other factors that cause habitat fragmentation have contributed to or been associated with Gunnison and greater sage-grouse extirpation (Wisdom

et al.

2011, pp. 465-468). Because of the loss and fragmentation of habitat within its range, no expansive, contiguous areas that could be considered strongholds (areas of occupied range where the risk of extirpation appears low) are evident for Gunnison sage-grouse (Wisdom

et al.,

2011, p. 469). However, landscapes containing large and contiguous sagebrush patches and sagebrush patches in close proximity have an increased likelihood of sage-grouse persistence (Wisdom

et al.

2011, p. 462).

Habitat loss and fragmentation has adverse effects on Gunnison sage-grouse populations. Many of the factors that result in fragmentation may be exacerbated by the effects of climate change, which may influence long-term habitat and population trends. The following sections examine factors that can contribute to habitat loss and fragmentation to determine whether they threaten Gunnison sage-grouse and their habitat.

Residential Development

Human population growth in the rural Rocky Mountains is driven by the availability of natural amenities, recreational opportunities, aesthetically desirable settings, grandiose viewscapes, and perceived remoteness (Riebsame

et al.

1996, p. 396, 402; Theobald

et al.

1996, p. 408; Gosnell and Travis 2005, pp. 192-197; Mitchell

et al.

2002, p. 6; Hansen

et al.

2005, pp. 1899-1901). Human population growth is occurring throughout much of the range of Gunnison sage-grouse. The human population in all counties within the range of Gunnison sage-grouse averaged a 70 percent increase since 1980 (Colorado Department of Local Affairs (CDOLA) 2009a, pp. 2-3). The year 2050 projected human population for the Gunnison River basin (an area that encompasses the majority of the current range of Gunnison sage-grouse) is expected to be 2.3 times greater than the 2005 population (CWCB 2009, p. 15). The population of Gunnison County, an area that supports more than 80 percent of all Gunnison sage-grouse, is predicted to more than double to approximately 31,100 residents by 2050 (CWCB 2009, p. 53).

The increase in residential and commercial development associated with the expanding human population is different from historic land use patterns in these areas (Theobald 2001, p. 548). The allocation of land for resource-based activities such as agriculture and livestock production is

decreasing as the relative economic importance of these activities diminishes (Theobald

et al.

1996, p. 413; Sammons 1998, p. 32; Gosnell and Travis 2005, pp. 191-192). Currently, agribusiness occupations constitute approximately 3 percent of the total job base in Gunnison County (CDOLAb 2009, p. 4). Recent conversion of farm and ranch lands to housing development has been significant in Colorado (Odell and Knight 2001, p. 1144). Many large private ranches in the Rocky Mountains, including the Gunnison Basin, are being subdivided into both high-density subdivisions and larger, scattered ranchettes with lots typically greater than 14 ha (35 ac), which encompass a large, isolated house (Riebsame

et al.

1996, p. 399; Theobald

et al.

1996, p. 408).

The resulting pattern of residential development is less associated with existing town sites or existing subdivisions, and is increasingly exurban in nature (Theobald

et al.

1996, pp. 408, 415; Theobald 2001, p. 546). Exurban development is described as low-density growth outside of urban and suburban areas (Clark

et al.

2009, p. 178; Theobald 2004, p. 140) with less than one housing unit per 1 ha (2.5 ac) (Theobald 2003, p. 1627; Theobald 2004, p. 139). The resulting pattern is one of increased residential lot size and the diffuse scattering of residential lots in previously rural areas with a premium placed on adjacency to federal lands and isolated open spaces (Riebsame

et al.

1996, p. 396, 398; Theobald

et al.

1996, pp. 413, 417; Theobald 2001, p. 546; Brown

et al.

2005, p. 1858). The residential subdivision that results from exurban development causes landscape fragmentation (Gosnell and Travis 2005, p. 196) primarily through the accumulation of roads, buildings, (Theobald

et al.

1996, p. 410; Mitchell

et al.

2002, p. 3) and other associated infrastructure such as power lines, and pipelines. In the East River Valley of Gunnison County, for example, residential development in the early 1990s increased road density by 17 percent (Theobald

et al.

1996, p. 410). The habitat fragmentation resulting from this development pattern is especially detrimental to Gunnison sage-grouse because of their dependence on large areas of contiguous sagebrush (Patterson 1952, p. 48; Connelly

et al.

2004, p. 4-1; Connelly

et al.

2011, p. 72; Wisdom

et al.

2004, pp. 452-453).

Residential Development in the Gunnison Basin Population Area

—Nearly three quarters (approximately 71 percent) of the Gunnison Basin population of Gunnison sage-grouse occurs within Gunnison County, with the remainder occurring in Saguache County. Within Gunnison County, approximately 30 percent of the occupied range of this species occurs on private lands. We performed a GIS analysis of parcel ownership data that was focused on the spatial and temporal pattern of human development within occupied Gunnison sage-grouse habitat. Some of our analyses were limited to the portion of occupied habitat in Gunnison County because parcel data was only available for Gunnison County and not for Saguache County. This analysis determined that the cumulative number of human developments has increased dramatically in Gunnison County, especially since the early 1970s (USFWS 2010a, p. 1). The number of new developments averaged approximately 70 per year from the late 1800s to 1969, increasing to approximately 450 per year from 1970 to 2008 (USFWS 2010a, pp. 2-5). Furthermore, there has been an increasing trend toward development away from major roadways (primary and secondary paved roads) into areas of occupied Gunnison sage-grouse habitat that had previously undergone very limited development (USFWS 2010b, p. 7). Between 1889 and 1968, approximately 51 human developments were located more than 1.6 km (1 mi) from a major road in currently occupied Gunnison sage-grouse habitat. Between 1969 and 2008, this number increased to approximately 476 developments (USFWS 2010b, p. 7).

A landscape-scale spatial model predicting Gunnison sage-grouse nesting probability was developed based on nesting data from the western portion of the Gunnison Basin (Aldridge

et al.

2011, entire). The model was extrapolated to the entire Gunnison Basin to predict the likelihood of Gunnison sage-grouse nesting in the area (Aldridge

et al.

2011, pp. 7-9). Results of the model indicate that Gunnison sage-grouse tend to select nest sites in larger landscapes (1.5 km [0.9 mi] radii) with a low density of residential development (<1 percent) (Aldridge

et al.

2011, p. 10). The study indicates nest site selection by Gunnison sage-grouse decreases near residential developments, until approximately 2.5 km (1.6 mi) from any given residential development (Aldridge

et al.

2011, p. 10).

Within occupied Gunnison sage-grouse habitat in Gunnison County, 49 percent of the land area within the range of Gunnison sage-grouse has at least one housing unit within a radius of 1.5 km (0.9 mi) (USFWS 2010b, p. 7). This level of residential development is strongly decreasing the likelihood of Gunnison sage-grouse using these areas as nesting habitat. Furthermore, since early brood-rearing habitat is often in close proximity to nest sites (Connelly

et al.

2000a, p. 971), the loss of nesting habitat is closely linked with the loss of early brood-rearing habitat. Limitations in the quality and quantity of nesting and early brood-rearing habitat are particularly problematic because Gunnison sage-grouse population dynamics are most sensitive during these life history stages (GSRSC 2005, p. G-15).

We recognize that the potential percentages of habitat loss mentioned above, whether direct or functional, will not necessarily correspond to the same percentage loss in sage-grouse numbers. The recent efforts to conserve Gunnison sage-grouse and their habitat within the Basin provide protection into the future for several areas of high-quality habitat (see discussion below in Factors A and D). Nonetheless, given the large landscape-level needs of this species, we expect future habitat loss, degradation, and fragmentation from residential development, as described above, to substantially limit the probability of persistence of Gunnison sage-grouse in the Gunnison Basin.

The GSRSC (2005, pp. 160-161) hypothesize that residential density in excess of one housing unit per 1.3 km

(0.5 mi

) could cause declines in Gunnison sage-grouse populations. However, because the analyses that formed the basis of this hypothesis were preliminary and did not take into account potential lags in Gunnison sage-grouse population response to development, the threshold at which impacts are expected could be higher or lower (GSRSC 2005, p. F-3). The resulting impacts are expected to occur in nearly all seasonal habitats, including moderate to severe winter use areas, nesting and brood-rearing areas, and leks (GSRSC 2005, p. 161). Within Gunnison County, approximately 18 percent of the land area within the range of Gunnison sage-grouse has a residential density greater than one housing unit per 1.3 km

(0.5 mi

) (USFWS 2010b, p. 8). Therefore, according to the GSRSC estimate of potential residential impacts, human residential densities in the Gunnison Basin population area are such that we expect they are limiting the Gunnison sage-grouse population in at least 18 percent of the population area. However, based on results from the quantitative model for nesting probability described above (Aldridge

et al.

2011), residential development currently may be impacting 49 percent

of the Gunnison Basin population area (USFWS 2010b, p. 7).

Based on population projections (CWCB 2009, p. 15) and the corresponding increased need for housing, we expect the density and distribution of human residences to expand in the future. Of the private land in Gunnison County not protected by conservation easements, approximately 20,236 ha (50,004 ac) on approximately 1,190 parcels currently lack human development in occupied Gunnison sage-grouse habitat (USFWS 2010b, p. 11). These lands are scattered throughout occupied Gunnison sage-grouse habitat in the Gunnison Basin. We used the 20,236 ha (50,004 ac) as an initial basis to assess the potential impacts of future development. A lack of parcel data availability from surrounding counties precluded expanding this analysis beyond Gunnison County; however, the analysis area constitutes 71 percent of the Gunnison Basin population area.

Approximately 93 percent of occupied Gunnison sage-grouse habitat in Gunnison County consists of parcels greater than 14.2 ha (35 ac), which are exempt from some county land development regulations. Applying a 1.7 percent average annual population increase under a “middle” growth scenario (CWCB 2009, p. 56) and an average 2.29 persons per household (CDOLA 2009b, p. 6) to the 2008 Gunnison County human population estimate results in the potential addition of nearly 7,000 housing units to the county by 2050. Currently, approximately two-thirds of the human population in Gunnison County occurs within the currently mapped occupied range of Gunnison sage-grouse. Assuming this pattern will continue, two-thirds of the population increase will occur within occupied Gunnison sage-grouse habitat. The above projection could potentially result in the addition of approximately 4,630 housing units and the potential for 25,829 ha (63,824 ac) of new habitat loss, whether direct or functional, on parcels that currently have no development. This potential for additional habitat loss constitutes 15 percent of the currently occupied Gunnison sage-grouse habitat in the Gunnison Basin population area (USFWS 2010b, p. 14). Combined with the 49 percent of occupied habitat potentially impacted by current residential development (USFWS 2010b, p.7), approximately 64 percent of Gunnison sage-grouse occupied habitat may be impacted by residential development in the foreseeable future. We also anticipate increased housing density in many areas of occupied Gunnison sage-grouse habitat because the anticipated number of new housing units will exceed the number of undeveloped parcels by nearly four times (USFWS 2010b, p. 16).

Some of this anticipated development and subsequent habitat loss will undoubtedly occur on parcels that currently have existing human development, which could lessen the effects to Gunnison sage-grouse. However, the above calculation of an increase in future housing units is likely an underestimate because it does not take into account the expected increase in second home development (CDOLA 2009b, p. 7), which would increase negative effects to Gunnison sage-grouse. The U.S. Census Bureau only tallies the inhabitants of primary residences in population totals. This methodology results in an underestimate of the population, particularly in amenity communities like Gunnison, because of the increased number of part-time residents inhabiting second homes and vacation homes in these areas (Riebsame

et al.

1996, p. 397; Theobald 2001, p. 550, Theobald 2004, p. 143). In Gunnison County, approximately 90 percent of vacant housing units were composed of seasonal use units (CDOLA 2009c, p. 1), and the housing vacancy rate was 42.5 percent in Gunnison County over the last two decades (CDOLA 2009d, p. 2).

We expect some development to be moderated by the establishment of additional voluntary landowner conservation easements such as those currently facilitated by the CPW and land trust organizations. The CPW has spent more than $30 million to protect approximately 13,413 ha (33,145 ac) since 2003 (CPW 2012b, p. 6). Conservation easements, if properly managed, can minimize the overall impacts to Gunnison sage-grouse. Including CPW and nongovernmental organization held properties, approximately 17,466 ha (43,160 ac), or 25 percent, of private lands in occupied Gunnison sage-grouse habitat have been placed in conservation easements or are protected because the fee title was acquired to protect the land (CPW 2011c, pp. 9-10; CPW 2012b, p. 6). Due to the cost of acquisition we do not expect the amount of land potentially placed in future easements will adequately offset the overall effects of human development and subsequent habitat fragmentation.

Current and anticipated fragmentation is also ameliorated somewhat by the approximate 5,012 ha (12,385 ac), or 7 percent, of private lands in the Gunnison Basin currently enrolled under the Gunnison sage-grouse CCAA (CPW 2012b, p. 11). However, approximately one-third of this area is already covered under conservation easements as described above. Accounting for this overlap, conservation easements and fee title properties held by CPW and conservation organizations, and the CCAA as described above currently protect approximately 20,824 ha (51,458 ac), or 30 percent, of private lands in the Gunnison Basin population area.

Residential Development in All Other Population Areas

—In 2004, within the Crawford population area, approximately 951 ha (2,350 ac), or 7 percent of the occupied Gunnison sage-grouse habitat was subdivided into 48 parcels (CDOW 2009b, p. 59). Local landowners and the National Park Service (NPS) have ongoing efforts to protect portions of the subdivided area through conservation easements. Residential subdivision continues to occur in the northern part of the Poncha Pass population area, and the CPW considers this to be the highest priority threat to this population (CDOW 2009b, p. 124). The rate of residential development in the San Miguel Basin population area increased between 2005 and 2008 but slowed in 2009 (CDOW 2009b, p. 135). However, a 429-ha (1,057-ac) parcel north of Miramonte Reservoir is currently being developed. The CPW reports that potential impacts to Gunnison sage-grouse resulting from this development may be reduced by possibly placing a portion of the property into a conservation easement and the relocation of a proposed major road to avoid occupied habitat (CDOW 2009b, p. 136). Scattered residential development has recently occurred along the periphery of occupied habitat in the Cerro Summit-Cimarron-Sims Mesa population (CDOW 2009b, p. 45). With the exception of the Monticello subpopulation and the Crawford population, the remaining limited amounts of habitat, the fragmented nature of this remaining habitat, and the anticipated increases in exurban development pose a threat to the remaining four smaller Gunnison sage-grouse populations.

Summary of Residential Development

Because Gunnison sage-grouse are dependent on expansive, contiguous areas of sagebrush habitat to meet their life history needs, the development patterns described above have resulted in the direct and functional loss of sagebrush habitat and have negatively affected the species by limiting already scarce habitat, especially within the six smaller populations. The collective

influences of fragmentation and disturbance from human activities around residences and associated roads reduce the effective habitat around these areas, making them inhospitable to Gunnison sage-grouse (Aldridge

et al.

2011, p. 14; Knick

et al.

2011, pp. 212-219 and references therein; Aldridge and Boyce 2007, p. 520). Human population growth that results in a dispersed exurban development pattern throughout sagebrush habitats will reduce the likelihood of sage-grouse persistence in these areas. Human populations are increasing throughout the range of Gunnison sage-grouse, and we expect this trend to continue. Given the demographic and economic trends of the past few decades described above, we believe residential development in Gunnison sage-grouse habitat will continue at least through 2050, and likely longer. The resulting habitat loss and fragmentation from residential development is a principal threat to Gunnison sage-grouse persistence.

Roads

Impacts to Gunnison sage-grouse from roads may include direct habitat loss, direct mortality, barriers to migration corridors or seasonal habitats, facilitation of predation and spread of invasive vegetative species, and other indirect influences such as noise (Forman and Alexander 1998, pp. 207-231). Greater sage-grouse mortality resulting from collisions with vehicles does occur, but mortalities are typically not monitored or recorded (Patterson 1952, p. 81). Therefore, we are unable to determine the importance of direct mortality from roads on sage-grouse populations.

Although we have no information on the number of direct mortalities of Gunnison sage-grouse resulting from vehicles or roads, because of similarities in their habitat and habitat use, we expect other effects to be similar to those observed in greater sage-grouse. Roads within Gunnison sage-grouse habitats have been shown to impede movement of local populations between the resultant patches, with road avoidance presumably being a behavioral means to limit exposure to predation (Oyler-McCance

et al.

2001, p. 330).

The presence of roads increases human access and resulting disturbance effects in remote areas (Forman and Alexander 1998, p. 221; Forman 2000, p. 35; Connelly

et al.

2004, pp. 7-6 to 7-25). In addition, roads can provide corridors for predators to move into previously unoccupied areas. Some mammalian species known to prey on sage-grouse, such as red fox

(Vulpes vulpes),

raccoons

(Procyon lotor),

and striped skunks

(Mephitis mephitis),

have greatly increased their distribution by dispersing along roads (Forman and Alexander 1998, p. 212; Forman 2000, p. 33; Frey and Conover 2006, pp. 1114-1115). Corvids (Family Corvidae: crows, ravens, magpies, etc.) also use linear features such as primary and secondary roads as travel routes (Bui 2009, p. 31), expanding their movements into previously unused regions (Knight and Kawashima 1993, p. 268; Connelly

et al.

2004, p. 12-3). Corvids are significant sage-grouse nest predators and were responsible for more than 50 percent of nest predations in Nevada (Coates 2007, pp. 26-30). See Factor C below for further discussion of predation.

The expansion of road networks also contributes to exotic plant invasions via introduced road fill, vehicle transport, and road maintenance activities (Forman and Alexander 1998, p. 210; Forman 2000, p. 32; Gelbard and Belnap 2003, p. 426; Knick

et al.

2003, p. 619; Connelly

et al.

2004, p. 7-25). Invasive species are not limited to roadsides, but also encroach into surrounding habitats (Forman and Alexander 1998, p. 210; Forman 2000, p. 33; Gelbard and Belnap 2003, p. 427). Upgrading unpaved four-wheel-drive roads to paved roads resulted in increased cover of exotic plant species within the interior of adjacent plant communities (Gelbard and Belnap 2003, p. 426). This effect was associated with road construction and maintenance activities and vehicle traffic, and not with differences in site characteristics. The incursion of exotic plants into native sagebrush systems can negatively affect Gunnison sage-grouse through habitat losses and conversions (see further discussion below in the Invasive Plants section).

Gunnison sage-grouse may avoid road areas because of noise, visual disturbance, pollutants, and predators moving along a road, which further reduces the amount of habitat available to support them. The landscape-scale spatial model predicting Gunnison sage-grouse nest site selection showed strong avoidance of areas with high road densities of roads classed 1 through 4 (primary paved highways through primitive roads with 2-wheel drive sedan clearance) within 6.4 km (4 mi) of nest sites (Aldridge

et al.

2011, p. 14). Nest sites also decreased with increased proximity to primary and secondary paved highways (roads classes 1 and 2) (Aldridge

et al.

2011, p. 14). Male greater sage-grouse lek attendance was shown to decline within 3 km (1.9 mi) of a methane well or haul road with traffic volume exceeding one vehicle per day (Holloran 2005, p. 40). Male sage-grouse depend on acoustical signals to attract females to leks (Gibson and Bradbury 1985, p. 82; Gratson 1993, p. 692). If noise from roads interferes with mating displays, and thereby female attendance, younger males will not be drawn to the lek and eventually leks will become inactive (Amstrup and Phillips 1977, p. 26; Braun 1986, pp. 229-230).

In a study on the Pinedale Anticline in Wyoming, greater sage-grouse hens that bred on leks within 3 km (1.9 mi) of roads associated with oil and gas development traveled twice as far to nest as did hens that bred on leks greater than 3 km (1.9 mi) from roads. Nest initiation rates for hens bred on leks close to roads also were lower (65 versus 89 percent), affecting population recruitment (33 versus 44 percent) (Lyon 2000, p. 33; Lyon and Anderson 2003, pp. 489-490). Roads may be the primary impact of oil and gas development to sage-grouse, due to their persistence and continued use even after drilling and production have ceased (Lyon and Anderson 2003, p. 490). Lek abandonment patterns suggested that daily vehicular traffic along road networks for oil wells can impact greater sage-grouse breeding activities (Braun

et al.

2002, p. 5). Because Gunnison sage-grouse and greater sage-grouse are similar, closely related species, we believe the effects of vehicular traffic on Gunnison sage-grouse, regardless of its purpose (e.g., in support of energy production or local commuting and recreation), are similar to those observed in greater sage-grouse.

Road density was not an important factor affecting greater sage-grouse persistence or rangewide patterns in sage-grouse extirpation (Aldridge

et al.

2008, p. 992). However, the authors did not consider the intensity of human use of roads in their modeling efforts. They also indicated that their analyses may have been influenced by inaccuracies in spatial road data sets, particularly for secondary roads (Aldridge

et al.

2008, p. 992). Historic range where greater and Gunnison sage-grouse have been extirpated has a 25 percent higher density of roads than occupied range (Wisdom

et al.

2011, p. 467). Wisdom

et al.'s

(2011) greater and Gunnison sage-grouse rangewide analysis supports the findings of numerous local studies showing that roads can have both direct and indirect impacts on sage-grouse distribution and individual fitness (reproduction and survival) (e.g., Lyon and Anderson 2003 p. 490, Aldridge and Boyce 2007, p. 520).

Recreational activities including off-highway vehicles (OHV), all-terrain vehicles, motorcycles, mountain bikes,

and other mechanized methods of travel have also been recognized as a potential direct and indirect threat to Gunnison sage-grouse and their habitat (BLM 2009, p. 36). In Colorado, the number of annual off-highway vehicle (OHV) registrations has increased dramatically from 12,000 in 1991 to 131,000 in 2007 (BLM 2009, p. 37). Four wheel drive, OHV, motorcycle, specialty vehicle, and mountain bike use is expected to increase in the future based on increased human population in Colorado and within the range of Gunnison sage-grouse. Numerous off-road routes and access points to habitat used by Gunnison sage-grouse combined with increasing capabilities for mechanized travel and increased human population further contribute to habitat fragmentation.

Roads in the Gunnison Basin Population Area—

On BLM lands in the Gunnison Basin currently 2,050 km (1,274 mi) of roads are within 6.4 km (4 mi) of Gunnison sage-grouse leks. Eighty-seven percent of all Gunnison sage-grouse nests were located less than 6.4 km (4 mi) from the lek of capture (Apa 2004, p. 21). However, the BLM proposes to reduce the roads on its Gunnison Basin lands to 1,157 km (719 mi) (BLM 2010, p. 147).

Currently, 1,349 km (838 mi) of roads accessible to 2-wheel-drive passenger cars exist in occupied Gunnison sage-grouse habitat in the Gunnison Basin. Four-wheel-drive vehicle roads, as well as motorcycle, mountain bike, horse, and hiking trails are heavily distributed throughout the range of Gunnison sage-grouse (BLM 2009, pp. 27, 55, 86), which further increases the overall density of roads and their direct and indirect effects on Gunnison sage-grouse. User-created roads and trails have increased since 2004 (BLM 2009, p. 33), although we do not know the scope of this increase.

Using a spatial dataset of roads in the Gunnison Basin, we performed GIS analyses on the potential effects of roads to Gunnison sage-grouse and their habitat. To account for secondary effects from invasive weed spread from roads (see discussion below in Invasive Plants), we applied a 0.7-km (0.4-mi) buffer (Bradley and Mustard 2006, p. 1146) to all roads in the Gunnison Basin. These analyses indicate that approximately 85 percent of occupied habitat in the Gunnison Basin has an increased likelihood of current or future road-related invasive weed invasion. When all roads in the Gunnison basin are buffered by 6.4 km (4 mi) or 9.6 km (6 mi) to account for decreased nesting probability (Aldridge

et al.

2011, p. 14) and secondary effects from mammal and corvid foraging areas (Knick

et al

2011, p. 216), respectively, all occupied habitat in the Gunnison Basin is indirectly affected by roads.

Roads in All Other Population Areas

—Approximately 140 km (87 mi), 243 km (151 mi), and 217 km (135 mi) of roads (all road classes) occur on BLM lands within the Cerro Summit-Cimarron-Sims Mesa, Crawford, and San Miguel Basin population areas, respectively, all of which are managed by the BLM (BLM 2009, p. 71). We do not have information on the total length of roads within the Monticello-Dove Creek, Piñon Mesa, or Poncha Pass Gunnison sage-grouse populations. However, several maps provided by the BLM show that roads are widespread and common throughout these population areas (BLM 2009, pp. 27, 55, 86).

Summary of Roads

As described above in the `Residential Development' section, the human population is increasing throughout the range of Gunnison sage-grouse (CDOLA 2009a, pp. 2-3; CWCB 2009, p. 15), and data indicates this trend will continue. Gunnison sage-grouse are dependent on large contiguous and unfragmented landscapes to meet their life history needs (GSRSC 2005, pp. 26-30), and the existing road density throughout much of the range of Gunnison sage-grouse has negatively affected the species. The collective influences of fragmentation and disturbance from roads reduce the effective habitat as they are avoided by sage-grouse (Aldridge

et al.

2011, p. 14; Aldridge and Boyce 2007, p. 520; Knick

et al.

2011, pp. 212-219 and references therein). Given the current human demographic and economic trends described above in the Residential Development section, we believe that increased road use and increased road construction associated with residential development will continue at least through 2050, and likely longer. The resulting habitat loss, degradation, and fragmentation from roads are a major threat to Gunnison sage-grouse persistence.

Powerlines

Powerlines can directly affect greater sage-grouse by posing a collision and electrocution hazard (Braun 1998, pp. 145-146; Connelly

et al.

2000a, p. 974) and can have indirect effects by decreasing lek recruitment (Braun

et al.

2002, p. 10), increasing predation (Connelly

et al.

2004, p. 13-12), fragmenting habitat (Braun 1998, p. 146), and facilitating the invasion of exotic annual plants (Knick

et al.

2003, p. 612; Connelly

et al.

2004, p. 7-25). Proximity to powerlines is associated with Gunnison and greater sage-grouse extirpation (Wisdom

et al.

2011, pp. 467-468). Due to the potential spread of invasive species and predators as a result of powerline construction and maintenance, the impact from a powerline is greater than its actual footprint. The effects of powerlines to Gunnison sage-grouse should be similar to those observed in greater sage-grouse.

In areas where the vegetation is low and the terrain relatively flat, power poles provide an attractive hunting, roosting, and nesting perch for many species of raptors and corvids (Steenhof

et al.

1993, p. 27; Connelly

et al.

2000a, p. 974; Manville 2002, p. 7; Vander Haegen

et al.

2002, p. 503). Power poles increase a raptor's range of vision, allow for greater speed during attacks on prey, and serve as territorial markers (Steenhof

et al.

1993, p. 275; Manville 2002, p. 7). Raptors may actively seek out power poles where natural perches are limited. For example, within 1 year of construction of a 596-km (370-mi) transmission line in southern Idaho and Oregon, raptors and common ravens began nesting on the supporting poles (Steenhof

et al.

1993, p. 275). Within 10 years of construction, 133 pairs of raptors and ravens were nesting along this stretch (Steenhof

et al.

1993, p. 275). Raven counts increased by approximately 200 percent along the Falcon-Gondor transmission line corridor in Nevada within 5 years of construction (Atamian

et al.

2007, p. 2). The increased abundance of corvids within occupied Gunnison sage-grouse habitats can result in increased predation.

As with corvids, eagles can also increase following power line installation. Golden eagle

(Aquila chryrsaetos)

predation on sage-grouse on leks increased from 26 to 73 percent of the total predation after completion of a transmission line within 200 meters (m) (220 yards (yd)) of an active sage-grouse lek in northeastern Utah (Ellis 1985, p. 10). The lek was eventually abandoned, and Ellis (1985, p. 10) concluded that the presence of the powerline resulted in changes in sage-grouse dispersal patterns and caused fragmentation of the habitat. Golden eagles are found throughout the range of Gunnison sage-grouse (USGS 2010, p. 1), and golden eagles were found to be the dominant species recorded perching on power poles in Utah in Gunnison sage-grouse habitat (Prather and Messmer 2009, p. 12). The increased abundance of eagles within occupied Gunnison sage-grouse habitats can result in increased predation.

Leks within 0.4 km (0.25 mi) of new powerlines constructed for coalbed methane development in the Powder River Basin of Wyoming had significantly lower growth rates, as measured by recruitment of new males onto the lek, compared to leks further from these lines, presumably resulting from increased raptor predation (Braun

et al.

2002, p. 10). Connelly

et al.

(2004, p. 7-26) assumed a 5- to 6.9-km (3.1- to 4.3-mi) radius buffer around the perches, based on the average foraging distance of these corvids and raptors, and estimated that the area potentially influenced by additional perches provided by powerlines was 672,644 to 837,390 km

(259,641 to 323,317 mi

), or 32 to 40 percent of their assessment area. The impact on an area would depend on corvid and raptor densities within the area (see discussion in Factor C, below).

Powerlines may fragment sage-grouse habitats even if raptors are not present. The use of otherwise suitable habitat by sage-grouse near powerlines increased as distance from the powerline increased for up to 600 m (660 yd) (Braun 1998, p. 8). Based on those unpublished data, Braun (1998, p. 8) reported that the presence of powerlines may limit Gunnison and greater sage-grouse use within 1 km (0.6 mi) in otherwise suitable habitat. Similar results were recorded for other grouse species. For example, lesser and greater prairie-chickens

(Tympanuchus pallidicinctus

and

T. cupido,

respectively) avoided otherwise suitable habitat near powerlines (Pruett

et al.

2009, p. 6). Additionally, both species also crossed powerlines less often than nearby roads, which suggests that powerlines are a particularly strong barrier to movement (Pruett

et al.

2009, p. 6).

Sage-grouse also may avoid powerlines as a result of the electromagnetic fields present (Wisdom

et al.

2011, p. 467). Electromagnetic fields alter the behavior, physiology, endocrine systems and immune function in birds, with negative consequences on reproduction and development (Fernie and Reynolds 2005, p. 135). Birds are diverse in their sensitivities to electromagnetic field exposures, with domestic chickens being very sensitive. Many raptor species are less affected (Fernie and Reynolds 2005, p. 135). No studies have been conducted specifically on sage-grouse. Therefore, we do not know the impact to the Gunnison sage-grouse from electromagnetic fields.

Linear corridors through sagebrush habitats can facilitate the spread of invasive species, such as cheatgrass

(Bromus tectorum)

(Gelbard and Belnap 2003, pp. 424-426; Knick

et al.

2003, p. 620; Connelly

et al.

2004, p. 1-2). However, we were unable to find any information regarding the amount of invasive species incursion as a result of powerline construction.

Powerlines in the Gunnison Basin Population Area

—On approximately 121,000 ha (300,000 ac) of BLM land in the Gunnison Basin, 36 rights-of-way for power facilities, power lines, and transmission lines have resulted in the direct loss of 350 ha (858 ac) of occupied habitat (Borthwick 2005a, pers. comm.). As discussed above, the impacts of these lines likely extend beyond their actual footprint. We performed a GIS analysis of transmission line location in relation to overall habitat area and Gunnison sage-grouse lek locations in the Gunnison Basin population area to obtain an estimate of the potential effects in the Basin. These analyses indicate that 68 percent of the Gunnison Basin population area is within 6.9 km (4.3 mi) of an electrical transmission line and is potentially influenced by avian predators using the additional perches provided by transmission lines. This area contains 65 of 109 active leks (60 percent) in the Gunnison Basin population. These results suggest that potential increased predation resulting from transmission lines has the potential to affect a substantial portion of the Gunnison Basin population.

Powerlines in All Other Population Areas

—A transmission line runs through the Dry Creek Basin group in the San Miguel Basin population, and the Beaver Mesa group has two transmission lines. None of the transmission lines in the San Miguel Basin have raptor proofing, nor do most distribution lines (Ferguson 2005, pers. comm.), so their use by raptors and corvids as perch sites for hunting and use for nest sites is not discouraged. One major electric transmission line runs east-west in the northern portion of the current range of the Monticello group (San Juan County Gunnison Sage-grouse Working Group 2005, p. 17). Powerlines do not appear to be present in sufficient density to pose a threat to Gunnison sage-grouse in the Piñon Mesa population at this time. One transmission line parallels Highway 92 in the Crawford population and distribution lines run from there to homes on the periphery of the current range (Ferguson 2005, pers. comm.).

Summary of Powerlines

Human populations are projected to increase in and near most Gunnison sage-grouse populations (see discussion under Residential Development). As a result, we expect an associated increase in distribution powerlines to meet this increased demand. Powerlines are likely negatively affecting Gunnison sage-grouse as they contribute to habitat loss and fragmentation and facilitation of predators of Gunnison sage-grouse. Given the current demographic and economic trends described above, we believe that existing powerlines and anticipated distribution of powerlines associated with residential development will continue at least through 2050, and likely longer. The resulting habitat loss and fragmentation from powerlines is a major threat to Gunnison sage-grouse persistence.

Domestic Grazing and Wild Ungulate Herbivory

At least 87 percent of occupied Gunnison sage-grouse habitat on Federal lands is currently grazed by domestic livestock (USFWS 2010c, entire). We lack information on the proportion of Gunnison sage-grouse habitat on private lands that is currently grazed, but we expect the proportion of the area subject to grazing is similar to that on Federal lands. Excessive grazing by domestic livestock during the late 1800s and early 1900s, along with severe drought, significantly impacted sagebrush ecosystems (Knick

et al.

2003, p. 616). Although current livestock stocking rates in the range of Gunnison sage-grouse are substantially lower than historical levels (Laycock

et al.

1996, p. 3), long-term effects from historic overgrazing, including changes in plant communities and soils, persist today (Knick

et al.

2003, p. 116).

Although livestock grazing and associated land treatments have likely altered plant composition, increased topsoil loss, and increased spread of exotic plants, the impacts on Gunnison sage-grouse populations are not clear. Few studies have directly addressed the effect of livestock grazing on sage-grouse (Beck and Mitchell 2000, pp. 998-1000; Wamboldt

et al.

2002, p. 7; Crawford

et al.

2004, p. 11), and little direct experimental evidence links grazing practices to Gunnison sage-grouse population levels (Braun 1987, pp. 136-137, Connelly and Braun 1997, p. 7-9). Rowland (2004, pp. 17-18) conducted a literature review and found no experimental research that demonstrates grazing alone is responsible for reduction in sage-grouse numbers.

Despite the obvious impacts of grazing on plant communities within the range of the species, the GSRSC (2005, p. 114) could not find a direct correlation between historic grazing and reduced Gunnison sage-grouse numbers.

While implications on population-level impacts from grazing can be made based on impacts of grazing on individuals and habitat conditions, no studies have documented the impacts (positively or negatively) of grazing at the population level.

Sage-grouse need significant grass and shrub cover for protection from predators, particularly during nesting season, and females will preferentially choose nesting sites based on these qualities (Hagen

et al.

2007, p. 46). In particular, nest success in Gunnison sage-grouse habitat is related to greater grass and forb heights and shrub density (Young 1994, p. 38). The reduction of grass heights due to livestock grazing in sage-grouse nesting and brood-rearing areas has been shown to negatively affect nesting success when cover is reduced below the 18 cm (7 in.) needed for predator avoidance (Gregg

et al.

1994, p. 165). Based on measurements of cattle foraging rates on bunchgrasses both between and under sagebrush canopies, the probability of foraging on under-canopy bunchgrasses depends on sagebrush size and shape. Consequently, the effects of grazing on nesting habitats might be site specific (France

et al.

2008, pp. 392-393).

Grazing by livestock could reduce the suitability of breeding and brood-rearing habitat, negatively affecting sage-grouse populations (Braun 1987, p. 137; Dobkin 1995, p. 18; Connelly and Braun 1997, p. 231; Beck and Mitchell 2000, pp. 998-1000). Domestic livestock grazing reduces water infiltration rates and the cover of herbaceous plants and litter, compacts the soil, and increases soil erosion (Braun 1998, p. 147; Dobkin

et al.

1998, p. 213). These impacts change the proportion of shrub, grass, and forb components in the affected area, and facilitate invasion of exotic plant species that do not provide suitable habitat for sage-grouse (Mack and Thompson 1982, p. 761; Miller and Eddleman 2000, p. 19; Knick

et al.

2011, pp. 228-232).

Livestock may compete directly with sage-grouse for rangeland resources. Cattle are grazers, feeding mostly on grasses, but they will make seasonal use of forbs and shrub species like sagebrush (Vallentine 1990, p. 226), a primary source of nutrition for sage-grouse. A sage-grouse hen's nutritional condition affects nest initiation rate, clutch size, and subsequent reproductive success (Barnett and Crawford 1994, p. 117; Coggins 1998, p. 30). Other effects of direct competition between livestock and sage-grouse depend on condition of the habitat and the grazing practices. Thus, the effects vary across the range of Gunnison sage-grouse. For example, poor livestock management in mesic sites results in a reduction of forbs and grasses available to sage-grouse chicks, thereby affecting chick survival (Aldridge and Brigham 2003, p. 30). Chick survival is one of the most important factors in maintaining Gunnison sage-grouse population viability (GSRSC 2005, p. 173).

Livestock can trample sage-grouse nests and nesting habitat. Although the effect of trampling at a population level is unknown, outright nest destruction has been documented, and the presence of livestock can cause sage-grouse to abandon their nests (Rasmussen and Griner 1938, p. 863; Patterson 1952, p. 111; Call and Maser 1985, p. 17; Holloran and Anderson 2003, p. 309; Coates 2007, p. 28). Sage-grouse have been documented to abandon nests following partial nest depredation by cows (Coates 2007, p. 28). In general, all recorded encounters between livestock and grouse nests resulted in hens flushing from nests, which could expose the eggs to predation. Visual predators like ravens likely use hen movements to locate sage-grouse nests (Coates 2007, p. 33). Livestock also may trample sagebrush seedlings, thereby removing a source of future sage-grouse food and cover (Connelly

et al.

2004, pp. 7-31). Trampling of soil by livestock can reduce or eliminate biological soil crusts making these areas susceptible to cheatgrass invasion (Mack 1981, pp. 148-149; Young and Allen 1997, p. 531).

Livestock grazing may have positive effects on sage-grouse under some habitat conditions. Sage-grouse use grazed meadows significantly more during late summer than ungrazed meadows because grazing had stimulated the regrowth of forbs (Evans 1986, p. 67). Greater sage-grouse sought out and used openings in meadows created by cattle grazing in northern Nevada (Klebenow 1981, p. 121). Also, both sheep and goats have been used to control invasive weeds (Mosley 1996

Connelly

et al.

2004, pp. 7-49; Merritt

et al.

2001, p. 4; Olsen and Wallander 2001, p. 30) and woody plant encroachment (Riggs and Urness 1989, p. 358) in sage-grouse habitat.

Sagebrush plant communities are not adapted to domestic grazing disturbance. Grazing changed the functioning of systems into less resilient, and in some cases, altered communities (Knick

et al.

2011, pp. 229-232). The ability to restore or rehabilitate areas depends on the condition of the area relative to the ability of a site to support a specific plant community (Knick

et al.

2011, pp. 229-232). For example, if an area has a balanced mix of shrubs and native understory vegetation, a change in grazing management can restore the habitat to its potential historic species composition (Pyke 2011, pp. 536-538). Wambolt and Payne (1986, p. 318) found that rest from grazing had a better perennial grass response than other treatments. Active restoration is likely required where native understory vegetation is much reduced (Pyke 2011, pp. 536-540). But, if an area has soil loss or invasive species, returning the site to the native historical plant community may be impossible (Daubenmire 1970, p. 82; Knick

et al.

2011, pp. 230-231; Pyke 2011, p. 539).

Aldridge

et al.

(2008, p. 990) did not find any relationship between sage-grouse persistence and livestock densities. However, the authors noted that livestock numbers do not necessarily correlate with range condition. They concluded that the intensity, duration, and distribution of livestock grazing are more influential on rangeland condition than the livestock density values (Aldridge

et al.

2008, p. 990). Currently, little direct evidence links grazing practices to population levels of Gunnison or greater sage-grouse. Although grazing has not been examined at large spatial scales, as discussed above, we do know that grazing can have negative impacts to individuals, nests, breeding productivity, and sagebrush and, consequently, to sage-grouse at local scales. However, how these impacts operate at large spatial scales and thus on population levels is currently unknown. The potential for population-level impacts should be further studied. Although baseline vegetation monitoring has been conducted in the past, detailed baseline vegetation monitoring efforts were conducted in the Gunnison Basin in 2010. In comparison to the best available information on habitat guidelines for the maintenance of Gunnison sage-grouse habitat (GSRSC 2005, Appendix H-1), cover and height estimates were within the breeding and summer-to-fall habitat guidelines, especially in cover and sagebrush height for dry mountain loam and mountain loam ecological sites across the Basin. Comparisons of existing conditions to winter habitat guidelines were not made in this assessment.

Livestock Grazing and Habitat Monitoring Methods

—Our analysis of grazing is focused on BLM lands because nearly all of the information available to us regarding current grazing management within the range of Gunnison sage-grouse was provided by this agency. Similar information was

provided by the USFS, but was more limited since the USFS has less occupied habitat in grazing allotments and has a different habitat monitoring approach than BLM (see discussion below). A summary of domestic livestock grazing management on BLM and USFS lands in occupied Gunnison sage-grouse habitat is provided in Table 2.

Much of the available information on domestic livestock grazing and its relationship to habitat conditions on Federal lands is in the form of BLM's Land Health Assessment (LHA) data. The purpose of LHAs are to determine the status of resource conditions within a specified geographic area at a specific time, and livestock grazing practices are coupled to these LHA determinations. The LHA process incorporates land health standards that define minimum resource conditions that must be achieved and maintained. Further discussion on the LHA process is provided in the following section.

The USFS does not apply the LHA process, but monitors allotment trends through a combination of procedures including seasonal inspections, permanent photo points, and inventory and mapping of plant community conditions and changes over time (USFS 2010). The majority of Gunnison sage-grouse occupied habitat in USFS grazing allotments is located in the Gunnison Basin population area (Tables 1 and 2), and grazing information as it relates to Gunnison sage-grouse is therefore limited to this area (USFWS 2010c, p2).

Although grazing also occurs on lands owned or managed by other entities, we have no information on the extent of grazing in these areas. Livestock grazing on private lands, where present, has a greater potential to impact Gunnison sage-grouse because these areas are not required to meet agency-mandated land health standards, but we lack sufficient data to make an informed assessment of these areas.

Table 2—Summary of Domestic Livestock Grazing Management on BLM

and USFS

Lands in Occupied Habitat for Each of the Gunnison Sage-Grouse Populations (From BLM (2012) and USFWS (2010c), Compilation of Data Provided by BLM and USFS)

Population

Percent

Number of

active USFS

allotments

Number of

active BLM

allotments

Active

allotments

with GUSG

objectives

BLM

allotments with completed LHA

Assessed BLM allotments meeting LHA objectives

Gunnison

100

San Miguel Basin

no data

Monticello—Dove Creek:

Dove Creek

n/a

Monticello

n/a

100

Piñon Mesa

no data

100

Cerro Summit-Cimarron-Sims Mesa

n/a

Crawford

n/a

100

Poncha Pass

no data

100

Rangewide Averages

Bureau of Land Management.

United States Forest Service.

Gunnison sage-grouse.

Land Health Assessments.

No United States Forest land in occupied habitat in this population area.

Includes allotments on National Park Service lands but managed by the Bureau of Land Management.

BLM Land Health Assessment Standards

—LHA standards are based on the recognized characteristics of healthy ecosystems and include considerations of upland soils, riparian systems, plant and animal communities, habitat conditions and populations of special status species, and water quality (BLM 1997, pp. 6-7). Each LHA standard, such as the condition and health of soils, riparian areas, or plant communities, has varying degrees of applicability to basic Gunnison sage-grouse habitat needs. The most applicable LHA standard to Gunnison sage-grouse is LHA standard number four, which is specific to special status species (BLM 1997, p. 7).

Special status species

include Federally threatened, endangered, proposed, and candidate species; recently delisted (5 years or less) species; and BLM sensitive species.

BLM sensitive species

are those that require special management consideration to promote their conservation and reduce the likelihood and need for future listing under the ESA; they are designated by the BLM State Director(s) (BLM 2008). Gunnison sage-grouse was designated a BLM sensitive species in 2000 when it and greater sage-grouse were recognized as separate species (BLM 2009, p. 7).

In addition to requiring stable and increasing populations and suitable habitat for special status species, the specific indicators for LHA standard four include the presence of: minimal noxious weeds, sustainably reproducing native plant and animal communities, mixed age classes sufficient to sustain recruitment and mortality fluctuations, habitat connectivity, photosynthetic activity throughout the growing season, diverse and resilient plant and animal communities in balance with habitat potential, plant litter accumulation, and several plant communities in a variety of successional stages and patterns (BLM 1997, p. 7).

We recognize that LHAs are largely qualitative and other factors in addition to recent domestic livestock grazing, including the lingering effects of historic overgrazing, may influence the outcome of LHA determinations. Furthermore, BLM's application of LHA standards, methodologies used, and data interpretation varies depending on the Field Office. Therefore, the relationship between LHA determinations and the effects of domestic livestock grazing on Gunnison sage-grouse is imprecise. We also recognize that if an allotment does not meet LHA standard four, it does not mean the habitat is completely unsuitable for Gunnison sage-grouse. However, the fact that some grazing allotments or areas are not meeting LHA

objectives indicates that habitat conditions are likely degraded for Gunnison sage-grouse in portions of its range, and that domestic livestock grazing is contributing to these conditions.

Federal Lands Grazing in the Gunnison Basin Population Area

—The BLM manages approximately 122,376 ha (301,267 ac), or 51 percent of the area currently occupied by Gunnison sage-grouse in the Gunnison Basin. Approximately 98 percent (119,941 ha [296,381 ac]) of this area is actively grazed (USFWS 2010c, p. 1). The USFS manages approximately 34,544 ha (85,361 ac), or 14 percent of the occupied portion of the Gunnison Basin population area. Therefore, this information is pertinent to approximately 65 percent of occupied habitat in the Gunnison Basin.

Within the 296,381 acres of occupied Gunnison sage-grouse habitat that are actively grazed on BLM Gunnison Field Office lands, and with respect to LHA standard four, approximately 24,208 acres (8 percent) are “meeting” the standard; 51,314 acres (17 percent) are “moving towards” meeting the standard; 187,387 acres (63 percent) are “not meeting” the standard; and 33,472 acres (11 percent) are of “unknown” status (BLM 2012, pp. 2-3).

This analysis indicates that, without taking into account habitat conditions on private lands and other Federal and State lands, at least 32 percent (187,387 acres “not meeting” standard four) of occupied Gunnison sage-grouse habitat in the Gunnison Basin (592,936 total ac) has diminished habitat conditions and likely a reduction in habitat quality for Gunnison sage-grouse.

Including those areas “moving towards” meeting LHA standard four (assuming conditions are less than optimal in these areas), overall habitat conditions for Gunnison sage-grouse may be worse than estimated above. Combining areas “not meeting” and “moving toward” standard four, as much as 81 percent (238,701 ac) of occupied habitat on BLM lands in the Gunnison Basin may have reduced habitat quality for Gunnison sage-grouse. Under these assumptions, as much as 40 percent (238,701 ac) of total occupied habitat in the Gunnison Basin (592,936 ac) may have reduced habitat quality for Gunnison sage-grouse. This estimate may be conservative since it assumes habitat conditions are being met for Gunnison sage-grouse in occupied habitat on the remaining, un-assessed (“unknown”) BLM lands as well as private, State, and other Federal lands in the Gunnison Basin.

In 2007 and 2008, the BLM Gunnison Field Office conducted Gunnison sage-grouse habitat assessments in two major occupied habitat locations in the Gunnison Basin population quantifying vegetation structural characteristics and plant species diversity. Data were collected and compared to Gunnison sage-grouse Structural Habitat Guidelines in the 2005 Rangewide Conservation Plan (RCP) (GSRSC, 2005, Appendix H) during optimal growing conditions in these two major occupied areas. Guidelines for sage cover, grass cover, forb cover, sagebrush height, grass height, and forb height were met in 45, 30, 25, 75, 81, and 39 percent, respectively, of 97 transects (BLM 2009, pp. 31-32). In addition, grazing has negatively impacted several Gunnison sage-grouse treatments (projects aimed at improving habitat condition) in the Gunnison Basin (BLM 2009, p. 34). Although these areas are generally rested from domestic livestock grazing for 2 years after treatment, several have been heavily used by cattle shortly after the treatment and the effectiveness of the treatments decreased (BLM 2009, p. 34), which reduced the potential benefits of the treatments.

As noted earlier, the USFS does not use the LHA process, but monitors allotment trends through a combination of procedures including seasonal inspections, permanent photo points, and inventory and mapping of plant community conditions and changes over time (USFS 2010). Three (9 percent) of the 35 USFS allotments in Gunnison sage-grouse occupied habitat in the Gunnison Basin population area have incorporated habitat objectives in their grazing plans. However, we have no specific data that evaluate allotment conditions as they relate to these objectives. Overall, USFS grazing allotments in the Gunnison Basin population area appear to be improving in forb and grass cover but are declining in sagebrush cover (USFS 2010).

All of this information indicates that grazing management has likely resulted in degraded habitat conditions for Gunnison sage-grouse in portions of the Gunnison Basin. Based on available LHA data for occupied habitat on BLM lands, 32 to 40 percent of total occupied habitat in the Gunnison Basin may have reduced habitat quality for Gunnison sage-grouse. This estimate may be conservative since it assumes habitat conditions are being met for Gunnison sage-grouse in occupied habitat on the remaining, un-assessed (“unknown”) BLM lands as well as private, State, and other Federal lands in the Gunnison Basin. Assuming conditions in occupied habitat on other lands are similar to those on BLM-administered lands, more than 40 percent of Gunnison sage-grouse occupied habitat in the Gunnison Basin may have reduced habitat conditions for Gunnison sage-grouse. Therefore, current and past livestock grazing may be negatively impacting the Gunnison Basin population.

However, the BLM has recently been modifying grazing permit terms and conditions in areas determined to be “not meeting” LHA standards through the permit renewal process. Examples of new permit terms or conditions required by the BLM include implementation of rotational grazing systems, deferment or elimination of grazing in certain pastures, reduced grazing duration (season of use), reduced stocking rates, fencing livestock out of riparian areas, or incorporating specific habitat objectives for Gunnison sage-grouse or other special status species (BLM 2012, pp. 1-2). It is anticipated that these changes will minimize further impacts to habitat and, in the future, improve degraded habitats for Gunnison sage-grouse in the Gunnison Basin, but there is no data at this time to substantiate this expectation.

Some data indicate habitat conditions within a portion of the Gunnison Basin may be favorable to Gunnison sage-grouse (Williams and Hild 2011, entire). Detailed vegetation monitoring was conducted on six study sites across the Gunnison Basin during the summer of 2010 in order to determine baseline habitat conditions for a potential future study of the effects of manipulating livestock grazing on Gunnison sage-grouse habitat (Williams and Hild 2011, entire). Transects were conducted on private, BLM, USFS, and CPW land. Results of this study indicated that, despite lower than average precipitation in the preceding year (2010), most vegetation measurements were within the structural habitat guidelines for Gunnison sage-grouse from the 2005 Rangewide Conservation Plan (GSRSC

2005, pp. H-6-H-8). However, the study did not describe the extent of past or ongoing livestock grazing in these areas, nor did it compare un-grazed to grazed areas. Further, transect locations were prioritized and selected in areas used by radio-collared Gunnison sage-grouse. Therefore, the relationship between livestock grazing and habitat conditions is unclear, and the ability to infer conditions in other portions of the Gunnison Basin not prioritized for sampling is limited.

Federal Lands Grazing in All Other Population Areas

—The BLM manages approximately 36 percent of the area currently occupied by Gunnison sage-grouse in the San Miguel Basin, and

approximately 79 percent of this area is actively grazed. Grazing certainly occurs on lands owned or managed by other entities, but we have no information on the extent of grazing in these areas. Within the occupied range in the San Miguel population, no active BLM grazing allotments have Gunnison sage-grouse habitat objectives incorporated into the allotment management plans or Records of Decision for permit renewals (USFWS 2010c, p. 9). In 2009, 10 of 15 (77 percent) active allotments had LHAs completed in the last 15 years, 4 of 10 allotments (40 percent) were deemed by the BLM to meet LHA objectives. Gunnison sage-grouse habitats within the 60 percent of allotments not meeting LHA objectives and the 5 allotments with no LHAs completed are likely impacted by grazing in the same manner and proportion. Therefore, it appears that grazing is reducing habitat quality for Gunnison sage-grouse in a large portion of this population area.

More than 81 percent of the area occupied by the Dove Creek group is privately owned. The BLM manages 11 percent of the occupied habitat, and 41 percent of this area is actively grazed. Within the occupied range in the Dove Creek group of the Monticello-Dove Creek population, no active BLM grazing allotments have Gunnison sage-grouse habitat objectives incorporated into the allotment management plans or Records of Decision for permit renewals (USFWS 2010c, p. 3). In 2009, no active allotments in occupied habitat had completed LHAs. Gunnison sage-grouse are not explicitly considered in grazing management planning and the lack of habitat data limits our ability to determine the impact to the habitat on public lands.

More than 95 percent of the area occupied by the Monticello group is privately owned. The BLM manages 4 percent of the occupied habitat, and 83 percent of this area is grazed. Within the occupied range in the Monticello group, all 6 active BLM grazing allotments have Gunnison sage-grouse habitat objectives incorporated into the allotment management plans or Records of Decision for permit renewals (USFWS 2010c, p. 6). In 2009, 88 percent of the area of occupied habitat in active allotments had a recently completed LHA. Approximately 60 percent of the area in occupied habitat in active allotments was deemed by the BLM to meet LHA objectives. Given the small amount of land managed by the BLM in this area, this information suggests that grazing the majority of lands managed by the BLM is likely not contributing to Gunnison sage-grouse habitat degradation in the Monticello population group.

Grazing certainly occurs on lands owned or managed by other entities but we have no information on the extent of grazing in these areas. Livestock grazing on private lands, where present, has a greater potential to impact Gunnison sage-grouse; however, we lack information to make an assessment. Conservation Reserve Program (CRP) land has provided a considerable amount of brood-rearing habitat in the Monticello group because of its forb component. Grazing of CRP land in Utah occurred in 2002 under emergency Farm Bill provisions due to drought and removed at least some of the grass and forb habitat component, thus likely negatively affecting Gunnison sage-grouse chick survival. Radio-collared males and non-brood-rearing females exhibited temporary avoidance of grazed fields during and after grazing (Lupis

et al.

2006, pp. 959-960), although one hen with a brood continued to use a grazed CRP field.

The BLM manages 28 percent of occupied habitat in the Piñon Mesa population area, and approximately 97 percent of this area is grazed. Over 50 percent of occupied habitat in this population area is privately owned, and while grazing certainly occurs on these lands, we have no information on its extent. Within the occupied range in the Piñon Mesa population, 8 of 15 (53 percent) active BLM grazing allotments have Gunnison sage-grouse habitat objectives incorporated into the allotment management plans or Records of Decision for permit renewals (USFWS 2010c, p. 5). In 2009, 23 percent of the area of occupied Gunnison sage-grouse habitat in active allotments in the Piñon Mesa population area had LHAs completed in the last 15 years, and all of these were deemed by the BLM to meet LHA objectives. Therefore, for the portion of the Piñon Mesa population area for which we have information, it appears that grazing is managed in a manner consistent with Gunnison sage-grouse habitat requirements.

Over 76 percent of the area occupied by the Cerro Summit-Cimarron-Sims Mesa population area is privately owned. The BLM manages only 13 percent of the occupied habitat, and 83 percent of this area is grazed. Within the occupied range in the Cerro Summit-Cimarron-Sims Mesa population, 1 of 10 active BLM grazing allotments have Gunnison sage-grouse habitat objectives incorporated into the allotment management plans or Records of Decision for permit renewals (USFWS 2010c, p. 7). In 2009, of the 10 active allotments, 5 had LHAs completed in the last 15 years, and 3 of these were deemed by the BLM as not meeting LHA objectives. Therefore, for the small portion of the Cerro Summit-Cimarron-Sims Mesa population area for which we have information, it appears that grazing is reducing habitat quality for Gunnison sage-grouse in portions of this population area. Grazing certainly occurs on lands owned or managed by other entities but we have no information on the extent of grazing in these areas. Livestock grazing on private lands, where present, has a greater potential to impact Gunnison sage-grouse because these areas are not required to meet agency-mandated land health standards. Because we lack information on how these lands are managed; we assume that impacts to Gunnison sage-grouse from grazing are similar to the BLM lands.

Lands administered by the BLM and NPS comprise over 75 percent of occupied habitat in the Crawford population, and 96 percent of this area is actively grazed. Grazing allotments on NPS lands in this area are administered by the BLM. Within occupied range in the Crawford population, 1 of 7 active BLM grazing allotments have Gunnison sage-grouse habitat objectives incorporated into the allotment management plans or Records of Decision for permit renewals (USFWS 2010c, p. 8). In 2009, all of the active allotments had LHAs completed in the last 15 years, and 86 percent met LHA objectives. In addition, seasonal forage utilization levels were below 30 percent in most Crawford population allotments, although a small number of allotments had nearly 50 percent utilization (BLM 2009, p. 68). Based on this information, it appears that grazing is managed in a manner consistent with Gunnison sage-grouse conservation in the majority of the Crawford population area.

The BLM manages nearly half of occupied habitat in the Poncha Pass population area, and approximately 98 percent of this area is actively grazed. Within the occupied range in the Poncha Pass population, 1 of 8 active BLM grazing allotments have Gunnison sage-grouse habitat objectives incorporated into the allotment management plans or Records of Decision for permit renewals (USFWS 2010c, p. 4). In 2009, all active allotments in occupied habitat had completed LHAs and all were meeting LHA objectives. Based on this information it appears that grazing is managed in a manner consistent with Gunnison sage-grouse conservation in the majority of the Poncha Pass population area.

Wild Ungulate Herbivory in All Population Areas

—Overgrazing by deer and elk may cause local degradation of habitats by removal of forage and residual hiding and nesting cover. Hobbs

et al.

(1996, pp. 210-213) documented a decline in available perennial grasses as elk densities increased. Such grazing could negatively impact nesting cover for sage-grouse. The winter range of deer and elk overlaps the year-round range of the Gunnison sage-grouse. Excessive but localized deer and elk grazing has been documented in the Gunnison Basin (BLM 2005a, pp. 17-18; Jones 2005, pers. comm.).

Grazing by deer and elk occurs in all Gunnison sage-grouse population areas. Although we have no information indicating that competition for resources is limiting Gunnison sage-grouse in the Gunnison Basin, BLM observed that certain mountain shrubs were being browsed heavily by wild ungulates (BLM 2009, p. 34). Subsequent results of monitoring in mountain shrub communities indicated that drought and big game were having large impacts on the survivability and size of mountain mahogany

(Cercocarpus utahensis),

bitterbrush

(Purshia tridentata),

and serviceberry

(Amelanchier alnifolia)

in the Gunnison Basin (Jupuntich

et al.

2010, pp. 7-9). The authors raised concerns that observed reductions in shrub size and vigor will reduce drifting snow accumulation resulting in decreased moisture availability to grasses and forbs during the spring melt. Reduced grass and forb growth could negatively impact Gunnison sage-grouse nesting and early brood-rearing habitat.

Domestic Grazing and Wild Ungulate Herbivory Summary

Livestock management and domestic grazing have the potential to degrade Gunnison sage-grouse habitat. Grazing can adversely impact nesting and brood-rearing habitat by decreasing vegetation available for concealment from predators. Grazing also has been shown to compact soils, decrease herbaceous abundance, increase erosion, and increase the probability of invasion of exotic plant species (GSRSC 2005, p. 173).

The impacts of livestock operations on Gunnison sage-grouse depend upon stocking levels and season of use. We recognize that not all livestock grazing results in habitat degradation, and many livestock operations within the range of Gunnison sage-grouse are employing innovative grazing strategies and conservation actions (BLM 2012, pp. 1-2; Gunnison County Stockgrowers 2009, entire) in collaboration with the BLM and Forest Service. As discussed above, habitat conditions are likely favorable to Gunnison sage-grouse in a portion of the Gunnison Basin (Williams and Hild 2011, entire), although the extent of livestock grazing in those areas is unknown.

Available information suggests that LHA objectives important to Gunnison sage-grouse are not being met across portions of the species' range and that livestock grazing is contributing to those conditions. Reduced habitat quality in those areas, as reflected in unmet LHA objectives, is likely negatively impacting Gunnison sage-grouse in most of the populations, including the Gunnison Basin. However, the relationship between LHA determinations and the effects of domestic livestock grazing on Gunnison sage-grouse is imprecise.

We know that grazing can have negative impacts to sagebrush and consequently to Gunnison sage-grouse at local scales. Impacts to sagebrush plant communities as a result of grazing are occurring on a large portion of the range of the species. Given the widespread nature of grazing within the range of Gunnison sage-grouse, the potential for population-level impacts is likely. We expect grazing to persist throughout the range of Gunnison sage-grouse for at least several decades. Effects of domestic livestock grazing are likely being exacerbated by intense browsing of woody species by wild ungulates in portions of the Gunnison Basin. Habitat degradation that can result from improperly managed grazing, particularly with the interacting factors of invasive weed expansion and climate change, is a threat to Gunnison sage-grouse persistence.

Fences

The effects of fencing on sage-grouse include direct mortality through collisions, creation of raptor and corvid perch sites, the potential creation of predator corridors along fences (particularly if a road is maintained next to the fence), incursion of exotic species along the fencing corridor, and habitat fragmentation (Call and Maser 1985, p. 22; Braun 1998, p. 145; Connelly

et al.

2000a, p. 974; Beck

et al.

2003, p. 211; Knick

et al.

2003, p. 612; Connelly

et al.

2004, p. 1-2).

Sage-grouse frequently fly low and fast across sagebrush flats, and fences can create a collision hazard resulting in direct mortality (Call and Maser 1985, p. 22; Christiansen 2009, pp. 1-2). Not all fences present the same mortality risk to sage-grouse. Mortality risk appears to be dependent on a combination of factors including design of fencing, landscape topography, and spatial relationship with seasonal habitats (Christiansen 2009, pp. 1-2). This variability in fence mortality rate and the lack of systematic fence monitoring make it difficult to determine the magnitude of direct strike mortality impacts to sage-grouse populations; however, in some cases the level of mortality is likely significant to localized areas within populations. Greater sage-grouse fence collisions during the breeding season in Idaho were found to be relatively common and widespread, with collisions being influenced by the technical attributes of the fences, fence length and density, topography, and distance to nearest active sage-grouse lek (Stevens 2011, pp. 102-107). We assume that Gunnison sage-grouse are also killed by fences but do not have species-specific data.

Although the effects of direct strike mortality on populations are not fully analyzed, fences are generally ubiquitous across the landscape. At least 1,540 km (960 mi) of fence are on BLM lands within the Gunnison Basin (Borthwick 2005b, pers. comm.; BLM 2005a, 2005e) and an unquantified amount of fence is located on land owned or managed by other landowners. Fences are present within all other Gunnison sage-grouse population areas, but we have no quantitative information on the amount or types of fencing in these areas.

Fence posts create perching places for raptors and corvids, which may increase their ability to prey on sage-grouse (Braun 1998, p. 145; Oyler-McCance

et al.

2001, p. 330; Connelly

et al.

2004, p. 13-12). This is particularly significant for sage-grouse reproduction because corvids were responsible for more than 50 percent of nest predations in Nevada (Coates 2007, pp. 26-30). Greater sage-grouse avoidance of habitat adjacent to fences, presumably to minimize the risk of predation, effectively results in habitat fragmentation even if the actual habitat is not removed (Braun 1998, p. 145). We anticipate that the effect on sage-grouse populations through the creation of new raptor perches and predator corridors into sagebrush habitats is similar to that of powerlines discussed above (Braun 1998, p. 145; Connelly

et al.

2004, p. 7-3). Because of similarities in behavior and habitat use, the response of Gunnison sage-grouse should be similar to that observed in greater sage-grouse.

Summary of Fences

Fences contribute to habitat fragmentation and increase the potential for loss of individual grouse through collisions or enhanced predation. We expect that the majority of existing

fences will remain on the landscape indefinitely. In the smaller Gunnison sage-grouse populations, fencing is another source of mortality that cumulatively affects the ability of the species to persist. We also recognize that fences are located throughout all Gunnison sage-grouse populations and are, therefore, contributing to the fragmentation of remaining habitat and are a source of mortality within all populations. For these reasons, fences may be another factor contributing to the decline of Gunnison sage-grouse, both directly and indirectly. However, we have no specific data on the scope of this threat.

Invasive Plants

For the purposes of this proposed rule, we define invasive plants as those that are not native to an ecosystem and that have a negative impact on Gunnison sage-grouse habitat. Invasive plants alter native plant community structure and composition, productivity, nutrient cycling, and hydrology (Vitousek 1990, p. 7) and may cause declines in native plant populations through competitive exclusion and niche displacement, among other mechanisms (Mooney and Cleland 2001, p. 5446). Invasive plants reduce and can eliminate vegetation that sage-grouse use for food and cover. Invasive plants do not provide quality sage-grouse habitat. Sage-grouse depend on a variety of native forbs and the insects associated with them for chick survival, and on sagebrush, which is used exclusively throughout the winter for food and cover.

Along with replacing or removing vegetation essential to sage-grouse, invasive plants fragment existing sage-grouse habitat. They can create long-term changes in ecosystem processes, such as fire-cycles (see discussion under Fire below) and other disturbance regimes that persist even after an invasive plant is removed (Zouhar

et al.

2008, p. 33). A variety of nonnative annuals and perennials are invasive to sagebrush ecosystems (Connelly

et al.

2004, pp. 7-107 and 7-108; Zouhar

et al.

2008, p 144). Cheatgrass is considered most invasive in Wyoming big sagebrush communities (Connelly

et al.

2004, p. 5-9). Other invasive plants found within the range of Gunnison sage-grouse that are reported to take over large areas include: Spotted knapweed

(Centaurea maculosa),

Russian knapweed

(Acroptilon repens),

oxeye daisy

(Leucanthemum vulgare),

yellow toadflax

(Linaria vulgaris),

and field bindweed

(Convolvulus arvensis)

(BLM 2009, p. 28, 36; Gunnison Watershed Weed Commission (GWWC) 2009, pp. 4-6).

Although not yet reported to create large expanses in the range of Gunnison sage-grouse, the following weeds are also known from the species' range and have successfully invaded large expanses in other parts of western North America: Diffuse knapweed

(Centaurea diffusa),

whitetop

(Cardaria draba),

jointed goatgrass

(Aegilops cylindrica),

and yellow starthistle

(Centaurea solstitialis).

Other invasive plant species present within the range of Gunnison sage-grouse that are problematic yet less likely to overtake large areas include: Canada thistle

(Cirsium arvense),

musk thistle

(Carduus nutans),

bull thistle

(Cirsium vulgare),

houndstongue

(Cynoglossum officinale),

black henbane

(Hyoscyamus niger),

common tansy

(Tanacetum vulgare),

and absinth wormwood

(A. biennis)

(BLM 2009, p. 28, 36; GWWC 2009, pp. 4-6).

Cheatgrass impacts sagebrush ecosystems by potentially shortening fire intervals from several decades, depending on the type of sagebrush plant community and site productivity, to as low as 3 to 5 years, perpetuating its own persistence and intensifying the role of fire (Whisenant 1990, p. 4). Cheatgrass presence can shorten fire intervals to less than 10 years resulting in the elimination of shrub cover and reducing the availability and quality of forb cover (Connelly

et al.

2004, p. 7-5). As discussed in the climate change section below, temperature increases may increase the competitive advantage of cheatgrass in higher elevation areas (such as the range of the Gunnison sage-grouse) where its current distribution is limited (Miller

et al.

2011, pp. 181-183). Decreased summer precipitation reduces the competitive advantage of summer perennial grasses, reduces sagebrush cover, and subsequently increases the likelihood of cheatgrass invasion (Bradley 2009, pp. 202-204; Prevey

et al.

2009, p. 11). This change could increase the susceptibility of sagebrush areas in Utah and Colorado to cheatgrass invasion (Bradley 2009, p. 204).

A variety of restoration and rehabilitation techniques are used to treat invasive plants, but they can be costly and are mostly unproven and experimental at a large scale. In the last 100 years, no broad-scale cheatgrass eradication method has been developed. Habitat treatments that either disturb the soil surface or deposit a layer of litter increase cheatgrass establishment in the Gunnison Basin when a cheatgrass seed source is present (Sokolow 2005, p. 51). Therefore, researchers recommend using habitat treatment tools, such as brush mowers, with caution and suggest that treated sites should be monitored for increases in cheatgrass emergence (Sokolow 2005, p. 49).

Invasive Plants in the Gunnison Basin Population Area

—Quantifying the total amount of Gunnison sage-grouse habitat impacted by invasive plants is difficult due to differing sampling methodologies, incomplete sampling, inconsistencies in species sampled, and varying interpretations of what constitutes an infestation (Miller

et al.,

2011, pp. 155-156). Cheatgrass has invaded areas in Gunnison sage-grouse range, supplanting sagebrush habitat in some areas (BLM 2009, p. 60). However, we do not have a reliable estimate of the amount of area occupied by cheatgrass in the range of Gunnison sage-grouse. While not ubiquitous, cheatgrass is found at numerous locations throughout the Gunnison Basin (BLM 2009, p. 60). Cheatgrass infestation within a particular area can range from a small number of individuals scattered sparsely throughout a site, to complete or near-complete understory domination of a site. Cheatgrass has increased throughout the Gunnison Basin in the last decade and is becoming increasingly detrimental to sagebrush community types (BLM 2009, p. 7). Currently in the Gunnison Basin, cheatgrass attains site dominance most often along roadways; however, other highly disturbed areas have similar cheatgrass densities. Cheatgrass is currently present in almost every grazing allotment in Gunnison sage-grouse occupied habitat and other invasive plant species, such as Canada thistle, black henbane, spotted knapweed, Russian knapweed, Kochia, bull thistle, musk thistle, oxeye daisy, yellow toadflax and field bindweed, are found in riparian areas and roadsides throughout the Gunnison Basin (BLM 2009, p. 7).

Although disturbed areas most often contain the highest cheatgrass densities, cheatgrass can readily spread into less disturbed and even undisturbed habitat. A strong indicator for future cheatgrass invasion is the proximity to current locations (Bradley and Mustard 2006, p. 1146) as well as summer, annual, and spring precipitation, and winter temperature (Bradley 2009, p. 196). Although we lack the information to make a detailed determination on the actual extent or rate of increase, given its invasive nature, it appears that cheatgrass and its negative influence on Gunnison sage-grouse will increase in the Gunnison Basin in the future because of potential exacerbation from climate change interactions and the

limited success of broad-scale control efforts. Based on experience from other areas in sagebrush ecosystems concerning the rapid spread of cheatgrass and the shortened fire return intervals that can result, the spread of cheatgrass within Gunnison sage-grouse habitat and the likely negative effects to Gunnison sage-grouse populations will increase.

Invasive Plants in All Other Population Areas

—Cheatgrass is present throughout much of the current range in the San Miguel Basin (BLM 2005c, p. 6), but is most abundant in the Dry Creek Basin group (CDOW 2005, p. 101), which comprises 62 percent of the San Miguel Basin population. It is present in the five Gunnison sage-grouse subpopulations east of Dry Creek Basin, although at much lower densities that do not currently pose a serious threat to Gunnison sage-grouse (CDOW 2005, p. 101). Invasive species are present at low levels in the Monticello group (San Juan County GSGWG 2005, p. 20). However, there is no evidence that they are affecting the population.

Cheatgrass dominates 10-15 percent of the sagebrush understory in the current range of the Piñon Mesa population (Lambeth 2005, pers. comm.). It occurs in the lower elevation areas below Piñon Mesa that were formerly Gunnison sage-grouse range. Cheatgrass invaded two small prescribed burns in or near occupied habitat conducted in 1989 and 1998 (BLM 2005d, p. 6), and continues to be a concern with new ground-disturbing projects. Invasive plants, especially cheatgrass, occur primarily along roads, other disturbed areas, and isolated areas of untreated vegetation in the Crawford population. The threat of cheatgrass may be greater to sage-grouse than all other nonnative species combined and could be a major limiting factor when and if disturbance is used to improve habitat conditions, unless mitigated (BLM 2005c, p. 6).

Within the Piñon Mesa Gunnison sage-grouse population area, 520 ha (1,284 ac) of BLM lands are currently mapped with cheatgrass as the dominant species (BLM 2009, p. 3). This is not a comprehensive inventory of cheatgrass occurrence, as it only includes areas where cheatgrass dominates the plant community and does not include areas where the species is present at lower densities. Cheatgrass distribution has not been comprehensively mapped for the Monticello-Dove Creek population area; however, cheatgrass is beginning to be assessed on a site-specific and project-level basis. No significant invasive plant occurrences are currently known in the Poncha Pass population area.

Summary of Invasive Plants

Invasive plants negatively impact Gunnison sage-grouse primarily by reducing or eliminating native vegetation that sage-grouse require for food and cover, resulting in habitat loss and fragmentation. Although invasive plants, especially cheatgrass, have affected some Gunnison sage-grouse habitat, the impacts do not currently appear to be threatening individual populations or the species rangewide. However, invasive plants continue to expand their range, facilitated by ground disturbances such as fire, grazing, and human infrastructure. Climate change will likely alter the range of individual invasive species, increasing fragmentation and habitat loss of sagebrush communities. Even with treatments, given the history of invasive plants on the landscape, and our continued inability to control such species, invasive plants will persist and will likely continue to spread throughout the range of the species indefinitely. Therefore, invasive plants and associated increased fire risk will be on the landscape indefinitely. Although currently not a major threat to the persistence of Gunnison sage-grouse at the species level, we anticipate invasive species to become an increasing threat to the species in the future, particularly when considered in conjunction with future climate projections and potential changes in sagebrush plant community composition and dynamics.

Fire

The nature of historical fire patterns in sagebrush communities, particularly in Wyoming big sagebrush, is not well understood, and a high degree of variability likely occurred (Miller and Eddleman 2000, p. 16; Zouhar

et al.

2008, p. 154; Baker 2011, p. 195). In general, mean fire return intervals in low-lying, xeric (dry) big sagebrush communities range from over 100 to 350 years, and return intervals decrease from 50 to over 200 years in more mesic (wet) areas, at higher elevations, during wetter climatic periods, and in locations associated with grasslands (Baker 2006, p. 181; Mensing

et al.

2006, p. 75; Baker 2011, pp. 194-195; Miller

et al.

2011, p. 166).

Mountain big sagebrush, the most important and widespread sagebrush species for Gunnison sage-grouse, is killed by fire and can require decades to recover. In nesting and wintering sites, fire causes direct loss of habitat due to reduced cover and forage (Call and Maser 1985, p. 17). While there may be limited instances where burned habitat is beneficial, these gains are lost if alternative sagebrush habitat is not readily available (Woodward 2006, p. 65). As we describe above in the Current Distribution and Population Estimates section, little alternative habitat is available for Gunnison sage-grouse, so beneficial effects of fire are highly unlikely.

Herbaceous understory vegetation plays a critical role throughout the breeding season as a source of forage and cover for Gunnison sage-grouse females and chicks. The response of herbaceous understory vegetation to fire varies with differences in species composition, pre-burn site condition, fire intensity, and pre- and post-fire patterns of precipitation. In general, when not considering the synergistic effects of invasive species, any beneficial short-term flush of understory grasses and forbs is lost after only a few years and little difference is apparent between burned and unburned sites (Cook

et al.

1994, p. 298; Fischer

et al.

1996a, p. 196; Crawford 1999, p. 7; Wrobleski 1999, p. 31; Nelle

et al.

2000, p. 588; Paysen

et al.

2000, p. 154; Wambolt

et al.

2001, p. 250). In addition to altering plant community structure through shrub removal and potential weed invasion, fires can influence invertebrate food sources (Schroeder

et al.

1999, p. 5). However, because few studies have been conducted and the results of those available vary, the specific magnitude and duration of the effects of fire on insect communities is still uncertain.

The invasion of the exotic annual grass cheatgrass increases fire frequency within the sagebrush ecosystem (Zouhar

et al.

2008, p. 41; Miller

et al.

2011, p. 170). Cheatgrass readily invades sagebrush communities, especially disturbed sites, and changes historical fire patterns by providing an abundant and easily ignitable fuel source that facilitates fire spread. While sagebrush is killed by fire and is slow to reestablish, cheatgrass recovers within 1 to 2 years of a fire event (Young and Evans 1978, p. 285). This annual recovery leads to a readily burnable fuel source and ultimately a reoccurring fire cycle that prevents sagebrush reestablishment (Eiswerth

et al.

2009, p. 1324). The extensive distribution and highly invasive nature of cheatgrass poses substantial increased risk of fire and permanent loss of sagebrush habitat, as areas disturbed by fire are highly susceptible to further invasion and ultimately habitat conversion to an altered community state. For example, Link

et al.

(2006, p. 116) show that risk of fire increases from approximately 46

to 100 percent when ground cover of cheatgrass increases from 12 to 45 percent or more. We do not have a reliable estimate of the amount of area occupied by cheatgrass in the range of Gunnison sage-grouse. However, cheatgrass is found at numerous locations throughout the Gunnison Basin (BLM 2009, p. 60).

A clear positive response of Gunnison or greater sage-grouse to fire has not been demonstrated (Braun 1998, p. 9). The few studies that have suggested fire may be beneficial for greater sage-grouse were primarily conducted in mesic areas used for brood-rearing (Klebenow 1970, p. 399; Pyle and Crawford 1996, p. 323; Gates 1983,

Connelly

et al.

2000c, p. 90; Sime 1991,

Connelly

et al.

2000a, p. 972). In this type of habitat, small fires may maintain a suitable habitat mosaic by reducing shrub encroachment and encouraging understory growth. However, without available nearby sagebrush cover, the utility of these sites is questionable, especially within the six small Gunnison sage-grouse populations where fire could further degrade and fragment the remaining habitat.

Fire in the Gunnison Basin Population Area

—Six prescribed burns have occurred on BLM lands in the Gunnison Basin since 1984, totaling approximately 409 ha (1,010 ac) (BLM 2009, p. 35). The fires created large sagebrush-free areas that were further degraded by poor post-burn livestock management (BLM 2005a, p. 13). As a result, these areas are no longer suitable as Gunnison sage-grouse habitat. Approximately 8,470 ha (20,930 ac) of prescribed burns occurred on Forest Service lands in the Gunnison Basin since 1983 (USFS 2009, p. 1). A small wildfire on BLM lands near Hartman Rocks burned 8 ha (20 ac) in 2007 (BLM 2009, p. 35). The total area of occupied Gunnison sage-grouse habitat burned in recent decades is approximately 8,887 ha (21,960 ac), which constitutes 1.5 percent of the occupied Gunnison sage-grouse habitat area. Cumulatively, this area equates to a relatively small amount of habitat burned over a period of nearly three decades. This information suggests that there has not been a demonstrated change in fire cycle in the Gunnison Basin population area to date.

Fire in All Other Population Areas

—Two prescribed burns conducted in 1986 (105 ha (260 ac)) and 1992 (140 ha (350 ac)) on BLM land in the San Miguel Basin on the north side of Dry Creek Basin had negative impacts on sage-grouse. The burns were conducted for big game forage improvement, but the sagebrush died and was largely replaced with weeds (BLM 2005b, pp. 7-8). The Burn Canyon fire in the Dry Creek Basin and Hamilton Mesa areas burned 890 ha (2,200 ac) in 2000. Three fires have occurred in Gunnison sage-grouse habitat since 2004 on lands managed by the BLM in the Crawford, Cerro Summit-Cimarron-Sims Mesa, and San Miguel Basin population areas. There have been no fires since 2004 on lands managed by the BLM within the Monticello-Dove Creek population. Because these fires were mostly small in size, we do not believe they resulted in substantial impacts to Gunnison sage-grouse.

Several wildfires near or within the Piñon Mesa population area have occurred in the past 20 years. One fire burned a small amount of occupied Gunnison sage-grouse habitat in 1995, and several fires burned in potential Gunnison sage-grouse habitat. Individual burned areas ranged from 3.6 ha (9 ac) to 2,160 ha (5,338 ac). A wildfire in 2009 burned 1,053 ha (2,602 ac), predominantly within vacant or unknown Gunnison sage-grouse habitat (suitable habitat for sage-grouse that is separated from occupied habitats that has not been adequately inventoried, or without recent documentation of grouse presence) near the Piñon Mesa population. Since 2004, a single 2.8-ha (7-ac) wildfire occurred in the Cerro Summit-Cimarron-Sims Mesa population area, and two prescribed fires, both less than 12 ha (30 ac), were implemented in the San Miguel population area. There was no fire activity within occupied Gunnison sage-grouse habitat in the last two decades in the Poncha Pass population area (CDOW 2009b, pp. 125-126) or the Monticello-Dove Creek population area (CDOW 2009b, p. 75; UDWR 2009, p. 5). Because fires have burned primarily outside of occupied Gunnison sage-grouse habitat in the Piñon Mesa population area and fire has been recently absent or minimal in most other population areas, fire has not resulted in substantial impacts to Gunnison sage-grouse in these population areas.

Summary of Fire

Fires can cause the proliferation of weeds and can degrade suitable sage-grouse habitat, which may not recover to suitable conditions for decades, if at all (Pyke 2011, p. 539). Recent fires in Gunnison sage-grouse habitat were mostly small in size and did not result in substantial impacts to Gunnison sage-grouse, and there has been no obvious change in fire cycle in any Gunnison sage-grouse population area to date. Therefore, we do not consider fire to be a threat to the persistence of Gunnison sage-grouse at this time. We do not have the information to predict the extent or location of future fire events. However, the best available data indicates that fire frequency may increase in the future as cheatgrass continues to encroach on the sagebrush habitat and with the projected effects of climate change (see Invasive Plants and Climate Change discussions, above and below, respectively). Fire is, therefore, likely to become a threat to the persistence of Gunnison sage-grouse in the future.

Climate Change

Our analyses under the Endangered Species Act include consideration of ongoing and projected changes in climate. The terms “climate” and “climate change” are defined by the Intergovernmental Panel on Climate Change (IPCC). “Climate” refers to the mean and variability of different types of weather conditions over time, with 30 years being a typical period for such measurements, although shorter or longer periods also may be used (IPCC 2007, p. 78). The term “climate change” thus refers to a change in the mean or variability of one or more measures of climate (e.g., temperature or precipitation) that persists for an extended period, typically decades or longer, whether the change is due to natural variability, human activity, or both (IPCC 2007, p. 78). Various types of changes in climate can have direct or indirect effects on species. These effects may be positive, neutral, or negative and they may change over time, depending on the species and other relevant considerations, such as the effects of interactions of climate with other variables (e.g., habitat fragmentation) (IPCC 2007, pp. 8-14, 18-19). In our analyses, we use our expert judgment to weigh relevant information, including uncertainty, in our consideration of various aspects of climate change.

According to the Intergovernmental Panel on Climate Change (IPCC), “Warming of the climate system in recent decades is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global sea level” (IPCC 2007, p. 1). Average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than during any other 50-year period in the last 500 years and likely the highest in at least the past 1,300 years (IPCC 2007, p. 30). Over the past 50 years cold days, cold nights, and frosts have become less frequent over most land areas, and hot days and hot nights have become more

frequent. Heat waves have become more frequent over most land areas, and the frequency of heavy precipitation events has increased over most areas (IPCC 2007, p. 30).

For the southwestern region of the United States, including western Colorado, warming is occurring more rapidly than elsewhere in the country (Karl

et al.

2009, p. 129). Annual average temperature in west-central Colorado increased 3.6 °C (2 °F) over the past 30 years, but high variability in annual precipitation precludes the detection of long-term precipitation trends (Ray

et al.

2008, p. 5). Under high greenhouse gas emission scenarios, future projections for the southwestern United States show increased probability of drought (Karl

et al.

2009, pp. 129-134) and the number of days over 32 °C (90 °F) could double by the end of the century (Karl

et al.

2009, p. 34). Climate models predict annual temperature increase of approximately 2.2 °C (4 °F) in the Southwest by 2050, with summers warming more than winters (Ray

et al.

2008, p. 29). Projections also show declines in snowpack across the West with the most dramatic declines at lower elevations (below 2,500 m (8,200 ft)) (Ray

et al.,

p. 29).

Colorado's complex, mountainous topography results in a high degree of spatial variability across the State. As a result, localized climate projections are problematic for mountainous areas because current global climate models are unable to capture this variability at local or regional scales (Ray

et al.

2008, pp. 7, 20). To obtain climate projections specific to the range of Gunnison sage-grouse, we requested a statistically downscaled model from the National Center for Atmospheric Research for a region covering western Colorado. The resulting projections indicate the highest probability scenario is that average summer (June through September) temperature could increase by 2.8 °C (5.1 °F), and average winter (October through March) temperature could increase by 2.2 °C (4.0 °F) by 2050 (University Corporation for Atmospheric Research (UCAR) 2009, pp. 1-15). Annual mean precipitation projections for Colorado are unclear; however, multimodel averages show a shift towards increased winter precipitation and decreased spring and summer precipitation (Ray

et al.

2008, p. 34; Karl

et al.

2009, p. 30). Similarly, the multimodel averages show the highest probability of a 5 percent increase in average winter precipitation and a 5 percent decrease in average spring-summer precipitation in 2050 (UCAR 2009, p. 15). It is unclear at this time whether or not the year 2050 predicted changes in precipitation and temperature will be of enough magnitude to significantly alter sagebrush plant community composition and dynamics.

For sagebrush, spring and summer precipitation comprises the majority of the moisture available to the species; thus, the interaction between reduced precipitation in the spring-summer growing season and increased summer temperatures will likely decrease growth of mountain big sagebrush. This could result in a significant long-term reduction in the distribution of sagebrush communities (Miller

et al.

2011, pp. 171-174). In the Gunnison Basin, increased summer temperature was strongly correlated with reduced growth of mountain big sagebrush (Poore

et al.

2009, p. 558). Based on these results and the likelihood of increased winter precipitation falling as rain rather than snow and the corresponding increase in evaporation and decrease in deep soil water recharge, Poore

et al

(2009, p. 559) predict decreased growth of mountain big sagebrush, particularly at the lower elevation limit of the species. Because Gunnison sage-grouse are sagebrush obligates, loss of sagebrush would result in a reduction of suitable habitat and negatively impact the species. The interaction of climate change with other stressors likely has impacted and will impact the sagebrush steppe ecosystem within which Gunnison sage-grouse occur.

Climate change is likely to alter fire frequency, community assemblages, and the ability of nonnative species to proliferate. Increasing temperature as well as changes in the timing and amount of precipitation will alter the competitive advantage among plant species (Miller

et al.

2011, pp. 175-179), and may shift individual species and ecosystem distributions (Bachelet

et al.

2001, p. 174). Temperature increases may increase the competitive advantage of cheatgrass in higher elevation areas where its current distribution is limited (Miller

et al.

2011, p. 182). Decreased summer precipitation reduces the competitive advantage of summer perennial grasses, reduces sagebrush cover, and subsequently increases the likelihood of cheatgrass invasion (Prevey

et al.

2009, p. 11). This impact could increase the susceptibility of areas within Gunnison sage-grouse range to cheatgrass invasion (Bradley 2009, p. 204), which would reduce the overall cover of native vegetation, reduce habitat quality, and potentially decrease fire return intervals, all of which would negatively affect the species.

Under drought conditions, plants generally are less vigorous and less successful in reproduction and may require several years to recover following drought (Weltzin

et al.

2003, p. 946). Increased drought and shifts in the magnitude and timing of temperature and precipitation could reduce herbaceous and insect production within Gunnison sage-grouse habitats. A recent climate change vulnerability index applied to Gunnison sage-grouse ranked the species as “highly vulnerable” to modeled climate change by the year 2050 (The Nature Conservancy 2011, p. 11). The mechanism of this vulnerability was considered to be the degradation of high-quality brood-rearing habitat due to the loss of adequate moisture to maintain mesic meadows, springs, seeps, and riparian areas, as well as potential changes in the fire regime and subsequent loss of sagebrush cover. A reduction in the quality and amount of these resources will likely affect key demographic processes such as the productivity of breeding hens and survival of chicks and result in reduced population viability. The drought conditions from 1999 through 2003 were closely associated with reductions in the sizes of all populations, although population estimates did recover to pre-drought levels in some populations (CDOW 2009, entire). The small sizes of six of seven Gunnison sage-grouse populations make them particularly sensitive to stochastic fluctuations, and these fluctuations are exacerbated by drought (GSRSC 2005, p. G-22).

Summary of Climate Change

Climate change predictions are based on models with assumptions, and there are uncertainties regarding the magnitude of associated climate change parameters such as the amount and timing of precipitation and seasonal temperature changes. There is also uncertainty as to the magnitude of effects of predicted climate parameters on sagebrush plant community dynamics. These factors make it difficult to predict whether or to what extent climate change will affect Gunnison sage-grouse. We recognize that climate change has the potential to alter Gunnison sage-grouse habitat by facilitating an increase in the distribution of cheatgrass and concurrently increasing the potential for wildfires, and reducing herbaceous vegetation and insect production in drought years, which would have negative effects on Gunnison sage-grouse. We do not consider climate change to be a threat to the persistence of Gunnison sage-grouse at this time

because of the uncertainties described above. However, based on the best available information on climate change projections into the next 40 years, climate change has the potential to alter the distribution and extent of cheatgrass and sagebrush and associated fire frequencies, and key seasonal Gunnison sage-grouse food resources, and, therefore, is likely to become an increasingly important threat to the persistence of Gunnison sage-grouse.

Renewable Energy Development—Geothermal, Wind, Solar

Geothermal Energy Development

—Geothermal energy production is similar to oil and gas development in that it requires surface exploration, exploratory drilling, field development, and plant construction and operation and likely results in similar degrees of direct and functional habitat loss. Wells are drilled to access the thermal source. This can require 3 weeks to 2 months of continuous drilling (Suter 1978, p. 3), which may cause disturbance to sage-grouse. The ultimate number of wells, and, therefore, potential loss of habitat, depends on the thermal output of the source and expected production of the plant (Suter 1978, p. 3). Pipelines are needed to carry steam or superheated liquids to the generating plant, which is similar in size to a coal- or gas-fired plant, resulting in further habitat destruction and indirect disturbance. Direct habitat loss occurs from well pads, structures, roads, pipelines and transmission lines, and impacts would be similar to those described below for oil and gas development. The development of geothermal energy requires intensive human activity during field development and operation, which could lead to habitat loss. Furthermore, geothermal development could cause toxic gas release. The type and effect of these gases depends on the geological formation in which drilling occurs (Suter 1978, pp. 7-9). The amount of water necessary for drilling and condenser cooling may be high. Local water depletions may be a concern if such depletions result in the loss or degradation of brood-rearing habitat.

Geothermal Energy in the Gunnison Basin Population Area

—Approximately 87 percent of the entire occupied range of Gunnison sage-grouse, including the entire Gunnison Basin, is within a region of known geothermal potential (BLM and USFS 2010, p. 1). We have no information on the presence of active geothermal energy generation facilities; however, we are aware of three current applications for geothermal leases within the range of Gunnison sage-grouse. All of the applications are located in the Gunnison Basin in the same general vicinity on private, BLM, USFS, and Colorado State Land Board lands near Tomichi Dome and Waunita Hot Springs in southeastern Gunnison County. The cumulative area of the geothermal lease application parcels is approximately 4,061 ha (10,035 ac), of which approximately 3,802 ha (9,395 ac) is occupied Gunnison sage-grouse habitat, or approximately 2 percent of the Gunnison Basin population area.

One active lek and two inactive leks are located within the lease application parcels. In addition, six active leks and four inactive leks are within 6.4 km (4 mi) of the lease application parcels indicating that a high degree of seasonal use may occur within the area surrounding these leks (GSRSC 2005, p. J-4). There are 74 active leks in the Gunnison Basin population, so approximately 10 percent of active leks may be affected. A significant amount of high-quality Gunnison sage-grouse nesting habitat also exists on and near the lease application parcels (Aldridge

et al.

2011, p. 9). If geothermal development occurs on the lease application parcels, it would likely negatively impact Gunnison sage-grouse through the direct loss of habitat and the functional loss of habitat resulting from increased human activity in the area. However, we cannot determine the potential extent of the impacts of such development at this time because the size and location of potential geothermal energy generation infrastructure and final resource protection conditions currently are unknown, nor do we know where potential geothermal developments might occur.

Geothermal Energy in All Other Population Areas

—We could find no information on the presence of existing, pending, or authorized geothermal energy sites, nor any other areas with high potential for geothermal energy development, within any other Gunnison sage-grouse population area.

Wind Energy Development

—Most published reports of the effects of wind development on birds focus on the risks of collision with towers or turbine blades. No published research is specific to the effects of wind farms on Gunnison or greater sage-grouse. However, the avoidance of human-made structures such as powerlines and roads by sage-grouse and other prairie grouse is documented (Holloran 2005, p. 1; Pruett

et al.

2009, pp. 1255-1256). Renewable energy facilities, including wind power, typically require many of the same features for construction and operation as do nonrenewable energy resources. Therefore, we anticipate that potential impacts from direct habitat losses, habitat fragmentation through roads and powerlines, noise, and increased human presence (Connelly

et al.

2004, pp. 7-40 to 7-41) will generally be similar to those discussed below for nonrenewable energy development.

Wind farm development begins with site monitoring and collection of meteorological data to accurately characterize the wind regime. Turbines are installed after the meteorological data indicate the appropriate siting and spacing. Roads are necessary to access the turbine sites for installation and maintenance. Each turbine unit has an estimated footprint of 0.4 to 1.2 ha (1 to 3 ac) (BLM 2005e, pp. 3.1-3.4). One or more substations may be constructed depending on the size of the farm. Substation footprints are 2 ha (5 ac) or less in size (BLM 2005e, p. 3.7).

The average footprint of a turbine unit is relatively small from a landscape perspective. Turbines require careful placement within a field to avoid loss of output from interference with neighboring turbines. Spacing improves efficiency but expands the overall footprint of the field. Sage-grouse populations are impacted by the direct loss of habitat, primarily from construction of access roads as well as indirect loss of habitat due to avoidance of the wind turbines. Sage-grouse could be killed by flying into turbine rotors or towers (Erickson

et al.

2001, entire), although reported collision mortalities have been few. One sage-grouse was found dead within 45 m (148 ft) of a turbine on the Foote Creek Rim wind facility in south-central Wyoming, presumably from flying into a turbine (Young

et al.

2003, Appendix C, p. 61). This is the only known sage-grouse mortality at this facility during three years of monitoring. We have no recent reports of sage-grouse mortality due to collision with a wind turbine; however, many facilities may not be monitored. No deaths of gallinaceous birds were reported in a comprehensive review of avian collisions and wind farms in the United States; the authors hypothesized that the average tower height and flight height of grouse, and diurnal migration habitats of some birds minimized the risk of collision (Johnson

et al.

2000, pp. ii-iii; Erickson

et al.

2001, pp. 8, 11, 14, 15).

Noise is produced by wind turbine mechanical operation (gear boxes, cooling fans) and airfoil interaction with the atmosphere. No published studies have focused specifically on the effects of wind power noise and Gunnison or greater sage-grouse. In studies

conducted in oil and gas fields, noise may have played a factor in habitat selection and decrease in greater sage-grouse lek attendance (Holloran 2005, pp. 49, 56). However, comparison between wind turbine and oil and gas operations is difficult based on the character of sound. Adjusting for manufacturer type and atmospheric conditions, the audible operating sound of a single wind turbine has been calculated as the same level as conversational speech at 1 m (3 ft) at a distance of 600 m (2,000 ft) from the turbine. This level is typical of background levels of a rural environment (BLM 2005e, p. 5-24). However, commercial wind farms do not have a single turbine, and multiple turbines over a large area would likely have a much larger noise print. Low-frequency vibrations created by rotating blades also produce annoyance responses in humans (van den Berg 2003, p. 1), but the specific effect on birds is not documented.

Moving blades of turbines cast moving shadows that cause a flickering effect producing a phenomenon called “shadow flicker” (AWEA 2008, p. 5-33). Shadow flicker could mimic predator shadows and elicit an avoidance response in birds during daylight hours, but this potential effect has not been investigated. However, greater sage-grouse hens with broods have been observed under turbines at Foote Creek Rim (Young 2004, pers. comm.).

Wind Energy in the Monticello Subpopulation Area

—There appears to be an increasing interest in wind energy development in the vicinity of the Monticello subpopulation as two energy development companies have recently leased private properties for wind turbine construction (UDWR 2011, p. 3). We have no further information on potential plans for development, or the size or scope of any planned development. A 388-ha (960-ac) wind energy generation facility is also authorized on BLM lands in San Juan County, UT. However, the authorized facility is approximately 12.9 km (8 mi) from the nearest lek in the Monticello subpopulation.

The State of Utah recently completed a statewide screening study to identify geographic areas with a high potential for renewable energy development (UDNR 2009, entire). An approximately 80,200-ha (198,300-ac) area northwest of the city of Monticello, UT, was identified, with a high level of confidence, as a wind power production zone with a high potential for utility-scale wind development (production of greater than 500 megawatts) (UDNR 2009, p. 19). The mapped wind power production zone overlaps with nearly all Gunnison sage-grouse occupied habitat in the Monticello subpopulation, as well as the large area surrounding the perimeter of occupied habitat. The Monticello subpopulation is currently small (approximately 100 individuals).

Wind Energy in All Other Population Areas

—We could find no information on the presence of existing, pending, or authorized wind energy sites, or any other areas with high potential for wind energy development within any other Gunnison sage-grouse population area.

Solar Energy Development

—Current information does not indicate that solar energy development is under consideration in the Gunnison sage-grouse range, and, therefore, there is no information indicating that the species may be exposed to any threats posed by such development.

Summary of Renewable Energy Development

Because of the lack of information on future development, we do not consider renewable energy development to be a threat to the persistence of Gunnison sage-grouse at this time. However, geothermal energy development could increase in the Gunnison Basin in the future and could (depending on the level of development and minimization and mitigation measures) influence the overall long-term viability of the Gunnison Basin population. Similarly, wind energy development could increase in the future in the Monticello subpopulation, which may lead to further population declines in this already small population and could lead to the extirpation of this subpopulation. Because we have no information indicating the presence of existing, pending, or authorized solar energy sites, nor any solar energy study areas within the range of Gunnison sage-grouse, we do not consider solar energy to be a threat to Gunnison sage-grouse.

Nonrenewable Energy Development

Energy development on Federal (BLM and USFS) lands is regulated by the BLM and can contain conservation measures for wildlife species (see Factor D for a more thorough discussion). The BLM (1999a, p. 1) has classified the area encompassing all Gunnison sage-grouse habitat for its gas and oil potential. Two populations have areas with high oil and gas development potential (San Miguel Basin, Monticello-Dove Creek) or medium (Crawford) oil and gas potential

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