Snow Mesa and Wishbone Sheep Allotments

Transcription

1 United States Department of Agriculture Forest Service Snow Mesa and Wishbone Sheep Allotments Volume II DRAFT Appendix A: Assessment of Risk of Physical Contact between Rocky Mountain Bighorn Sheep and Domestic Sheep in the Snow Mesa Sheep Allotment Grazing Landscape Divide Ranger District, Rio Grande National Forest Mineral County, Colorado Domestic sheep at the base of Baldy Cinco on the Snow Mesa Allotment.

2 The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C , or call (800) (voice) or (202) (TDD). USDA is an equal opportunity provider and employer.

3 DRAFT Snow Mesa and Wishbone Risk Assessment Snow Mesa and Wishbone Sheep Allotments DRAFT Risk Assessment Divide Ranger District, Rio Grande National Forest, Mineral County, Colorado Lead Agency: Responsible Official: For Further Information: Documents Available at: USDA Forest Service Martha Williamson, District Ranger Divide Ranger District Rio Grande National Forest W. Highway 160 Del Norte, Colorado (719) Tanner Dutton or Dale Gomez Divide Ranger District W. Highway 160 Del Norte, Colorado (719) Rio Grande National Forest Projects webpage Abstract: This appendix is a public document that provides supporting information for the Environmental Assessment prepared for the Snow Mesa Sheep Allotments. The goal of the Risk Assessment contained within is to provide an objective evaluation of the risk of contact between bighorn sheep and domestic sheep for each allotment. i

4 USDA Forest Service ii

5 DRAFT Snow Mesa and Wishbone Risk Assessment Table of Contents INTRODUCTION... 1 PURPOSE OF THIS DOCUMENT... 3 WHY THE CONCERN NOW: CHANGE IN CONDITIONS... 6 ALTERNATIVES EVALUATED... 7 KEY CONCEPTS, GUIDANCE, AND RECOMMENDATION DOCUMENTS HISTORY AND CURRENT STATUS OF DOMESTIC SHEEP GRAZING STATUS OF CENTRAL SAN JUAN BIGHORN HERD POPULATION BIGHORN SHEEP SUITABLE SUMMER (SOURCE) HABITAT IN THE SNOW MESA LANDSCAPE AFFECTED BIGHORN SHEEP HERDS S-22 SAN LUIS PEAK SUB-HERD S-53 BRISTOL HEAD SUB-HERD S-36 BELLOWS CREEK SUB-HERD RISK OF CONTACT TOOL DISEASE HISTORY RISK ASSESSMENT OUTCOMES MODELING RESULTS WITH THE RISK OF CONTACT TOOL SNOW MESA ALLOTMENT TABLE ALLOTMENT MINERS ALLOTMENT OURAY ALLOTMENT WISHBONE ALLOTMENT DISCUSSION UNCERTAINTIES REFERENCES CITED APPENDIX ALTERNATIVE 3 (ALLOTMENT BOUNDARY RECONFIGURATION) ALTERNATIVE 4 (PERMITTEE SUGGESTED) ALTERNATIVE 5 (WISHBONE ALLOTMENT) APPENDIX APPENDIX APPENDIX iii

6 USDA Forest Service List of Tables TABLE 1. POPULATION ESTIMATE OF CENTRAL SAN JUAN HERD BY GAME MANAGEMENT UNIT TABLE 2. DISEASE STATUS OF ROCKY MOUNTAIN BIGHORN SHEEP ON THE RIO GRANDE NATIONAL FOREST TABLE 3. RATING FACTORS CONSIDERED TABLE 4. INPUT VALUES USED IN THE RISK OF CONTACT TOOL FOR BIGHORN SHEEP HERDS IN THE SNOW MESA ALLOTMENT GRAZING ANALYSIS AREA TABLE 5. EXAMPLE OF MODEL RESULTS FOR THE TABLE ALLOTMENT ONLY AND THE SAN LUIS PEAK BIGHORN HERD (S-22) UNDER CURRENT ALLOTMENT CONFIGURATION (ALTERNATIVE 2) TABLE 6. SNOW MESA ALLOTMENT RISK OF CONTACT TOOL COMPARISON FOR ALTERNATIVE TABLE 7. SNOW MESA ALLOTMENT RISK OF CONTACT TOOL COMPARISON FOR ALTERNATIVE TABLE 8. TABLE ALLOTMENT RISK OF CONTACT TOOL COMPARISON FOR ALTERNATIVE TABLE 9. TABLE ALLOTMENT RISK OF CONTACT TOOL COMPARISON FOR ALTERNATIVE TABLE 10. MINERS ALLOTMENT RISK OF CONTACT TOOL COMPARISON FOR ALTERNATIVE TABLE 11. MINERS ALLOTMENT RISK OF CONTACT TOOL COMPARISON FOR ALTERNATIVE TABLE 12. MINERS ALLOTMENT RISK OF CONTACT TOOL COMPARISON FOR ALTERNATIVE TABLE 13. OURAY ALLOTMENT RISK OF CONTACT TOOL COMPARISON FOR ALTERNATIVE TABLE 14. OURAY ALLOTMENT RISK OF CONTACT TOOL COMPARISON FOR ALTERNATIVE TABLE 15. WISHBONE ALLOTMENT RISK OF CONTACT TOOL COMPARISON FOR ALTERNATIVE TABLE 16. RISK OF CONTACT TOOL PREDICTIONS AND RISK RATINGS FOR EACH ALTERNATIVE TABLE 3-1. PROJECT DESIGN CRITERIA FOR ALTERNATIVES 1, 2, 3, AND List of Figures FIGURE 1. LOCATION OF THE GRAZING ALLOTMENTS IN RIO GRANDE NATIONAL FOREST FIGURE 2. LOCATION OF CENTRAL SAN JUAN ROCKY MOUNTAIN BIGHORN SHEEP HERD (RBS-22) AND GAME MANAGEMENT UNITS FIGURE 3. ALTERNATIVE 2 - CONTINUED GRAZING FIGURE 4. ALTERNATIVE 3 - ALLOTMENT BOUNDARY RECONFIGURATION FIGURE 5. ALTERNATIVE 4 PERMITTEE-SUGGESTED BOUNDARY RECONFIGURATION FIGURE 6. ALTERNATIVE 5 LOCATION OF PASTURES WITHIN THE WISHBONE ALLOTMENT FIGURE 7. CRYSTAL BASIN, SHALLOW, DEEP CREEK, AND SIXMILE FLATS PASTURES WITHIN THE WISHBONE ALLOTMENT FIGURE 8. SOUTH RIVER PASTURE WITHIN THE WISHBONE ALLOTMENT FIGURE 9. EAST BENCH PASTURE WITHIN THE WISHBONE ALLOTMENT FIGURE 10. COLLER PASTURE WITHIN THE WISHBONE ALLOTMENT FIGURE 11. ALTERNATIVE 5 PASTURES AND TRAILING ROUTES FIGURE 12. LOCATION OF CORE HERD HOME RANGES (CHHR) AND DOCUMENTED BIGHORN SHEEP HERDS, AND PROXIMITY TO CURRENT ALLOTMENT BOUNDARIES FIGURE 13. SUITABLE SOURCE SUMMER HABITAT FOR BIGHORN SHEEP IN THE SNOW MESA VICINITY iv

7 DRAFT Snow Mesa and Wishbone Risk Assessment Introduction The Snow Mesa landscape is located about 5 miles northwest of Creede, Colorado, within Mineral and Hinsdale counties and the Divide Ranger District of the Rio Grande National Forest (Fig. 1). The landscape includes about 34,558 acres consisting of three active domestic sheep allotments (Snow Mesa, Table, and Miners) and one vacant sheep allotment (the Ouray Allotment, vacant since 1988). Livestock grazing has occurred in this landscape since the early 1920s. The current permittees (permitted since 1998) are authorized to graze up to 1,000 ewes (with one or more lambs) from July 11 to September 15 on a yearly basis with one combined band of sheep. The Snow Mesa landscape also encompasses the boundary of the Central San Juan Rocky Mountain Bighorn Sheep Herd (RBS-22) (Fig. 2). RBS-22 is comprised of four discrete subherds, which are managed as one larger interconnected herd due to likely population connectivity throughout the RBS-22 landscape. The four sub-herds consist of S-22 (San Luis Peak), S-53 (Bristol Head), S-36 (Bellows Creek), and S-52 (Rock Creek). For simplification purposes, the main bighorn herd is referred to as RBS-22. The S-52 (Rock Creek) herd is not included in this analysis due to distance from the allotments (>15 miles) and small herd size (<25 animals). Snow Mesa Allotment with Baldy Cinco and the Continental Divide in the background

8 USDA Forest Service Figure 1. Location of the grazing allotments in Rio Grande National Forest. 2

9 DRAFT Snow Mesa and Wishbone Risk Assessment Figure 2. Location of Central San Juan Rocky Mountain Bighorn Sheep Herd (RBS-22) and Game Management Units. Source: Colorado Parks and Wildlife GIS Team. Purpose of this Document Rocky Mountain bighorn sheep are designated by the U.S. Forest Service Rocky Mountain Regional Office (also known as Region 2) as a Sensitive Species on National Forest System lands within the Rocky Mountain Region (USDA Forest Service 2011a). This designation implies that there is concern for the long-term viability and/or conservation status of bighorn sheep on National Forest System lands in the Region (Beecham et al. 2007). For this reason, all agency actions that have the potential to affect bighorn sheep conservation are analyzed for their potential impacts to bighorn sheep. Analyzing and disclosing the potential effects of domestic sheep grazing on bighorn sheep is needed to meet Forest Service Manual 2670 direction for sensitive species management, as described in FSM Although habitat degradation from fire suppression, highways, livestock grazing, and human disturbance is of concern, the susceptibility of bighorn sheep herds to population declines or extirpation due to respiratory diseases, which can be transmitted by domestic sheep or goats (Besser et al. 2012b, Cassirer et al. 2013), appears to be the greatest concern for bighorn 3

10 USDA Forest Service sheep population persistence on the Rio Grande National Forest (USDA Forest Service 2010). Mortality and depressed recruitment resulting from pathogens introduced by domestic livestock are regarded as the limiting factor for bighorn sheep in Colorado (Colorado Parks and Wildlife 2009). Physical contact between domestic sheep or goats and bighorn sheep increases the risk of disease transmission from domestic animals to bighorn sheep. The primary disease agents are respiratory diseases to which domestic sheep and goats are typically resistant or unaffected, and to which bighorn sheep have little resistance (Cassirer et al. 2013; Besser et al. 2012a, 2012b, and 2014; George et al. 2008; WAFWA 2012). Pneumonia caused by bacterial respiratory pathogens is considered the most virulent disease impacting bighorn sheep today (Besser et al. 2012b, George et al. 2008, Beecham et al. 2007). It can result in all-age die-offs followed by suppressed lamb recruitment up to several decades after the initial die-off (George et al. 2008). Survivors become carriers of the disease and serve as a source of infection for other animals in the same herd, or other populations, through natural movements, forays, or translocations. The complete range of mechanisms and/or causal agents that lead to disease events and low recruitment in bighorn sheep is still debated, and not all bighorn sheep disease events can be attributed to contact with domestic sheep or goats (Besser et al. 2012b). However, when contact between bighorn sheep and domestic sheep or goats is documented, the severity of the bighorn sheep die-off is typically more pronounced. In some cases, bighorn sheep disease events can be devastating, population-limiting events with outbreaks affecting animals of all age classes, and resulting in prolonged periods of low lamb survival (Cassirer et al. 2013, Besser et al. 2012b, and Besser et al. 2014). The majority of scientific literature supports the potential for respiratory diseases to be transmitted from domestic sheep and goats to bighorn sheep, frequently followed by bighorn mortality events (Cassirer et al. 2013; WAFWA 2012; Besser et al. 2012a, 2012b, and 2014; USDA Forest Service 2010 and 2011b; Schommer and Woolever 2001; Martin et al. 1996). It is recognized that opposing arguments question this science and dispute the connection. The majority of literature, however, supports the potential for disease transmission between domestic sheep and bighorn sheep, and documents bighorn die-offs after contact with domestic sheep. Research continues on the science of disease transmission, bighorn mortality events, and the potential for development of effective vaccines. But until the science is better understood, it is prudent to consider and implement management actions designed to keep the species separate as a means to prevent the potential for disease transmission and subsequent bighorn mortality events. Within the Snow Mesa landscape, portions of two active domestic sheep allotments (Snow Mesa and Miners) overlap with Core Herd Home Range (CHHR) for bighorn sheep, as mapped jointly by the Rio Grande National Forest and Colorado Parks and Wildlife and based upon professional knowledge and verified sightings and surveys. Direct overlap exists between mapped CHHR for bighorn sheep and areas currently grazed or suitable for grazing by domestic sheep. Additional source (suitable) habitat for bighorn sheep extends across other areas of all four of the allotments, suggesting that bighorn sheep could travel or disperse (i.e., foray) into currently unoccupied, but suitable, source habitat, creating a potential risk of physical contact between bighorn and domestic sheep among the sub-herds. 4

11 DRAFT Snow Mesa and Wishbone Risk Assessment The sub-herds are grouped together and managed as one larger herd due to likely population connectivity throughout RBS-22, including the Snow Mesa landscape. The risk of contact between foraying bighorn sheep and domestic sheep allotments corresponds to the number of bighorn sheep in a herd, proximity of domestic sheep allotments, the distribution of bighorn sheep source habitats (suitable habitat) across the landscape, and distance and frequency of bighorn sheep forays outside their CHHR. As part of this analysis process, the Risk of Contact Tool Users Guide, prepared by the USDA Forest Service Bighorn Sheep Working Group (USDA Forest Service 2013), and the related Wildlife Society Bulletin article, Incorporating Foray Behavior Into Models Estimating Contact Risk Between Bighorn Sheep and Areas Occupied by Domestic Sheep (O Brien et al. 2014), were used to help evaluate bighorn sheep movements outside of their Core Herd Home Range (CHHR), and assess the potential for risk of contact between bighorn sheep and domestic sheep allotments in the Snow Mesa landscape. This Risk Assessment analysis is focused on the risk of contact between bighorn sheep and domestic sheep allotments. Following bighorn sheep contact with an allotment, no presumption is made that physical contact between the two species would always lead to disease transmission or a subsequent bighorn sheep mortality event. However, the assumption is made that physical contact between bighorn sheep and domestic sheep results in an increased risk of disease transmission potential to bighorn sheep, with increased potential for a subsequent bighorn mortality event. Therefore it is prudent to reduce the risk of contact, and/or increase the distance and/or degree or effectiveness of separation, between the two species (Colorado Parks and Wildlife 2009; WAFWA 2012). The presence of bighorn sheep on a domestic sheep allotment increases the likelihood of comingling between domestic and bighorn sheep, thereby increasing the likelihood of transmission of infectious disease agents. The goal of this Risk Assessment is to provide the decision maker with an objective evaluation of the risk of contact between bighorn sheep and domestic sheep for each allotment. Modeling results from the Risk of Contact Tool provide the decision maker with an objective evaluation of foray probabilities of bighorn sheep into each domestic sheep allotment in the Snow Mesa landscape and potential contact rates between bighorn and domestic sheep. Other qualitative information is provided and combined with results from the Risk of Contact Tool to determine a final ranking of risk of physical contact between bighorn sheep and domestic sheep. The decision maker will then use the results of this Risk Assessment as an important factor of consideration in their decision regarding domestic sheep grazing in the Snow Mesa landscape. As with most quantitative and qualitative approaches to evaluating risk of contact, a variety of uncertainties must be recognized and considered. A more detailed discussion about uncertainties associated with the Risk of Contact Tool, with domestic sheep management techniques, and with ecological factors unique to the Snow Mesa landscape and RBS-22 is provided later in this document. 5

12 USDA Forest Service Why the Concern Now: Change in Conditions As discussed in Volume I of the Environmental Assessment (EA), the main concern brought forth during internal and external scoping for this analysis is the potential for disease transmission given the risk of contact between domestic and bighorn sheep. Concerns regarding contact between domestic and bighorn sheep on the allotments have been expressed to the Rio Grande National Forest by Colorado Parks and Wildlife and the Gunnison National Forest for a number of years. These concerns have been especially elevated in recent years due to a variety of factors, including: 1. Rocky Mountain bighorn sheep were designated as a Forest Service Rocky Mountain Region Sensitive Species on June 8, Although habitat degradation from fire suppression, highways, livestock grazing, and human disturbance is of concern in some herds, the susceptibility of herds to extirpation as a result of diseases that may be transmitted by domestic sheep or goats appears to be the greatest threat. The long history and continued substantial risk of disease epizootics, combined with small size and high degree of isolation of most herds, led to the conclusion that sensitive status was warranted in the Forest Service Rocky Mountain Region (Beecham et al. 2007). a. Sensitive species require a more in-depth analysis regarding species viability during planning. This includes thorough reviews and analyses of management actions that could affect populations of bighorn sheep or their habitat to ensure species viability and to preclude demographic trends that would result in the need for Federal listing. 2. Direction from the USDA Forest Service Washington Office (USDA Forest Service 2011b) instructs Forests to conduct bighorn sheep risk assessments using a suggested four-step viability analysis outline. This analysis follows that outline, which includes: 1) Gather Applicable data and information from appropriate sources; 2) Assess spatial and temporal overlap of bighorn sheep CHHRs with domestic sheep allotments, use areas, and driveways; 3) Assess likelihood and rate of contact based on spatial and temporal overlap between allotments and bighorn sheep herds; and 4) Identify management practices with the goal of separation between domestic and bighorn sheep where necessary to provide for Forest-wide bighorn sheep viability. A followup letter from the Forest Service Rocky Mountain Regional Office containing additional information regarding bighorn sheep analysis for National Environmental Policy Act (NEPA) documents was also released (USDA Forest Service 2011c). 3. The Snow Mesa Allotment Term Permit/NEPA is outdated; the last analysis was completed in 1977 through an Environmental Analysis Report. 4. Three out of four of the subpopulations making up the Central San Juan Sheep Herd are either stagnant or decreasing in size due to low recruitment and high lamb mortality (Colorado Parks and Wildlife 2013). 5. A greater awareness and emphasis by agencies and the public regarding potential disease transmission. 6. The Final Bighorn Sheep Management Plan for the herd identifies it as a Tier 2, primary population in Colorado. More information on what defines a Tier 2 primary population is discussed in the history of the Central San Juan Bighorn Herd section. 6

13 DRAFT Snow Mesa and Wishbone Risk Assessment 7. Improved survey work by both Colorado Parks and Wildlife and the Rio Grande National Forest, which has resulted in updated information regarding domestic sheep use of the allotments, more accurate information on the number of bighorn sheep in the area and their use of the allotments, and more accurate depictions of current bighorn sheep CHHRs. 8. Bighorn sheep are documented immediately adjacent to and within the northern portion of the allotments, primarily along the Continental Divide (See. Fig. 12, presented later in the Status of Central San Juan Bighorn Herd Population section of this document). 9. The presence of adult ewe groups, groups of bachelor rams in the summer/fall, and rams harvested in the fall immediately north of the allotments indicate that at least the northern portion of the allotments is used year-round by bighorn sheep. These use patterns were used in the identification of the CHHR. 10. There is a lack of spatial and/or temporal separation between the two species, particularly in the northern portion of the allotment. The two species graze within the same area (spatially) at the same time (temporally) during the summer, particularly in the Baldy Cinco, Baldy Chato, head of Miners Creek, and Oso Creek areas, all of which are along the Continental Divide. 11. There are no known effective landscape barriers preventing contact. 12. There is suitable but currently unoccupied bighorn sheep habitat in the allotments with adequate connectivity existing throughout. 13. Ewe groups in the S-22 and S-53 herds immediately to the north and south of the allotments have been experiencing little to no lamb recruitment in recent years. Alternatives Evaluated Alternative 1 No Grazing; the allotments would become vacant. Alternative 2 Continued grazing with project design criteria. (Fig. 3). Alternative 3 Allotment boundary reconfiguration to exclude those areas of highest risk on the northern perimeter of the allotments and including a portion of the vacant Ouray Allotment to help replace loss of acres suitable for grazing. Project design criteria are also incorporated (Fig. 4). 7

14 USDA Forest Service Figure 3. Alternative 2 - Continued Grazing. Figure 4. Alternative 3 - Allotment Boundary Reconfiguration. 8

15 DRAFT Snow Mesa and Wishbone Risk Assessment Alternative 4 A permittee-suggested alternative (referred to as Alternative 4) would completely remove the Snow Mesa Allotment from the analysis area but would add more acres of the vacant Ouray Allotment to form a new allotment boundary (Fig. 5). This option would slightly reduce the risk to the S-22 bighorn sheep herd to the north by removing the Snow Mesa Allotment from grazing consideration but increase the risk to the S-53 bighorn herd to the south. The Risk of Contact Model was run on this alternative. Due to overlap with the S-53 Core Herd Home (occupied by bighorn), it has a high risk rating that is not expected to result in an acceptable contact rate. Due to this high risk rating, lack of topographical barriers separating the two species, and the need to not rely solely on best management practices to reduce the risk of species association, this alternative was not considered feasible for achieving the purpose and need and was not evaluated further in the EA. The modeling results of Alternative 4 are contained in Tables 3-4 and 3-12 in the EA. However, the modeling results of this alternative are carried forth within this document. Other Alternatives Considered but not further pursued or evaluated are included in the EA. Figure 5. Alternative 4 Permittee-suggested boundary reconfiguration. 9

16 USDA Forest Service Alternative 5 The Snow Mesa, Table, and Miners allotments will be vacated. A portion of the Ouray Allotment (Crystal Basin) along with up to seven smaller pastures on the valley floor near Creede will be incorporated into a new domestic sheep allotment referred to as the Wishbone Allotment (Figs. 6 11). Figure 6. Alternative 5 Location of pastures within the Wishbone Allotment. 10

17 DRAFT Snow Mesa and Wishbone Risk Assessment Figure 7. Crystal Basin, Shallow, Deep Creek, and Sixmile Flats pastures within the Wishbone Allotment. Figure 8. South River pasture within the Wishbone Allotment. 11

18 USDA Forest Service Figure 9. East Bench pasture within the Wishbone Allotment. Figure 10. Coller pasture within the Wishbone Allotment. 12

19 DRAFT Snow Mesa and Wishbone Risk Assessment Figure 11. Alternative 5 pastures and trailing routes. 13

20 USDA Forest Service The decision maker will consider the results of the risk of contact analysis as one factor for consideration in the decision regarding future domestic sheep grazing on the allotments. The Risk of Contact Model evaluates the probability and rates of contact resulting from bighorn sheep forays onto the allotment. The analysis regarding the potential for disease transmission and long-term viability of bighorn sheep herd are based on the outcome of the contact analysis associated with each alternative. Assumptions associated with disease transmission and effects on viability are based on available disease probabilities and literature regarding this subject (Foreyt 1990; George et al. 2008). The information in these references represents the best available science regarding potential viability outcomes due to interspecies contact between bighorn sheep and domestic sheep. Key Concepts, Guidance, and Recommendation Documents The documents described below provide guidance and suggestions for consideration by land management agencies evaluating domestic sheep grazing activities within or in proximity to bighorn sheep range. As generally accepted principles for achieving consensus-based conservation of bighorn sheep, these documents provide key concepts that can help land management agencies achieve species conservation goals while also meeting multiple use goals. These documents, and a wide variety of scientific literature, were reviewed and key concepts were considered in the development of project design criteria (Appendix 8) and this Risk Assessment. 1. Bighorn Sheep Analysis for NEPA Documents, Washington Office Letter. August 19, Joel D. Holtrop Deputy Chief, National Forest System (USDA Forest Service 2011b). Provides national direction to address potential implications of disease transmission from domestic sheep/goats to bighorn sheep. Forests were instructed to conduct bighorn sheep risk assessments using a provided viability analysis outline. 2. Bighorn Sheep Analysis for NEPA Documents, Forest Service Rocky Mountain Regional Office Letter. September 14, Glenn Casamassa, Acting Deputy Regional Forester, Resources (USDS Forest Service 2011c). Letter re-emphasized the importance of conducting risk assessments in accordance with the viability analysis outlined in the Washington Office letter where management objectives include maintenance or enhancement of bighorn sheep populations. 3. Bighorn Sheep Analysis for NEPA Documents, Washington Office Letter. July 31, Leslie A. C. Weldon. Deputy Chief, National Forest System (USDS Forest Service 2014). Provides national direction to line officers to identify and analyze potential replacement allotments when developing management alternatives; and to continue ongoing collaborative efforts to identify and develop site-specific solutions. 4. Memorandum of Understanding Signed April of 2014 by the Forest Service Rocky Mountain Region, Bureau of Land Management Colorado State Office, Colorado Division of Wildlife, Colorado Department of Agriculture, and the Colorado Woolgrowers Association. The purpose of the memorandum is to provide general guidance for cooperation in reducing contact between domestic and bighorn sheep in order to minimize potential interspecies disease transmission and to ensure healthy 14

21 DRAFT Snow Mesa and Wishbone Risk Assessment bighorn sheep populations while sustaining an economically viable domestic sheep industry in Colorado. The MOU has six sections: I Purpose, II Statement of mutual benefits and interest, III Authority, IV All parties agreements, V Colorado Parks and Wildlife and CWGA agreements, and VI Mutual agreement and understanding by all parties. Under Section IV, All Parties Agree, the Forest Service agrees that the goal is to minimize contact by decreasing the opportunities for domestic/bighorn sheep interaction. The Forest Service is not bound by sections explicitly restricted to Colorado Parks and Wildlife and CWGA. 5. USDA Forest Service (2013). Bighorn Sheep Risk of Contact Tool Users Guide. USDA Forest Service, Intermountain Region. Prepared by USDA Forest Service Bighorn Sheep Working Group, Critigen, Inc. 6. Supplement to the Forest Plan Biological Evaluation and Conservation Assessment for Rocky Mountain Bighorn Sheep Rio Grande National Forest (R. Ghormley). Bighorn sheep were designated as a Forest Service Rocky Mountain Region Sensitive Species on June 8, 2007, and were not addressed as a sensitive species in the Forest Plan biological evaluation. This document updated the Rio Grande National Forests biological evaluation and determined that the Forest Plan Alternative G does not provide the management direction needed to ensure that effective separation is maintained between domestic and domestic sheep. Without additional considerations, the analysis determined that Forest Plan Alternative G is likely to result in a loss of viability in the Planning Area. However, this determination is not expected to result in a trend toward Federal listing because, although significantly reduced, many Rocky Mountain bighorn sheep populations in Colorado and the west remain secure. 7. Rocky Mountain Bighorn Sheep: A Technical Conservation Assessment Prepared for the USDA Forest Service Rocky Mountain Region, Species Conservation Project (Beecham et al. 2007). This report was designed to provide land managers, biologists, and the public with a thorough discussion of the biology, ecology, conservation status, and management of target species based on current scientific knowledge. It discusses management approaches used or recommended in Western States and provinces. 8. Bighorn Sheep Management Plan, Data Analysis Unit RBS-22, Central San Juans, Game Management Units S-22, S-36, S-52, & S-53). (Colorado Parks and Wildlife 2013). Provides management direction for an extended period of time (typically 10 years) for the Central San Juan Sheep Herd. Identifies the herd as a Tier 2 primary core population. The plan establishes objectives for herd size, hunting success rates, and average age of rams harvested. The plan also provides information on habitat, herd history, and primary concerns for the population. The report specifically mentions domestic sheep grazing on the Snow Mesa Sheep Allotments as a primary concern. 9. Colorado Bighorn Sheep Management Plan, Special Report Number 81. (Colorado Parks and Wildlife 2009). Directs Colorado Parks and Wildlife to, among other things, prioritize conservation of bighorn sheep herds in Colorado on the basis of herd size, native status, management history, and potential for interaction with 15

22 USDA Forest Service domestic sheep. State management goals for the bighorn sheep herds affected by this project were considered by local Colorado Parks and Wildlife staff that provided information regarding affects this project might have on bighorn sheep. 10. Recommendations for Domestic Sheep and Goat Management in Wild Sheep Habitat. Western Association of Fish and Wildlife Agencies, Wild Sheep Working Group (WAFWA 2012). A report published by a collection of State and provincial wildlife management agencies that seek to work collaboratively with the livestock industry to reduce the potential for wild sheep die-offs. This report articulates concerns about potential disease transmission between domestic livestock and wildlife, and suggests an array of management approaches to minimize such risks. This report advocates, among other things, that effective separation (both temporal and/or spatial) of wild and domestic sheep should be a primary management goal. 11. A Process for Finding Management Solutions to the Incompatibility between Domestic and Bighorn Sheep (Schommer and Woolever 2001). Provides Forest Service staff with recommendations for using a collaborative approach to find management solutions to reduce or eliminate contact between wild sheep and domestic sheep. History and Current Status of Domestic Sheep Grazing The Snow Mesa allotments (Fig. 1) cover approximately 34,558 acres. Earliest records regarding domestic sheep grazing on the allotments date back to the 1920s. The current permittees (since 1998) are authorized to graze one band of sheep (1,000 ewes with one or more lambs) from July 11 to September 15, with minor yearly variations. The Ouray Allotment has been managed as vacant since Photo: Sheep leaving the trucks on July 11, At the beginning of the grazing season, sheep are trucked from private pasture on the Valley floor to the McKenzie Stock Driveway. The sheep, herders, and horses overnight on the Shallow C&H Allotment and are then trailed on the McKenzie Stock Driveway to the Table Allotment. In 2013 and 2014, a portion of the Ouray Allotment was used for 7 10 days prior to sheep being trailed to the Table Allotment. Sheep are trailed to the Miners Allotment and then to the Snow Mesa Allotment. The rotation is reversed later in the season back through Table and down the McKenzie Stock Driveway. The sheep are then trailed to the Deep Creek Road, down Highway 149 with an overnight near Wagon Wheel Gap, and continue down Highway 149. Sheep then trail to private pastures on the Valley floor (fall barley stubble and other crop aftermath are important forage sources), with primary trailing routes located on Rio Grande and Saguache County roads. 16

23 DRAFT Snow Mesa and Wishbone Risk Assessment Increased monitoring of camps throughout the grazing season has improved Forest Service knowledge of band management, trailing routes, camp locations, salting locations, bed ground conditions, and domestic sheep distribution on the landscape. The sheep are managed under the once-over strategy, meaning they graze each area one time over the grazing season. There is minor regrazing late in the season as sheep are trailed through areas previously grazed early in the season. Sheep are grazed in an open fashion and are scattered as they graze across the landscape. The herders stay with the sheep during the day, and sheep are bedded near the camp at night to minimize predation loss and straying. Allotment monitoring has provided better information about bighorn sheep distribution within and adjacent to the allotments. Due to the concern of potential contact between domestic and bighorn sheep, Annual Operating Instructions were modified to exclude those portions of the Miners and Snow Mesa allotments adjacent to the Continental Divide on a trial basis. Areas excluded were Oso Creek, the headwaters of Miners Creek, and areas north of the Continental Divide National Scenic Trail on Snow Mesa. These areas were offset by including portions of the vacant Ouray Allotment for the 2013 and 2014 grazing seasons. Based on the Colorado Bighorn Sheep Management Plan, the Central San Juan Bighorn Herd is designated a secondary (Tier 2) core bighorn sheep population. Secondary core (Tier 2) bighorn populations are medium to large (i.e., >75 animals for >80% of the years since 1986 or since becoming fully established populations consisting of one or more interconnected herds that are native or have resulted from translocations (Colorado Parks and Wildlife 2009). Tier 2 herds may represent indigenous or introduced bighorn sheep populations (and combinations thereof) that have less genetic diversity and more limited ranges that may or may not be able to persist in sizable numbers in the face of various adversities. RBS-22 encompasses native bighorn sheep habitat, where native bighorn sheep still reside. However, because of the number of transplants that have occurred over time, the unit technically meets the criteria for Tier 2 designation (Colorado Parks and Wildlife 2013). Managers continue to consider this Data Analysis Unit a regional priority for several reasons: 1) The S-22 sub-herd is native, was historically one of the most prolific sheep herds in the State, and has never specifically been the focus of transplant efforts. Transplanted animals have made their way into the Game Management Unit through association with native sheep, but the core S-22 herd has remained relatively pure. And 2) Records indicate that bighorn sheep were native to the three other Game Management Units in this Data Analysis Unit, and transplants were the only viable method of reintroducing animals to their historic range following extirpation. 17

24 USDA Forest Service Tier 2 herds are worthy of a high level of investment and protection (Colorado Parks and Wildlife 2013). There are an estimated 7,000 bighorn sheep in the State of Colorado; the current population estimate for RBS-22 is about 250 animals (Table 1). Table 1. Population estimate of central San Juan herd by Game Management Unit Game Management Unit and Subpopulation S-22 (San Luis Peak) 70 S-36 (Bellows Creek) 45 Central San Juan Bighorn Herd (RBS-22) S-52 (Rock Creek) 25 (not included in this analysis) S-53 (Bristol Head) 110 TOTAL 250 Status of Central San Juan Bighorn Herd Population The CHHR for three of the four sub-herds that make up RBS-22 is shown in Figure 12. The CHHR can be thought of as that portion of the overall range where 90% of individual bighorn sheep are located between spring green-up and the first heavy snowfall. The CHHR for these herds was produced by personnel from both Rio Grande National Forest and Colorado Parks and Wildlife, and it is based upon professional knowledge and verified sightings and surveys. Bighorn sightings and locations are also shown on Figure 12 and are intended to demonstrate general bighorn distribution and not necessarily every documented sighting. The Suitable Summer (Source) habitat in the Snow Mesa landscape is shown in Figure 13. Summer source maps have been developed for Colorado by Colorado Parks and Wildlife personnel using their extensive statewide bighorn sheep telemetry data set. The model was determined to be effective, covering 91% of telemetry points from their pooled bighorn telemetry location datasets. 18

25 DRAFT Snow Mesa and Wishbone Risk Assessment Figure 12. Location of core herd home ranges (CHHR) and documented bighorn sheep herds, and proximity to current allotment boundaries. Note that bighorn sheep locations are not meant to reflect all known sightings, but instead are used to show distribution and relative key areas within the CHHRs as determined from documented sightings. 19

26 USDA Forest Service Bighorn Sheep Suitable Summer (Source) Habitat in the Snow Mesa Landscape Habitat models identify a large percentage of the allotments as suitable bighorn sheep habitat. Bighorn sheep habitat in the allotments is well distributed and connected. Habitat connectivity increases opportunities for bighorn dispersal across the area, increasing the potential for bighorn sheep to come into contact with domestic sheep and increasing the chance of a disease event spreading beyond just the impacted herd. The Data Analysis Unit contains large expanses of suitable habitat that should be capable of supporting a considerably larger population of wild sheep. Much of the area and habitat is made up of large expanses of open country in which bighorn can easily pass through, but most likely these areas are not used, to a large extent, by bighorn sheep during an average year. All recent bighorn sightings have been along the Continental Divide to the north and on the far southern end of the Ouray Allotment. Figure 13. Suitable source summer habitat for bighorn sheep in the Snow Mesa vicinity. 20

27 DRAFT Snow Mesa and Wishbone Risk Assessment Affected Bighorn Sheep Herds S-22 San Luis Peak Sub-Herd Historical Occurrence and Distribution The San Luis Peak bighorn herd is indigenous to the region encompassed by Game Management Unit S-22. Informal surveys for bighorn sheep in this unit date back to the 1930s (USDA Forest Service 2010), with anecdotal reports of wild sheep going back to the early 1900s. No documented translocations have occurred in the unit, further corroborating their native origin. The unit contains large expanses of suitable habitat that likely supported a much larger herd of wild sheep prior to European settlement. Though poorly documented, most accounts suggest that historically, one population of bighorn sheep inhabited an overall range that included Game Management Units S-22, S-36, S-52, and S-53. The northern reaches of this Data Analysis Unit (i.e., S-52) would have provided excellent winter range habitat for bighorn sheep migrating from higher elevations; the same is true of the southern reaches between Creede and South Fork. The greater La Garita/San Juan region includes some of the most productive bighorn habitats in Colorado, and it is logical to assume that bighorn populations were connected historically at a much grander scale, with possible exchange also occurring among adjacent Game Management Units S-33, S-28, S-16, and S-15. Photo: Baldy Cinco East, head of Miners Creek along the Continental Divide. Current Occurrence and Distribution This population has been on a declining trend over the last 5 years as a result of poor lamb recruitment. The La Garita Mountains offer abundant wild sheep habitat; however, bighorn sheep have shown strong fidelity to particular areas in recent years. On the other hand, in some areas where bighorn used to be frequently observed, such as near Machin Lake, fewer observations have been made. Wild sheep distribution in this unit appears to be similar to what was reported historically; however the overall range has likely constricted. Evidence of range constriction is evident in a historic bighorn distribution map produced by the Forest Service Cebolla District. That map indicates that bighorn were present in the North Fork of Saguache Creek above Stone Cellar, where bighorns are no longer present. Many factors likely contribute to bighorn distribution in this unit, including population size, loss of migratory knowledge, site fidelity, human recreation, domestic sheep grazing, and, as is the case with most wild ungulates, forage quality and availability. S-22 is relatively remote and includes a sizeable wilderness area. Routine observations of bighorn are not possible, and managers have relied on periodic helicopter surveys, incidental ground observations, and hunter reports to document bighorn distribution over time. In recent years, bighorn have been documented in a variety of areas within S-22 on both sides of the Continental Divide. Notable use areas in the unit include the Rough and Mineral Creek drainages; the Mineral 21

28 USDA Forest Service Mountain region; the Spring Creek drainage, particularly the east side, including San Luis Peak, Stewart Peak, Baldy Alto, and Baldy Chato; the Stewart Creek drainage, Organ Mountain, and the headwaters of the Cochetopa including Canyon Diablo; and the heads of East Willow Creek, Oso Creek, Miners Creek, and Baldy Cinco. This list is not intended to be all-inclusive or prioritized. Rather, it is an attempt to document some of the important geographic areas where sheep have been observed over the last 5 years. In the future, if this population increases, it is likely that bighorn use would increase across the Game Management Unit within suitable habitats (Colorado Parks and Wildlife 2013). Specific Issues Domestic sheep grazing on the Snow Mesa Allotments pose the greatest threat to the S-22 bighorn sheep subpopulation (Colorado Parks and Wildlife 2013). Confirmed range overlap occurs on the northern portion of the allotment from Baldy Cinco eastward to Oso Creek. Bighorn have been observed at the headwaters of Miners Creek on what is referred to locally as Baldy Cinco East in 2011 (group of rams by bighorn sheep hunter), 2012 (six rams by Forest Service personnel), and 2013 (three ewes by Forest Service personnel). Scat samples collected on Baldy Cinco East in 2013 were also identified through DNA analysis as bighorn sheep. A log book on the peak also mentions bighorn sheep sightings. Domestic sheep graze the south face of Baldy Cinco East. In 2012, the permittees were asked to not graze the area from the headwaters of Miners Creek (Baldy Cinco East) to Oso Creek. No domestic sheep grazing has occurred in this area since 2012; however, grazing still occurs from the head of Miners Creek westward toward Baldy Cinco. Domestic sheep typically graze up the slopes of Baldy Cinco up to the Continental Divide. In 2008, the herder was tragically killed by lightning at the head of Oso Creek. The domestic sheep band was unattended for approximately 5 10 days before being discovered, and it is not known where the band wandered or if the band separated into several groups before being rounded up. During a 2011 field reconnaissance trip involving Forest Service and Colorado Parks and Wildlife personnel in the Oso Creek Drainage, the herder mentioned that bighorn would come down from the Continental Divide and lick from his salt blocks. It is probable that wild and domestic sheep were in contact in 2011 along the Continental Divide (Colorado Parks and Wildlife 2013). 22

29 DRAFT Snow Mesa and Wishbone Risk Assessment Historically, several areas along the divide exist where salt was placed on the ground for domestic sheep. These old salt licks continue to attract big game to the Continental Divide and onto the Snow Mesa Allotments, mainly in the Oso Creek area. Domestic sheep currently graze the Continental Divide between Baldy Cinco and the head of Miners Creek (Baldy Cinco East) where bighorn are documented. Photo: Domestic sheep in the Miners Creek Allotment Domestic sheep have been documented in recent years (2012) grazing on the Gunnison Forest outside of the allotment boundary and within close proximity of known bighorn sheep locations. In some years, stray sheep are reported in Miners/Shallow Creek after the main herd has passed through these areas on their way off the forest. In 2013, two stray bands of domestic sheep of about 25 total head were located near the Creede airport a month after the official off-date. It is not known where these sheep were during that timeframe. Also in 2013, a single stray sheep was observed by Forest Service personnel off of Highway 149 near lower Coller State Wildlife Area in November. This sheep was never seen again and ownership was never determined. Domestic sheep grazing north of trail 787 (Continental Divide Trail), just below Baldy Cinco, was documented by Forest Service personnel in Not grazing north of the trail has been part of the Annual Operating Instructions and is a key project design criteria in Alternative 3. A domestic ewe and lamb were observed at the staging area near Miners Creek in 2015 several days after the main herd trailed up the McKenzie Stock Driveway. Issues with salting, bedding ground use, herding, and stray management have improved, but continue to be issues with the allotment. Photo: S-36 Bighorn Ram

30 USDA Forest Service S-53 Bristol Head Sub-Herd Historical Occurrence and Distribution Reports by early explorers dated around 1822 confirm the presence of bighorn sheep in the south San Juan Mountains. Documentation of bighorn sheep in the area during the late 1800s and early 1900s mainly focuses on the neighboring Pole Creek Mountain herd to the west, which is part of the RBS-21 population. Given the close proximity between these two populations, their distributions were likely linked. Local residents, interviewed by Wildlife Conservation Officer Glen Hinshaw, recalled sightings of bighorns at Bristol Head dating back to Federal surveyors noted 14 bighorn at the source of Boulder Creek in Photo: Box Canyon along the North Fork of the Rio Grande. On Bristol Head, five to seven bighorns were recorded for many years until they were harvested during (Bear and Jones 1973). Not much is known about the status of the S-53 herd during the mid-20th century. Bighorns at Bristol Head likely were poached out by 1940 according to G. Hinshaw. Some locals thought that bighorns were functionally extinct from the area following the construction of Santa Maria Reservoir. In the 1980s, bighorn sheep were transplanted from other populations into S-53. The herd remained stable in the 1990s, increased gradually in the early 2000s, then increased more rapidly in the mid- 2000s. Accordingly, S-53 is designated as a transplanted herd, indicating that it has resulted entirely or primarily from translocated bighorns (Colorado Parks and Wildlife 2009). Current Occurrence and Distribution This sub-herd has remained relatively stable over the past 5 years. Lambs and yearlings are regularly observed in the unit during surveys, indicating a moderate level of annual recruitment. An exception may be the Bristol Head group of this population where lamb recruitment appears to be very poor. Overall, the herd does not appear to be increasing substantially and is in more of a maintenance mode. Bighorn subgroups are somewhat widely distributed throughout this unit, likely as a result of where transplants have been introduced over time (Colorado Parks and Wildlife 2009). While bighorns occur broadly within the unit, they tend to be broken into two main subgroups, which are generally east or west of Highway 149. This isolation reduces the potential for bighorn interaction that likely occurred historically in S-53 (Beecham et al. 2007). Similar to other herds in RBS-22, several factors may be contributing to the current distribution of bighorns in S-53. Unlike S-36, there is no definitive evidence of large die-offs due to respiratory disease. However, Colorado Parks and Wildlife personnel have documented instances of individual sheep dying of pneumoniarelated symptoms in 1988 (yearling ram), 1996 (old ram), and 1997 (old ram). Monitoring of this herd occurs through ground and helicopter surveys. These efforts have determined that S-53 sheep are predominantly present in two general locations, as reported by Colorado 24

31 DRAFT Snow Mesa and Wishbone Risk Assessment Parks and Wildlife District Wildlife Manager Brent Woodward (personal communication, 2015): 1) Bristol Head Peak and Long Ridge and 2) in the Box Canyon of the Rio Grande River and River Hill. The bighorn sheep in the Bristol Head/Long Ridge area are present primarily at the head of Shallow Creek, Fir Creek, Bristol Head Peak, Seepage Creek, Clear Creek, and Long Ridge. The bighorn sheep in the Box Canyon/River Hill band are present primarily in Crooked Creek, Long Canyon, Road Canyon, Box Canyon, Sawmill Canyon, and north of Rio Grande Reservoir (Colorado Parks and Wildlife 2013). Photo: Ewes and small lamb crossing Highway 149, fall of Specific Issues The majority of the allotment acres are within the S-53 herd boundary, but the closest CHHR is S-22. It is very likely that S-53 bighorn interchange with the S-33 (Pole Mountain) herd farther west, as Forest Service surveys have documented bighorn from these two groups within 1 mile of each other. Interchange between separate bighorn groups is likely and management in any one of the four Game Management Units likely exerts influence over the other units in the Data Analysis Unit and potentially within other Game Management Units. The amount of interchange between S-22 and S-53 bighorn has not been documented and is unknown. Photo: Ewes from the S-53 herd, fall of A small group of domestic goats have free range in the privately owned Santa Maria Reservoir area. The presence of these goats could also provide an avenue for disease transmission to the S-53 bighorn sheep. 25

32 USDA Forest Service S-36 Bellows Creek Sub-Herd Historical Occurrence and Distribution The S-36 sub-herd is designated as part of the native San Luis Peak population (Colorado Parks and Wildlife 2009). When the Creede mining rush occurred in the early 1890s, the number of bighorns declined, likely related to altered habitat conditions and subsistence hunting. Prior to this influx of people in 1889, the number of bighorn sheep observed in Wason Park was documented at 50. Bighorn sheep were known to occupy Bellows Creek (Bear and Jones 1973) in the 1950s. Three rams were observed in the area in , but following unsuccessful search efforts in what is now Game Management Unit S-36, these bighorns were assumed to be migrants (USDA Forest Service 2010). S-36 was formerly referred to as S-55W, indicating connectedness with S-55 (Natural Arch population) to the east. In the 1980s, bighorns were transplanted from other populations into S-36. As a result, S-36 is presently considered a supplemented herd, which is defined as an indigenous herd that has been supplemented with translocated bighorn (Colorado Parks and Wildlife 2009). Photo: East Bellows Creek. Current Occurrence and Distribution The Bellows Creek herd remains stagnant following a presumed pasteurella outbreak presumably due to contact with domestic sheep in the late 1990s. The population was reduced from an estimated high of 125 animals to a low of 30 by The numbers in this herd have slowly increased since 2001 and appear to be on a slow upward trend to an estimated 45 animals today. Monitoring has shown that numerous lambs are present in the herd in June and July but their numbers are greatly diminished by late August. This type of lamb die-off is typical of herds still experiencing impacts of past disease events. In this herd instance, it has taken approximately 20 years for the herd to slowly recover and expand. Photo: S-36 Ram, fall of On the basis of recent population surveys, bighorn sheep currently appear to be more widely distributed in the unit compared to the late-1800s through mid-1900s (Bear and Jones 1973). Transplanted bighorns may have contributed to the re-colonization of some historic bighorn range (Bear 1979). However, disease seems to have prevented this herd from increasing enough to restore interactions with other herds to a 26

33 DRAFT Snow Mesa and Wishbone Risk Assessment noticeable level (Beecham et al. 2007). As with S-22, other factors such as fragmentation of subgroups, human activities across the landscape, and habitat condition likely are affecting herd numbers and distribution. Documenting the range of bighorn sheep in RBS-22 is challenging given the rugged and often remote terrain that bighorns occupy throughout the year. Ground survey efforts by the U.S. Forest Service Divide Ranger District and Colorado Parks and Wildlife provide minimal counts in accessible areas. Expensive helicopter surveys provide a Game Management Unit-wide perspective, but these surveys rarely occur more than once a year. Annual surveys and observations by Colorado Parks and Wildlife District Wildlife Manager Brent Woodward (personal communication, 2015) indicate that bighorn sheep generally have been observed in the area from Mammoth Mountain south to the head of Blue Creek. Bighorn are routinely present in Farmer s Creek, West and East Bellows Creek, Spring Gulch, Wagon Wheel Gap, and Blue Creek (Colorado Parks and Wildlife 2013). Specific Issues The main concern involving S-36 is fall trailing and overnighting of domestic sheep, specifically in the Wagon Wheel Gap area. Bighorn are frequently present in Wagon Wheel Gap, which is a very narrow area along Highway 149 about 4 miles southeast of Creede. Domestic sheep are bedded down for the night on private property in the gap, further compounding the issue and increasing the risk of contact with bighorn in the area. Photo: Domestic sheep trailing through Wagon Wheel Gap on the railroad track, September 18, Photo: S-36 bighorn sheep in Wagon Wheel Gap on the railroad track, April

34 USDA Forest Service Risk of Contact Tool In response to a need for tools to assist with the analysis of risk of contact between domestic and bighorn sheep, the USDA Forest Service Bighorn Sheep Working Group developed a methodology for calculating probabilities and rates of contact between bighorn sheep and domestic sheep allotments. This Risk of Contact Tool is a geospatial desktop application developed for use by field unit resource managers as a tool for evaluating the risk of physical contact between bighorn sheep and domestic sheep allotments under various management scenarios (USDA Forest Service 2013; O Brien et al. 2014). Modeling results obtained with the Risk of Contact Tool provide a consistent framework by which various management scenarios can be compared. The model results allow the user to compare and contrast management scenarios as to their potential to affect modeled rates of contact between bighorn sheep and domestic sheep allotments. From these results and alternative comparisons, inferences can be drawn about how various management alternatives and project designs might increase or decrease the potential for physical contact and presumed potential for subsequent pneumonia-related disease transmission to adjacent bighorn sheep herds. The proposed project design criteria rely heavily on recommendations made in the Western Association of Fish and Wildlife Agency s Recommendations for Domestic Sheep and Goat Management in Wild Sheep Habitat (WAFWA 2012). These recommendations may help reduce the risk to bighorn under circumstances where the risk has already been largely lowered by other factors such as distance, terrain features, and habitat fragmentation. WAFWA guidelines explicitly note that effectiveness of management practices designed to reduce risk of association are not proven and therefore should not be solely relied upon to achieve effective separation. For the past two grazing seasons (2014 and 2015), the allotment boundary configuration and design criteria for Alternative 3 have been tested through direction in the Snow Mesa Sheep Allotments Annual Operating Instructions. Project design criteria regarding stray management and herd management have not been implemented successfully. This supports the WAFWA (2012) guidelines that management practices should not be relied on solely to achieve separation. The Risk of Contact Tool utilizes bighorn sheep CHHR information, a summer source habitat model representing suitable bighorn summer habitat, ram and ewe foray rates, and domestic sheep allotment boundaries to calculate probabilities that rams and ewes may leave a CHHR, undertake a foray, and subsequently contact a specific domestic sheep allotment. Output from the tool also calculates rates of contact between individual bighorns from specific bighorn herds with specific domestic sheep allotments. A CHHR can be thought of as that portion of bighorn overall range where 90% of individual bighorn sheep are located between spring green-up and the first heavy snowfall. The CHHR for the S-36, S-53, and S-22 bighorn herds was produced by representatives from both the Rio Grande National Forest and Colorado Parks and Wildlife personnel based upon professional knowledge, expertise, and verified sightings and surveys specifically for these herds. 28

35 DRAFT Snow Mesa and Wishbone Risk Assessment The summer source habitat model used by the Risk of Contact Tool was primarily developed and tested by Colorado Parks and Wildlife personnel using their extensive statewide bighorn sheep telemetry data set. The model was determined to be effective, covering 91% of telemetry points from their pooled bighorn telemetry location datasets. The summer source habitat model assigns all areas surrounding the CHHR to one of three habitat classes source (suitable) habitat, connectivity areas, and non-habitat. Source habitat includes factors such as vegetation cover type, ruggedness, and horizontal visibility. Connectivity areas do not meet source habitat criteria, but are located within 350 meters of source habitat, or 525 meters if between two areas of source habitat (such as a meadow area between two canyons). Areas of non-habitat do not meet these criteria and are located more than 350 meters from source habitat. It is assumed that bighorn sheep spend less than 1% of their time in these non-habitat areas. Data from other areas indicate bighorn sheep are 34 times more likely to be in source habitat than non-habitat, and are six times more likely to be in source habitat than connectivity areas. The summer source habitat model is used to infer habitat suitability based on species requisites and observed bighorn habitat preferences. However, there is no assumption that areas identified by the model as suitable for bighorns are in fact occupied. The only areas known to be occupied by bighorn sheep in this analysis are those areas identified as CHHR for the three sub-herds analyzed. Currently, bighorn summer source habitat does not appear to be limiting for bighorn sheep in the Snow Mesa landscape. Bighorn sheep make occasional long-distance movements beyond their CHHR. Singer et al. (2001) called these movements, forays and defined them as any short-term movement of an animal away from, then subsequently back to its herd s CHHR. This life-history trait places bighorn sheep at risk of contact with domestic sheep, particularly when bighorn summer source habitats are well connected to or overlap with domestic sheep use areas. The risk of contact between foraying bighorn sheep (mostly rams) and domestic sheep is related to the extent of bighorn sheep source habitat, proximity of domestic sheep allotments, distance of bighorn forays outside their CHHR, and the frequency of bighorn forays outside their CHHRs. Because information on foray distance and frequency is lacking for bighorn sheep herds on the Rio Grande National Forest, the analysis in this Risk Assessment uses the default value in the Risk of Contact Tool (USDA Forest Service 2013; O Brien et al. 2014). The default value for foray frequency is 14.1% for rams and 1.5% for ewes, indicating that 14.1% of rams and 1.5% of ewes are predicted to foray outside of their CHHR during the summer season. On the basis of known bighorn sheep preferences for each of the three habitat classes, the model estimates the proportion of rams and ewes reaching each 1- kilometer band outside of the CHHR. The model estimates this proportion out to 35 kilometers (21 miles) away from the CHHR, which incorporates the extent of most forays throughout the Western United States (USDA Forest Service 2013; O Brien et al. 2014). The Tool s default values were derived from an extensive bighorn sheep radio telemetry dataset on the Payette National Forest (USDA Forest Service 2013; O Brien et al. 2014). The default values represent the proportion of radio-collared adult bighorns observed outside their CHHR during the summer grazing season. 29

36 USDA Forest Service The Risk of Contact Tool uses the inputs to conduct a bighorn foray analysis (USDA Forest Service 2013; O Brien et al. 2014). This foray analysis determines how frequently bighorn foray movements occur, as well as how far beyond the CHHR bighorn rams and ewes are likely to travel, relative to the amount and connectivity of bighorn summer source habitat across the landscape. Together, the source habitat, CHHR, and foray models, along with bighorn herd size and sex ratio (i.e. proportion of rams to ewes) are used to estimate the probability that a ewe or a ram from a particular herd will leave their CHHR and reach a domestic sheep allotment in a given year (USDA Forest Service 2013). Based on these probabilities, rates of contact with a particular allotment by individual rams and ewes from a specific bighorn CHHR can be calculated. Because predicted rates of contact are sensitive to bighorn herd size, the largest bighorn herds have the greatest impact on the calculated contact probabilities. Direct overlap between a bighorn CHHR and an allotment presumes a 100% probability of contact between bighorns and the allotment (USDA Forest Service 2013). Therefore, by definition, an allotment which that with bighorn CHHR is assumed to experience at least one bighorn contact per year. Although the Tool assumes a contact rate of 1.0 for allotments that overlap bighorn CHHR, annual contact rates could be higher with multiple contacts occurring per year. When there is direct overlap between an allotment and bighorn CHHR there is automatically high risk for contact and therefore no need to model the potential for contact by foray. The sequence of events described in the Risk of Contact Model by which contact between bighorn sheep and domestic sheep in a permitted grazing allotment located outside a bighorn CHHR might occur and are broken down into a number of steps (1-7). In general, the steps are simplified and are not meant to describe the infectious disease agent transmission life history, which can result in pneumonia. First, to reach an active domestic sheep allotment, a bighorn sheep must (1) leave their CHHR; (2) travel far enough to reach the domestic sheep grazing allotment; and (3) intersect the allotment. For an infectious pneumonia-related disease agent transmission to occur, the bighorn must (4) come into physical contact with a domestic sheep in the allotment; and (5) contract an infectious disease agent from the domestic sheep. Finally for an infectious disease outbreak to affect the bighorns home herd, the infected bighorn must (6) return to their CHHR and (7) transmit an infectious disease agent to other members of their home herd (Carpenter et al. 2014). For domestic sheep allotments that overlap portions of bighorn CHHR such as the Snow Mesa Sheep Allotments, steps 1 3 and 6 do not need to occur, thereby likely increasing the potential for an infectious disease event to occur, and also likely increasing the potential for a subsequent infectious disease outbreak in the bighorn home herd. The Risk of Contact Tool provides a calculated probability that bighorn forays will intersect a given domestic sheep allotment, and the total annual predicted rate of contact with the allotment (USDA Forest Service 2013). The total herd contact rate (i.e., aggregate rate of both rams and ewes) is the most important output of the analysis. More frequent contacts implies a greater probability of a bighorn coming into physical contact with a domestic sheep, and thus greater potential for disease transmission and potential for a subsequent bighorn mortality event. 30

37 DRAFT Snow Mesa and Wishbone Risk Assessment The Risk of Contact Tool represents the best available science regarding estimating the probability of bighorn sheep contacting domestic sheep allotments. Results of the Risk of Contact Tool are then reviewed and a conclusion is drawn regarding the relative risk of contact with the potential for disease transmission and subsequent bighorn mortality event, and the effect that event might have on bighorn population viability. This analysis will utilize recent disease transmission information on the Rio Grande National Forest for comparison to better inform the outcome of each alternative regarding their relative potential for contributing to the long-term viability of bighorn sheep on the Snow Mesa landscape. Disease History On the Rio Grande National Forest, four bighorn sheep herds are still experiencing lingering effects (low lamb recruitment) of past pneumonia-related disease events dating back to the early to mid-1990s. Of the four herds, only one (S-36 Bellows Creek) is demonstrating slight recovery from a dramatic die-off 20 years ago. The other three herds (S-55 Carnero Creek/Natural Arch; S-29 Alamosa Canyon, and S-10 Trickle Mountain) are stagnant or continue to decline in numbers reaching the point that herd persistence is unlikely (<30 animals) (Table 2). Numerous examples of bighorn sheep herds die-offs followed by lengthy periods of poor lamb recruitment due to exposure to domestic sheep are well documented in the literature (Foreyt 1990, Drew et al. 2014, George et al. 2008). Recovery rates can vary significantly depending upon the pathogen involved and other factors, and recovery can take decades to occur or possibly not occur at all (Besser et al. 2012). For the Snow Mesa analysis it was assumed that a minimum of 25 years may be required before signs of recovery might be detectible in a bighorn sheep herd that has contracted pneumonia originating from bacterial pathogens associated with bighorn sheep. This assumption is based on herd health and lamb recruitment observations and data associated with the four local bighorn sheep herds mentioned above that have experienced disease-related die-off events on the Rio Grande National Forest. Using the Alamosa Canyon Herd (S-29) as an example, the first known epizootic die-offs occurred in 1991 with no current sign of recovery 25 years later. When evaluating the one bighorn sheep herd included in this analysis (Bellows Creek, S-36) it has been 24 years since the first all-age die-off occurred in , and roughly 15 years since the latter spike in mortality occurred in

38 USDA Forest Service Table 2. Disease status of Rocky Mountain bighorn sheep on the Rio Grande National Forest [Source: Supplement to the Forest Plan Biological Evaluation and Conservation Assessment for Rocky Mountain Bighorn Sheep, Rio Grande National Forest, April 2009] Herd Name/Unit Herd Size Forest Disease Status Huerfano S-8 65 Rio Grande-Conejos Peak Pike San Isabel Sangre de Cristo S Rio Grande-Saguache Pike San Isabel No specific disease testing. Anecdotal information suggests historic disease influence Historic Pasteurella >20 years *Trickle Mtn S-10 <40 Rio Grande-Saguache Disease Event and all-age die-off in the 1990s. Pasteurella multicoda, bovine syncytial respiratory virus, and parainfluenza-3 virus detected. Sheep Mountain S Rio Grande -Divide San Juan No known disease or testing San Luis Peak S Rio Grande-Divide Gunnison Pasteurella potentially present *Alamosa Canyon S-29 Conejos River (S-30) Lake Fork/Pole Mtn S-33 *Bellows Creek (S-36) 35 Rio Grande-Conejos Peak Disease Event 1990s. Mycoplasma ovipneumoniae, Mannheimia haemolytics, leukotoxin, parainfluenza-3 virus, bovine syncytial respiratory virus 75 Rio Grande-Conejos Peak Same as S Rio Grande-Divide Gunnison Historic Pasteurella >20 years 45 Rio Grande-Divide Presumed pasteurella related outbreak and all-age dies off 1990s. Bristol Head (S-53) 110 Rio Grande-Divide Pasteurella potentially present *Carnero/Natural Arch S-55 Total 1, Rio Grande- Divide/Saguache Same as S-36. *Denotes the local herds on the Rio Grande NF experiencing lingering effects (low lamb recruitment) from past disease events. While three of these four herds currently show little to no signs of recovery, the Bellows Creek herd has recently displayed improved lamb recruitment and slow population growth, suggesting that recovery might be occurring. Although the Bellows Creek herd remains at risk of future contacts and potential disease events associated with domestic sheep, we therefore assume that it may take at least 25 years for some respiratory disease pathogens to run their course and begin to diminish from a population. The purpose for this assumption is to help establish a baseline timeframe from which to estimate and compare project alternatives in association with estimated contact rates and the disease transmission 32

39 DRAFT Snow Mesa and Wishbone Risk Assessment probability utilized. For this assumption to be valid, however, it is important that no additional contacts with domestic sheep occur during this timeframe that further complicate recovery. It should be noted that this assumption is based on observational and coarse population data only, and has not been informed by demographic or epidemiologic data associated with more rigorous models that suggest a much longer timeframe for recovery to occur, depending upon contact rates (Clifford et al. 2009, Carpenter et al. 2014). Therefore, our assumptions pertain to this analysis only and should not be extrapolated to other project areas. This analysis utilizes recent disease transmission modeling information as a reference to better inform the outcome of each alternative in regards to their likelihood of providing for the long-term viability of bighorn sheep in S-22, S-53, and S-36 and the Central San Juan Bighorn Herd as a whole. In combination with our local herd recovery information described previously, we assumed that there is a moderate probability that a contact will result in a disease transmission event. In this case, a moderate probability is defined as 25%, or that one in every four contacts will result in a disease transmission event. Recent peer-reviewed published literature evaluating the disease transmission probability assumptions was reviewed, and it suggests that a 25% probability is a conservative approach to estimating potential disease transmission rates when shared ranges are involved (Carpenter et al. 2014). Other recent publications involving science that demonstrates pathogen transmission from domestic sheep to bighorn sheep (Lawrence et al. 2010) and disease epizootic models (Sells et al. 2015) provided documentation to support concerns regarding disease transmission from domestic sheep to bighorn sheep. We believe that this is a conservative estimate given the history of disease-related die-offs on the Rio Grande National Forest. Based on the disease probability and herd recovery assumptions described above, our analysis suggests that disease outbreaks of every 32 years or less would result in a bighorn sheep population that, although potentially in the initial stages of recovery, would be constantly exposed to ongoing disease transmission events and resultant outbreaks. This would result in a bighorn sheep population that would most likely experience an all-age dieoff followed by low lamb recruitment for an extended period of time. As with S-36, the herd may slowly start to recover by the end of the second decade (20 years) but be subject to another contact that results in a disease outbreak prior to attaining the amount of time needed to fully recover from the previous outbreak. This type of scenario results in a cycle of dramatic die-offs followed by slow population rebuilding. The population would likely be extirpated over time as a result of consistent exposure to disease exposure. Based on our analysis, contact rates that result in a disease event within a local bighorn sheep herd every 32 years or less is assumed to result in a High Risk to bighorn sheep long-term viability and a Low Probability of Population Persistence and Viability. We believe this is a conservative assumption based on evidence from one local herd that may be in the initial stages of recovery (S-36) and several other herds that have not yet displayed any signs of recovery from pneumonia-related die-offs in about a 25-year timeframe. We acknowledge that our rating factors for low, medium, and high risk are based primarily on local qualitative information and should not be extrapolated elsewhere for use in other project areas. However, we believe our rating factors are also fully informed by the large volume of published literature regarding this subject and represent a rational approach to establishing risk parameters in the absence of local empirical data associated with population demographics and epidemiology. 33

40 USDA Forest Service There are an estimated 7,000 bighorn sheep in Colorado. Eleven distinct herds are either entirely located or partially located on the Rio Grande National Forest, representing 15% of the bighorn in the state. Numerous strains of Pasteurella and other bacteria result in respiratory illness in bighorn sheep. Some of these bacteria can result in an all-age die-off typically followed by a long period of poor lamb recruitment and mortality. Various other bacteria such as Mycoplasma that are present in domestic sheep may result in weakening immune systems, making bighorn more susceptible to other sicknesses and/or poor lamb survival. The bighorn sheep die-offs on the Rio Grande National Forest in the 1990s demonstrate the devastating effects and long-term impacts of respiratory illness in and between bighorn sheep populations among adjacent herds from known or suspected interactions with domestic sheep. Photo: Sickly lamb in the S-36 herd, fall of Risk Assessment Outcomes The risk of physical contact between bighorn sheep and a domestic sheep allotment, with the potential for disease transmission followed by a potential subsequent bighorn mortality event, was given a qualitative rating of High, Moderate, or Low based on three factors carried forth throughout this analysis: 1) Number of years between bighorn sheep making contact with the allotment, 2) Disease potential expressed in years, and 3) (Allotment) Distance from Bighorn Sheep CHHR with adequate source connective habitat available. A summary of the three rating factors is presented in Table 3. Each allotment can be compared with each sub-herd per alternative in Tables 6 17 based on these factors. Table 3. Rating factors considered RATING FACTOR HIGH MODERATE LOW Number of years between bighorn sheep making contact with the allotment <8 years 8 10 years >10 years Disease Potential, expressed in years <32 years years 40+ years Distance from bighorn sheep CHHR, with adequate source connective habitat available </=10 miles miles 15+ miles Disease potential expressed in years is only an estimate of relative level of risk for physical contact between domestic and bighorn sheep and displays what could potentially occur. The likelihood of disease transmission following physical contact, and the potential for a subsequent bighorn mortality event, is not known with certainty and remains the subject of debate. This issue is discussed in more depth in the Uncertainties section. A rating of High risk indicates that contact within the allotment where domestic sheep and bighorn sheep share a common range is thought to be likely in the immediate future, although disease transmission resulting in a subsequent bighorn mortality event is not assumed to be a certainty. Conversely, if allotments have been operated for many years without evidence of disease transmission, we do not use this observation to infer a lower risk rating. The fact that 34

41 DRAFT Snow Mesa and Wishbone Risk Assessment contact has not been observed, or a bighorn disease event has not been detected, does not necessarily imply a lower risk for such events happening in the future. Close proximity to each other and the high potential for forays by wild sheep is likely, leading to more certainty that comingling may occur. For this reason, the allotment could still receive a rating of High risk. A rating of Moderate risk indicates that physical contact within allotments between bighorn and domestic sheep may occur at some point in the future, but that a higher degree of uncertainty exists that separation might be achieved and/or maintained for many years using design criteria that are expected to add value to the goal of effective separation. The risk of physical contact between bighorn and domestic sheep, with the potential for a subsequent bighorn disease outbreak, is thought to be less certain than for allotments in the high risk category, but is still of concern. Assumptions associated with the moderate risk category are further complicated by the fact that a higher degree of uncertainty is still associated with this risk category, and that monitoring feedback mechanisms and quick adaptive management adjustments may be necessary if situations indicate. Factors that reduce the apparent risk of contact could include: the presence of towns, the presence of terrain features and/or habitat features that act as barriers to bighorn sheep movement (Schommer and Woolever 2001), bighorn sheep distribution patterns, and application of herding techniques and other project design criteria. A rating of Low risk indicates that physical contact between a allotments between domestic and bighorn sheep is believed to be unlikely or irregular and unpredictable, with the potential for a subsequent bighorn disease outbreak thought to be unlikely in the future under the configuration of allotments and bighorn CHHRs. After assigning an initial risk rating for each allotment and alternative, additional factors were considered and a determination was made whether to maintain or alter the initial risk rating. Factors such as the application of improved project design criteria were considered. However, because of uncertainty about the effectiveness of project design criteria, their application is not relied on as the sole reason for assigning a lower risk rating under Alternative 2 or 3. These rating factors are based on local information from bighorn herds on the Rio Grande National Forest as discussed in the Disease History Section. Contact every 8 years equates to a potential disease event every 32 years. A moderate rating essentially equates to an acceptable amount of risk if additional factors, such as a robust monitoring and reporting scheme, are established alongside design criteria believed to add value to the goal of achieving effective separation. However, the relationship between moderate and acceptable disease prevention is not well known and a high amount of uncertainty may exist. Modeling Results with the Risk of Contact Tool The input values used in the Risk of Contact Tool for each bighorn herd in the Snow Mesa landscape analysis is shown in Table 4. The values used for ram and ewe annual foray probabilities were the default values provided by the Risk of Contact Tool application because no similar data were available for bighorn herds in the Snow Mesa landscape. The Tool s default values were derived from an extensive bighorn sheep radio telemetry dataset on the Payette National Forest (USDA Forest Service 2013). The default values represent the 35

42 USDA Forest Service proportion of radio-collared adult bighorns observed outside their CHHR during the summer grazing season, May through October. The values used for bighorn herd sex ratio (ram:ewe) were the default values provided by the Risk of Contact Tool application because only limited sex ratio data were available for bighorn herds in the Snow Mesa landscape. These ratios were reviewed by local Colorado Parks and Wildlife personnel and are believed to be a reasonable estimate of sex ratios for bighorn herds in the Snow Mesa landscape. The Tool s default values for bighorn sex ratios were calculated from an extensive observation dataset of Hells Canyon area herds on the Payette National Forest (USDA Forest Service 2013; O Brien et al. 2014). Values for total population size of bighorn herds in the Snow Mesa landscape were provided by Colorado Parks and Wildlife (Stephanie Ferrero and Brandon Diamond, personal communication), and the number of rams and number of ewes in each bighorn herd were then calculated by multiplying the sex ratio by the total population size of each herd. Table 4. Input values used in the Risk of Contact Tool for bighorn sheep herds in the Snow Mesa Allotment grazing analysis area Input Values for the Model S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek Annual Foray Probability (rams) (14.1%) (14.1%) (14.1%) Annual Foray Probability (ewes) (1.5%) (1.5%) (1.5%) Total Population Size bighorn 110 bighorn 45 bighorn Sex Ratio (ram:ewe) 35:65 (rams:ewes) 35:65 (rams:ewes) 35:65 (rams:ewes) Number of rams 25 rams in S rams in S rams in S-36 Number of ewes 45 ewes in S ewes in S ewes in S-36 Photo: Bighorn ewe, S Photo: Bighorn rams, S The Risk of Contact Tool produced similar output tables for each combination of allotments, bighorn herd, and the three action alternatives (includes Alternative 4 in this document) in the Snow Mesa landscape (Tables 5 18). For the sake of brevity, only the example in Table 5 is described. The complete tables and information for all allotments, bighorn herds, and action alternatives are included in Appendices 1 and 2. 36

43 DRAFT Snow Mesa and Wishbone Risk Assessment Table 5. Example of model results for the Table Allotment only and the San Luis Peak bighorn herd (S-22) under current allotment configuration (Alternative 2) [The full tables for Alternatives 2 through 5 are contained in Appendix 1.] S-22 San Luis Peak Herd Alternative 2 Allotment Probability of Ram Contact Table (5.5%) Probability of Ewe Contact (3.2%) Single Ram (0.78%) Annual Contact Rates via Foray Single Ewe (0.04%) All Rams All Ewes Herd Contact Rate Probability of Ram Contact Annual probability that once a ram in the S-22 population leaves its CHHR on a foray it will contact the Table Allotment (5.5%). For this example: Not every ram in a herd leaves its CHHR on a foray. The probability of ram contact is then multiplied by the default for rams (14.1%). The resulting number is the probability that a single ram will leave the S-22 CHHR and contact the Table Allotment * = (0.78%). Maps of ram forays for each alternative of each sub-herd and total ram foray probabilities for all three sub-herds are shown in Appendices 3 6. Probability of Ewe Contact Annual probability that once a ewe in the S-22 population leaves its CHHR on a foray it will contact the Table Allotment (3.2%). For this example: Only a small portion of the ewes in a herd leaves their CHHR on a foray. The probability of ewe contact is then multiplied by the default for ewes (1.5%). The resulting number is the probability that a single ewe will leave the S-22 CHHR and contact the Table Allotment * = (0.04%). Single Ram Contact Rate For this example: There is a 0.78% summer seasonal probability that any given ram will leave the S-22 CHHR and will make contact with this allotment. Single Ewe Contact Rate For this example: There is a 0.04% summer seasonal probability that any given ewe will leave the S-22 CHHR and will make contact with this allotment. 37

44 USDA Forest Service All Rams Contact Rate This column displays the rate of contact with the Table Allotment for all rams in the S-22 population. This is the expected number of rams to contact the allotment each summer season. For this example: Based on the number or rams in the S-22 herd (25) and their individual contact probabilities (0.78%), it is estimated that S-22 rams will foray from their CHHR and make contact with the Table Allotment at a rate of per summer season. In other words, contact with the Table Allotment by a foraying ram is expected once every 5.3 years (1/ ). All Ewes Contact Rate This column displays the rate of contact with the Table Allotment for all ewes in the S-22 population. This is the expected number of ewes to contact the allotment each summer season. For this example: Based on the number or ewes in the S-22 herd (45) and their individual contact probabilities (0.04%), it is estimated that S-22 ewes will foray from their CHHR and make contact with the Table Allotment at a rate of per summer season. In other words, contact with the Table Allotment by a foraying ewe is expected once every 45 years (1/ ). Total Herd Contact Rate The total herd contact rate is the number of adult bighorn sheep (rams plus ewes) expected to foray from the S-22 CHHR and contact the Table Allotment each summer season. For this example: Based on the aggregate ram and ewe contact rates (All Rams + All Ewes; contacts/summer season), it is estimated that an adult bighorn sheep would leave the S-22 CHHR on a foray and make contact with the Table Allotment at a rate of times per summer season. In other words, given the estimate of 70 bighorns in the S-22 sub-herd, bighorn sheep from S-22 are expected to contact the Table Allotment once every 4.8 years (1/ ). Photo: S-36 Bighorn group,

45 DRAFT Snow Mesa and Wishbone Risk Assessment Results for Individual Domestic Sheep Allotments Snow Mesa Allotment Alternative 2 Snow Mesa is the smallest of the three active allotments (4,365 acres) and also has the highest percentage of overlap between bighorn sheep suitable summer habitat and acres suitable for domestic sheep grazing at 90% (3,394 acres), which represents 78% of the total allotment. Table 6. Snow Mesa Allotment Risk of Contact Tool Comparison for Alternative 2 Snow Mesa Allotment Annual Herd Contact Rate Bighorn from this subherd are predicted to contact this allotment every X years. S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek /1.0 = 1 1/ = 6 1/ = 14 Cumulative Annual Herd Contact Rate for all Three Bighorn Sheep Herds 1/ = 0.81; Potential contact with the allotment by bighorn sheep in RBS- 22 can be expected approximately once every 0.81 years. Equates to a potential disease transmission every X years on this allotment. Distance from Bighorn CHHR 1* 4 = 4. Potentially every 4 years. 6 * 4 = 24. Potentially every 24 years. 14 * 4 = 56. Potentially every 56 years. Overlap 3.2 miles 10.4 miles Based on modeled contact rates and an assumed moderate probability of disease transmission, given contact (0.25 or 1 in every four contacts), a disease transmission event with potential for subsequent bighorn mortality could occur once every 3.2 years (0.81 * 4 = 3.2). This potential varies considerably from 4 to 56 years among bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP with BIGHORN SHEEP HABITAT Total Allotment Acres 4,365 Capable Domestic Sheep Grazing Acres (Percentage of Allotment) 3,764 (86%) Bighorn Summer Source Habitat Acres (Percentage of Allotment) 3,619 (83%) Percentage of capable domestic sheep grazing acres that overlap with bighorn sheep summer habitat. S-22 San Luis Peak Bighorn Herd 3,394 or 90% (which represents 78% of the allotment) Under Alternative 2, there is direct overlap with the San Luis Peak bighorn herd. As there is direct overlap, bighorn do not need to go on a foray to contact the allotment. Bighorn rams have been documented in the very far northeast portion of the allotment and along the Continental Divide in the same areas and at the same time as the domestic sheep. Bighorn then contact this allotment on a yearly basis and more than likely by more than one ram a year. Using a moderate estimate of one out of four (25%) contacts resulting in a disease transmission event with potential for subsequent bighorn mortality, this allotment contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 4 years in the S-22 sub-herd. 39

46 USDA Forest Service S-53 Bristol Head Bighorn Herd The Bristol Head Bighorn Herd is separated by 3.2 miles of fair to good connectivity habitat from the Snow Mesa Allotment. Bighorn from this herd are expected to contact the allotment every 6 years equating to a disease transmission with potential for subsequent bighorn mortality once every 24 years in the S-53 sub-herd. S-36 Bellows Creek Bighorn Herd The Bellows Creek Bighorn Herd is approximately 10.4 miles from the Snow Mesa Allotment with fair connectivity. Bighorn from this herd are expected to contact the allotment every 14 years equating to a disease transmission with potential for subsequent bighorn mortality once every 56 years in the S-53 sub-herd. Photo: Domestic sheep and camp on Snow Mesa. Cumulatively, the annual herd contact rate for all three bighorn herds is 0.81, meaning that bighorn are expected to contact the Snow Mesa Allotment more than once every year (less than a year <1.0). Additionally, due to the influence from the S-53 and S-36 herds, contact rates combined with the amount of suitable bighorn sheep habitat and the relatively close distance to the allotment, a disease transmission with potential for subsequent bighorn mortality could occur every 3.2 years. Based on the information presented above, a rank of High Risk was assigned to the Snow Mesa Allotment under Alternative 2. The reasons for assigning a rank of High Risk are as follows: There is direct overlap between the allotment and bighorn sheep CHHR. There is no spatial or temporal separation between the two species. The allotment contains a large amount of overlap between bighorn habitat and acres capable for domestic sheep grazing at 90%. Separation between the allotment and the three herds consists of overlap for S-22, 3.2 miles for S-53, and 10.4 miles for S-36. Bighorn are expected to contact the allotment from the three sub-herds at rates of every year for S-22, every 6 years for S-53, and every 14 years for S-36. A disease transmission with potential subsequent bighorn mortality could occur every 4 years in the S-22 herd component, but cumulatively could occur every 3.2 years due to the influence from all three herds combined. 40

47 DRAFT Snow Mesa and Wishbone Risk Assessment Alternative 3 Alternative 3 moves the northern boundary of the allotment away from the S-22 CHHR by 0.5 mile. This change decreases the size of the allotment to 3,315 acres. The amount of overlap between bighorn sheep suitable summer habitat and acres suitable for domestic sheep grazing remains at 90% (2,614 acres), representing 79% of the total allotment. Table 7. Snow Mesa Allotment Risk of Contact Tool Comparison for Alternative 3 Snow Mesa Allotment Annual Herd Contact Rate Bighorn from this subherd are predicted to contact this allotment every X years. Equates to a potential disease transmission every X years on this allotment. Distance from Bighorn CHHR S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek / = 3 3* 4 = 12. Potentially every 12 years. 1/ = 6 6 * 4 = 24. Potentially every 24 years. 1/ = * 4 = 72. Potentially every 72 years. 0.5 mile 3.2 miles 10.4 miles Cumulative Annual Herd Contact Rate for all Three Bighorn Sheep Herds 1/ = 1.9; Potential contact with the allotment by bighorn sheep in RBS-22 can be expected approximately once every 1.9 years. Based on modeled contact rates and an assumed moderate probability of disease transmission, given contact (0.25 or 1 in every four contacts), a disease transmission event with potential for subsequent bighorn mortality could occur once every 7.6 years (1.9 * 4 = 7.6). This potential varies considerably from 12 to 72 years among bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP with BIGHORN SHEEP HABITAT Total Allotment Acres 3,315 Capable Domestic Sheep Grazing Acres (Percentage of Allotment) 2,846 (86%) Bighorn Summer Source Habitat Acres (Percentage of Allotment) 2,771 (84%) Percentage of capable domestic sheep grazing acres that overlap with bighorn sheep summer habitat. S-22 San Luis Peak Bighorn Herd 2,614 or 92% (which represents 79% of the allotment) Under Alternative 3 there will no longer be known direct overlap with the San Luis Peak bighorn herd. This allotment boundary change results in decreasing the bighorn contact rate to once every 3 years compared to every year with Alternative 2. Using a moderate estimate of one out of four (25%) contacts resulting in a disease transmission event with potential for subsequent bighorn mortality, this allotment contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 12 years in the S-22 sub-herd. S-53 Bristol Head Bighorn Herd Changing the northern boundary of the Snow Mesa Allotment will not change the herd contact rate or potential disease transmission for this herd. The number of years between allotment contact with this herd, herd contact rate, disease transmission potential, and distance from the herd to the allotment remain the same as Alternative 2. 41

48 USDA Forest Service S-36 Bellows Creek Bighorn Herd The distance from this herd to the allotment will remain at approximately 10.4 miles. However, changing the northern boundary of the Snow Mesa Allotment decreases the foray potential for this herd coming from the north and decreases the expected contact potential to every 18 years, equating to a disease transmission with potential for subsequent bighorn mortality to once every 72 years. Cumulatively, the annual herd contact rate for all three bighorn herds under Alternative 3 is 1.9, meaning that bighorn are expected to contact the Snow Mesa Allotment essentially every 2 years. Additionally, due to the influence from the S-53 and S-36 herds, a disease transmission with potential for subsequent bighorn mortality could occur every 7.6 years. Based on the information presented above, a rank of High Risk was assigned to the Snow Mesa Allotment under Alternative 3. The reasons for assigning a rank of High Risk are as follows: Modifying the allotment boundary more than doubles the amount of time between allotment contact from Alternative 2 (less than 1 year 0.81 to 1.9 years). There will no longer be any known direct overlap between the allotment and bighorn sheep CHHR. The S-22 CHHR will be approximately 0.5 mile from the new boundary of the allotment. There will be very little spatial (0.5 mile) or temporal separation between the two species. The allotment will contain a large amount of overlap between bighorn habitat and acres capable for domestic sheep grazing at 92%. Separation between the allotment and the three herds consists of 0.5 mile for S-22, 3.2 miles for S-53, and 10.4 miles for S-36. Bighorn are expected to contact the allotment from the three sub-herds at rates of every 3 years for S-22, every 6 years for S-53, and every 18 years for S-36. A disease transmission with potential subsequent bighorn mortality could occur every 12 years in the S-22 herd component, but cumulatively could occur every 7.6 years due to the influence from all three herds combined. 42

49 DRAFT Snow Mesa and Wishbone Risk Assessment Photo: Snow Mesa Allotment. Alternative 4 The Snow Mesa Allotment would become vacant as part of Alternative 4. Alternative 5 The Snow Mesa Allotment would become vacant as part of Alternative 5. Photo: S-36 Bighorn Ram,

50 USDA Forest Service Table Allotment Alternative 2 The Table Allotment is approximately 5,049 acres in size. The allotment contains 52% (1,485 acres) overlap between bighorn sheep suitable summer habitat and acres suitable for domestic sheep grazing, which represents 29% of the total allotment. Table 8. Table Allotment Risk of Contact Tool Comparison for Alternative 2 Table Allotment Annual Herd Contact Rate S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek Cumulative Annual Herd Contact Rate for all Three Bighorn Sheep Herds Bighorn from this sub-herd are projected to contact this allotment every X years. 1/ = 4.8 1/ = 4.6 1/ = /47412 = 2.1; Potential contact with the allotment by bighorn sheep in RBS-22 can be expected approximately once every 2.1 years. Equates to a potential disease transmission every X years on this allotment. Distance from Bighorn CHHR 4.8 * 4 = 19. Potentially every 19 years. 4.6 * 4 = 18. Potentially every 18 years. 20 * 4 = 80. Potentially every 80 years. 0.5 mile 1.86 miles 8 miles Based on modeled contact rates and an assumed moderate probability of disease transmission, given contact (0.25 or 1 in every four contacts), a disease transmission event with potential for subsequent bighorn mortality could occur once every 8.4 years (2.1 * 4 = 8.4). This potential varies considerably from 18 to 80 years among bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP with BIGHORN SHEEP HABITAT Total Allotment Acres 5,049 Capable Domestic Sheep Grazing Acres (Percentage of Allotment) 2,864 (57%) Bighorn Summer Source Habitat Acres (Percentage of Allotment) 1,953 (39%) Percentage of capable domestic sheep grazing acres that overlap with bighorn sheep summer habitat. S-22 San Luis Peak Bighorn Herd 1,485 or 52% (which represents 29% of the allotment) Under Alternative 2, bighorn are separated from the allotment by 0.5 mile of suitable habitat and are expected to contact the Table Allotment every 4.8 years. Using a moderate estimate of one out of four (25%) contacts resulting in a disease transmission event with potential for subsequent bighorn mortality, this allotment contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 19 years in the S-22 sub-herd. 44

51 DRAFT Snow Mesa and Wishbone Risk Assessment S-53 Bristol Head Bighorn Herd The Bristol Head Bighorn Herd is separated by 1.86 miles of fair to good connectivity habitat from the Table Allotment. Bighorn from this herd are expected to contact the allotment every 4.6 years equating to a disease transmission with potential for subsequent bighorn mortality once every 18 years in the S-53 sub-herd. S-36 Bellows Creek Bighorn Herd The Bellows Creek Bighorn Herd is about 8 miles from the Table Allotment with fair connectivity. Bighorn from this herd are expected to contact the allotment every 20.1 years equating to a disease transmission with potential for subsequent bighorn mortality once every 80 years in the S-53 sub-herd. Cumulatively, the annual herd contact rate for all three bighorn herds is 2.1, meaning that bighorn are expected to contact the Table Allotment every 2 years. Additionally, due to the influence of all three herds, contact rates combined with the amount of suitable bighorn sheep habitat and the relatively close distance to the allotment, a disease transmission with potential for subsequent bighorn mortality could occur every 8.4 years. Based on the information presented above, a rank of High Risk, was assigned to the Table Allotment under Alternative 2. The reasons for assigning a rank of High Risk are as follows: There is no direct overlap between the allotment and bighorn sheep CHHR. There will be very little spatial (0.5 mile) or temporal separation between the two species The allotment contains a moderate amount of overlap between bighorn habitat and acres capable for domestic sheep grazing at 52%. Separation between the allotment and the three herds consists of 0.5 mile for S-22, 1.86 miles for S-53, and 8 miles for S-36. Bighorn are expected to contact the allotment from the three sub-herds at rates of every 4.8 years for S-22, every 4.6 years for S-53, and every 20.1 years for S-36. A disease transmission with potential subsequent bighorn mortality could occur every 18 years in the S-53 herd component, but cumulatively could occur every 8.4 years due to the influence from all three herds combined. 45

52 USDA Forest Service Photo: Hanging Basin, Table Allotment. Alternative 3 Alternative 3 results in little change upon the allotment acres or annual bighorn herd contact rate from Alternative 2. Distance from the nearest CHHR (S-22) will remain at 0.5 mile. The allotment decreases by approximately 6 acres to 5,043 acres. The amount of overlap between bighorn sheep suitable summer habitat and acres capable for domestic sheep grazing remains at 52% (1,479 acres), representing 29% of the total allotment. Table 9. Table Allotment Risk of Contact Tool Comparison for Alternative 3 Table Allotment Annual Herd Contact Rate Bighorn from this subherd are projected to contact this allotment every X years. Equates to a potential disease transmission every X years on this allotment. S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek / = * 4 = 19. Potentially every 19 years. 1/ = * 4 = 19. Potentially every 19 years. 1/ = * 4 = 84. Potentially every 84 years. Distance from CHHR 0.5 mile 1.86 miles 8 miles Cumulative Annual Herd Contact Rate for all Three Bighorn Sheep Herds 1/ = 2.1; Potential contact with the allotment by bighorn sheep in RBS-22 can be expected approximately once every 2.1 years. Based on modeled contact rates and an assumed moderate probability of disease transmission, given contact (0.25 or 1 in every four contacts), a disease transmission event with potential for subsequent bighorn mortality could occur once every 8.4 years (2.1 * 4 = 8.4). This potential varies considerably from 19 to 84 years among bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP with BIGHORN SHEEP HABITAT Total Allotment Acres 5,043 Capable Domestic Sheep Grazing Acres (Percentage of Allotment) 2,858 (57%) Bighorn Summer Source Habitat Acres (Percentage of Allotment) 1,947 (39%) Percentage of capable domestic sheep grazing acres that overlap with bighorn sheep summer habitat. 1,479 or 52% (which represents 29% of the allotment. 46

53 DRAFT Snow Mesa and Wishbone Risk Assessment S-22 San Luis Peak Bighorn Herd Similar to Alternative 2, bighorn sheep are separated from the allotment by 0.5 mile of suitable habitat and are expected to contact the Table Allotment every 4.8 years. Using a moderate estimate of one out of four (25%) contacts resulting in a disease transmission event with potential for subsequent bighorn mortality, this allotment contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 19 years in the S-22 sub-herd. S-53 Bristol Head Bighorn Herd The Bristol Head Bighorn Herd will continue to be separated by 1.86 miles of fair to good connectivity habitat from the Table Allotment. Bighorn from this herd are expected to contact the allotment every 4.7 years equating to a disease transmission with potential for subsequent bighorn mortality once every 19 years in the S-53 sub-herd. S-36 Bellows Creek Bighorn Herd The Bellows Creek Bighorn Herd will remain at 8 miles away from the Table Allotment with fair connectivity. Bighorn from this herd are expected to contact the allotment every 21 years equating to a disease transmission with potential for subsequent bighorn mortality once every 84 years in the S-36 sub-herd. This slight change from Alternative 2 is most likely a result of changing the northern boundary of the allotment(s), which decreases the foray potential for this herd coming from the north, slightly impacting the annual herd contact rate and potential for subsequent disease transmission. Cumulatively, the annual herd contact rate for all three bighorn herds is the same as Alternative 2 at 2.1, meaning that bighorn are expected to contact the Table Allotment every 2 years. Similarly, due to the influence of all three herds, contact rates combined with the amount of suitable bighorn sheep habitat, and the relatively close distance to the allotment, a disease transmission with potential for subsequent bighorn mortality could occur every 8.4 years. Based on the information presented above, a rank of High Risk was assigned to the Table Allotment under Alternative 2. The reasons for assigning a rank of High Risk are as follows: There is no direct overlap between the allotment and bighorn sheep CHHR. There will be very little spatial (0.5 mile) or temporal separation between the two species The allotment will contain a moderate amount of overlap between bighorn habitat and acres capable for domestic sheep grazing at 52%. Separation between the allotment and the three herds consists of 0.5 mile for S-22, 1.86 miles for S-53, and 8 miles for S

54 USDA Forest Service Bighorn are expected to contact the allotment from the three sub-herds at rates of every 4.8 years for S-22, every 4.7 years for S-53, and every 21 years for S-36. A disease transmission with potential subsequent bighorn mortality could occur every 19 years in both the S-22 and S-53 herds, but cumulatively could occur every 8.4 years due to the influence from all three herds combined. Photo: Ram and ewe, S Alternative 4 Alternative 4 results in no change upon the allotment acres or annual bighorn herd contact rate from Alternative 3. The results from the Risk of Contact Tool are the same as Alternative 3. Alternative 5 The Table Allotment would become vacant as part of Alternative 5. Photo: S-36 Bighorn group,

55 DRAFT Snow Mesa and Wishbone Risk Assessment Miners Allotment Alternative 2 Miners is the largest of the three active allotments (13,297 acres) and contains a moderate percentage of overlap between bighorn sheep suitable summer habitat and acres capable for domestic sheep grazing at 67% (3,863 acres), which represents 29% of the total allotment. Table 10. Miners Allotment Risk of Contact Tool Comparison for Alternative 2 Miners Allotment Annual Herd Contact Rate Bighorn from this sub-herd are projected to contact this allotment every X years. Equates to a potential disease transmission every X years on this allotment. Distance from Bighorn CHHR S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek /1.0 = 1 1/ = * 4 = 4. Potentially every 4 years. 4.4 * 4 = 18. Potentially every 18 years. 1/ = * 4 = 38. Potentially every 38 years. Overlap 1.27 miles 3.71 miles Cumulative Annual Herd Contact Rate for all Three Bighorn Sheep Herds 1/ = 0.75; Potential contact with the allotment by bighorn sheep in RBS- 22 can be expected approximately once every 0.75 year. Based on modeled contact rates and an assumed moderate probability of disease transmission, given contact (0.25 or 1 in every four contacts), a disease transmission event with potential for subsequent bighorn mortality could occur once every 3 years (0.75 * 4 = 3). This potential varies considerably from 4 to 38 years among bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP with BIGHORN SHEEP HABITAT Total Allotment Acres 13,297 Capable Domestic Sheep Grazing Acres (Percentage of Allotment) 5,805 (44%) Bighorn Summer Source Habitat Acres (Percentage of Allotment) 7,659 (58%) Percentage of capable domestic sheep grazing acres that overlap with bighorn sheep summer habitat. S-22 San Luis Peak Bighorn Herd 3,863 or 67% (represents 29% of the allotment). Under Alternative 2, there is direct overlap with the San Luis Peak bighorn herd. As there is direct overlap, bighorn do not need to go on a foray to contact the allotment. Bighorn have been documented at the head of Miners Creek, along the Continental Divide, and at the head of Oso Creek in the northern boundary of the allotment. Bighorn then contact this allotment on a yearly basis and more than likely by more than 1 ram a year. Using a moderate estimate of one out of four (25%) contacts resulting in a disease transmission event with potential for subsequent bighorn mortality, this allotment contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 4 years in the S-22 sub-herd. 49

56 USDA Forest Service S-53 Bristol Head Bighorn Herd The Bristol Head Bighorn Herd is separated by 1.27 miles of fair to good connectivity habitat from the Miners Allotment. Bighorn from this herd are expected to contact the allotment every 4.4 years, equating to a disease transmission with potential for subsequent bighorn mortality once every 18 years in the S-53 sub-herd. S-36 Bellows Creek Bighorn Herd The Bellows Creek Bighorn Herd is approximately 3.71 miles from the Miners Allotment, with fair connectivity. Bighorn from this herd are expected to contact the allotment every 9.4 years, equating to a disease transmission with potential for subsequent bighorn mortality once every 38 years in the S-53 sub-herd. Photo: Head of Willow Creek, Miners Allotment. Cumulatively, the annual herd contact rate for all three bighorn herds is 0.75, meaning that bighorn are expected to contact the Miners Allotment more than once every year (less than a year <1.0). Additionally, due to the influence from the S-53 and S-36 herds, contact rates combined with the amount of suitable bighorn sheep habitat and the relatively close distance to the allotment, a disease transmission with potential for subsequent bighorn mortality could occur every 3 years. Based on the information presented above, a rank of High Risk, was assigned to the Miners Allotment under Alternative 2. The reasons for assigning a rank of High Risk are as follows: There is direct overlap between the allotment and bighorn sheep CHHR. There is no spatial or temporal separation between the two species. The allotment contains a moderate amount of overlap between bighorn habitat and acres capable for domestic sheep grazing at 67%. Separation between the allotment and the three herds consists of overlap for S-22, 1.27 miles for S-53, and 3.71 miles for S-36. Bighorn are expected to contact the allotment from the three sub-herds at rates of every year for S-22, every 4.4 years for S-53, and every 9.4 years for S-36. A disease transmission with potential subsequent bighorn mortality could occur every 4 years in the S-22 herd component, but cumulatively could occur every 3 years due to the influence from all three herds combined. 50

57 DRAFT Snow Mesa and Wishbone Risk Assessment Alternative 3 Alternative 3 moves the northern boundary of the allotment away from the S-22 CHHR by 0.5 mile. This change decreases the size of the allotment to 7,147 acres. The amount of overlap between bighorn sheep suitable summer habitat and acres capable for domestic sheep grazing decreases to 59% (1,983 acres), representing 28% of the total allotment. Table 11. Miners Allotment Risk of Contact Tool Comparison for Alternative 3 Miners Allotment Annual Herd Contact Rate Bighorn from this subherd are projected to contact this allotment every X years. Equates to a potential disease transmission every X years on this allotment. Distance from Bighorn CHHR S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek / = * 4 = 11 Potentially every 11 years. 1/ = * 4 = 27 Potentially every 27 years. 1/ = 14 14* 4 = 56 Potentially every 56 years. 0.5 mile 1.27 miles 3.71 miles Cumulative Annual Herd Contact Rate for all Three Bighorn Sheep Herds 1/ = 1.7; Potential contact with the allotment by bighorn sheep in RBS-22 can be expected approximately once every 1.7 years. Based on modeled contact rates and an assumed moderate probability of disease transmission, given contact (0.25 or 1 in every four contacts), a disease transmission event with potential for subsequent bighorn mortality could occur once every 6.8 years (1.7 * 4 = 6.8). This potential varies considerably from 11 to 56 years among bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP with BIGHORN SHEEP HABITAT Total Allotment Acres 7,147 Capable Domestic Sheep Grazing Acres (Percentage of Allotment) 3,360 (47%) Bighorn Summer Source Habitat Acres (Percentage of Allotment) 3,675 (51%) Percentage of capable domestic sheep grazing acres that overlap with bighorn sheep summer habitat. S-22 San Luis Peak Bighorn Herd 1,983 or 59% (represents 28% of the allotment) Under Alternative 3 there will no longer be known direct overlap with the San Luis Peak bighorn herd. This allotment boundary change results in decreasing the bighorn contact rate to once every 2.7 years compared to every year with Alternative 2. Using a moderate estimate of one out of four (25%) contacts resulting in a disease transmission event with potential for subsequent bighorn mortality, this allotment contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 11 years in the S-22 sub-herd. S-53 Bristol Head Bighorn Herd The distance from this herd to the allotment will remain at approximately 1.27 miles Changing the northern boundary of the Miners Allotment will change the herd contact rate to every 6.8 years and will reduce the chance of disease transmission with potential subsequent bighorn mortality to once every 27 years in the S-53 sub-herd. This decrease is most likely due to the decrease in suitable bighorn sheep habitat on the north end of the allotment resulting from the boundary change. 51

58 USDA Forest Service S-36 Bellows Creek Bighorn Herd The distance from this herd to the allotment will remain at approximately 3.71 miles. However, changing the northern boundary of the Miners Allotment decreases the foray potential for this herd coming from the north and decreases the expected contact potential to every 14 years, equating to a disease transmission with potential for subsequent bighorn mortality to once every 56 years. Cumulatively, the annual herd contact rate for all three bighorn herds under Alternative 3 is 1.7, meaning that bighorn are expected to contact the Miners Allotment essentially every 2 years. Additionally, due to the influence from the S-53 and S-36 herds, a disease transmission with potential for subsequent bighorn mortality could occur every 6.8 years. Based on the information presented above, a rank of High Risk, was assigned to the Miners Allotment under Alternative 3. The reasons for assigning a rank of High Risk are as follows: Modifying the allotment boundary more than doubles the amount of time between allotment contact from Alternative 2 (less than 1 year 0.75 to 1.7 years). There will no longer be any known direct overlap between the allotment and bighorn sheep CHHR. The S-22 CHHR will be about 0.5 mile from the new boundary of the allotment. There will be very little spatial (0.5 mile) or temporal separation between the two species. The allotment will contain a moderate amount of overlap between bighorn habitat and acres suitable for domestic sheep grazing at 59%. Separation between the allotment and the three herds consists of 0.5 mile for S-22, 1.27 miles for S-53, and 3.71 miles for S-36. Bighorn are expected to contact the allotment from the three sub-herds at rates of every 2.7 years for S-22, every 6.8 years for S-53, and every 14 years for S-36. A disease transmission with potential subsequent bighorn mortality could occur every 11 years in the S-22 components, but cumulatively could occur every 6.8 years due to the influence from all three herds combined. Alternative 4 Alternative 4 moves the majority of the northern boundary of the allotment further south compared to Alternative 3. However, the Northwest portion boundary of the allotment remains the same as Alternative 3 and results in similar annual bighorn herd contact rates as Alternative 3. This change decreases the size of the allotment to 6,307 acres. The amount of overlap between bighorn sheep suitable summer habitat and acres capable for domestic sheep grazing decreases to 55% (1,689 acres), representing 24% of the total allotment. 52

59 DRAFT Snow Mesa and Wishbone Risk Assessment Table 12. Miners Allotment Risk of Contact Tool Comparison for Alternative 4 Miners Allotment Annual Herd Contact Rate Bighorn from this subherd are projected to contact this allotment every X years. S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek / = 2.7 1/ = 6.8 1/ = 14 Cumulative Annual Herd Contact Rate for all Three Bighorn Sheep Herds 1/ = 1.7; Potential contact with the allotment by bighorn sheep in RBS-22 can be expected approximately once every 1.7 years. Equates to a potential disease transmission every X years on this allotment. Distance from Bighorn CHHR 2.7 * 4 = 11 Potentially every 11 years. 6.8 * 4 = 27 Potentially every 27 years. 14* 4 = 56 Potentially every 56 years. 0.5 mile 1.27 miles 3.71 miles Based on modeled contact rates and an assumed moderate probability of disease transmission, given contact (0.25 or 1 in every four contacts), a disease transmission event with potential for subsequent bighorn mortality could occur once every 6.8 years (1.7 * 4 = 6.8). This potential varies considerably from 11 to 56 years among bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP with BIGHORN SHEEP HABITAT Total Allotment Acres 6,307 Capable Domestic Sheep Grazing Acres (Percentage of Allotment) 3,047 (47%) Bighorn Summer Source Habitat Acres (Percentage of Allotment) 3,093 (51%) Percentage of capable domestic sheep grazing acres that overlap with bighorn sheep summer habitat. S-22 San Luis Peak Bighorn Herd 1,689 or 55% (represents 24% of the allotment) Under Alternative 4 there will no longer be known direct overlap with the San Luis Peak bighorn herd. This allotment boundary change does not result in any further distance between bighorn sheep CHHR and the allotment at 0.5 miles. The model results are the same as Alternative 3 for the S-22 sub herd. S-53 Bristol Head Bighorn Herd The allotment boundary change does not result in any further distance between bighorn sheep CHHR and the allotment at 1.27 miles. The model results are the same as Alternative 3 for the S-53 sub herd. S-36 Bellows Creek Bighorn Herd The distance from this herd to the allotment will remain at approximately 3.71 miles. The model results are the same as Alternative 3 for the S-53 sub herd. Cumulatively, the annual herd contact rate for all three bighorn herds under Alternative 4 is 1.7, meaning that bighorn are expected to contact the Miners Allotment essentially every 2 years. Additionally, due to the influence from the S-53 and S-36 herds, a disease transmission with potential for subsequent bighorn mortality could occur every 6.8 years. Based on the information presented above, a rank of High Risk, was assigned to the Miners Allotment under Alternative 4. The reasons for assigning a rank of High Risk are as follows: 53

60 USDA Forest Service Modifying the allotment boundary more than doubles the amount of time between allotment contact from Alternative 2 but remains the same as Alternative 3 (less than 1 year 0.75 to 1.7 years). There will no longer be any known direct overlap between the allotment and bighorn sheep CHHR. The S-22 CHHR will remain at about 0.5 mile from the new boundary of the allotment. There will be very little spatial (0.5 mile) or temporal separation between the two species. The allotment will contain a moderate amount of overlap between bighorn habitat and acres suitable for domestic sheep grazing at 55%. Separation between the allotment and the three herds consists of 0.5 mile for S-22, 1.27 miles for S-53, and 3.71 miles for S-36. Bighorn are expected to contact the allotment from the three sub-herds at rates of every 2.7 years for S-22, every 6.8 years for S-53, and every 14 years for S-36. A disease transmission with potential subsequent bighorn mortality could occur every 11 years in the S-22 components, but cumulatively could occur every 6.8 years due to the influence from all three herds combined. Alternative 5 The Miners Allotment would become vacant as part of Alternative 5. Ouray Allotment Alternative 2 The Ouray Allotment is currently a vacant sheep allotment and is not considered as part of Alternative 2. Alternative 3 Photo: Bighorn rams. Alternative 3 moves the northern boundary of the allotment away from the S-22 CHHR but also moves the boundary of the southern part of the allotment closer to the S-53 CHHR. The intent of this change is to make up for grazing acres lost in the north half of the allotment with additional acres on the south half of the allotment. The total allotment acreage of the Ouray Allotment incorporated into Alternative 3 is 6,836 acres. The amount of overlap between bighorn sheep suitable summer habitat and acres capable for domestic sheep grazing is 37% (1,087) representing 16% of the total allotment. 54

61 DRAFT Snow Mesa and Wishbone Risk Assessment Table 13. Ouray Allotment Risk of Contact Tool Comparison for Alternative 3 Ouray Allotment Annual Herd Contact Rate Bighorn from this sub-herd are projected to contact this allotment every X years. S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek / = 6 1/ = 3.7 1/ = 13 Cumulative Annual Herd Contact Rate for all Three Bighorn Sheep Herds 1/ = 1.9; Potential contact with the allotment by bighorn sheep in RBS- 22 can be expected approximately once every 1.9 years. Equates to a potential disease transmission every X years on this allotment. Distance from Bighorn CHHR 6 * 4 = 24. Potentially every 24 years. 3.7 * 4 = 15. Potentially every 15 years. 13 * 4 = 52. Potentially every 52 years. 3.3 miles 0.65 mile 4.7 miles Based on modeled contact rates and an assumed moderate probability of disease transmission, given contact (0.25 or 1 in every four contacts), a disease transmission event with potential for subsequent bighorn mortality could occur once every 7.6 years (1.9 * 4 = 7.6). This potential varies considerably from 15 to 52 years among bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP with BIGHORN SHEEP HABITAT Total Allotment Acres 6,836 Capable Domestic Sheep Grazing Acres (Percentage of Allotment) 2,914 (43%) Bighorn Summer Source Habitat Acres (Percentage of Allotment) 1,087 (16%) Percentage of capable domestic sheep grazing acres that overlap with bighorn sheep summer habitat. S-22 San Luis Peak Bighorn Herd 1,087 or 37% (represents 16% of the allotment) S-22 bighorn sheep are separated from the allotment by 3.3 miles of moderately suitable habitat and are expected to contact the Ouray Allotment every 6 years. Using a moderate estimate of one out of four (25%) contacts resulting in a disease transmission event with potential for subsequent bighorn mortality, this allotment contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 24 years in the S-22 sub-herd. S-53 Bristol Head Bighorn Herd The Bristol Head Bighorn Herd will be separated from the allotment by 0.65 mile of very open, but considered to be mostly unsuitable, habitat. Bighorn from this herd are expected to contact the allotment every 3.7 years, equating to a disease transmission with potential for subsequent bighorn mortality once every 15 years in the S-53 sub-herd. S-36 Bellows Creek Bighorn Herd The Bellows Creek Bighorn Herd will be separated from the allotment by 4.7 miles of fair to good suitable habitat. Bighorn from this herd are expected to contact the allotment every 13 years, equating to a disease transmission with potential for subsequent bighorn mortality once every 52 years in the S-36 sub-herd. The model suggests that movement from S-36 into the Ouray Allotment is most likely from the north. 55

62 USDA Forest Service Cumulatively, the annual herd contact rate for all three bighorn herds is 1.9, meaning that bighorn are expected to contact the Ouray Allotment every 2 years. Due to the influence of all three herds, contact rates combined with the amount of suitable bighorn sheep habitat and the relatively close distance to the allotment, a disease transmission with potential for subsequent bighorn mortality could occur every 7.6 years. Based on the information presented above, a rank of High Risk was assigned to the Ouray Allotment under Alternative 3. The reasons for assigning a rank of High Risk are: There is no direct overlap between the allotment and bighorn sheep CHHR. There will be very little spatial (0.65 mile) or temporal separation between the two species. The Ouray Allotment will contain a low to moderate amount of overlap between bighorn habitat and acres suitable for domestic sheep grazing at 37%. Separation between the allotment and the three herds consists of 3.3 miles for S-22, 0.65 mile for S-53, and 4.7 miles for S-36. Photo: Domestic sheep leaving the allotments in mid-september Alternative 4 Bighorn are expected to contact the allotment from the three subherds at rates of every 6 years for S- 22, every 3.7 years for S-53, and every 13 years for S-36. A disease transmission with potential subsequent bighorn mortality could occur every 15 years in the S-53 herd, but could occur cumulatively for all three bighorn herds every 7.6 years due to the influence from all three herds combined. Alternative 4 slightly moves the northern boundary of the allotment away from the S-22 CHHR but moves the boundary of the southern part of the allotment within the CHHR of S-53. The amount of overlap between bighorn sheep suitable summer habitat and acres capable for domestic sheep grazing is 58% (2,677), representing 28% of the total allotment. 56

63 DRAFT Snow Mesa and Wishbone Risk Assessment Table 14. Ouray Allotment Risk of Contact Tool Comparison for Alternative 4 Ouray Allotment Annual Herd Contact Rate S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek Cumulative Annual Herd Contact Rate for all Three Bighorn Sheep Herds Bighorn from this sub-herd are projected to contact this allotment every X years. Equates to a potential disease transmission every X years on this allotment. Distance from Bighorn CHHR 1/ = 6 6 * 4 = 24. Potentially every 24 years. 1/1.0=1 1/ = 18 1 * 4 = 4. Potentially every 4 years. 18 * 0.4 = Potentially every 72 years. 3.4 miles Overlap 5 miles 1/ = ; Potential contact with the allotment by bighorn sheep in RBS-22 can be expected approximately every 0.81 years. Based on modeled contact rates and an assumed moderate probability of disease transmission, given contact (0.25 or 1 in every four contacts), a disease transmission mortality could occur every 3.2 years (0.81 * 4 = 3.2). This potential varies considerably from 4 to 72 years among bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP with BIGHORN SHEEP HABITAT Total Allotment Acres 9,555 Capable Domestic Sheep Grazing Acres (Percentage of Allotment) 4,627 (48%) Bighorn Summer Source Habitat Acres (Percentage of Allotment) 3,087 (32%) Percentage of capable domestic sheep grazing acres that overlap with bighorn sheep summer habitat. S-22 San Luis Peak Bighorn Herd 2,677 or 58% (which represents 28% of the allotment) S-22 bighorn are separated from the allotment by 3.4 miles of moderately suitable habitat and are expected to contact the Ouray Allotment every 6 years. Using a moderate estimate of one out of four (25%) contacts resulting in a disease transmission event with potential for subsequent bighorn mortality, this allotment contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 24 years in the S-22 sub-herd. S-53 Bristol Head Bighorn Herd Under Alternative 4, there is direct overlap with the Bristol Head herd. As there is direct overlap, bighorn do not need to go on a foray to contact the allotment. Bighorn sheep have been documented in the Boulder Creek area as recently as October of 2016 within the area designated by this alternative. Bighorn then contact this allotment on a yearly basis and more than likely by more than one ram a year. Using a moderate estimate of one out of four (25%) contacts resulting in a disease transmission event with potential for subsequent bighorn mortality, this allotment contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 4 years in the S-53 sub-herd. 57

64 USDA Forest Service S-36 Bellows Creek Bighorn Herd The Bellows Creek bighorn herd will be separated from the allotment by 5.0 miles of fair to good suitable habitat. Bighorn from this herd are expected to contact the allotment every 18 years, equating to a disease transmission with potential for subsequent bighorn mortality once every 72 years in the S-36 sub-herd. Cumulatively, the annual herd contact rate for all three bighorn herds is 0.81, meaning that bighorn are expected to contact the Ouray Allotment every 0.81 years. Due to the influence of all three herds, contact rates combined with the amount of suitable bighorn sheep habitat and the relatively close distance to the allotment, a disease transmission with potential for subsequent bighorn mortality could occur every 3.2 years. Based on the information presented above, a rank of High Risk was assigned to the Ouray Allotment under Alternative 4. The reasons for assigning a rank of High Risk are: Alternative 5 There is direct overlap between the allotment and bighorn sheep CHHR (S-53). The Ouray Allotment will contain a moderate amount of overlap between bighorn habitat and acres capable for domestic sheep grazing at 58%. Separation between the allotment and the three herds consists of 3.4 miles for S-22, overlap with S-53, and 5.0 miles for S-36. Bighorn are expected to contact the allotment from the three sub-herds at rates of every 6 years for S-22, every year for S-53, and every 18 years for S-36. A disease transmission with potential subsequent bighorn mortality could occur every 4 years in the S-53 herd, but cumulatively could occur every 3.2 years for all three bighorn herds due to the influence from all three herds combined. The Ouray Allotment would remain vacant. A portion of Ouray Allotment will be incorporated into the Wishbone Allotment and is included in the Wishbone Alternative 5 analysis. Wishbone Allotment Alternatives 2 through 4 The Wishbone Allotment is not applicable to Alternatives 2 through 4. Alternative 5 This alternative would result in no overlap between bighorn sheep CHHR and domestic sheep. The results of the Risk of Contact Model are summarized in Table 15 and discussed below for each bighorn herd. 58

65 DRAFT Snow Mesa and Wishbone Risk Assessment Table 15. Wishbone Allotment Risk of Contact Tool Comparison for Alternative 5 Wishbone Allotment Annual Herd Contact Rate S-22 San Luis Peak S-53 Bristol Head S-36 Bellows Creek Cumulative Annual Herd Contact Rate for all Three Bighorn Sheep Herds Bighorn from this sub-herd are projected to contact this allotment every X years. 1/ = 4.6 1/ = = /1.0894=0.92;Potential contact with the allotment by bighorn sheep in RBS-22 can be expected approximately once every 0.92 years. Equates to a potential disease transmission every X years on this allotment. 4.6 * 4 = 18. Potentially every 18 years. 1.3 * 4 = 5. Potentially every 5 years * 4 = 4. Potentially every 4 years. Based on modeled contact rates and an assumed moderate probability of disease transmission, given contact (0.25 or 1 in every four contacts), a disease transmission mortality could occur every 3.7 years (0.92 * 4 = 3.7). This potential varies from 4 to 18 years among bighorn herds. Distance from Bighorn CHHR 4.0 miles 1.75 miles 1.0 mile ALLOTMENT ACREAGE STATISTICS and OVERLAP with BIGHORN SHEEP HABITAT Total Allotment Acres 10,487 Capable Domestic Sheep Grazing Acres (Percentage of Allotment) 7,096 (68%) Bighorn Summer Source Habitat Acres (Percentage of Allotment) 4,239 (40%) Percentage of capable domestic sheep grazing acres that overlap with bighorn sheep summer habitat. S-22 San Luis Peak Bighorn Herd 2,413 or 34% (which represents 23% of the allotment) Under Alternative 5, Wishbone Allotment, there will be approximately 4.0 miles of separation between the S22 CHHR and the Crystal Basin pasture of the Wishbone Allotment. Bighorn can be expected to contact the allotment every 4.6 years. Using a moderate estimate of one out of four (25%) contacts resulting in a disease transmission event with potential for subsequent bighorn mortality, this allotment contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 18 years in the S-22 sub-herd. Domestic sheep are planned to graze the Crystal Basin Pasture approximately 22 days, limiting the amount of potential contact time between the two species. According to existing maps, approximately 893 acres of the 3,352 acre pasture consists of bighorn sheep source summer habitat. Bighorn sheep have not been documented near the Crystal Basin Pasture. 59

66 USDA Forest Service S-53 Bristol Head Bighorn Herd Under Alternative 5, there will be approximately 1.75 miles of separation between the CHHR of the S53 herd and the South River Pasture of the Wishbone Allotment. Bighorn can be expected to contact the allotment every 1.3 years. This contact rate equates to a disease transmission with potential subsequent bighorn mortality once every 5 years in the S-53 subherd. Domestic sheep are planned to graze the South River Pasture for approximately 22 days, limiting the amount of potential contact time between the two species. According to existing maps, approximately 344 acres of the 2,085 acre pasture consists of bighorn sheep source summer habitat. Bighorn sheep have not been documented near the South River Pasture. S-36 Bellows Creek Bighorn Herd Under Alternative 5, there will be approximately 1.0 mile of separation between the CHHR of the S36 herd and the East Bench Pasture of the Wishbone Allotment. Bighorn can be expected to contact the allotment every year. This contact rate equates to a disease transmission with potential subsequent bighorn mortality every 4 years in the S-36 sub-herd. Domestic sheep are planned to graze the East Bench Pasture for approximately 5 days, limiting the amount of potential contact time between the two species. According to existing maps, approximately 49 acres of the 525 acre pasture consists of bighorn sheep source summer habitat. Bighorn sheep have not been documented near the East Bench Pasture. Domestic sheep are trailed along Highway 149 through the Coller-Wagon Wheel Gap area. Bighorn sheep are commonly sighted in this area. Trailing poses a risk of contact to the S36 bighorn group. Project design features such as completing a drive through to haze any bighorn away from the highway prior to the domestic sheep passing through will help to reduce any conflicts. Cumulatively, due to relatively close proximity to known bighorn sheep herds in several of the pastures, results from the model demonstrated a high risk rating overall. However, due to an overall low amount of suitable source bighorn habitat in most pastures, existing topographical barriers such as the Rio Grande River, Highway 149 and several subdivisions, the likelihood of success of project design features is higher than that of any other grazing alternative. These factors will decrease the level of risk as displayed in the model to Moderate. A rating of Moderate risk indicates that physical contact within allotments between bighorn and domestic sheep may occur at some point in the future, but that a higher degree of uncertainty exists that separation might be achieved and/or maintained for many years using design features that are expected to add value to the goal of effective separation. The risk of physical contact between bighorn and domestic sheep, with the potential for a subsequent bighorn disease outbreak, is thought to be less certain than for allotments in the high risk category, but is still of concern. Assumptions associated with the moderate risk category are further complicated by the fact that a higher degree of uncertainty is still associated with this risk category, and that monitoring feedback mechanisms and quick adaptive management adjustments may be necessary if situations indicate. Factors that reduce the apparent risk of contact could include: the presence of towns, the presence of terrain features and/or habitat 60

67 DRAFT Snow Mesa and Wishbone Risk Assessment features that act as barriers to bighorn sheep movement (Schommer and Woolever 2001), bighorn sheep distribution patterns, and application of herding techniques and other project design criteria. Accessibility of each of the pastures is also much improved than the backcountry of the Snow Mesa Allotments. Improved accessibility will result in improved monitoring and management of the domestic sheep, making adherence to the project design features more effective. Based on the information presented above, a rank of Moderate Risk was assigned to the Wishbone Allotment under Alternative 5. The reasons for assigning a rank of Moderate Risk are: There is no direct overlap between the Wishbone Allotment and bighorn sheep Core Herd Home Ranges for any of the three bighorn sub herds. The Wishbone Allotment contains a smaller percentage of overlap between bighorn habitat and acres capable for domestic sheep grazing than any of the other alternatives. Project design features can be better implemented and more effective in the Wishbone Allotment than compared to the remote Snow Mesa Allotments. Existing topographical barriers such as the Rio Grande River, Highway 149 and several subdivisions will help increase the success of both temporal and spatial separation than any of the other grazing alternatives. Improved accessibility will result in improved monitoring and management of the domestic sheep, making adherence to the project design features more effective. Project design criteria are in place to reduce the risk of continued trailing through Wagon Wheel Gap Palisade Campground. 61

68 USDA Forest Service Table 16. Risk of Contact Tool predictions and Risk Ratings for each alternative [Values are cumulative for all three sub-herds. Risk of Contact Tool predictions are for contact. Potential for subsequent disease following contact is based on a moderate rate of four contacts (0.25). Distance from bighorn sheep CHHR. Risk rating for each allotment per bighorn herd.] Risk of Contact Tool Predictions Risk Rating Snow Mesa Table Miners Ouray ALTERNATIVE 2: Cumulative for all three sub herds (S22, S53, and S36) BHS are predicted to contact this allotment every X years (Cumulative) Wishbone N/A N/A Disease potential expressed in years N/A N/A Closest Allotment Distance from BHS Core Here Home Range Percentage of suitable domestic sheep grazing acres that overlap with BHS summer habitat Overlap 0.5 mile Overlap N/A N/A 90% 52% 67% N/A N/A Risk Rating (High, Medium, Low) High High High N/A N/A ALTERNATIVE 3: Cumulative for all three sub herds (S22, S53, and S36) BHS are predicted to contact this allotment every X years (Cumulative) N/A Disease potential expressed in years N/A Closest Allotment Distance from BHS Core Here Home Range Percentage of suitable domestic sheep grazing acres that overlap with BHS summer habitat 0.5 mile 0.5 mile 0.5 mile 0.65 mile N/A 92% 52% 59% 37% N/A Risk Rating (High, Medium, Low) High High High High N/A ALTERNATIVE 4: Cumulative for all three sub herds (S22, S53, and S36) BHS are predicted to contact this allotment every X years (Cumulative) N/A N/A Disease potential expressed in years N/A N/A Closest Allotment Distance from BHS Core Here Home Range Percentage of suitable domestic sheep grazing acres that overlap with BHS summer habitat N/A 0.5 mile 0.5 mile Overlap N/A N/A 52% 55% 58% N/A Risk Rating (High, Medium, Low) N/A High High High N/A ALTERNATIVE 5: Cumulative for all three sub herds (S22, S53, and S36) BHS are predicted to contact this allotment every X years (Cumulative) N/A N/A N/A N/A 0.92 Disease potential expressed in years N/A N/A N/A N/A 3.7 Closest Allotment Distance from BHS Core Here Home Range Percentage of suitable domestic sheep grazing acres that overlap with BHS summer habitat N/A N/A N/A N/A 1.0 mile N/A N/A N/A N/A 34% Risk Rating (High, Medium, Low) N/A N/A N/A N/A *Medium *Reduced from High to Medium due to project design criteria likely being more effective, topographical features serving as barriers, increased distance from CHHR, a lesser amount of overlap between suitable domestic sheep grazing acres and bighorn sheep habitat and less amount of bighorn sheep source summer habitat within the boundary of the Wishbone Allotment. 62

69 DRAFT Snow Mesa and Wishbone Risk Assessment Discussion This analysis evaluated the risk of physical contact between bighorn and domestic sheep on an individual allotment basis for each of the three individual bighorn sub-herds. Examining each individual allotment s risk of physical contact provides an objective look at examining and comparing the risk of physical contact and disease transmission event with potential for subsequent bighorn mortality on an individual allotment and sub-herd basis. All three allotments considered under Alternative 2, all four allotments in Alternative 3 and all three allotments in Alternative 4 have a high risk rating. There is no single allotment in these alternatives that stands out as having a much lower risk of physical contact than any other, decreasing the potential opportunity of continued grazing on any one allotment with a low risk. The Wishbone Allotment, Alternative 5, provides for the lowest amount of risk of any of the grazing alternatives. Under Alternative 1 (No Grazing), there will be no risk of contact or potential for subsequent disease transmission providing for a bighorn sheep mortality event from these allotments. The probability of long-term herd persistence of the RBS-22 Central San Juan Bighorn Herd is the highest under this alternative. Alternative 2 (Continued Grazing) provides for the highest amount of risk of physical contact and therefore the highest potential for subsequent disease transmission and a bighorn sheep mortality event. The probability of long-term herd persistence of the RBS-22 Central San Juan Bighorn Herd is the lowest under this alternative. Alternative 3 (Allotment Boundary Reconfiguration) provides for a lower amount of risk of physical contact than Alternative 2, but risk remains high. The probability of long-term herd persistence of the RBS-22 Central San Juan Bighorn Herd is improved over Alternative 2 but remains low in the long term. Alternative 4 (Permittee suggestion) provides an effort to reduce potential contact on the north end of the current allotment but increases the potential for direct contact by moving the southern end of the allotment within known occupied CHHR of the S-53 herd. The probability of long-term herd persistence of the RBS-22 Central San Juan Bighorn Herd is low under this alternative. Alternative 5 (Wishbone Allotment) provides for continued grazing by the permittees while also providing the best chance of any of the grazing alternatives for preventing contact between bighorn and domestic sheep allotments. This alternative would result in no overlap between bighorn and domestic sheep. The Risk of Contact Model was run on this alternative. Due to close proximity to known bighorn sheep herds, results from the model demonstrated a high risk rating. However, a higher degree of likelihood of success of project design criteria is expected to add value to the goal of effective separation as are potential topographical barriers including the Rio Grande River, Highway 149 and several subdivisions. This alternative provides for a lower amount of suitable summer source bighorn habitat within the allotment and also the lowest amount of overlap between suitable summer 63

70 USDA Forest Service source habitat for bighorn sheep and acres capable for domestic sheep grazing. Accessibility of each of the pastures is also much improved than the backcountry of the Snow Mesa Allotments. Improved accessibility will result in improved monitoring and management of the domestic sheep. The likelihood of physical contact between the two species is less than the other grazing alternatives but is not without risk. A source of continued potential risk is trailing domestic sheep along Highway 149 through the Wagon Wheel Gap-Upper Coller area. During trailing through this area in July of 2016, a bighorn ewe approached the domestic sheep flock to within approximately 50 yards before running off. Project design features are in place to look for and haze away if necessary, any bighorn sheep which may happen to be along the trailing route as the domestics are passing through. The probability of long-term herd persistence of the RBS-22 Central San Juan Bighorn Herd is improved over the other grazing alternatives supporting a moderate level of persistence. Uncertainties As with most quantitative and qualitative approaches such as utilizing models, there are typically a variety of uncertainties that must be recognized and considered. These uncertainties are typically unique factors specific to the particular project and area. The following addresses these uncertainties as applied to the Snow Mesa analysis. Photo: Headwaters of Willow Creek on the Snow Mesa Allotment. There is uncertainty regarding the applicability of the default values suggested for use with the Risk of Contact Tool to the bighorn sheep herds of the southern Rocky Mountains. There is no data from the Snow Mesa landscape by which to test the model s assumptions, especially those related to foray rates and distances. In contrast to Hells Canyon on the Payette National Forest, bighorn habitat in the Snow Mesa landscape is dominated by very open alpine terrain above timberline. Forays in the Snow Mesa landscape could then potentially be greater than those in the Hells Canyon Herd. For this reason, the appropriate level of confidence that should be placed on the total herd contact rates generated by the model is not known for certain. However, this uncertainty is unlikely to vary by alternative and thus there is no reason to believe that the uncertainty associated with the model s default foray values would favor one alternative over another. For this reason, the Tool is unlikely to bias the selection of one alternative versus another. There is uncertainty about how the Risk of Contact Tool predictions for bighorn contact with an allotment might relate to actual physical contact between individual 64

71 DRAFT Snow Mesa and Wishbone Risk Assessment bighorns and domestic sheep. If domestic sheep are not grazed equally among the allotments or across the individual allotments, there could be some allotments or portions of allotment where the potential for physical contact between the species is less or more than that predicted by the Risk of Contact Tool. A moderate disease transmission probability was considered to be one in four contacts resulting in a disease transmission event (25% disease transmission probability). There is uncertainty regarding what level of confidence should be placed on the precise actual total herd contact values produced by the Risk of Contact Tool based upon the past history of domestic sheep grazing and presumed bighorn sheep distribution and abundance patterns within the Snow Mesa landscape. Results from the Risk of Contact Tool predict that multiple contacts with active domestic sheep allotments, and multiple disease transmission events, should have occurred in this landscape during the past 75+ years. Over this time period, there has been no evidence of an all-age bighorn disease outbreak in the S-22 or S-53 herds. However, the S-22 herd is in a declining trend as a result of poor lamb recruitment, particularly in the ewe groups in closest proximity to the Snow Mesa landscape. The S-53 subherd remains relatively stable overall, but the ewe group also in closest proximity to Snow Mesa has experienced little to no lamb recruitment over the past 3 5 years. An all-age disease event in the S-36 herd in the late 1990s reduced the population from an estimated 125 down to a low of 30 by The numbers in this herd have slowly increased since 2001 and appear to be on a slow upward trend to an estimated 45+ animals today. Monitoring has shown that numerous lambs are present in the herd in June and July but their numbers greatly diminish by late August. This type of lamb die-off is typical of herds still experiencing impacts of past disease events (Colorado Parks and Wildlife 2009). In this herd instance, it has taken more than 20 years for the herd to slowly recover, which suggests that the contact rates may be indicative of a risk of disease transmission. The moderate (0.25%) disease transmission assumption is a conservative approach to evaluate the contact rates based on these factors. Given the appearance of a contradiction between an apparently lack of an all-age disease event in the S-22 and S-53 herds and the Risk of Contact Tool predictions for contact and disease transmission happening in the landscape, this creates some degree of uncertainty about the efficacy of the Tool s total herd contact rate predictions. There may be many reasons for this lack of recent and known disease outbreaks in these two herds, such as the natural tendency for bighorn sheep to remain in their CHHR, which may be especially strong in these herds. It is also possible that straying domestic sheep that might pose substantial risks for physical contact in other landscapes have lower survival rates wandering in the terrain of the Snow Mesa landscape, thereby preventing contact that might have otherwise occurred in other areas. There are also numerous strains of Pasteurellaceae, some of which are much more virulent than others. It is possible that contact with domestic sheep has occurred but contact has not yet occurred with a strain strong enough to cause an all-age dieoff. Poor lamb survival in S-22 and S-53 is an indication that a less deadly strain that results in lamb mortality but not adult mortality is present. It has also been shown that domestic sheep herds often contain numerous strains of Pasteurellaceae among individual animals, and contact with what is known as a hot domestic ewe simply 65

72 USDA Forest Service hasn t occurred by chance alone. It is also possible that the random nature of a very few foraying bighorn sheep on a very large landscape has produced few physical contacts; in essence, bighorns have been lucky enough to date to not encounter domestic sheep for no other reason than random chance alone. Nonetheless, this contrast between past history and predictions by the Risk of Contact Tool for multiple physical contacts and disease transmission events, especially involving the San Luis Peak Herd S-22, is not readily explained and remains a source of uncertainty about how much confidence to place on the values generated by the Tool. Photo: Ram and ewe, S There is uncertainty involving the season of bighorn use considered in the model compared to the actual authorized grazing period. The model accounts for risk potential from May through September for each allotment, while domestic sheep grazing occurs on the landscape as a whole from July 11 through September 15. There is no method to make adjustments in the model to account for a shorter time period of risk. There is uncertainty regarding the successful implementation of project design criteria meant to reduce species contact, and how effective they might be even when fully implemented. It must be recognized that the effectiveness of many of the project design criteria have not been fully tested or verified. During the 2014 and 2015 grazing seasons, the permittees were instructed to follow the proposed project design criteria as part of the action alternatives, with mixed results. For this reason, there is uncertainty about their long-term success. It is logical to expect that perfect implementation of all project design criteria has the potential to improve the goal of effective separation. However, because there is uncertainty about the effectiveness of project design criteria they should not be relied upon solely to achieve effective separation, particularly in areas of close association. Because of uncertainty about the effectiveness of project design criteria, application of project-level monitoring is a very important strategy to document the effectiveness of project design criteria within individual project areas. Failure to apply, monitor, and potentially adjust management practices may result in unrealistic confidence being placed in the effectiveness of management practices, with potential for negative consequences to bighorn sheep. Project design criteria are included in Chapter 2 of the EA. There is uncertainty regarding how the behavioral attraction between domestic and bighorn sheep could increase the risk of contact within the landscape, above that predicted by the Risk of Contact Tool. The tool does not consider or attempt to model the natural attractive instincts of bighorn and domestic sheep. While on forays, because of this mutual attraction, bighorns are more likely to come into contact with domestic sheep bands. Also, domestic sheep strays are more likely to contact bighorn sheep bands while traveling across the landscape. The effect of this mutual attraction is likely increased potential for physical contact between the species if they are 66

73 DRAFT Snow Mesa and Wishbone Risk Assessment present in the same area at the same time, but the degree of increased potential for contact is not known. There is uncertainty regarding stray domestic sheep and the risk of contact within and outside of permitted allotments. The tool does not consider or attempt to model the movements of domestic sheep straying away from their bands and outside their permitted allotment. Straying domestic sheep are more likely to contact bighorn sheep than are domestics that remain within their permitted allotments. The natural behavioral attraction of bighorn and domestic sheep make it more likely that straying domestic sheep may seek out and comingle with bighorn sheep when separated from the main flock. For this reason, straying domestic sheep increase the likelihood of physical contact occurring between the species. The presence of strays on the landscape may increase the risk of physical contact above that predicted by the Risk of Contact Tool. Strays within and outside of the allotments are documented, but the yearly occurrence of domestic sheep strays is not known for certain and thus it is not possible to determine with certainty to what degree strays might increase the risk of physical contact between domestic and bighorn sheep. There are risk factors outside the scope of the Forest s authority or control that may influence bighorn sheep populations in the Snow Mesa landscape. For example, a small herd of hobby domestic goats is known to occur in the Santa Maria Reservoir subdivision within the CHHR of the S-53 sub-herd near Bristol Mountain. There is potential for bighorn to make contact with these goats, potentially introducing disease to the herd and thereby affecting bighorn populations in the landscape. There is uncertainty regarding the connectedness of the individual sub-herds within RBS-22 itself and other bighorn herds. The individual sub-herds within RBS-22 are combined into one larger herd unit due to their high potential for interaction and connection. The level of interaction is not known for certain. Additionally, it is not known how much interaction there is between other nearby bighorn herds such as S-33 and S-55 with RBS-22. In the case of a disease event, it is not known how great the potential is for a disease in one herd to impact several herds both within RBS-22 and potentially spreading beyond the boundaries of the Snow Mesa landscape. Bighorn sheep collaring projects involving bighorn on the Rio Grande has shown more movement than expected from one herd unit into another. There is uncertainty regarding bighorn sheep movement across the Snow Mesa landscape in response to spruce beetle (Dendroctonus rufipennis) influence that has recently occurred throughout the area. The beetle influence has the potential to substantially alter habitat conditions for bighorn sheep, likely improving habitat connectivity for bighorn sheep in the most heavily affected areas by opening the canopy of mature closed-canopy stands, potentially greatly improving bighorn forage and travel habitats. Bighorn mobility across the landscape could be substantially improved, thereby increasing the potential for foraying bighorns to contact active allotments and come into physical contact with domestic sheep. 67

74 USDA Forest Service Photo: Domestic sheep in the hanging valley within the Table Allotment, Continental Divide and S-22 CHHR are in the background. 68

75 DRAFT Snow Mesa and Wishbone Risk Assessment References Cited Bear, G.D. (1979). Evaluation of bighorn transplants in two Colorado localities. Colorado Division of Wildlife Special Report Number pp. Bear, G.D., and Jones, G.W. (1973). History and distribution of bighorn sheep in Colorado. Colorado Parks and Wildlife Research Report. 232 pp. Beecham, J.J., Collins, C.P., and Reynolds, T.D. (2007). Rocky Mountain bighorn sheep (Ovis Canadensis): A technical conservation assessment. TREC, Inc. Rigby, ID. Prepared for USDA Forest Service, Rocky Mountain Region. 108 pp. Besser, T.E., Cassirer, E.F., Potter, K.A., Lahmers, K., and Oaks, J.L. (2014). Epizootic pneumonia of bighorn sheep following experimental exposure to Mycoplasma ovipneumoniae. PLoS ONE 9(10):e DOI: /journal.pone Besser, T.E., Cassirer, E.F., Yamada, C., Potter, K.A., Herndon, C., Foreyt, W.J., Knowles, D.P., and Srikumaran, S. (2012a). Survival of bighorn sheep (Ovis canadensis) comingled with domestic sheep (Ovis aries) in the absence of Mycoplasma ovipneumoiae. Journal of Wildlife Diseases 48: Besser, T.E., Highland, M.A., Baker, K., Cassirer, E.F., Anderson, N.J., Ramsey, J.M., Mansfield, K., Bruning, D.L., Wolff, P., Smith, J.B., and Jenks, J.A. (2012b). Causes of pneumonia epizootics among bighorn sheep, Western United States, Emerging Infectious Diseases 18: Carpenter, T.E., Coggins, V.L., McCarthy, C., Obrien, C., O Brien, J.M., and Schommer, T.J. (2014). A spatial risk assessment of bighorn sheep extirpation by grazing domestic sheep on public lands. Preventive Veterinary Medicine 114:3 10. Cassirer, E.F., Plowright, R.K., Manlove, K.R., Cross, P.C., Dobson, A.P., Potter, K.A., and Hudson, P.J. (2013). Spatio-temporal dynamics of pneumonia in bighorn sheep. Journal of Animal Ecology 82: Clifford, D.L., Schumaker, B.A., Stephenson, T.R., Bleich, V.C., Cahn, M.L., Gonzales, B.J., Boyce, W.M., and Mazet, J.A.K. (2009). Assessing disease risk at the wildlifelivestock interface: A study of Sierra Nevada bighorn sheep. Biological Conservation 142: Colorado Parks and Wildlife. (2009). Colorado Bighorn Sheep Management Plan Special Report Number 81. George, J.L., Kahn, R., Miller, M.W., and Watkins, B (eds.). 88 pp. Accessed August 22, 2016, at ManagementPlan pdf Colorado Parks and Wildlife. (2013). Bighorn Sheep Management Plan, Data Analysis Unit RBS-22, Central San Juans, Game Management Units S-22, S-36, S-52, & S-53. Prepared by Diamond, B., and Ferrero, S. Accessed August 22, 2016, at gementplanfinal.pdf Drew, M.L., Rudolph, K.M., Ward, C.S., and Weiser, G.C. (2014). Health status and microbial (Pasteurellaceae) flora of free-ranging bighorn sheep following contact with 69

76 USDA Forest Service domestic ruminants. Wildlife Society Bulletin 9999, pp DOI: /wsb.393. Accessed August 23, 2016, at Foreyt, W.J. (1990). Pneumonia in bighorn sheep: Effects of Pasteurella haemolytica from domestic sheep and the effects on survival and long-term reproduction. In: Proceedings of the Biennial Symposium of the Northern Wild Sheep and Goat Council, vol. 7, pp George, J.L., Martin, D.J., Lukacs, P.M., and Miller, M.W. (2008). Epidemic Pasteurellosis in a bighorn sheep population coinciding with the appearance of a domestic sheep. Journal of Wildlife Diseases 44: Lawrence, P.K., Shanthalingam, S., Dassanayake, R.P., Subramaniam, R., Herndon, C.N., Knowles, D.P., Rurangirwa, F.R., Foreyt, W.J., Wayman, G., Marciel, A.M., Highlander, S.K., and Srikumaran, S. (2010). Transmission of Mannheimia haemolyctica from domestic sheep (Ovis aries) to bighorn sheep (Ovis canadensis): Unequivocal demonstration with green fluorescent protein-tagged organisms. Journal of Wildlife Diseases 46: Martin, K.D., Schommer, T.J., and Coggins, V.L. (1996). Literature review regarding the compatibility between bighorn and domestic sheep. Proceedings of the Tenth Biennial Symposium of the Northern Wild Sheep and Goat Council 10: O Brien, J.M., O Brien, C.S., McCarthy, C., and Carpenter, T.E. (2014). Incorporating foray behavior into models estimating contact risk between bighorn sheep and areas occupied by domestic sheep. Wildlife Society Bulletin 38(2): DOI: /wsb.387. Schommer, T., and Woolever, M. (2001). A process for finding management solutions to the incompatibility between domestic and bighorn sheep. August USDA Forest Service. 20 pp. plus appendixes. Accessed August 16, 2016, at pdf Sells, S.N., Mitchell, M.S., Nowak, J.J., Lukacs, P.M., Anderson, N.J., Ramsey, J.M., Gude, J.A., and Krausman, P.R. (2015). Modeling risk of pneumonia epizootics in bighorn sheep. Journal of Wildlife Management 79(2): : DOI: /jwmg.824. Singer, F.J., Zeigenfuss, L.C., and Spicer, L., (2001). Role of patch size, disease, and movement in rapid extinction of bighorn sheep. Conservation Biology 15(5): USDA Forest Service. (2010). Final Supplement to the Forest Plan Biological Evaluation and Conservation Assessment for Rocky Mountain Bighorn Sheep. Rio Grande National Forest (R. Ghormley). USDA Forest Service. (2011a). Forest Service Manual 2600: Chapter 2670, Threatened, Endangered and Sensitive Plants and Animals. USDA Forest Service. (2011b). Bighorn Sheep Analysis for NEPA Documents letter R-1, 2, 3, 4, 5, and 6. James Pena for Joel D. Holtrop, Deputy Chief, Washington Office, Washington DC, August 19,

77 DRAFT Snow Mesa and Wishbone Risk Assessment USDA Forest Service. (2011c). Bighorn Sheep Analysis for NEPA Documents letter, Glenn Casamassa, Acting Deputy Regional Forester, Rocky Mountain Region, Denver, CO, September 14, USDA Forest Service. (2013). Bighorn sheep risk of contact tool users guide. USDA Forest Service, Intermountain Region. Prepared by USDA Forest Service Bighorn Sheep Working Group, Critigen, Inc. USDA Forest Service. (2014). Bighorn Sheep Analysis for NEPA Documents letter, Gregory Smith for Leslie A.C. Weldon, Deputy Chief, National Forest System, Washington, DC, July 31, Western Association of Fish and Wildlife Agencies (WAFWA). (2012). Recommendations for domestic sheep and goat management in wild sheep habitat. Wild Sheep Working Group. 28 pp. Accessed August 16, 2016, at 71

78 USDA Forest Service Appendix 1 ALTERNATIVE 2 (Continued Grazing) Risk of Contact Tool estimated annual herd contact rates (all adult rams and ewes combined) via foray for all allotments and bighorn sheep herds, in the Snow Mesa grazing analysis area under current allotment configuration. S-22 San Luis Peak Herd Alternative 2 Annual Contact Rates via Foray Allotment Snow Mesa Probability of Ram Contact Probability of Ewe Contact Single Ram Single Ewe All Rams All Ewes Herd Contact Rate This allotment intersects the CHHR polygon and is therefore not included in the analysis. Herd Contact Rate is 1.0. Table Miners This allotment intersects the CHHR polygon and is therefore not included in the analysis. Herd Contact Rate is 1.0. S-53 Bristol Herd Alternative 2 Annual Contact Rates via Foray Allotment Snow Mesa Probability of Ram Contact Probability of Ewe Contact Single Ram Single Ewe All Rams All Ewes Herd Contact Rate Table Miners Allotment S-36 Bellows Creek Herd Alternative 2 Probability of Ram Contact Probability of Ewe Contact Single Ram Annual Contact Rates via Foray Single Ewe All Rams All Ewes Herd Contact Rate Snow Mesa Table Miners

79 DRAFT Snow Mesa and Wishbone Risk Assessment Alternative 3 (Allotment Boundary Reconfiguration) Risk of Contact Tool estimated annual herd contact rates (all adult rams and ewes combined) via foray for all allotments and bighorn sheep herds, in the Snow Mesa grazing analysis area under a modified allotment configuration. S-22 San Luis Peak Herd Alternative 3 Allotment Probability of Ram Contact Probability of Ewe Contact Single Ram Annual Contact Rates via Foray Single Ewe All Rams All Ewes Herd Contact Rate Snow Mesa Table Miners Ouray S-53 Bristol Herd Alternative 3 Annual Contact Rates via Foray Allotment Probability of Ram Contact Probability of Ewe Contact Single Ram Single Ewe All Rams All Ewes Herd Contact Rate Snow Mesa Table Miners Ouray Allotment S-36 Bellows Creek Herd Alternative 3 Probability of Ram Contact Probability of Ewe Contact Single Ram Annual Contact Rates via Foray Single Ewe All Rams All Ewes Herd Contact Rate Snow Mesa Table Miners Ouray

80 USDA Forest Service Alternative 4 (Permittee Suggested) Risk of Contact Tool estimated annual herd contact rates (all adult rams and ewes combined) via foray for all allotments and bighorn sheep herds, in the Snow Mesa grazing analysis area under a permittee suggested allotment configuration. S-22 San Luis Peak Herd Alternative 4 Allotment Snow Mesa Annual Contact Rates via Foray Probability of Ram Contact Probability of Ewe Contact Single Ram Single Ewe All Rams All Ewes Herd Contact Rate N/A N/A N/A N/A N/A N/A N/A Table Miners Ouray S-53 Bristol Herd Alternative 4 Annual Contact Rates via Foray Allotment Probability of Ram Contact Probability of Ewe Contact Single Ram Single Ewe All Rams All Ewes Herd Contact Rate Snow Mesa Table Miners Ouray This allotment intersects the CHHR polygon and is therefore not included in the analysis. Herd Contact Rate is 1.0. S-36 Bellows Creek Herd Alternative 4 Allotment Probability of Ram Contact Probability of Ewe Contact Single Ram Annual Contact Rates via Foray Single Ewe All Rams All Ewes Herd Contact Rate Snow Mesa Table Miners Ouray

81 DRAFT Snow Mesa and Wishbone Risk Assessment Alternative 5 (Wishbone Allotment) Risk of Contact Tool estimated annual herd contact rates (all adult rams and ewes combined) via foray for all allotments and bighorn sheep herds, in the Snow Mesa grazing analysis area under the Wishbone Allotment configuration. Allotment S-22 San Luis Peak Herd Alternative 5 Probability of Ram Contact Probability of Ewe Contact Single Ram Annual Contact Rates via Foray Single Ewe All Rams All Ewes Snow Mesa N/A N/A N/A N/A N/A N/A N/A Table N/A N/A N/A N/A N/A N/A N/A Miners N/A N/A N/A N/A N/A N/A N/A Ouray N/A N/A N/A N/A N/A N/A N/A Herd Contact Rate Wishbone S-53 Bristol Herd Alternative 5 Annual Contact Rates via Foray Allotment Probability of Ram Contact Probability of Ewe Contact Single Ram Single Ewe All Rams All Ewes Snow Mesa N/A N/A N/A N/A N/A N/A N/A Table N/A N/A N/A N/A N/A N/A N/A Miners N/A N/A N/A N/A N/A N/A N/A Ouray N/A N/A N/A N/A N/A N/A N/A Herd Contact Rate Wishbone Allotment S-36 Bellows Creek Herd Alternative 5 Probability of Ram Contact Probability of Ewe Contact Single Ram Annual Contact Rates via Foray Single Ewe All Rams All Ewes Snow Mesa N/A N/A N/A N/A N/A N/A N/A Table N/A N/A N/A N/A N/A N/A N/A Miners N/A N/A N/A N/A N/A N/A N/A Ouray N/A N/A N/A N/A N/A N/A N/A Herd Contact Rate Wishbone

82 USDA Forest Service Appendix 2 Ram Foray Probability Maps of All Three Subherds for Alternative 2 The illustration below proved a display produced by the Risk of Contact Tool that illustrates bighorn ram CHHR for each of the three subherds combined, distribution of summer source habitat, domestic sheep allotments under Alternative 2, and estimated rates of ram contact extending out from the CHHRs. Blue indicates areas with the highest foray probability and yellow indicates the lowest. 76

83 DRAFT Snow Mesa and Wishbone Risk Assessment Ram Foray Probability Maps of All Three Subherds for Alternative 3 The illustration below proved a display produced by the Risk of Contact Tool that illustrates bighorn ram CHHR for each of the three subherds combined, distribution of summer source habitat, domestic sheep allotments under Alternative 3, and estimated rates of ram contact extending out from the CHHRs. Blue indicates areas with the highest foray probability and yellow indicates the lowest. 77

84 USDA Forest Service Ram Foray Probability Maps of All Three Subherds for Alternative 4 The illustration below proved a display produced by the Risk of Contact Tool that illustrates bighorn ram CHHR for each of the three subherds combined, distribution of summer source habitat, domestic sheep allotments under Alternative 4, and estimated rates of ram contact extending out from the CHHRs. Blue indicates areas with the highest foray probability and yellow indicates the lowest. 78

85 DRAFT Snow Mesa and Wishbone Risk Assessment Ram Foray Probability Maps of All Three Subherds for Alternative 5 The illustration below proved a display produced by the Risk of Contact Tool that illustrates bighorn ram CHHR for each of the three subherds combined, distribution of summer source habitat, domestic sheep allotments under Alternative 5, and estimated rates of ram contact extending out from the CHHRs. Blue indicates areas with the highest foray probability and yellow indicates the lowest. 79