Federal Register: April 18, 2006 (Volume 71, Number 74)
DOCID: FR Doc 06-3619
DEPARTMENT OF THE INTERIOR
Veterans Affairs Department
CFR Citation: 50 CFR Part 17
NOTICE: Part III
DOCUMENT ACTION: Final listing determination.
Endangered and Threatened Wildlife and Plants; Final Listing Determination for the Gunnison Sage-Grouse as Threatened or Endangered
DATES: The determination announced in this document was made on April 11, 2006. Although further listing action will not result from this determination, we request that you submit new information concerning the status of or threats to this species whenever it becomes available.
We, the U.S. Fish and Wildlife Service (Service), announce a final listing determination for the Gunnison sagegrouse (Centrocercus minimus) as threatened or endangered under the Endangered Species Act of 1973, as amended (Act). After reviewing the best available scientific and commercial information, we find that listing is not warranted. Thus, we no longer consider the species to be a candidate for listing. We ask the public to submit to us any new information that becomes available concerning the status of or threats to the species. This information will help us monitor and encourage the conservation of this species.
Interior Department, Fish and Wildlife Service,
Previous Federal Action
On January 18, 2000, the Director of the Service designated the Gunnison sagegrouse as a candidate species under the Act, with a listing priority of 5. The Federal Register notice regarding this decision was not published until December 28, 2000 (65 FR 82310, December 28, 2000). Candidates are species for which the Service has determined that the species warrants listing as a threatened or endangered species, but listing is precluded by higher listing priorities for other species. A listing priority of 5 indicates that there is a high magnitude of threats, but they are considered non imminent.
On January 26, 2000, The American Lands Alliance, Biodiversity Legal Foundation, and others petitioned the Service to list the species (Webb 2000). On January 10, 2001, some of the same plaintiffs sued the Service alleging the Service had not made required petition findings. In 2003, the U.S. District Court ruled that the Service's determination that the Gunnison sagegrouse was a candidate constituted a 12month finding on the petition (American Lands Alliance v. Gale A. Norton, C.A. No. 002339, (D.D.C., 2003).
The 2003 Candidate Notice of Review elevated the species' listing priority number to 2 (69 FR 24876), as the imminence of the perceived threats had increased. The 2004 Candidate Notice of Review (70 FR 24870) maintained the listing priority number as a 2.
Plaintiffs amended their complaint in May 2004 to allege that the Service's warrantedbutprecluded finding and decision not to emergency list the Gunnison sagegrouse were in violation of the Act. The parties filed a stipulated settlement agreement with the court on November 14, 2005, which includes a provision that the Service would make a listing determination by March 31, 2006. On March 28, 2006, the plaintiffs agreed to a one week extension (April 7, 2006) for this determination.
Section 4(b)(1)(A) of the Act requires us to consider the best scientific and commercial data available as well as efforts being made by States or other entities to protect a species when making a listing decision. To meet this standard we collected information on the Gunnison sagegrouse, its habitats, threats, and environmental factors affecting the species from a wide array of sources. Most of the available scientific literature on Gunnison sagegrouse is summarized in the Gunnison Sagegrouse Rangewide Conservation Plan, a document published in April 2005 under the auspices of the Gunnison Sagegrouse Rangewide Steering Committee [GSRSC]. The GSRSC is comprised of biologists from state and Federal agencies with responsibility for managing the Gunnison sagegrouse or its habitat. The scientific literature on Gunnison sagegrouse and its sagebrush habitats is limited. Where information on Gunnison sagegrouse life history was lacking, we used, as appropriate information on greater sagegrouse to analyze habitat usage, threats, and environmental factors affecting the Gunnison sagegrouse. In addition we received a substantial amount of unpublished information from other Federal agencies, States, counties, environmental organizations, and individuals. We also solicited information on all Federal, State, or local conservation efforts currently in operation or planned for the Gunnison sagegrouse or its habitats.
In April 2005, Colorado Division of Wildlife (CDOW) applied to the
Service for a Gunnison sagegrouse Enhancement of Survival Permit
pursuant to section 10(a)(1)(A) of the Act. The permit application
included a proposed Candidate Conservation Agreement with Assurances
(CCAA) between CDOW and the Service. The standard that a CCAA must meet
is that the benefits of the conservation measures implemented 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. The CCAA, the permit application, and the Environmental
Assessment were made available for public comment on July 6, 2005 (70
FR 38977). Public comments and other internal comments from the Service
and CDOW were incorporated into revisions of the CCAA and Environmental
Assessment; the documents are scheduled to be finalized shortly.
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. These participants provide
certain Gunnison sagegrouse habitat protection or enhancement measures
on their lands. If the Gunnison sagegrouse is listed under the Act,
the permit authorizes incidental take of Gunnison sagegrouse due to
otherwise lawful activities 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 activities identified in
the Certificate of Inclusion. Although we strongly encourage continued conservation of the Gunnison sage
grouse, we did not rely upon this CCAA to support our listing determination.
In this determination, we use information specific to the Gunnison sagegrouse where available. However, where such information is lacking we use information on life history, habitat requirements, and effects of threats on greater sagegrouse. Except where referenced, the following life history information is taken from the Schroeder et al. (1999) literature review on sagegrouse (Centrocercus spp.).
The sagegrouse is the largest grouse in North America and was first described by Lewis and Clark in 1805 (Schroeder et al. 1999). Sagegrouse are most easily identified by their large size, dark brown color, distinctive black bellies, long, pointed tails and association with sagebrush habitats. They are dimorphic in size, with females being smaller. Both sexes have yellowgreen eye combs, which are less prominent in females. Sagegrouse are known for their elaborate mating ritual where males congregate on strutting grounds called leks and ``dance'' to attract a mate. During the breeding season males have conspicuous filoplumes (specialized erectile feathers on the neck), and exhibit yellowgreen apteria (fleshy bare patches of skin) on their breasts (Schroeder et al. 1999).
For many years sagegrouse were considered a single species. Young et al. (2000) identified Gunnison sagegrouse (Centrocercus minimus) as a distinct species based on morphological (Hupp and Braun 1991; Young et al. 2000), genetic (Kahn et al. 1999; OylerMcCance et al. 1999), and behavioral (Barber 1991; Young 1994; Young et al. 2000) differences and geographical isolation. Based on these differences, the American Ornithologist's Union (2000) accepted the Gunnison sagegrouse as a distinct species. The current ranges of the two species are not overlapping (Schroeder et al. 2004). We have considered the Gunnison sagegrouse as a distinct species consistent with the petition under review here. We acknowledge that there are questions regarding the validity of this taxon, however it is not the purpose of this action to elucidate taxonomic questions. The purpose of this action is to determine the status of the taxon within the context of the ESA.
Gunnison sagegrouse and greater sagegrouse have similar life histories and habitat requirements (Young 1994). Nesting success for Gunnison sagegrouse is highest in areas where forbs and grass covers are found below a sagebrush canopy cover of 15 to 30 percent (Young et al. 2000). These numbers are comparable to those reported for the greater sagegrouse (Connelly et al. 2000a). Connelly et al. (2000a) also state that nest success for greater sagegrouse is greatest where grass cover is present. Therefore, factors identified in the greater sagegrouse literature that affect nesting habitat quality can affect Gunnison sagegrouse nesting habitat in a similar manner if those factors occur within the range of the Gunnison sagegrouse. Characteristics of sagegrouse winter habitats are also similar through the range of both species (Connelly et al. 2000a). In winter, Gunnison sagegrouse are restricted to areas of 15 to 30 percent sagebrush cover, similar to the greater sagegrouse (Connelly et al. 2000a; Young et al. 2000). However, they may also use areas with more deciduous shrubs during the winter (Young et al. 2000).
Dietary requirements of the two species also are similar, being composed of nearly 100 percent sagebrush in the winter (Schroeder et al. 1999; Young et al. 2000). Forbs and insects are important during the summer and early fall. Gunnison and greater sagegrouse do not possess muscular gizzards and, therefore, lack the ability to grind and digest seeds (Rasmussen and Griner 1938; Leach and Hensley 1954). Gunnison sagegrouse chick dietary requirements of insects and forbs also are expected to be similar to greater sagegrouse and other grouse species (Tony Apa, CDOW, pers. comm. 2005).
In the spring, sagegrouse gather on traditional breeding areas
referred to as leks (Patterson 1952). Lek displaying occurs from mid
March through late May, depending on elevation (Rogers 1964). For
Gunnison sagegrouse, 87 percent of all nests were located less than 6
kilometers (km) (4 miles (mi)) from the lek of capture (Apa 2004). Mean
clutch size for Gunnison sagegrouse is 6.8
During the preegg laying period, female sagegrouse select forbs that have generally higher amounts of calcium and crude protein than sagebrush has (Barnett and Crawford 1994). Chicks are precocial and leave the nest with the hen shortly after hatching. Females with chicks move to areas containing succulent forbs and insects, often in wet meadow habitat, where cover is sufficiently tall to conceal broods and provide shade. The availability of food and cover are key factors that affect chick and juvenile survival. During the first 3 weeks after hatching, insects are the primary food of chicks (Patterson 1952; Klebenow and Gray 1968; Peterson 1970; Johnson and Boyce 1990; Johnson and Boyce 1991; Drut et al. 1994b; Pyle and Crawford 1996; Fischer et al. 1996b). Diets of 4 to 8weekold greater sagegrouse chicks were found to have more plant material (Peterson 1970). Succulent forbs are predominant in the diet until chicks exceed 3 months of age, at which time sagebrush becomes a major dietary component (Klebenow 1969; Connelly and Markham 1983; Connelly et al. 1988; Fischer et al. 1996b).
During late summer and early fall, intermixing of broods and flocks of adult birds is common and the birds move from riparian areas to sagebrushdominated landscapes that continue to provide green forbs. From late autumn through early spring the diet of greater and Gunnison sagegrouse is almost exclusively sagebrush (Rasmussen and Griner 1938; Batterson and Morse 1948; Patterson 1952; Leach and Hensley 1954; Barber 1968; Wallestad et al. 1975; Young et al. 2000). Many species of sagebrush can be consumed (Remington and Braun 1985; Welch et al. 1988, 1991; Myers 1992). Flock size in winter is variable (15 to 100+), and flocks frequently consist of a single sex (Beck 1977; Hupp 1987). During particularly severe winters, sagegrouse are dependent on tall sagebrush, which is exposed even above deep snow, providing a consistently available food source. In response to severe winters, Gunnison sagegrouse have been documented to move as far as 27 km (17 mi) (Root 2002). The extent of movement varies with severity of winter weather, topography, and vegetation cover. Sagegrouse may travel short distances or many miles between seasonal ranges. Movements in fall and early winter (SeptemberDecember) exceed 3 km (2 mi).
In one study, Gunnison sagegrouse survival from April 2002 through
March 2003 was 48 (
Sagegrouse are sagebrush obligates (Patterson 1952; Connelly et al. 2000a). They depend on a variety of shrubsteppe habitats throughout their life cycle and are considered obligate users of several species of sagebrush (Patterson 1952; Braun et al. 1976; Schroeder et al. 1999; Connelly et al. 2000a; Connelly et al. 2004). Sagebrush serves as a primary food for adults yearround (Wallestad et al. 1975) and also provides cover for nests (Connelly et al. 2000a). Sagegrouse move between seasonal ranges based on suitable habitat availability. Connelly et al. (2000a) segregated habitat requirements into four seasons: (1) Breeding; (2) summerlate broodrearing; (3) fall; and (4) winter. Depending on habitat availability and proximity, some seasonal habitats may be indistinguishable.
Breeding habitat includes leks and prelaying, nesting, and early broodrearing areas. Male Gunnison sagegrouse attend leks from mid March to midMay. Leks are typically in the same location from year to year; some Gunnison sagegrouse leks have been used since the 1950s (Rogers 1964). Leks are usually flat to gently sloping areas of less than 15 percent grade in broad valleys or on ridges (Hanna 1936; Patterson 1952; Giezentanner and Clark 1974; Wallestad 1975; Autenrieth 1981; Klott and Lindzey 1989). Leks have good visibility and low vegetation structure (Tate et al. 1979; Connelly et al. 1981; Gates 1985), and acoustical qualities that allow sounds of breeding displays to carry (Patterson 1952; Wiley 1973, 1974; Bergerud 1988; Phillips 1990). Leks are often surrounded by denser shrubsteppe cover, which is used for escape, thermal, and feeding cover. Leks can be formed opportunistically at any appropriate site within or adjacent to nesting habitat (Connelly et al. 2000a) and, therefore, lek habitat availability is not considered to be a limiting factor for sagegrouse (Schroeder 1997). A relatively small number of dominant males accounts for the majority of breeding on each lek (Schroeder et al. 1999).
The prelaying period is from lateMarch to April. Prelaying habitats for sagegrouse need to provide a diversity of vegetation including forbs that are rich in calcium, phosphorous, and protein to meet the nutritional needs of females during the egg development period (Barnett and Crawford 1994; Connelly et al. 2000a).
Nesting occurs from midApril to June. Gunnison sagegrouse typically select nest sites under sagebrush cover with some forb and grass cover (Young 1994), and successful nests were found in higher shrub density and greater forb and grass cover than unsuccessful nests (Young 1994). The sagebrush understory of productive sagegrouse nesting areas contains native grasses and forbs, with horizontal and vertical structural diversity that provides an insect prey base, herbaceous forage for prelaying and nesting hens, and cover for the hen while she is incubating (Schroeder et al. 1999; Connelly et al. 2000a; Connelly et al. 2004). Shrub canopy and grass cover provide concealment for sagegrouse nests and young, and are critical for reproductive success (Barnett and Crawford 1994; Gregg et al. 1994; DeLong et al. 1995; Connelly et al. 2004). Few herbaceous plants are growing in April when nesting begins, so residual herbaceous cover from the previous growing season is critical for nest concealment in most areas (Connelly et al. 2000a).
Young (1994) found that radiotracked Gunnison sagegrouse nested an average of 4.3 km (2.7 mi) from the lek nearest to their capture site, with almost half nesting within 3 km (2 mi) of their capture site. While earlier studies indicated that most greater sagegrouse hens nest within 3 km (2 mi) of a lek, more recent research indicated that many hens actually move much further from leks to nest based on nesting habitat quality (Connelly et al. 2004). Female sagegrouse have been documented to travel more than 20 km (13 mi) to their nest site after mating (Connelly et al. 2000a). Female Gunnison and greater sage grouse exhibit fidelity to nesting locations (Connelly et al. 1988; Young 1994; Lyon 2000, Connelly et al. 2004, Holloran and Anderson 2005). The degree of fidelity to a specific nesting area appears to diminish if the female's first nest attempt in that area was unsuccessful (Young 1994; Connelly et al. 2004). However, there is no statistical indication that movement to new nesting areas results in increased nesting success (Connelly et al. 2004).
Early broodrearing habitat is found close to nest sites (Connelly et al. 2000a), although individual females with broods may move large distances (Connelly 1982; as cited in Connelly et al. 2000a). Young (1994) found that Gunnison sagegrouse with broods used areas with lower slopes than nesting areas, high grass and forb cover, and relatively low sagebrush cover and density. Broods frequently used hay meadows, but were often flushed from interfaces of wet meadows and habitats providing more cover, such as sagebrush or willowalder (SalixAlnus). Forbs and insects are essential nutritional components for sagegrouse chicks (Klebenow and Gray 1968; Johnson and Boyce 1991; Connelly et al. 2004). Therefore, early broodrearing habitat must provide adequate cover adjacent to areas rich in forbs and insects to assure chick survival during this period (Connelly et al. 2004).
As fall approaches sagegrouse move from riparian to upland areas and start to shift to a winter diet (GSRSC 2005). By late summer and into the early fall, individuals become more social, and flocks are more concentrated (Patterson 1952). This is the period when Gunnison sagegrouse can be observed in atypical habitat such as agricultural fields (Commons 1997). However, radiotracking studies in the Gunnison Basin have found that broods typically do not use hay meadows further away than 50 meters (m) (165 feet [ft]) of the edge of sagebrush stands (Gunnison Basin Conservation Plan 1997).
Movements to winter ranges are slow and meandering. Sagebrush stand selection in winter is influenced by snow depth (Patterson 1952; Connelly 1982 as cited in Connelly et al. 2000a) and in some areas, topography (Beck 1977; Crawford et al. 2004). Winter areas are typically characterized by canopy cover greater than 25 percent and sagebrush greater than 30 to 41 cm (12 to 16 in) tall (Shoenberg 1982) associated with drainages, ridges, or southwest aspects with slopes less than 15 percent (Wallestad 1975; Beck 1977). Lower flat areas and shorter sagebrush along ridge tops provide roosting areas. In extreme winter conditions, greater sagegrouse will spend nights and portions of the day burrowed into ``snow roosts'' (Back et al. 1987).
Hupp and Braun (1989) found that most Gunnison sagegrouse feeding activity in the winter occurred in drainages and on slopes with south or west aspects in the Gunnison Basin. During a severe winter in the Gunnison Basin in 1984, less than 10 percent of the sagebrush was exposed above the snow and available to sagegrouse. In these conditions, the tall and vigorous sagebrush typical in drainages was an especially important food source.
Based on historical records, museum specimens, and potential sage
grouse habitat, Schroeder et al. (2004) concluded that Gunnison sage
grouse historically occurred in southwestern Colorado, northwestern New
Mexico, northeastern Arizona, and southeastern Utah. Accounts of
Gunnison sagegrouse in Kansas and Oklahoma, as suggested by Young et al. (2000), are not
supported with museum specimens, and Schroeder et al. (2004) found inconsistencies with the historical records and the sagebrush habitat currently available in those areas. Applegate (2001) found that none of the sagebrush species closely associated with sagegrouse occurred in Kansas. He attributed historical, anecdotal reports as mistaken locations or misidentification of lesser prairie chickens. For these reasons, southwestern Kansas and western Oklahoma are not considered within the historic range of Gunnison sagegrouse (Schroeder et al. 2004). The GSRSC (2005) modified the historic range from Schroeder et al. (2004), based on more complete knowledge of historic and current habitat and the distribution of the species (GSRSC 2005). Based on this information, the maximum Gunnison sagegrouse historical
(presettlement) range is estimated to have been 55,350 square kilometers (sq km) (21,370 square miles [sq mi]) (GSRSC 2005). To be clear, only a portion of the historical range would have been occupied at any one time, while all of the current range is considered occupied. Also, we do not know what portion of the historical range was occupied, or what the total population was.
Rogers (1964) qualitatively discussed a decrease in sagebrush range due to overgrazing from the 1870's until about 1934. Additional effects occurred as a result of newer range management techniques implemented to support livestock by the Bureau of Land Management (BLM), Soil Conservation Service, and U.S. Forest Service (Rogers 1964). Rogers (1964) discussed sagebrush eradication (by spraying and burning) in the 1950s, and used two examples (Uncompaghre Plateau, Flattop Mountain in Gunnison County, CO) within the current range to illustrate the large acreages (35,000 acres) treated, but stated that longterm effects were yet to be determined. Rogers (1964) demonstrated a much broader distribution of sagebrush in Colorado than what currently exists. Rogers (1964) also presents maps that show decreases in distribution from previous literature.
Much of what was once sagebrush was already lost prior to 1958. Through the use of lowlevel aerial photography, OylerMcCance et al. (2001) documented a loss of only or 155,673 ha (20 percent) of sagebrush habitat from 1958 to 1993 within Gunnison sagegrouse range. Thirtyseven percent of the plots sampled underwent substantial fragmentation of sagebrush vegetation during that same time period. OylerMcCance et al. (2001) stated that sagegrouse habitat in southwestern Colorado (the range of Gunnison sagegrouse) has been more severely impacted than sagebrush habitat elsewhere in Colorado. However, the Gunnison Basin was not as significantly affected as other areas.
The Colorado River Storage Project (CRSP) resulted in construction of three reservoirs within the Gunnison Basin in the midlate 1960s (Blue Mesa and Morrow) and mid1970s (Crystal). Several projects associated with CRSP were constructed in this same general timeframe to provide additional water storage and resulted in the loss of an unquantified, but likely small, amount of sagebrush habitat. These projects provide water storage and, to a certain extent, facilitate agricultural activities throughout the range of Gunnison sagegrouse.
Riebsame et al (1996) discussed a greater rural growth rate in Colorado from the 1970s through the 1990s, compared to the rest of the U.S., which has resulted in land use conversion. They noted a pattern of private ranches shifting to residential communities within Gunnison sagegrouse habitat. The Gunnison Basin Working Group Research Sub committee (February, 2006) cited two regions within the Basin to be of the highest priority for conservation easements due to development pressures.
In summary, a substantial amount of sagebrush habitat within the range of the Gunnison sagegrouse had been lost prior to 1960. In the years since, habitat loss and fragmentation has slowed, although development pressures have been on the rise. Conservation efforts are being developed to help address developmentrelated issues.
Current Distribution and Population Estimates
Gunnison sagegrouse currently occur in seven widely scattered and
isolated populations in Colorado and Utah, occupying 4,720 sq km (1,820
sq mi) (GSRSC 2005). The seven populations are Gunnison Basin, San
Miguel Basin, MonticelloDove Creek, Pi[ntilde]on Mesa, Crawford, Cerro
SummitCimarronSims Mesa, and Poncha Pass (Figure 1). A comparative summary of the seven populations is presented in Table 1.
[GRAPHIC] [TIFF OMITTED] TR18AP06.000
Table 1.Population Size, Extent of Occupied Habitat, Land Ownership, and Urban Development Pressures Population size 2005 population Currently occupied Name of population range 19952005* estimate area Land ownership Development pressure Gunnison Basin Population........ 2,2034,763......... 4,763............... 240,000 hectares 51 percent BLM, 14 Gunnison County (ha) 593,000 (ac). percent USFS, 2 percent currently has a low NPS, 1 percent CDOW, 1 population density of 5 percent Colorado State people/sq mi in 2000 Land Board, 31 percent (GSRSC 2005), with private (GSRSC 2005). projected growth rates ranging from .1 to 1.6 percent per year. These rates result in a population increase of about 5700 people by 2030 (41 percent or 7 people/sq mi) (CDLA 2004). A 30 percent housing increase is projected from 2000 2020 (GSRSC 2005). San Miguel Basin Population...... 206446............. 334................. 40,500 ha (100,500 Dry Creek57 percent The population in San ac). BLM, 12 percent, CDOW, 1 Miguel County is percent, Colorado State expected to double to Land Board, 30 percent 18 people/sq mi between private. 2000 and 2030 (CDLA Hamilton Mesa85 percent 2004), accompanied by a private, 11 percent 62 percent increase in Colorado State Land housing units by 2020 Board, 4 percent BLM. (GSRSC 2005). Miramonte76 percent private, 15 percent CDOW, 7 percent USFS, 2 percent BLM. Gurley Reservoir91 percent private, USFS 4 percent, BLM 3 percent, the Colorado State Land Board 2 percent. Beaver Mesa99.5 percent private, 0.5 percent BLM. Iron Springs89 percent private, 6 percent USFS, 5 percent Colorado State Land Board (GSRSC 2005). MonticelloDove Creek Population. 162510 (Combined).. 196 (162 Monticello 40,000 ha (98,920 Monticello95 percent The Monticello, UT group and 34 Dove Creek). ac) (Combined). private, 4 percent BLM, has approximately 2 1 percent State of Utah people/sq mi (GSRSC land. 2005) with a projected increase of roughly 18% to 2600 people (2.4 people/sq mi) by 2030 (Utah Governor's Office of Planning and Budget 2005). 123280 (Monticello) .................... Monticello28,500 Dove Creek87 percent ha (71,000 ac). privately owned, 13 percent BLM (GSRSC 2005). 10358 (Dove Creek). .................... Dove Creek11,500 ha (28,000 ac). Pi[ntilde]on Mesa Population..... 79206.............. 167................. 16,000 ha (39,000 70 percent private, 28 Population density of 55 ac). percent BLM, 2 percent people/sq mi in 2000 USFS (GSRSC 2005). (GSRSC 2005) with a projected increase to 105 people/sq mi by 2030 (CDLA 2004). [[Page 19960]]
Crawford Population.............. 118314............. 191................. 14,000 ha (35,000 63 percent BLM, 13 Estimate of 24 people/sq ac). percent NPS, 24 percent mi living in and near private (GSRSC 2005). this population in 2000 (GSRSC 2005). Montrose County contains the southeastern 75 percent of the current range of the Crawford population. The county was identified as one of the fastest growing counties in the country, with human population expected to double from 20002030 (CDLA 2004) and housing expected to increase by 68 percent by 2020. The northwestern 25 percent of the current range is in Delta County, which is projected to increase in population by 79 percent by 2030 (CDLA 2004) with an increase in housing of 58 percent by 2020 (GSRSC 2005). Cerro SummitCimarronSims Mesa 2583............... 25.................. 15,000 ha (37,000 43 percent private, 51 Population threats not Population. ac). percent BLM, 6 percent evaluated. CDOW (GSRSC 2005). Poncha Pass Population........... 544................ 44.................. 8,300 ha (20,400 ac) 48 percent BLM, 26 Population threats not percent USFS, 24 percent evaluated. in private holdings, 2 percent Colorado State Land Board (GSRSC 2005). * The numbers presented are the lowest and highest population estimates during the 11year period. The lows and highs did not all fall in the same years for each population.
Gunnison Basin PopulationThe Gunnison Basin is an intermontane 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 range from 2,300 to 2,900 m (7,500 to 9,500 ft). Big sagebrush (Artemesia tridentata) dominates the upland vegetation and has a highly variable growth form depending on local site conditions. Up to 84 leks have been surveyed annually for breeding activity in the Gunnison Basin (CDOW, unpubl. lit. 2005a). Approximately 37 percent of these leks occur on private land and 63 percent on public land, primarily BLM (GSRSC 2005). In 2005, 44 of these leks were active, 38 inactive, and 2 are of unknown status. Rogers (1964) stated that Gunnison County had one of the largest sage grouse populations in Colorado.
San Miguel Basin PopulationThe San Miguel Basin population is in Montrose and San Miguel Counties in Colorado, and is composed of six groups using different areasDry Creek Basin, Hamilton Mesa, Miramonte Reservoir, Gurley Reservoir, Beaver Mesa, and Iron Springs. Some of these six areas are used yearround by sagegrouse, and others are used seasonally. Recent radiotelemetry studies have suggested that sage grouse in the San Miguel Basin move widely and between these areas (Apa 2004; Stiver, unpubl. lit. 2005).
Sagebrush habitat in the Dry Creek Basin area is patchily distributed and the understory is either lacking in grass and forb diversity or nonexistent. Where irrigation is possible, private lands in the southeast portion of Dry Creek Basin are cultivated. Sagebrush habitat on private land has been heavily thinned, or removed entirely (GSRSC 2005). Gunnison sagegrouse use the Hamilton Mesa area in the summer, but use during other seasons is unknown. Miramonte Reservoir occupied sagegrouse habitat is approximately 4,700 ha (11,600 ac) (GSRSC 2005). Sagebrush stands are generally contiguous with a mixed grass and forb understory. Occupied habitat at the Gurley Reservoir area is heavily fragmented and the understory is a mixed grass and forb community. Farming attempts in the early 20th century led to the removal of much of the sagebrush, although agricultural activities now are restricted primarily to the seasonal irrigation 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). Sagebrush stands in the Iron Springs and Beaver Mesa areas are contiguous with a mixed grass understory. The Beaver Mesa area has numerous scattered patches of oakbrush (Quercus gambelii).
The 2005 population estimate for the entire San Miguel Basin was 334 (CDOW, unpubl. lit. 2005b) on 9 leks. Rogers (1964) reported that all big sagebrushdominated habitats in San Miguel and Montrose Counties were historically used by sagegrouse. The historic distribution was highly fragmented by forests, rocky canyons and dry basins void of sagebrush habitats.
MonticelloDove Creek PopulationThis population has two disjunct groups of Gunnison sagegrouse. Currently, the largest group is near the town of Monticello, Utah. Gunnison sagegrouse in this group inhabit a broad plateau on the northeast side of the Abajo Mountains with fragmented patches of sagebrush interspersed with large grass pastures and agricultural fields. The Utah Division of Wildlife Resources (UDWR) estimates that Gunnison sagegrouse currently occupy about 24,000 ha (60,000 ac) in the Monticello group. The 2005 population estimate for Monticello was 162 individuals with 2 active and 2 inactive leks (G. Wallace, UDWR pers. comm. 2005). Leks in the Monticello area were first identified and counted in 1968.
The Dove Creek group 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. 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. Lek counts in the Dove Creek area were over 50 males in 1999, suggesting a population of about 245 birds, but declined to 7 males in 2005 (CDOW, unpubl. lit. 2005c). All leks are located in agricultural fields on private lands. 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; Apa 2004). Rogers (1964) reported that all sagebrushdominated habitats in Dolores and Montezuma Counties within Gunnison sagegrouse range in Colorado were historically used by sagegrouse.
Pi[ntilde]on Mesa PopulationThe Pi[ntilde]on Mesa population occurs on the northwest end of the Uncompahgre Plateau in Mesa County, about 35 km (22 mi) southwest of Grand Junction, Colorado. Eight leks are known (CDOW, unpubl. lit. 2004). However, one is inactive and another was not active in 2005 (CDOW unpubl. lit. 2005d). The Pi[ntilde]on Mesa area may have additional leks, but the high percentage of private land, a lack of roads, and heavy snow cover during spring makes locating additional leks difficult. Gunnison sage grouse likely occurred historically in all suitable sagebrush habitat in the Pi[ntilde]on Mesa area, including the Dominguez Canyon area of the Uncompaghre Plateau, southeast of Pi[ntilde]on Mesa proper (Rogers 1964). Their current distribution has been substantially reduced from historic levels (GSRSC 2005).
Crawford PopulationThe 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. tridentata) and black sagebrush (A. nova) dominate the midelevation uplands (GSRSC 2005). The 2005 population estimate for Crawford is 191 (CDOW, unpubl. lit. 2005e). Currently there are four active leks in the Crawford population on BLM lands in sagebrush habitat adjacent to an 11km (7mi) stretch of road. This area represents the largest contiguous sagebrushdominated habitat within the Crawford boundary (GSRSC 2005).
Cerro SummitCimarronSims Mesa PopulationThis population is in Montrose County, Colorado. The Cerro SummitCimarron group is centered about 24 km (15 mi) east of Montrose. The habitat consists of patches of sagebrush habitat fragmented by oakbrush and irrigated pastures. Three leks are known in the Cerro SummitCimarron group, but only one was verified to be active in 2005. Rogers (1964) noted a small population of sagegrouse 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 Sims Mesa area about 11 km (7 mi) south of Montrose consists of small patches of sagebrush that are heavily fragmented by pinyon juniper, residential and recreational development, and agriculture. The one known lek in Sims Mesa is inactive. Rogers (1964) counted eight males in a lek count at Sims Mesa in 1960. It is not known if sage grouse move between the CerroSummitCimarron and Sims Mesa groups.
Poncha Pass PopulationThe Poncha Pass sagegrouse population is located in Saguache County, approximately 16 km (10 mi) northwest of Villa Grove, Colorado. This population was established through the introduction of 30 birds from the Gunnison Basin in 1971 and 1972 during efforts to reintroduce the species to the San Luis Valley (GSRSC 2005). The known population distribution is in 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 extensive and continuous with little fragmentation; sagebrush habitat quality throughout the area is adequate (Nehring and Apa 2000). San Luis Creek runs through the area, providing a yearround water source and lush, wet meadow riparian habitat for broodrearing. The 2005 Poncha Pass sagegrouse population estimate is 44 (CDOW, unpubl. lit. 2005f). The only current lek is located on BLMadministered land. In 1992, a CDOW effort to simplify hunting restrictions inadvertently opened the Poncha Pass area to sagegrouse hunting and at least 30 grouse were harvested from this population. Due to declining population numbers since the 1992 hunt, CDOW transplanted 24 additional birds from the Gunnison Basin (Nehring and Apa 2000). In 2001 and 2002, 20 and 7 birds respectively also were moved to the Poncha Pass by CDOW (GSRSC 2005). Transplanted females have bred successfully (Apa, CDOW, pers. comm. 2004) and display activity resumed on the historic lek in spring 2001. Population Trends
Trends in abundance were analyzed for individual populations and the species rangewide using male lek count data from CDOW and UDWR (Garton 2005). Due to inconsistencies in data collection over time, trend analyses were conducted for two time periodsthe entire number of years lek data have been collected (19572005), and from 19952005 when sampling methodologies have been more consistent. Raw data collected for 2005 show a large increase in the numbers of males attending leks. Because of this, the analyses were conducted both with and without 2005 data; estimates did not change significantly when the 2005 lek counts were omitted in this analysis. Statistical analyses of the Cerro SummitCimarronSims Mesa and Dove Creek populations could not be completed due to low lek counts and inconsistencies in sampling over time. Similarly, the small Poncha Pass population was not analyzed because it has been surveyed for only 6 years and in that time the population was augmented with birds from Gunnison Basin.
The longterm analysis (19572005) found that the rangewide
population of Gunnison sagegrouse was neither increasing nor
decreasing during that time period. Annual rates of change were highly
variable, most likely as a result of sampling error rather than actual
changes in population sizes. The shorter analysis period (19952005)
yielded the same results, although the variability was reduced, likely
due to more consistent data collection methods. Individual populations
reflected the trends in the rangewide analysis, in that some
populations were slightly increasing and some were slightly decreasing (Table 2). As with similar analyses conducted for the
greater sagegrouse (Connelly et al. 2004), densitydependent models appeared to more accurately describe observed population trends (Garton 2005).
Table 2.Summary of Population Trends for the Gunnison SageGrouse \1\ Finite rate Population of change Rangewide....................................................... 1.049 Gunnison Basin.................................................. 1.05 Pi[ntilde]on Mesa............................................... 1.09 San Miguel Basin................................................ 0.9 Crawford........................................................ 0.999 Monticello...................................................... 0.99 \1\ Values are the finite rate of change in the population, where 1 is no change, numbers less than 1 indicate a decline, and numbers greater than 1 indicate an increase. The analysis is for 19952005 (data from Garton 2005).
Because we relied on the population trend analyses conducted by Garton (2005), we asked six peer reviewers to evaluate the report. We received comments from five of the reviewers, three generally favorable towards the report and its conclusions and two expressing concerns regarding limitations in the data sets, assumptions, and/or analyses. For example, one would have to assume that habitat availability over time would remain stable in order to conclude that Gunnison sagegrouse numbers are unlikely to experience a substantial decline in the future. Also, while the conclusions showed that the number of males per lek remained relatively stable over time, the proportion of leks on which males were counted appeared to have declined, which could be indicative of an overall population decline. In discussing the historic distribution of Gunnison sagegrouse, we concluded that much of the habitat loss, and by inference population decline, occurred prior to 1958.
It was also suggested that more appropriate statistical tests would need to be applied to come to any conclusion about potential population trends and that emphasis should be on an independent analysis of each geographically isolated population because each population exhibits independent population dynamics. Population trend analyses were conducted on a population basis (as well as rangewide). However, to further subdivide the data analyzed into smaller units (i.e. subpopulations) would have compromised the statistical integrity of the analysis due to small sample sizes. There was concern expressed that habitat loss over time was not accounted for, that population declines would go unnoticed, and that population trends would appear far too optimistic.
An identical population trend analysis was peer reviewed by the Ecological Society of America in the ``Conservation Assessment of Greater Sagegrouse and Sagebrush Habitats'' (Connelly et al. 2004). Additional clarifying information regarding model assumptions, the primary concern of the peer reviewers, was provided by Garton after the peer review was complete. Based on this late submission, and after careful review of the analysis, we believe that Garton (2005) constitutes the best currently available information.
Summary of Factors Affecting the Species
Section 4 of the Act (16 U.S.C. 1533) and regulations (50 CFR part 424) promulgated to implement the listing provisions of the Act set forth the procedures for adding species to the Federal lists. A species may be determined to be an endangered or threatened species due to one or more of the five factors described in section 4(a)(1). As part of our analysis, we chose, out of an abundance of caution, not to rely on the Cerro SummitCimarronSims Mesa and Poncha Pass populations and the Dove Creek group of the MonticelloDove Creek population for the longterm conservation of the species because of their small, isolated status. We also determined that these populations do not comprise a significant portion of the Gunnison sagegrouse range. Therefore, these populations/group were not evaluated further for future threats. Although we are not relying on these populations/group for the longterm conservation of the species, we nonetheless believe that conservation of these populations is worthwhile, and we will continue to support and encourage those efforts. However, we analyze the threats applicable to the remaining populations/group to determine whether the species as a whole meets the definition of threatened or endangered.
The Service considers the foreseeable future in Gunnison sage grouse to be between 30 and 100 years based on 10 Gunnison sagegrouse generations to 2 sagebrush habitat regeneration cycles. This is consistent with our 12month finding for the greater sagegrouse (70 FR 2244). Because the Gunnison sagegrouse has the same generation time and occupies habitat similar to the greater sagegrouse, we consider it prudent to use the same definition for the foreseeable future. A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range
Data indicate that the Gunnison sagegrouse was found in central and southwest Colorado, southeast Utah, northwestern New Mexico, and northeastern Arizona prior to European settlement (GSRSC 2005, modified from Schroeder et al. 2004). Gunnison sagegrouse currently occupy 4,719 sq km (1,822 sq mi) in southwestern Colorado and southeastern Utah (GSRSC 2005, modified from Schroeder et al. 2004). The following describes the issues affecting Gunnison sagegrouse within their current range.
Current Threats Due to Habitat Fragmentation: Habitat fragmentation is the separation or splitting apart of previously contiguous, functional habitat. Fragmentation of sagebrush habitats has been cited as a primary cause of the decline of sagegrouse populations (Patterson 1952; Connelly and Braun 1997; Braun 1998; Johnson and Braun 1999; Connelly et al. 2000a; Miller and Eddleman 2000; Schroeder and Baydack 2001; Aldridge and Brigham 2003; Connelly et al. 2004; Schroeder et al. 2004). While sagegrouse are dependent on interconnected expanses of sagebrush (Patterson 1952; Connelly et al. 2004), data are not available regarding optimum or even minimum sagebrush patch sizes necessary to support sagegrouse populations. In addition, there is a lack of data to assess how fragmentation influences specific sage grouse lifehistory parameters such as productivity, density, and home range.
OylerMcCance et al. (2001) documented loss and fragmentation of sagebrush vegetation in southwestern Colorado. In a genetic study of Gunnison sagegrouse populations, OylerMcCance et al. (2005) concluded that gene flow among populations of Gunnison sagegrouse is limited.
Notwithstanding the lack of specificity on effects of fragmentation, it is clear that as a whole, fragmentation can have an adverse effect on sagegrouse populations. The following sections examine activities that can contribute to habitat fragmentation to determine whether they threaten Gunnison sagegrouse habitat. Conversion to Agriculture and Water Development
In the mid1800s, western rangelands were converted to agricultural
lands on a large scale beginning with the series of Homestead Acts in
the 1800s (Braun 1998; Hays et al. 1998), especially where suitable deep soil terrain and
water were available (Rogers 1964). Influences resulting from agricultural activities adjoining sagebrush habitats extend into those habitats, and include increased predation and reduced nest success due to predators associated with agriculture (Connelly et al. 2004).
Agricultural conversion can provide some limited benefits for sage grouse. Some crops such as alfalfa (Medicago sativa) and young bean sprouts (Phaseolus spp.) are eaten or used for cover by sagegrouse (C. Braun, CDOW, pers. comm. 1998). However, crop monocultures do not provide adequate yearround food or cover (GSRSC 2005). Gunnison sage grouse will use hay pastures for foraging within about 50 m (165 ft) of the edge of the field but do not forage further into the pasture due to lack of suitable habitat (Gunnison Basin Conservation Plan 1997).
In the Gunnison Basin approximately 17,328 ha (42,800 ac) or 8 percent of the current range was converted to agricultural activities in the past and for the most part is no longer occupied (GSRSC 2005). Approximately 5,700 ha (14,000 ac) or 7 percent of the current range in the San Miguel Basin has been converted to agriculture and for the most part is unoccupied (GSRSC 2005). The arrangement of these converted lands has contributed to habitat fragmentation in these areas, although it is not negatively influencing sagegrouse numbers in this population (Garton 2005).
Approximately 30 percent of the 40,048 ha (98,920 ac) of the current range in the MonticelloDove Creek population has been converted to agriculture and for the most part is no longer occupied (GSRSC 2005). In the Monticello group, 43 percent has been converted to pasture (GSRSC 2005). San Juan County, Utah, where the Monticello group resides, also has approximately 15,000 ha (37,000 ac) enrolled in Conservation Reserve Program (CRP), of which about half is within current sagegrouse range (San Juan County Gunnison Sagegrouse Work Group [GSWG], unpubl. lit. 2005; GSRSC 2005). Under CRP, cropland is planted to pastureland and, except in emergency situations, not hayed or grazed. The CRP fields are used heavily by grouse as broodrearing areas but vary greatly in plant diversity and forb abundance, and generally lack any shrub cover (GSRSC 2005). Sagebrush patches have progressively become smaller and more fragmented limiting the amount of available winter habitat for the Monticello group (GSRSC 2005). Significant use of CRP as nesting or winter habitat will require establishment of sagebrush stands in these fields. The CRP has protected this area from more intensive agricultural use and development, and approximately 16,000 ha (40,000 ac) of CRP are up for renewal under the Farm Bill in the next 23 years.
Conversion to agriculture is limited in the Pi[ntilde]on Mesa area, with only 5 percent (500 ha (1,214 ac)) of the current range planted to grass/forb rangeland and for the most part no longer occupied (GSRSC 2005). Sagebrush occurs in some areas that may be converted to grassland for livestock (BLM, unpubl. lit. 2005a), but the continued conversion is considered to be a minor impact in the foreseeable future. Habitat conversion in the Crawford area due to agricultural activities has been limited (GSRSC 2005).
Although past conversion to agriculture has resulted in the loss of sagebrush habitat, we have no evidence to conclude that ongoing or anticipated agricultural conversion of sagebrush habitats is likely to threaten or endanger the Gunnison sagegrouse. Existing agricultural activities may fragment the species current range, but we have no data to determine that this is actually occurring, or is likely to occur.
Past development of irrigation projects has also resulted in loss of sagegrouse habitat (Braun 1998). Reservoir development in the Gunnison Basin flooded 3,700 ha (9,200 ac or 1.5 percent) of likely sagegrouse habitat (S. McCall, Bureau of Reclamation, pers. comm. 2005), and three other reservoirs inundated approximately 2 percent of habitat in the San Miguel Basin population area (J. Garner, CDOW, pers. comm. 2005). We are unaware of any plans for additional reservoir construction in the foreseeable future and do not consider water development a threat to the species.
Impacts from roads may include direct habitat loss, direct mortality, creation of barriers to migration to seasonal habitats (Forman and Alexander 1998), facilitation of mammalian (Forman and Alexander 1998; Forman 2000) and corvid predation (Connelly et al. 2000b; Aldridge and Brigham 2003; Connelly et al. 2004) and expansion into previously unused areas, spread of invasive weeds (Forman and Alexander 1998; Forman 2000; Gelbard and Belnap 2003; Knick et al. 2003; Connelly et al. 2004), noise in the vicinity of leks (Braun 1986; Forman and Alexander 1998; Holloran 2005), and increased recreational use and associated human disturbances (Forman and Alexander 1998; Massey 2001; Wyoming Game and Fish Department 2003). Specific effects of these factors on sagegrouse are discussed below.
Lyon (2000) suggested that roads may be the primary impact of oil and gas development to greater sagegrouse, due to their persistence and continued use even after drilling and production have ceased. Braun et al. (2002) suggested that daily vehicular traffic along road networks for oil wells can impact Gunnison and greater sagegrouse breeding activities based on a documented decrease in males at leks. Modeling done in Connelly et al. (2004) found that the number of active leks, lek persistence and lek activity increased with increasing distance from an interstate highway. Other than this single predictive model output, we have no quantitative information on the current impact of roads to Gunnison sagegrouse. It is unclear what specific factor relative to roads sagegrouse are responding to, and Connelly et al. (2004) caution that they have not included other potential sources of disturbance (e.g., powerlines) in their analyses.
Roads may have additional indirect effects that result from birds' behavioral avoidance of road areas because of noise, visual disturbance, pollutants, and predators moving along them. The absence of screening vegetation in arid and semiarid regions further exacerbates any problems (Suter 1978). Male sagegrouse depend on acoustical signals to attract females to leks (Gibson and Bradbury 1985; Gratson 1993). If noise interferes with mating displays, and thereby female attendance, it is possible that younger males will not be drawn to the lek and eventually leks will become inactive (Braun 1986; Holloran 2005). Dust from roads and exposed roadsides can damage vegetation through interference with photosynthetic activities; the actual amount of potential damage depends on winds, wind direction, the type of surrounding vegetation and topography (Forman and Alexander 1998). Chemicals used for road maintenance, particularly in areas with snowy or icy precipitation, can affect the composition of roadside vegetation (Forman and Alexander 1998). While all of these potential effects are actually occurring or whether they have actually affected sagegrouse populations individually or at a species level.
Gunnison sagegrouse habitat is currently fragmented by a number of roads (BLM, unpubl. lit. 2005b, Colorado Department of Transportation (CDOT) 2004, Jim Ferguson, BLM, pers. comm. 2005, San Juan County GSWG, [[Page 19
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