Upper Green Allotment FEIS

Transcription

1 Upper Green Allotment FEIS Supplemental Wildlife Specialist Report For: North American Wolverine Region 4 Sensitive Species and Federal Candidate Species Bridger-Teton National Forest Prepared by: Ann Roberts Wildlife Biologist Pinedale Ranger District Ann Roberts 4/11/2016 Signature Date

2 Species Status Species Presence in project area North American Wolverine (Gulo gulo) Sensitive, Candidate Affected Environment Known Habita t prese nt Yes Habitat/Comments Suitable, occupied habitat occurs in and around the project area. Susceptible to being trapped during management actions or hunting for other species North American Wolverine: In North America, wolverines occur within a wide variety of alpine, boreal, and arctic habitats, including boreal forest, tundra, and montane forests throughout much of Alaska and Canada. The southern portion of the species range extends into the contiguous United States, including high-elevation alpine portions of Washington, Idaho, Montana, Wyoming. Individuals have recently been detected or radio-tracked to California and Colorado. Wolverines do not appear to specialize on specific vegetation or geological habitat aspects, but instead select areas that are cold and receive enough winter precipitation to reliably maintain deep persistent snow late into the warm season (Copeland et al. 2010). This species' requirement for cold, snowy conditions means that, in the southern portion of the species range where ambient temperatures are warmest (like Wyoming), wolverines occur principally at high (> 8,000 feet) elevations (Inman et al. 2007, Murphy et al. 2011). Deep snow is required for successful wolverine reproduction because female wolverines dig elaborate natal dens in the snow. Such structures protect wolverine kits from predators and harsh winter and early spring weather (U.S. Fish and Wildlife Service 2010). Wolverines are opportunistic feeders and consume a variety of foods depending on availability. They primarily scavenge carrion, but also prey on small animals and birds, and eat fruits, berries, and insects. Home ranges of wolverines are large, and vary greatly in size depending on availability of food, gender and age of the animal, and differences in habitat quality. Wolverines in the GYA had average adult male home ranges of 797 square kilometers (311 square miles) and average adult female home ranges of 329 square kilometers (128 square miles) (Inman et al. 2007). Demographics and Populations No systematic population census exists over the entire range of wolverines in the Rocky Mountains, although populations have increased from the mid-1900s (Aubry et al. 2007, U.S. Fish and Wildlife Service 2010). Based on current knowledge of occupied habitat and animal densities, wolverines in the contiguous United States number individuals. The bulk of the current population occurs in the northern Rocky Mountains with a few individuals in the North Cascades. Subalpine forest and alpine habitat in these areas is naturally fragmented, producing wolverine populations that are small and isolated (Aubry et al. 2007; Ruggerio et al. 2007). Wolverines naturally occur at low densities and have large spatial requirements, factors that contribute to low population viability (USFWS 2010). Range and Status at the Forest Level

3 The wolverine is designated as a Sensitive Species in U.S. Forest Service Regions 1 and 2, and 11 of 16 National Forests in U.S. Forest Service Region 4, including the Bridger-Teton National Forest (USFS 2011). The Bridger-Teton National forest consists of 3.4 million acres (14,000 km 2 ), of which 1.2 million acres are designated wilderness. Brock et al. (2007) estimated that the Bridger Teton NF holds 11,342 km 2 (2,802,669 acres) of predicted primary wolverine habitat (available). Of the approximately 74,572 acres of grazing capable in the project area, 47,873 of grazing capable overlap wolverine habitat. Figure X-X: Wolverine habitat (lavender) within and surrounding the project area, showing overlap with grazing capable land (coral). An understanding of wolverine distribution and status within the Bridger-Teton Forest is limited. Sightings have been reported recently from the Gros Ventre Range, the Northwestern Wind River Range, Teton Pass area, Togwotee Pass area, and the Wyoming Range (Beauvais and

4 Johnson 2004; Hoak et al. 1982). Wolverine presence has been confirmed in Pinedale, Jackson, and Buffalo Ranger Districts (Beauvais and Johnson 2004, Wilmot pers. comm. 2012). Evidence suggests that wolverines are mostly absent from Yellowstone National Park (YNP) proper, except two individuals (1 male and 1 female) straddled the eastern and southeastern borders of YNP and ranged into both the Bridger- Teton and Shoshone National Forests (Murphy et al 2011). The female was a known disperser from Montana s Gallatin Range. Also, a wolverine kinship group (male and female and apparent reproduction) inhabits the Absaroka Range in Montana immediately adjacent to the northern boundary of YNP (Murphy et al 2011, and unpublished data NRCC and Gallatin National Forest). Based on research in the Tetons in the recent past it is assumed that all territories in the Tetons are occupied (probably 2 adult males and 2 adult females and unknown number of juveniles) (Inman et al. 2007). To date, only one reproduction has been documented in Wyoming, when two female kits were born in the Tetons in 2005 (Caribou-Targhee NF). Further investigation of the Snake River Range, the Salt River Range, the Wyoming Range, the Wind River Range, the Gros Ventre Range, and the Teton Wilderness, all on the Bridger Teton NF, is warranted, as are investigations into wolverine presence in the eastern Absarokas (Shoshone NF) and the Bighorn Range (Bighorn NF) to give a more complete picture of the population in Wyoming. The 2009 dispersal of a young Wyoming male to Colorado suggests that Wyoming s population could be critical to recolonization of the southern Rockies, but this is contingent upon reproductive aged females successfully dispersing to Colorado. In turn, Wyoming s current and potential future wolverine inhabitants may be dependent upon dispersing wolverines from Montana (which has some of the lowest wolverine reproduction rates reported in the literature), central Idaho, successful reproduction more locally in the Tetons, or of unknown more regional or local origin. A radio-marked wolverine temporarily resided in the Togwotee Pass area in 2009 (Murphy et al. 2011). Although wolverines typically do not use ungulate winter ranges to obtain carrion during the winter (Inman et al. 2007, Murphy et al. 2011), they likely use lower elevation areas (< 8,000 feet) of watersheds for travel. Wolverine sightings have been reported in the northern Wind River Range and the Upper Green River watershed, and in April, 2015, a wolverine was confirmed visiting a bait station in a forested stand in the project area of effect (unpublished data, Inman, 2015). Occupied wolverine habitat exists in the project area, as shown in Figure X-X, above. Risks In the contiguous United States, wolverines likely exist as a metapopulation (Aubry et al. 2007). A metapopulation is a network of semi-isolated populations, each occupying a suitable patch of habitat in a landscape of otherwise unsuitable habitat. Metapopulation dynamics (the process of extinction and recolonization by subpopulations) rely on the ability of subpopulations to support one another through exchange of individuals for genetic and demographic enrichment. If metapopulation dynamics break down, either due to changes within subpopulations or loss of connectivity, then the entire metapopulation may be jeopardized due to subpopulations becoming unable to persist in the face of inbreeding or demographic and environmental stochasticity. The USFWS believes this outcome is likely for wolverine, due to their naturally low reproductive rates and low densities (USFWS 2010). Wolverines typically occupy severe, unproductive environments that support low numbers of adult females with characteristically low birth rates (Persson et al. 2006; Inman et al. 2007). The

5 life-history strategy of wolverines makes it unlikely that they could compensate for increased mortality due to disturbance (Krebs et al. 2007; Persson et al. 2006), and they may be more vulnerable to extirpation than species with high reproductive rates (USFWS 2010). Unregulated trapping is believed to have played a role in the historic decline of wolverines in North America in the late 1800s and early 1900s (Hash 1987). Wolverines are especially vulnerable to targeted trapping and predator reduction campaigns due to their habit of ranging widely in search of carrion, which would bring them into frequent contact with poison baits and traps (Copeland 1996; Inman et al. 2007; Packila et al. 2007; Squires et al. 2007). Human-caused mortality of wolverines likely additive to natural mortality due to the low reproductive rate and relatively long life expectancy of wolverines (Krebs et al. 2004; Squires et al. 2007). This means that trapped populations likely live at densities that are lower than carrying capacity, and may need to be reinforced by recruits from untrapped populations to maintain population viability and persistence. Harvest refugia, such as national parks and large wilderness, are important to wolverine persistence on the landscape because they can serve as sources of surplus individuals to bolster trapped populations (Squires et al. 2007, USFWS 2010). Climate warming over the next century is likely to significantly reduce wolverine habitat, to the point where persistence of wolverines in the contiguous United States, without intervention, is in doubt. Wolverine habitat will likely decrease in area and become more fragmented in the future as a result of climate changes that result in increasing temperatures, earlier spring snowmelt, and loss of deep, persistent, spring snowpack. These climate change impacts may reduce the number of wolverines that can be supported by available habitat and reduce the ability of wolverines to travel between patches of suitable habitat (U.S. Fish and Wildlife Service 2013a). The impact of climate warming may exacerbate the impact of other less significant threats such as recreational use of habitat, infrastructure development, and transportation corridors (U.S. Fish and Wildlife Service 2010). During February 2013, the U.S. Fish and Wildlife Service proposed to list the wolverine in the contiguous United States as a threatened species under the Endangered Species Act (U.S. Fish and Wildlife Service 2013a). According to the Service, wolverines were nearly extirpated from the contiguous United States in the early 20th century due to broad-scale predator trapping and poisoning programs. Since limiting these practices, they have been able to rebound. On August 13, 2014, after extended consideration of public comments, including conflicting scientific opinions, the U.S. Fish and Wildlife Service withdrew the proposal, citing steady recovery in the past half century from history from trapping and other sources of mortality (U.S. Fish and Wildlife Service 2014a). Conservationist groups challenged the decision, and on April 4, 2016, U.S. District Court judge Dana Christensen ordered USFWS to reconsider listing, citing the obvious threat posed to the wolverine by the effects of climate change at the reproductive denning scale, and the threat posed by small population size and lack of genetic diversity. The Wolverine is thus once again a Candidate for listing under the Endangered Species Act. The Wolverine remains a Sensitive Species in Region 4. With such a small population, maintaining existing presence and distribution of populations on the Bridger Teton and Greater Yellowstone Ecosystem will entail minimizing disturbance and unintended consequences from trapping

6 or hunting, and monitoring changes in habitat condition and extent to maintain high quality habitat wherever possible. Indicators are degree of disturbance, and potential for management actions to lead to harm of wolverines under the alternatives. Environmental Consequences North American Wolverine (Sensitive) Alternative 1 No Livestock Grazing (No Action Alternative) Direct and Indirect Effects Indicators: Degree of Disturbance Under this alternative, livestock grazing would cease in the project area (phased out over two years), and wolverines would no longer be subject to disturbance from any activities related to livestock management, or risks associated with management trapping for livestock/predator conflicts. In the absence of grazing, other types of human disturbances would still occur. Recreational activities such as snowmobiling on authorized (non-wilderness) routes would still occur. Traffic related to maintenance activities associated with the elk feedground would occur. A few private landowners and ranchers reside in the watershed, and could also be active in the watershed. Carrion would be available naturally, from ungulate mortalities due to the presence of primary predators such as grizzlies and wolves, and natural winter mortalities of prey species such as bighorn sheep or elk, to provide ample food sources. No management trapping of wolves would occur in response to livestock conflicts, thus no incidental trapping of wolverines would be attributed to such actions. Recreational hunting, trapping, and baiting of black bears, pine martens, foxes, etc., as well as trapping, baiting, or poisoning for removal of undesired wildlife on private lands could still occur throughout the watershed, as authorized by Wyoming Game and Fish Department. Such activities would continue to pose risks to wolverines, potentially causing accidental harm or death to one or more wolverines. Habitat loss or reduction in area of suitable habitat and connectivity due to climate change would continue to threaten wolverine populations across the planning unit and in the GYE. Alternatives 2 4 (Action Alternatives) Grazing Reauthorized Direct and Indirect Effects All of the action alternatives involve similar levels of management activities related to grazing, with similar minor potential for disturbance to individual wolverines, and carry similar potential risks to wolverines regarding incidental harm or death due to management removal trapping of

7 other species. Due to the low density of wolverines in the watershed and surrounding areas, such occurrences might be rare, but could result in loss of a wolverine, possibly a denning female, and possibly the only one in the watershed. Because there are very few wolverines on the Forest, the loss of a single individual would be significant for the planning unit because the loss would account for a large fraction of individuals. The only known locations of wolverines on the forest are the Upper Green River watershed/bridger Wilderness, Togwotee Pass area, and Teton Wilderness. Cumulative Effects (Action Alternatives)- North American wolverine: The Upper Green River watershed is the spatial scale appropriate to define the boundaries of the cumulative effects area for wolverines. This area is large enough to encompass the home ranges of 1 or more wolverines (Inman et al. 2012) and the ungulate winter ranges that could provide carrion of moose, bighorn sheep, and an occasional elk during the winter. The principal human-related actions that potentially affect wolverine in the Upper Green River watershed are effects on snowpack and summer temperatures related to climate change, incidental trapping during predator control trapping in response to livestock/canine conflicts, the potential for being shot or trapped during other legal hunting efforts, and human-caused disturbance associated with snowmobile-based recreation or management activities during winter. Other cumulative actions, such as summer recreation management, mining, timber harvest, or infrastructure and road development in the Upper Green River watershed are either too limited in spatial extent or have such minor direct or indirect effect on this wide-ranging species that their effect are not of strong concern (U.S. Fish and Wildlife Service 2010). Climate change effects wolverines by reducing snowpack needed for denning during winter and early spring, by increasing summer temperatures beyond the species' physiological tolerance, or reducing, the long-term acreage of high-elevation ecosystems upon which wolverines depend (U.S. Fish and Wildlife Service 2012). Climate change likely operates to degrade wolverine habitat in the Greater Yellowstone Ecosystem, including the Upper Green River watershed, but little is known about its effects on denning, foraging, and sheltering of individuals or populations (U.S. Fish and Wildlife Service 2010). Snowmobile traffic (recreational and administrative) commonly occurs from December to March along the main Upper Green River Road, with trips extending from the forest boundary to Green River Lakes, and to Union Pass, Gunsight Pass, and the Upper Gros Ventre watershed. Snowmobile trails are restricted to designated routes where they cross ungulate winter range at low elevations and along the main road, but off-trail activity is permitted, particularly at high elevations. Snowmobile activity is not permitted in the Wilderness areas. Snowmobile recreation potentially carries a negative effect on wolverine fitness, foraging, and denning, but little is known about how the species responds to machine noise and human presence. Wolverines have denned in areas such as the Tetons with high levels of human use and disturbance, including areas with snowmobile recreation (Heinenmeyer 2012). Determination Alternative 1

8 Because no wolverine losses are expected to occur due to management actions in this alternative, there will be no negative effects on the local population or at the scale of the Greater Yellowstone Ecosystem. The determination for wolverines under Alternative 1 is no impact. Determination Alternatives 2 4: All of the action alternatives carry similar risk of incidental trapping resulting in harm or death of one or more wolverines as a result of livestockrelated conflict-response management actions. The status of wolverine populations on the forest is largely unknown, so it is difficult to evaluate the effect of the loss of a wolverine or denning female in this area on forest population viability. However, because we likely have so few wolverines on the forest, the loss of even a single individual, especially a breeding adult or female, could be significant. With such a low density of individuals, however, there is also a low probability of incidental trapping due to management actions, given the limited extent and timing of such activities, and if agency protocols are followed, to minimize incidental capture of nonoffending animals. Loss of a single wolverine in the project area would not necessarily compromise viability on the forest scale, however. Thus, the determination for the action alternatives (2-4) is may impact individuals, but not likely to cause a trend toward federal listing or loss of viability on the forest. Compliance with Forest Plan and Other Relevant Laws, Regulations, Policies and Plans Complies with Forest Plan Forest plan direction for Sensitive species 1 Forest Plan Goal 3.3 (p. 118) Prevent sensitive species from becoming threatened Sensitive species are prevented from becoming a federally listed species in Wyoming 1 Forest Plan Goal 4.7 (p. 120) Avoid unacceptable effects from livestock use: Grazing use sustains or improves overall range, soils, water, wildlife and recreation values or experiences. yes_forest Plan Objective 4d Fisheries and Wildlife Prescriptions and Standards (p ) Provides habitat adequate to meet the needs of dependent fish and wildlife populations, including those of Threatened, endangered, and sensitive species 1 yes, 2-4 not for individuals_dfc 10 (p ) no affect or some beneficial effects 1 yes, 2-4 not for individuals_ DFC 12 (p ) Uncertainty 10 and 12 are tough for individual wolverines. The action alternatives do not meet the management emphasis statement for individuals, but did for the populations.

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