NEPA--Environmental Assessment

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Silverton Grazing Risk <strong>Assessment</strong> specific disease monitoring has occurred in S33, nor have these sheep ever been treated with fenbendazole. Based on the high level of recruitment observed in S33, it appears that this bighorn sheep herd is not experiencing any additive mortality from predation. Habitat quality in the unit is excellent (Beecham et al. 2007). Monitoring by the Colorado Division of Wildlife, along with recent (2009) sighting reports indicate this herd is in an expansion phase (Wait pers. comm.). CDOW believes it is likely that individual bighorns from S33 may pioneer into historic range as the population increases. If so, dispersal and range expansion may result in bighorns filling vacant habitat and occupying areas where they have not been documented in recent years, potentially placing S33 at an increased risk for contact with domestic sheep in nearby active allotments. S33 is recognized by the CDOW as comprising one large meta-population with S21, the Ouray-Cow Creek Herd, to the north and west. Together, this meta-population is estimated to be over 200 animals in size. There is no direct overlap between domestic sheep allotments in the Silverton Landscape and mapped summer range for the S21 Ouray/Cow Creek herd. Within S33, there are 3 historic subpopulations of bighorn sheep (Diamond 2005). These subpopulations are commonly referred to as the Pole Mountain herd, the Upper Lake Fork herd, and the Henson Creek herd. Exchange is likely to occur among these three subpopulations throughout the year. S33 is considered by CDOW to be an indigenous herd of > 100 animals and comprised of one or more interconnected herds. For this reason, the recently adopted Colorado Bighorn Sheep Management Plan (George et al. 2008) designates S33 as a primary (“Tier 1”) population and ranked as a high priority for conservation at a statewide level. This designation places S33 in the top priority for inventory, habitat protection and improvement, disease prevention, and research. These primary core populations are thought to represent those populations that have maintained the greatest genetic diversity, and their ranges may represent habitats where bighorn populations have best been able to persist in sizable numbers. As such, CDOW considers S33 to be among the most important bighorn herds in the state. For this reason, CDOW recommends taking all available opportunities to reduce the potential for disease transmission from domestic sheep to this herd. Records indicate the S33 herd has been supplemented with animals from other herds at least three times in the recent past. In 1987 there was a release on Pole Mountain of 3 animals from the Trickle Mountain herd, and a release on Upper Lake Fork of 2 animals from the San Luis/Cebolla herd. Several animals from the Georgetown herd released in the Animas River canyon in 2000 through 2003 were later observed in residence in the S33 herd. The CDOW continues to manage S33 for providing hunting opportunities. Between 1982 and 1990 CDOW issued between 2 and 5 ram tags annually. S33 was closed to hunting between 1991 and 2005, then re-opened for hunting in 2006 with 3 ram tags issued annually since then. Hunting success rate averages 30% for this unit (Diamond 2005). No ewe licenses have ever been issued for this herd. Under current management, the S33 bighorn herd overlaps with 3 active or vacant domestic sheep allotments: Picayne/Mineral Point (active), Eureka (active), and Minnie Gulch (vacant). All sheep grazing allotments that overlap with S33 summer range are BLM allotments. No FS grazing allotments in the Silverton Landscape overlap with S33 D-5
Silverton Grazing Risk <strong>Assessment</strong> bighorn summer range. Together, there is about 4,877 acres of overlap between these allotments and mapped summer range of the S33 herd. Within this area of overlap, about 821 acres (17%) are suitable for domestic sheep grazing. West Needles Herd (S71): The S71 West Needles Herd was established with animals translocated from the Georgetown Herd in 2000, and 2002-2003. The 2007 estimated population size of the West Needles herd was 75 animals (George et al. 2008), and reproduction and survival have been good (Beecham et al. 2007). Bighorn sheep use the entire Animas River canyon from Rockwood up to Needle Creek. The primary summer range of this herd is the West Needle Mountains, and primary winter and lambing range is the Animas River canyon from Rockwood up to the Cascade Wye. Immediately after release, two bighorns dispersed into the S21 Ouray-Cow Creek herd. Based on ear tag observations, several sheep dispersed into the S33 Pole Mountain/Upper Lake Fork herd. Six or seven sheep moved into the Hermosa Cliffs area to the west of the Animas River canyon and have remained there and produced lambs every year. The CDOW opened S71 for hunting for the first time in 2007 with 1 ram tag issued annually. No ewe licenses have ever been issued for this herd. S71 is considered a translocated herd by CDOW and therefore is lower priority for conservation at a statewide level (George et al. 2008). As a translocated population, CDOW recognizes the existence of pre-existing domestic sheep grazing to the north, east, and west of S71, and does not advocate closure of active domestic sheep allotments on public land based solely on the potential for interaction between domestic and bighorn sheep (Colorado Division of Wildlife 2009). CDOW does however, suggest working with existing permittees grazing sheep in areas of mapped overlap with bighorn sheep summer range to collaboratively take advantage of opportunities if/when they arise to reduce the potential for physical contact, and the subsequent potential for disease transmission, between domestic sheep and bighorn sheep of the S71 herd. Under current management, the S71 bighorn herd overlaps with 6 active or vacant domestic sheep allotments. Of these, 5 are FS allotments: West Lime (vacant), Little Molas/West needles (vacant), Needles Mountains (vacant), Flume (vacant), and Deer Creek/Engine Creek (active). One active BLM grazing allotment, Gladstone, overlaps with mapped summer range for S71. Together, there is about 36,554 acres of overlap between these 6 allotments and mapped summer range of the S71 herd. Within this area of overlap, about 9,464 acres (26%) is suitable for domestic sheep grazing. ALTERNATIVES CONSIDERED BUT ELIMINATED FROM FURTHER ANALYSIS We considered the possibility of moving domestic sheep bands from currently active allotments where the perceived risk of contact with bighorn sheep is “High” (see figure 3, below) to other currently vacant allotments where the perceived risk of contact with bighorns may be lower. Below is a brief discussion of the alternatives considered but eliminated, and the reasons for their elimination. Graysill and Flume allotments (FS, vacant allotments): These allotments have been vacant since 1989. They have been successfully used as a forage reserve as recently as 2002 with no adverse impacts to vegetation and soils. There are few if any conflicts with recreation. There is a small area of overlap with mapped summer range of the S71 West Needles bighorn sheep herd in the extreme south end of the Flume Allotment. Due to difficult D-6
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United States Department of Agricul
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Silverton Landscape Grazing Analysi
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These issues led the agency to deve
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administered with shared facilities
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Engine Creek/Deer Creek Allotment T
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Gladstone Allotment This allotment
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Gulch. In 1956, the numbers decreas
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Figure 1-1. Project Analysis Area 1
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Specific Management Emphasis Areas
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Livestock Grazing Permits Livestock
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Figure 1-3. Management Emphasis Are
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Desired Conditions for Bighorn: Red
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Figure 1-4. 2008 Data Collection Po
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Figure 1-6. Wilderness Overlap 24
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Issues ____________________________
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CHAPTER 2 - ALTERNATIVES This chapt
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Alternative Livestock Bedding 2 3 S
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Alternative Noxious Plants/Invasive
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Table 2-2. Project Design Criteria
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Alternative Minimization of Threat
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Alternative 2 - Current Management_
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Elk Creek Allot • Do not use the
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Figure 2-1. Proposed Action - Avoid
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Monitoring for Alternative 3 Monito
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• Photographs and Photo-points: P
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years in an emergency situation, su
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Comparison of Alternatives ________
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Water Quality _____________________
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ENVIRONMENTAL CONSEQUENCES Alternat
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from water or bedgrounds (Arnold an
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2008). It differs from the wetland
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Red Mountain Allotment Yellow toadf
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unlikely that any of these species
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Recreation Special Use Permits for
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livestock management would not chan
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Concurrent to this grazing analysis
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Alternative 2 Habitat conditions fo
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intensity on alpine plants appeared
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Page 79 and 80: lack bighorn sheep escape cover. Th
Page 81 and 82: trailing route, and lack of bighorn
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Page 85 and 86: ptarmigan is expected under Alterna
Page 87 and 88: CUMULATIVE IMPACTS Global warming i
Page 89 and 90: Wildlife - Management Indicator Spe
Page 91 and 92: and it will not be discussed in det
Page 93 and 94: Selecting Alternative 2 would have
Page 95 and 96: for MIS in the landscape. Wildlife
Page 97 and 98: The alpine tundra group would benef
Page 99 and 100: species of conservation concern as
Page 101 and 102: management options, while others ma
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Page 105 and 106: present state. In general, where un
Page 107 and 108: CHAPTER 4 - CONSULTATION AND COORDI
Page 109 and 110: APPENDIX B - CITATIONS AND REFERENC
Page 111 and 112: Martin, K.D., T.J. Schommer, and V.
Page 113 and 114: Regional Office, Durango, CO. Weste
Page 115 and 116: Species Habitat Present In the Spec
Page 117 and 118: Species Mammals (13) Allen’s big-
Page 119 and 120: MIS Species Preferred Habitat Broug
Page 121 and 122: Likelihood of Species Status* Prefe
Page 123 and 124: APPENDIX D - BIGHORN RISK ASSESSMEN
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NEPA--Environmental Assessment

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