Assessment of Risk of Physical Contact Between Rocky Mountain Bighorn Sheep and Domestic Sheep in the Snow Mesa Sheep Allotment Grazing Landscape

Assessment of Risk of Physical Contact between Rocky Mountain Bighorn Sheep and Domestic Sheep in the Snow Mesa Sheep Allotment Grazing Landscape

Rio Grande National Forest Divide Ranger District

Photo: Domestic sheep grazing below Baldy Cinco

TABLE OF CONTENTS

INTRODUCTION 3 PURPOSE OF THIS DOCUMENT 4 Why the Concern Now 6 ALTERNATIVES EVALUATED 8 KEY CONCEPTS, GUIDANCE AND RECOMMENDATION DOCUMENTS 10 HISTORY OF DOMESTIC SHEEP GRAZING ON THE SNOW MESA LANDSCAPE 12 CENTRAL SAN JUAN BIGHORN SHEEP HERD 14 AFFECTED BIGHORN SHEEP HERDS S-22 San Luis Peak Sub-Herd 18 S-53 Bristol Head Sub-Herd 20 S-36 Bellows Creek Sub-Herd 22 RISK OF CONTACT TOOL 24 DISEASE HISTORY 27 RISK ASSESSMENT OUTCOMES 29 RISK OF CONTACT TOOL RESULTS 30 Snow Mesa Allotment Alternative 2 34 Snow Mesa Allotment Alternative 3 36 Table Allotment Alternative 2 38 Table Allotment Alternative 3 40 Miners Allotment Alternative 2 42 Miners Allotment Alternative 3 44 Ouray Allotment Alternative 2 46 Ouray Allotment Alternative 3 47 SUMMARY TABLE 49 DISCUSSION 50 UNCERTAINTIES 51 LITERATURE CITED 56 APPENDIX 1: RISK OF CONTACT TOOL RESULTS FOR ALTERNATIVE 2 58 APPENDIX 2: RISK OF CONTACT TOOL RESULTS FOR ALTERNATIVE 3 59 APPENDIX 3: RAM FORAY PROBABILITY FOR SUBGROUPS ALTERNATIVE 2 60 APPENDIX 4: RAM FORAY PROBABILTY CUMULATIVE FOR ALTERNATIVE 2 61 APPENDIX 5: RAM FORAY PROBABILITY FOR SUBGROUPS ALTERNATIVE 3 62 APPENDIX 6: RAM FORAY PROBABILTY CUMULATIVE FOR ALTERNATIVE 3 63 APPENDIX 7: PROJECT DESIGN CRITERIA 64 APPENDIX 8: RISK ASSESSMENT PROCESS – FOUR STEP OUTLINE 68

INTRODUCTION

The Snow Mesa Landscape is located approximately 5 miles northwest of Creede, Colorado within Mineral and Hinsdale Counties within the Divide Ranger District of the Rio Grande National Forest.

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 1920’s. 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’s Rocky Mountain Bighorn Sheep Herd (RBS-22). RBS-22 is comprised of four discrete sub herds 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 number (<25 animals).

Photo: Snow Mesa Allotment with Baldy Cinco and the Continental Divide in the background.

PURPOSE OF THIS DOCUMENT

Rocky Mountain bighorn sheep are designated by the Forest Service Rocky Mountain Region (Region 2) as a Sensitive Species on National Forest System lands within the Region (USDA Forest Service 2007). This designation implies there is concern for the long-term viability and/or conservation status of bighorn sheep on NFS 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 2672.4.

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 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 (George et al. 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, Western Association of Fish and Wildlife Agencies 2012). Pneumonia caused by bacterial respiratory pathogens is considered the most virulent disease impacting bighorn sheep today (Besser et al. 2012b, George et al. 2009, 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, Besser et al. 2012a, 2012b and 2014, USDA Forest Service 2011a, USDA Forest Service 2010a, Western Association of Fish and Wildlife Agencies 2012, 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 NF and Colorado Parks and Wildlife (CPW) based upon professional knowledge and verified sightings and surveys. Direct overlap exists between mapped Core Herd Home Range 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. 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 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 the distance and frequency of bighorn sheep forays outside their Core Herd Home Range.

As part of this analysis process, the Risk of Contact Tool, prepared by the USDA Forest Service Bighorn Sheep Working Group (USDA Forest Service 2013), was used to help evaluate bighorn sheep movements outside their 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. No presumption is made that physical contact 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

5 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 (George et al 2009, Western Association of Fish and Wildlife Agencies 2012).

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. Results from the Risk of Contact Tool provide the decision maker with an objective evaluation of foray probabilities and potential contact rates between bighorn sheep and each domestic sheep allotment in the Snow Mesa Landscape. 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, there are a variety of uncertainties that 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.

Why the Concern Now - Change in Conditions

As discussed in the 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 (RGNF) by Colorado Parks and Wildlife (CPW) and the Gunnison National Forest (GNF) 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 added to the Region 2 Sensitive Species List on June 8, 2007 (USDA Forest Service 2007). 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 which 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 Region 2 (Beecham et. al 2007).

Sensitive species require a more in-depth analysis regarding their viability during planning. This includes thorough reviews and analyses of management actions that could affect populations of bighorn sheep or their habitat to ensure their viability and to preclude demographic trends that would result in the need for Federal listing.

2) Direction from the USDA Forest Service’s Washington Office (USDA Forest Service 2011a) instructs Forests to conduct bighorn sheep risk assessments using a suggested 4-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 core herd home ranges 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 follow-up letter from the USDA Rocky Mountain Regional Office containing additional information regarding Bighorn Sheep Analysis for NEPA Documents was also released (USDA Forest Service 2011b).

3) The Snow Mesa Allotment Term Permit/NEPA is outdated, with the last analysis being completed in 1977 through an Environmental Analysis Report (EAR).

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’s Bighorn Herd section.

7) Improved survey work by both CPW and the RGNF, which has resulted in updated information regarding domestic sheep use of the allotments and more accurate information on the number of bighorn in the area, their use of the allotments and more accurate depictions of current bighorn sheep core herd home ranges (CHHR).

8) Bighorn sheep are documented immediately adjacent to and within the northern portion of the allotments primarily along the Continental Divide. See Figure 4.

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, suggest that at least the northern portion of the allotments is used year-around by bighorn sheep. These use patterns were used in the identification of the Core Herd Home Range (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 Baldy Cinco, Baldy Chato, head of Miners Creek and Oso Creek areas, all 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 S53 herds immediately to the north and south of the allotments have been experiencing little to no lamb recruitment for the last 3-5 years.

ALTERNATIVES EVALUATED BY THIS ENVIRONMENTAL ASSESSMENT

Three alternatives are being evaluated by the Environmental Assessment (EA) and this Risk of Physical Contact Analysis:

1). Alternative 1- No Grazing, the allotments would become vacant.

2). Alternative 2 – Current Grazing Management with Project Design Criteria. See Figure 1, Alternative 2 and 3 Comparison.

3). Alternative 3 - Modifying the allotment boundary 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. See Figure 1, Alternative 2 and 3 Comparison.

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, Besser et. al. 2012a, Besser et al. 2012b and Besser et al. 2014). The information in these references represents the best available science regarding potential viability outcomes due to interspecies contact between bighorn sheep and domestic

sheep.

Other Alternatives Considered but not further pursued or evaluated are included in the EA.

Figure 1 compares Alternative 2 and 3. The red lines reflect those areas of the current allotment boundary which would be excluded from grazing and removed from the boundary of the allotments. The blue lines reflect those areas of the Ouray Allotment which would be added into the boundary of the allotment to offset those acres to the north removed.

Figure 1: Alternative 2 and 3 Comparison.

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 7) and this Risk Assessment.

1) Wild Sheep Working Group. 2012. Recommendations for Domestic Sheep and Goat Management in Wild Sheep Habitat. Western Association of Fish and Wildlife Agencies. 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.

2) Bighorn Sheep Management Plan for RBS-22, Central San Juans Sheep Herd (Data Analysis Unit 22 and Game Management Units S22, S36, S52 and S53). 2013. Colorado Parks and Wildlife. 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.

3) Bighorn Sheep Analysis for NEPA Documents, Washington Office Letter. July 31, 2014. Leslie A. C. Weldon. Deputy Chief, National Forest System. 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) Bighorn Sheep Analysis for NEPA Documents, Washington Office Letter. August 19, 2011. Joel D. Holtrop Deputy Chief, National Forest System. 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.

5) Bighorn Sheep Analysis for NEPA Documents, Region 2 Regional Office Letter. September 14, 2011. Glenn Casamassa, Acting Deputy Regional Forester, Resources. Letter re- emphasized the importance of conducting risk assessments in accordance with the viability analysis outlined in the WO letter where management objectives include maintenance or enhancement of bighorn sheep populations. Letter also provided information on GIS products available to help with analyses.

6) Supplement to the Forest Plan Biological Evaluation and Conservation Assessment for Rocky Mountain Bighorn Sheep. 2010. Rio Grande National Forest (R. Ghormley). Bighorn sheep were added to the Region 2 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) Memorandum of Understanding Signed in April of 2014 by the Forest Service Rocky Mountain Region, Bureau of Land Management Colorado State Office, Colorado Parks and 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 bighorn sheep populations while sustaining an economically viable domestic sheep industry in Colorado.”

8) Colorado Bighorn Sheep Management Plan, 2009-2019. Special Report Number 81. (George et al. 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 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.

9) Rocky Mountain Bighorn Sheep, A Technical Conservation Assessment. 2007. 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.

10) A Process for Finding Management Solutions to the Incompatibility Between Domestic and Bighorn Sheep. 2001. (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 OF DOMESTIC SHEEP GRAZING IN THE SNOW MESA LANDSCAPE and CURRENT STATUS

The Snow Mesa allotments are approximately 34,558 acres. Earliest records regarding domestic sheep grazing on the allotments date back to the 1920’s. 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 1988. Photo: Sheep leaving the trucks on July 11, 2014.

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 continuing 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.

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 CDNST on Snow Mesa. These areas were offset by including portions of the vacant Ouray allotment for the 2013 and 2014 grazing seasons.

Figure 2: The allotments relative to the Rio Grande National Forest.

CENTRAL SAN JUAN BIGHORN HERD POPULATION AND POPULATION STATUS

Snow Mesa

Figure 3: RBS-22/GMUs: Source: CPW GIS Team.

Table 1: Central San Juan Herd Population Estimate by GMU.

Game Management Unit and Central San Juan Bighorn Herd Subpopulation (RBS-22) S-22 (San Luis Peak) 70 S-36 (Bellows Creek) 45 S-52 (Rock Creek) 25 (not included in this analysis) S-53 (Bristol Head) 110 TOTAL 250

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 comprised of one or more interconnected herds that are native or have resulted from translocations” (George et al 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 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 DAU 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 GMU 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 other three GMU’s in this DAU, and transplants were the only viable method of reintroducing animals to their historic range following extirpation.

Tier 2 herds are worthy of a high level of investment and protection. There are an estimated 7,000 bighorn sheep in the state of Colorado; the current population estimate for RBS-22 is approximately 250 animals.

Figure 4 shows the Core Herd Home Range (CHHR) for 3 of the 4 sub herds which make up RBS-22. 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 representatives from both the Rio Grande National Forest and by Colorado Parks and Wildlife personnel based upon professional knowledge and verified sightings and surveys. Bighorn sightings and locations are also shown on the map and are intended to demonstrate bighorn distribution and not necessarily every documented sighting.

Figure 5 shows the Suitable Summer (Source) habitat in the Snow Mesa Landscape. Summer source maps have been developed for Colorado by Colorado Parks and Wildlife (CPW) using their extensive State-wide bighorn sheep telemetry data set and found to be effective, covering 91% of telemetry points from their pooled bighorn telemetry location datasets.

Figure 4. Core Herd Home Ranges and Documented BHS locations and Proximity to Current Allotment Boundaries. * BHS locations are not meant to reflect all known sightings but instead are used to show distribution and relative key areas within the CHHRs based off of documented sightings.

Bighorn Sheep Herd Size – RBS-22

S-22 (San Luis Peak) – 70

S-36 (Bellows Creek) – 45

S-53 (Bristol Head) – 110 S-52 (Rock Creek, not shown) – 25 16 Total RBS-22 – 250 Bighorn Sheep

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. 2011 Harvested Ram Bighorn sheep habitat in the allotments is well distributed and connected. Habitat connectivity Red Mountain Creek increases opportunities for bighorn dispersal across the area, increasing the potential for bighorn S15 to come into contact with domestic sheep and increasing the chance of a disease event spreading beyond just the impacted herd. The DAU 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 is not used, to a large extent, by bighorn 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 5: Snow Mesa Vicinity BHS Suitable Habitat (Summer).

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 GMU S-22. Informal surveys for bighorn sheep in this unit date back to the 1930’s (USDA Forest Service 2010), with anecdotal reports of wild sheep going back to the early 1900’s. No documented translocations have occurred in the unit, further corroborating their native origin. The unit contains large expanses of suitable habitat which 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 GMUs S-22, S-36, S-52 and S-53. The northern reaches of this DAU (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 the state, and it is logical to assume that bighorn populations were connected historically at a much grander scale, with possible exchange also occurring between adjacent GMU’s, 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 five years as a result of poor lamb recruitment. The La Garita Mountains offer abundant wild sheep habitat, however, bighorn 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 their overall range has likely constricted. Evidence of range constriction is found in a historic bighorn distribution map from the USFS “Cebolla District.” That map indicates that bighorn were present in the North Fork of Saguache Creek above Stone Cellar, where today bighorns do not occur. There are likely many factors contributing 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 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 five years. In the future, if this population increases, it is likely that bighorn use would increase across the GMU within suitable habitats (Colorado Parks and Wildlife 2013).

Specific Issues Domestic sheep grazing on the Snow Mesa Allotments pose the greatest threat to the S22 bighorn subpopulation (CPW 2013). There is confirmed range overlap 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 (6 rams by FS personnel) and in 2013 (3 ewes by FS 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 towards 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 were unattended for approximately 5-10 days before being discovered and it is not known where the band wandered to or if the band separated into several groups before being rounded up.

In 2011, during a field reconnaissance trip involving FS and CPW 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

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 Miners Creek Allotment.

Domestic sheep have been documented in recent years (2012) grazing on the Gunnison Forest outside of the allotment boundary within close proximity of known bighorn sheep locations. In some years, stray sheep are reported in the 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 approximately 25 head total 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 FS personnel off of Highway 149 near lower Coller State Wildlife area in November. This sheep was never found again and ownership never determined.

Domestic sheep grazing north of trail 787 (Continental Divide Trail) just below Baldy Cinco, was documented by FS personnel in 2014. Not grazing north of the trail has been part of the Annual Operating Instructions and is a key PDC in Alternative 3. A domestic ewe and lamb were found in 2015 several days after the main herd trailed up the McKenzie Stock Driveway at the staging area near Miners Creek. Issues with salting, bedding ground use, herding and stray management have improved, but continue to be issues with the allotment.

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 Juans. 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, 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 1890. Federal surveyors noted 14 bighorn at the source of Boulder Creek in 1910. 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 in 1922-1923 (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 creation 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 it “has resulted entirely or primarily from translocated bighorns” (George et al. 2009).

Current Occurrence and Distribution This sub-herd has remained relatively stable over the past five 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. The herd overall, does not appear to be increasing substantially, and is in more of a maintenance mode. Bighorns subgroups are somewhat widely distributed throughout this unit, likely as a result of where transplants have been introduced over time (George et al. 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 interaction of bighorns 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, there have been CPW documented instances of individual sheep dying of pneumonia related 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 found that S-53 sheep are predominately found in two general locations, as reported by District Wildlife Manager Brent Woodward: 1) Bristol Head Peak and Long Ridge and 2) in the Box Canyon of the Rio Grande River and River Hill. The bighorn sheep on Bristol Head/Long Ridge area are found 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 found 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 2014

Specific Issues

The majority of the allotment acres are within the S53 herd boundary but the closest CHHR is S22. It is very likely that S53 bighorn interchange with the S33 (Pole Mountain) herd further west as FS 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 GMUs likely exerts influence over the other units in the DAU and potentially within other GMUs. The amount of interchange between bighorn between S22 and S53 has not been documented and is unknown. Photo: Ewes S-53 herd, fall of 2014.

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 S53 bighorn.

S-36 Bellows Creek Sub-Herd

Historical Occurrence and Distribution The S-36 herd is designated as part of the native San Luis Peak population (George et. al 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 1950’s. In 1969-1970, 3 rams were observed in the area but following unsuccessful search efforts in what is now GMU 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” (George et al. 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 1990’s. The population was reduced from an estimated high of 125 animals to a low of 30 by 2001. 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: S36 Ram, fall of 2014.

Based on recent population surveys, bighorn sheep appear more widely distributed in the unit compared to the late-1800s through the mid-1900s (Bear and Jones 1973). Transplanted bighorns may have contributed to the re-colonizing 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 noticeable level (Beecham et al. 2007). As with S-22, other factors likely are affecting herd numbers and distribution such as fragmentation of subgroups, human activities across the landscape, and habitat condition. Documenting the range of bighorns in RBS-22 is challenging given the rugged and often remote terrain bighorn sheep occupy throughout the year. Ground survey efforts by the United States Forest Service Divide Ranger District and Colorado

Parks and Wildlife provide minimal counts in accessible areas. Expensive helicopter surveys provide a GMU-wide perspective, but rarely occur more than once a year. Based on annual surveys and observations by District Wildlife Manager Brent Woodward, bighorn sheep generally have been found in the area from Mammoth Mountain south to the head of Blue Creek. Bighorn are routinely found 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 S36 is fall trailing and overnighting of domestic sheep, specifically in the Wagon Wheel Gap area. Bighorn are frequently found in Wagon Wheel Gap which is a very narrow area along Highway 149 approximately 4 miles southeast of Creede. Domestics 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. 9/18/2013.

Photo: S-36 Bighorn in Wagon Wheel Gap on the railroad track. 4/2015.

RISK OF CONTACT TOOL In response to a need for tools to assist with the analysis of risk of contact of 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).

Results from the Risk of Contact Tool provide a consistent framework by which various management scenarios can be compared. Tool 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 disease transmission to adjacent bighorn sheep herds.

The Risk of Contact Tool does not consider the potential mitigating effect that full implementation of project design criteria (Appendix 7) might have on the probability of contact between bighorn and domestic sheep. Project design criteria are expected to enhance the potential for effective separation, thereby reducing the risk of physical contact of foraying bighorn sheep with domestic sheep and the subsequent potential for disease transmission. However, there is uncertainty about the effectiveness of project design criteria and it is unknown how much, if any, reduction might be expected in the contact probabilities produced by the Risk of Contact Tool from full and complete implementation of all project design criteria.

The Risk of Contact Tool utilizes bighorn sheep Core Herd Home Range (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.

The CHHR used by the Risk of Contact Tool for the Snow Mesa Analysis was produced by representatives of both the Rio Grande National Forest and by Colorado Parks and Wildlife personnel based upon professional knowledge and verified sightings and surveys.

The summer source habitat model used by the Risk of Contact Tool was primarily developed and tested by Colorado Parks and Wildlife using their extensive State-wide bighorn sheep telemetry data set and found 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 bighorns 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 Core Herd Home Range (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 CHHR’s. 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 2013b). The default value for foray frequency is 14.1% for rams and 1.4% 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. Based on known bighorn sheep preferences for each of the three habitat classes, the model estimates the proportion of rams and ewes reaching each one 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).

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 proportion of radio-collared adult bighorns observed outside their CHHR during the summer grazing season.

The Risk of Contact Tool uses the inputs to conduct a bighorn foray analysis (USDA Forest Service 2013). 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 overlaps 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 by which a contact between bighorn sheep and domestic sheep in a permitted grazing allotment located outside a bighorn CHHR might occur can be broken down into a number of steps. 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 disease transmission to occur, the bighorn must (4) come into physical contact with a domestic sheep in the allotment; and (5) contract a disease from the domestic sheep. Finally, for a disease outbreak to affect the bighorn’s home herd, the infected bighorn must (6) return to their CHHR; and (7) transmit disease to other members of their home herd. For domestic sheep allotments that overlap portions of bighorn CHHR, steps 1-3 and 6 do not need to occur, thereby likely increasing the potential for a disease transmission event to occur, and also likely increasing the potential for a subsequent 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 within the CHHR.

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 NF 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 (RGNF), four bighorn sheep herds are still experiencing lingering effects (low lamb recruitment) of past disease events dating back to the mid 1990’s. 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). See Table 2.

A conservative recovery rate based off of past localized disease events involving RGNF bighorn herds can potentially be considered to be a minimum of 32 years between disease events and possible eventual recovery. However, the relationship between moderate and acceptable disease prevention is not known. Numerous occurrences of bighorn sheep herds experiencing a dramatic die-off followed by lengthy periods of poor lamb recruitment are documented in the literature (Foreyt 1990, Besser et. al 2012a and George et. al 2008).

Local information suggests that disease outbreaks of every 32 years or less would result in a bighorn sheep population that is being constantly exposed to ongoing disease transmission and resultant outbreaks. Initially, the population would most likely suffer an all age die-off followed by low lamb recruitment for an extended period of time. The herd may slowly start to rebuild by the end of the first two decades following the initial die-off but will soon (<32 years) experience another disease outbreak resulting in a cycle of dramatic die-offs followed by slow population rebuilding. The population would likely be extirpated as a result of consistent exposure to disease in time. A disease event occurring within a Rio Grande NF bighorn herd every 32 years or less would result in a High Risk to bighorn sheep long term viability and a Low Probability of Population Persistence and Viability as evidenced from several local herds.

This analysis utilizes recent disease transmission 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, S53 and S-36 and the Central San Juan’s Bighorn Herd as a whole. We assume a moderate probability that a contact will result in a disease transmission event. In this case, a moderate probability is defined as 0.25%, or 1 out of every four contacts. We believe that this is a conservative estimate given the recent literature published on this subject (Besser et. al. 2012a, 2012b and 2014).

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.

Table 2: Rocky Mountain Bighorn Sheep on the Rio Grande National Forest.

Herd Name/Unit Herd Forest Disease Status Size Huerfano S-8 65 Rio Grande-Conejos Peak No specific disease testing. Anecdotal Pike San Isabel information suggests historic disease influence but the herd appears to be doing well. Sangre de Cristo S-9 325 Rio Grande-Saguache Historic Pasteurella >20 years Pike San Isabel Trickle Mtn S-10 <40 Rio Grande-Saguache Disease Event and all age die off in the 1990’s. Pasteurella multicoda, BSRV, and P13 detected. Sheep Mountain S-15 200 Rio Grande -Divide No known disease or testing. San Juan San Luis Peak S-22 70 Rio Grande-Divide Pasteurella Potentially Present. Gunnison Alamosa Canyon S-29 35 Rio Grande-Conejos Peak Disease Event 1990s. Mycoplasma ovipneumoniae, Mannheimia haemolytics, leukotoxin, P13, BSRV. Conejos River (S-30) 75 Rio Grande-Conejos Peak Same as S-29. Lake Fork/Pole Mtn S-33 90 Rio Grande-Divide Historic Pasteurella >20 years Gunnison Bellows Creek (S-36) 45 Rio Grande-Divide Presumed pasteurella related outbreak and all-age dies off 1990’s. Bristol Head (S-53) 110 Rio Grande-Divide Pasteurella Potentially Present Carnero/Natural Arch S-55 20 Rio Grande-Divide/Saguache Same as S-36. Total 1,070 Source: Supplement to the Forest Plan Biological Evaluation and Conservation Assessment for Rocky Mtn Bighorn Sheep, Rio Grande National Forest, April 2009.

There are numerous strains of Pasteurella and other bacteria that 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 found 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 NF in the 1990’s 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 2014.

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 including 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.

These three rating factors are displayed in Table 14 and the reader can compare each allotment with each sub herd per alternative in Tables 6-13 based on these factors.

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 between domestic sheep and bighorn sheep 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 contact has not been observed, or a bighorn disease event has not been detected, does not imply a lower risk for such events happening in the future. For this reason, the allotment could still receive a rating of “High” risk.

A rating of “Moderate” risk indicates that physical contact between bighorn and domestic sheep may occur at some point in the future, but effective separation may be achieved and/or maintained for many years. The risk of physical contact between bighorn and domestic sheep, with the potential for a subsequent bighorn disease outbreak, is thought to be less than for allotments in the high risk category, but is still of concern. 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 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 or irregular in the future under the configuration of allotments and bighorn CHHR’s.

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.

Table 3: RATING FACTORS CONSIDERED HIGH MODERATE LOW # Years between bighorn sheep making contact < 8 Years 8-10 Years >10 Years with the allotment Disease Potential expressed in years. < 32 Years 32- 40 Years 40 + Years Distance from BHS CHHR, with adequate

These rating factors are based off of local information from bighorn herds on the Rio Grande NF 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. However, the relationship between moderate and acceptable disease prevention is not well known.

RISK OF CONTACT TOOL RESULTS

Table 4 displays the input values used in the Risk of Contact Tool for each bighorn herd in the Snow Mesa Landscape analysis. 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 was 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 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 was 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 NF (USDA Forest Service 2013). Values for total population size of bighorn herds in the Snow Mesa Landscape were provided by Colorado Parks and Wildlife (Ferrero and Diamond pers. comm.), 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 S-53 S-36 San Luis Peak Bristol Head Bellows Creek Annual Foray Probability (Rams): 0.141 (14.1%) 0.141 (14.1%) 0.141 (14.1%) Annual Foray Probability (Ewes): 0.015 (1.5%) 0.015 (1.5%) 0.015 (1.5%) Total Population Size 2013: 70 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-22 39 rams in S-53 16 rams in S-36 Number of Ewes: 45 ewes in S-22 71 ewes in S-53 29 ewes in S-36

Photo: Bighorn rams, S-36.

Photo: Bighorn ewe, S-36.

The Risk of Contact Tool produced similar output tables for each combination of allotments, bighorn herd, and the two action alternatives in the Snow Mesa Landscape, totaling six independent tables. 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.

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). Appendices 1 and 2 contain the full tables for Alternatives 2 and 3.

S-22 San Luis Peak Herd – Annual Contact Rates via Foray Alternative 2 Allotment Prb of Ram Prb of Single Single All Rams All Ewes Herd Contact Ewe Ram Ewe Contact Contact Rate Table 0.05551 0.03253 0.00782 0.00048 0.18786 0.02244 0.21031 (5.5%) (3.2%) (0.78%) (0.04%)

Prb of Ram Contact

Annual probability that once a ram in the S-22 population leaves it Core Herd Home Range 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. 0.05551 * 0.141 = .00782 (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.

Prb of Ewe Contact

Annual probability that once a ewe in the S-22 population leaves it Core Herd Home Range 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 its 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. 0.03252 * 0.015 = .00048 (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.

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 0.18786 per summer season. In other words, contact with the Table Allotment by a foraying ram is expected once every 5.3 years (1/0.18786).

All Ewes Contact Rate

This column displays the rate of contact with the Table Allotment for all ewess 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 0.02244 per summer season. In other words, contact with the Table Allotment by a foraying ewe is expected once every 45 years (1/0.02244).

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; 0.18786 + 0.02244 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 0.21031 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 every 4.8 years (1/0.21031).

Results for Individual Domestic Sheep Allotments

Table 6: Snow Mesa Allotment Risk of Contact Tool for Alternative 2.

Table 6 SNOW MESA ALLOTMENT RISK OF CONTACT - ALTERNATIVE 2 Snow Mesa Allotment S-22 S-53 S-36 Cumulative Annual Herd Contact Rate for all three San Luis Bristol Bellows BHS Herds Peak Head Creek Annual Herd Contact Rate 1.00 0.16218 0.069751 1.231931 Bighorn from this sub 1/1.0 = 1 1/0.16218 1/0.06975 = 1/1.23193 = 0.81; Contact with the allotment by bighorn herd are expected to = 6 14 sheep in RBS-22 can be expected approximately once contact this allotment every 0.81 years. every X years. Equates to a potential 1* 4 = 4. 6 * 4 = 24. 14 * 4 = 56. Based on modeled contact rates and an assumed disease transmission every Potentially Potentially Potentially moderate probability of disease transmission given X years on this allotment. every 4 every 24 every 56 contact (0.25 or 1 in every four contacts) a disease years. years years transmission event with potential for subsequent bighorn Distance from Bighorn Overlap 3.2 miles 10.4 miles mortality could occur once every 3.2 years (0.81*4=3.2). Core Herd Home Range This potential varies considerably from 4-56 years (CHHR) between bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP WITH BIGHORN SHEEP HABITAT Total Allotment Acres 4,365 Suitable Domestic Sheep Grazing Acres (% of Allotment) 3,764 (86%) Bighorn Summer Source Habitat Acres (% of Allotment) 3,619 (83%) Acres of Overlap between BHS/Domestic Sheep and percentage of overlap 3,394 or 90% (which represents 78% of the allotment)

Snow Mesa Allotment – Alternative 2

Snow Mesa is the smallest of the three active allotments (4,365 acres) and also contains 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.

S-22 San Luis Peak Bighorn Herd: 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 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.

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 suitable for domestic sheep grazing at 90%.  Separation between the allotment and the 3 herds consists of overlap for S22, 3.2 miles (S53) and 10.4 miles (S36).  Bighorn are expected to contact the allotment from the three sub herds at rates of every year for S22, every 6 years (S53) and every 14 years (S36).  A disease transmission with potential subsequent bighorn mortality could occur every 4 years in the S22 herd component, but cumulatively could occur every 3.2 years due to the influence from all 3 herds combined.

Tables 7: Snow Mesa Allotment Risk of Contact Tool for Alternative 3.

Table 7 SNOW MESA ALLOTMENT RISK OF CONTACT - ALTERNATIVE 3 Snow Mesa Allotment S-22 S-53 S-36 Cumulative Annual Herd Contact Rate for all three San Luis Bristol Bellows BHS Herds Peak Head Creek Annual Herd Contact Rate 0.29876 0.16218 0.05593 0.51698 Bighorn from this sub herd 1/ 0.29876= 1/0.16218 1/0.05593 = 1/0.51698 = 1.9; Contact with the allotment by bighorn are expected to contact this 3 = 6 18 sheep in RBS-22 can be expected approximately once allotment every X years. every 1.9 years. Equates to a potential 3* 4 = 12. 6 * 4 = 24. 18 * 4 = 72. Based on modeled contact rates and an assumed disease transmission every Potentially Potentially Potentially moderate probability of disease transmission given X years on this allotment. every 12 every 24 every 72 contact (0.25 or 1 in every four contacts) a disease years. years years transmission event with potential for subsequent bighorn Distance from Bighorn 0.5 miles 3.2 miles 10.4 miles mortality could occur once every 7.6 years (1.9*4 = 7.6). Core Herd Home Range This potential varies considerably from 12-72 years (CHHR) between bighorn herds. ALLOTMENT ACREAGE STATISTICS and OVERLAP WITH BIGHORN SHEEP HABITAT Total Allotment Acres 3,315 Suitable Domestic Sheep Grazing Acres (% of Allotment) 2,846 (86%) Bighorn Summer Source Habitat Acres (% of Allotment) 2,771 (84%) Acres of Overlap between BHS/Domestic Sheep and percentage of overlap 2,614 or 92% (which represents 79% of the allotment)

Snow Mesa Allotment – Alternative 3

Alternative 3 moves the northern boundary of the allotment away from the S-22 CHHR by 0.5 miles. 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.

S-22 San Luis Peak Bighorn Herd: 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.

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

36 expected contact potential to every 18 years equating to a disease transmission with potential for subsequent bighorn mortality to once every 72 years. Photo: Snow Mesa Allotment.

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 one 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 miles from the new boundary of the allotment.  There will be very little spatial (0.5 miles) or temporal separation between the two species.  The allotment will contain a large amount of overlap between bighorn habitat and acres suitable for domestic sheep grazing at 92%.  Separation between the allotment and the 3 herds consists of 0.5 miles for S22, 3.2 miles (S53) and 10.4 miles (S36).  Bighorn are expected to contact the allotment from the three sub herds at rates of every 3 years for S22, every 6 years (S53) and every 18 years (S36).  A disease transmission with potential subsequent bighorn mortality could occur every 12 years in the S22 herd component, but cumulatively could occur every 7.6 years due to the influence from all 3 herds combined.

Table 8: Table Allotment Risk of Contact Tool Comparison for Alternative 2.

Table 8 TABLE ALLOTMENT RISK OF CONTACT - ALTERNATIVE 2 Table Allotment S-22 S-53 S-36 Cumulative Annual Herd Contact Rate for all three San Luis Bristol Bellows BHS Herds Peak Head Creek Annual Herd Contact Rate 0.21031 0.21544 0.04837 0.47412 Bighorn from this sub 1/0.21031 = 1/0.21544 1/0.04837 = 1/47412 = 2.1; Contact with the allotment by bighorn herd are expected to 4.8 = 4.6 20.1 sheep in RBS-22 can be expected approximately once contact this allotment every 2.1 years. every X years. Equates to a potential 4.8* 4 = 19. 4.6 * 4 = 20 * 4 = 80. Based on modeled contact rates and an assumed disease transmission every Potentially 18. Potentially moderate probability of disease transmission given X years on this allotment. every 19 Potentially every 80 contact (0.25 or 1 in every four contacts) a disease years. every 18 years transmission event with potential for subsequent bighorn years mortality could occur once every 8.4 years (2.1*4=8.4). Distance from Bighorn 0.5 miles 1.86 miles 8 miles This potential varies considerably from 18-80 years Core Herd Home Range between bighorn herds. (CHHR) ALLOTMENT ACREAGE STATISTICS and OVERLAP WITH BIGHORN SHEEP HABITAT Total Allotment Acres 5,049 Suitable Domestic Sheep Grazing Acres (% of Allotment) 2,864 (57%) Bighorn Summer Source Habitat Acres (% of Allotment) 1,953 (39%) Acres of Overlap between BHS/Domestic Sheep and percentage of overlap 1,485 or 52% (which represents 29% of the allotment)

Table Allotment – Alternative 2

Table 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.

S-22 San Luis Peak Bighorn Herd: Under alternative 2, bighorn are separated from the allotment by 0.5 miles 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 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 approximately 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 two 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 miles) or temporal separation between the two species  The allotment contains a moderate amount of overlap between bighorn habitat and acres suitable for domestic sheep grazing at 52%.  Separation between the allotment and the 3 herds consists of 0.5 miles for S22, 1.86 miles (S53) and 8 miles (S36).  Bighorn are expected to contact the allotment from the three sub herds at rates of every 4.8 years for S22, every 4.6 years (S53) and every 20.1 years (S36).  A disease transmission with potential subsequent bighorn mortality could occur every 18 years in the S53 herd component, but cumulatively could occur every 8.4 years due to the influence from all 3 herds combined.

Photo: Hanging Basin, Table Allotment.

Tables 9: Table Allotment Risk of Contact Tool Comparison for Alternative 3.

Table 9 TABLE ALLOTMENT RISK OF CONTACT - ALTERNATIVE 3 Table Allotment S-22 S-53 S-36 Cumulative Annual Herd Contact Rate for all three San Luis Bristol Bellows BHS Herds Peak Head Creek Annual Herd Contact Rate 0.20964 0.21430 0.04784 0.47178 Bighorn from this sub 1/0.20964 1/ 0.21430 1/ 0.04784 1/ 0.47178 = 2.1; Contact with the allotment by herd are expected to = 4.8 = 4.7 = 21 bighorn sheep in RBS-22 can be expected contact this allotment approximately once every 2.1 years. every X years. Equates to a potential 4.8* 4 = 19. 4.7 * 4 = 21 * 4 = 84. Based on modeled contact rates and an assumed disease transmission every Potentially 19. Potentially moderate probability of disease transmission given X years on this allotment. every 19 Potentially every 84 years contact (0.25 or 1 in every four contacts) a disease years. every 19 transmission event with potential for subsequent years bighorn mortality could occur once every 8.4 years Distance from Bighorn 0.5 miles 1.86 miles 8 miles (2.1*4=8.4). This potential varies considerably from Core Herd Home Range 19-84 years between bighorn herds. (CHHR) ALLOTMENT ACREAGE STATISTICS and OVERLAP WITH BIGHORN SHEEP HABITAT Total Allotment Acres 5,043 Suitable Domestic Sheep Grazing Acres (% of Allotment) 2,858 (57%) Bighorn Summer Source Habitat Acres (% of Allotment) 1,947 (39%) Acres of Overlap between BHS/Domestic Sheep and percentage of overlap 1,479 or 52% (which represents 29% of the allotment.

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 miles. The allotment decreases by approximately 6 acres to 5,043 acres. The amount of overlap between bighorn sheep suitable summer habitat and acres suitable for domestic sheep grazing remains at 52% (1,479 acres) representing 29% of the total allotment.

S-22 San Luis Peak Bighorn Herd: Similarly to alternative 2, bighorn are separated from the allotment by 0.5 miles 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 two 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 miles) 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 52%.  Separation between the allotment and the 3 herds consists of 0.5 miles for S22, 1.86 miles (S53) and 8 miles (S36).  Bighorn are expected to contact the allotment from the three sub herds at rates of every 4.8 years for S22, every 4.7 years (S53) and every 21 years (S36).  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 3 herds combined.

Photo: Ram and Ewe, S-53.

Table 10: Miners Allotment Risk of Contact Tool Comparison for Alternative 2.

Table 10 MINERS ALLOTMENT RISK OF CONTACT - ALTERNATIVE 2 Miners Allotment S-22 S-53 S-36 Cumulative Annual Herd Contact Rate for all San Luis Bristol Bellows three BHS Herds Peak Head Creek Annual Herd Contact Rate 1.00 0.22696 0.10659 1.33355

Bighorn from this sub 1/1.0 = 1 1/0.22696 1/0.10659 = 1/1.33355 = 0.75; Contact with the allotment by herd are expected to = 4.4 9.4 bighorn sheep in RBS-22 can be expected contact this allotment approximately once every 0.75 years. every X years. Equates to a potential 1* 4 = 4. 4.4 * 4 = 9.4 * 4 = 38. Based on modeled contact rates and an assumed disease transmission every Potentially 18. Potentially moderate probability of disease transmission given X years on this allotment. every 4 Potentially every 38 years contact (0.25 or 1 in every four contacts) a disease years. every 18 transmission event with potential for subsequent years bighorn mortality could occur once every 3 years Distance from Bighorn Overlap 1.27 miles 3.71 miles (0.75*4 = 3). This potential varies considerably from Core Herd Home Range 4-38 years between bighorn herds. (CHHR) ALLOTMENT ACREAGE STATISTICS and OVERLAP WITH BIGHORN SHEEP HABITAT Total Allotment Acres 13,297 Suitable Domestic Sheep Grazing Acres (% of Allotment) 5,805(44%) Bighorn Summer Source Habitat Acres (% of Allotment) 7,659 (58%) Acres of Overlap between BHS/Domestic Sheep and percentage of overlap 3,863 or 67% (represents 29% of the allotment).

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 suitable for domestic sheep grazing at 67% (3,863 acres) which represents 29% of the total allotment.

S-22 San Luis Peak Bighorn Herd: 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.

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 suitable for domestic sheep grazing at 67%.  Separation between the allotment and the 3 herds consists of overlap for S22, 1.27 miles (S53) and 3.71 miles (S36).  Bighorn are expected to contact the allotment from the three sub herds at rates of every year for S22, every 4.4 years (S53) and every 9.4 years (S36).  A disease transmission with potential subsequent bighorn mortality could occur every 4 years in the S22 herd component, but cumulatively could occur every 3 years due to the influence from all 3 herds combined.

Table 11: Miners Allotment Risk of Contact Tool Comparison for Alternative 3.

Table 11 MINERS ALLOTMENT RISK OF CONTACT - ALTERNATIVE 3 Miners Allotment S-22 S-53 S-36 Cumulative Annual Herd Contact Rate for all San Luis Bristol Bellows three BHS Herds Peak Head Creek Annual Herd Contact Rate 0.37438 0.14809 0.07047 0.59295

Bighorn from this sub 1/0.37438 = 1/0.14809 1/ 0.07047 = 1/0.59295 = 1.7; Contact with the allotment by herd are expected to 2.7 = 6.8 14 bighorn sheep in RBS-22 can be expected contact this allotment approximately once every 1.7 years. every X years. Equates to a potential 2.7 * 4 = 11 6.8 * 4 = 14* 4 = 56 Based on modeled contact rates and an assumed disease transmission every Potentially 27 Potentially moderate probability of disease transmission given X years on this allotment. every 11 Potentially every 56 years contact (0.25 or 1 in every four contacts) a disease years. every 27 transmission event with potential for subsequent years bighorn mortality could occur once every 6.8 years Distance from Bighorn 0.5 miles 1.27 miles 3.71 miles (1.7*4= 6.8). This potential varies considerably from Core Herd Home Range 11-56 years between bighorn herds. (CHHR) ALLOTMENT ACREAGE STATISTICS and OVERLAP WITH BIGHORN SHEEP HABITAT Total Allotment Acres 7,147 Suitable Domestic Sheep Grazing Acres (% of Allotment) 3,360 (47%) Bighorn Summer Source Habitat Acres (% of Allotment) 3,675 (51%) Acres of Overlap between BHS/Domestic Sheep and percentage of overlap 1,983 or 59% (represents 28% of the allotment)

Miners Allotment – Alternative 3

Alternative 3 moves the northern boundary of the allotment away from the S-22 CHHR by 0.5 miles. This change decreases the size of the allotment to 7,147 acres. The amount of overlap between bighorn sheep suitable summer habitat and acres suitable for domestic sheep grazing decreases to 59% (1,983 acres) representing 28% of the total allotment.

S-22 San Luis Peak Bighorn Herd: 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 a disease transmission with potential subsequent bighorn mortality to once every 27 years in the S-53 sub herd. This decrease

44 is most likely due to the decrease in suitable bighorn sheep habitat on the north end of the allotment resulting from the boundary change.

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 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 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 one 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 approximately 0.5 miles from the new boundary of the allotment.  There will be very little spatial (0.5 miles) 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 3 herds consists of 0.5 miles for S22, 1.27 miles (S53) and 3.71 miles (S36).  Bighorn are expected to contact the allotment from the three sub herds at rates of every 2.7 years for S22, every 6.8 years (S53) and every 14 years (S36).  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 3 herds combined.

Table 12: Ouray Allotment Risk of Contact Tool Comparison for Alternative 2.

Table 12 OURAY ALLOTMENT RISK OF CONTACT - ALTERNATIVE 2 Ouray Allotment S-22 S-53 S-36 Cumulative Annual Herd Contact Rate for all San Luis Bristol Bellows three BHS Herds Peak Head Creek Annual Herd Contact Rate 0 0 0 0

Bighorn from this sub herd N/A N/A N/A N/A are expected to contact this allotment every X years. Equates to a potential N/A N/A N/A disease transmission every X years on this allotment. Distance from Bighorn Core N/A N/A N/A Herd Home Range (CHHR) ALLOTMENT ACREAGE STATISTICS and OVERLAP WITH BIGHORN SHEEP HABITAT Total Allotment Acres N/A Suitable Domestic Sheep Grazing Acres (% of Allotment) N/A Bighorn Summer Source Habitat Acres (% of Allotment) N/A Acres of Overlap between BHS/Domestic Sheep and percentage of overlap N/A

Ouray Allotment – Alternative 2

The Ouray Allotment is currently a vacant sheep allotment and is not considered as part of Alternative 2.

There are no issues involving bighorn sheep and domestic sheep grazing on the Ouray Allotment as part of Alternative 2.

The south western half of the vacant allotment is within the CHHR of the S-53 Bristol Head Bighorn Sheep Herd.

Photo: S-36 Rams, fall of 2014.

Table 13: Ouray Allotment Risk of Contact Tool Comparison for Alternative 3.

Table 13 OURAY ALLOTMENT RISK OF CONTACT - ALTERNATIVE 3 Ouray Allotment S-22 S-53 S-36 Cumulative Annual Herd Contact Rate for all San Luis Bristol Bellows three BHS Herds Peak Head Creek Annual Herd Contact Rate 0.16434 0.27395 0.07718 0.51548

Bighorn from this sub herd 1/0.16434 1/0.27395 1/0.07718 = 1/0.51548 = 1.9; Contact with the allotment by are expected to contact this = 6 = 3.7 13 bighorn sheep in RBS-22 can be expected allotment every X years. approximately once every 1.9 years. Equates to a potential 6 * 4 = 24 3.7 * 4 = 13 * 4 = Based on modeled contact rates and an assumed disease transmission every Potentially Potentially Potentially moderate probability of disease transmission given X years on this allotment. every 24 every 15 every 52 years contact (0.25 or 1 in every four contacts) a disease years. years transmission event with potential for subsequent Distance from Bighorn Core 3.3 miles .65 miles 4.7 miles bighorn mortality could occur once every 7.6 years Herd Home Range (CHHR) (1.9*4=7.6). This potential varies considerably from 15-52 years between bighorn herds.

ALLOTMENT ACREAGE STATISTICS and OVERLAP WITH BIGHORN SHEEP HABITAT Total Allotment Acres 6,836 Suitable Domestic Sheep Grazing Acres (% of Allotment) 2,914 (43%) Bighorn Summer Source Habitat Acres (% of Allotment) 1,087 (16%) Acres of Overlap between BHS/Domestic Sheep and percentage of overlap 1,087 or 37% (represents 16% of the allotment)

Ouray Allotment – Alternative 3

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 acres of the Ouray Allotment incorporated into Alternative 3 is 6,836 acres. The amount of overlap between bighorn sheep suitable summer habitat and acres suitable for domestic sheep grazing is 37% (1,087) representing 16% of the total allotment.

S-22 San Luis Peak Bighorn Herd: S-22 bighorn 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 .65 miles 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.

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 two 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 as follows:

 There is no direct overlap between the allotment and bighorn sheep CHHR.  There will be very little spatial (0.65 miles) or temporal separation between the two species.  The Ouray allotment will contain a low-moderate amount of overlap between bighorn habitat and acres suitable for domestic sheep grazing at 37%.  Separation between the allotment and the 3 herds consists of 3.3 miles for S22, 0.65 miles (S53) and 4.7 miles (S36).  Bighorn are expected to contact the allotment from the three sub herds at rates of every 6 years for S22, every 3.7 years (S53) and every 13 years (S36).  A disease transmission with potential subsequent bighorn mortality could occur every 15 years in the S-53 herd, but cumulatively for all three bighorn herds could occur every 7.6 years due to the influence from all 3 herds combined.

SUMMARY

Table 14. Risk of Contact Tool Predicted number years for a contact, potential for subsequent disease following contact based off of a moderate rate of four contacts (.25), distance from BHS CHHR and Risk Rating for each allotment per Bighorn Herd for each alternative. Cumulative for all three sub herds.

Allotment Alternative Alternative Alternative 1 2 3 Snow Mesa # Years between bighorn sheep making N/A 0.81 1.9 contact with the allotment Disease Potential expressed in years 0 3.2 7.6 Distance from BHS Core Herd Home N/A Overlap 0.5 miles Range Risk Rating (High, Medium, Low) Low High High Table # Years between bighorn sheep making N/A 2.1 2.1 contact with the allotment Disease Potential expressed in years 0 8.2 8.4 Distance from BHS Core Herd Home N/A 0.5 miles 0.5 miles Range Risk Rating (High, Medium, Low) Low High High Miners # Years between bighorn sheep making N/A 0.75 1.7 contact with the allotment Disease Potential expressed in years 0 3.0 6.8 Distance from BHS Core Herd Home N/A Overlap 0.5 miles Range Risk Rating (High, Medium, Low) Low High High Ouray # Years between bighorn sheep making N/A N/A 1.9 contact with the allotment Disease Potential expressed in years 0 0 7.6 Distance from BHS Core Herd Home N/A N/A 0.65 miles Range Risk Rating (High, Medium, Low) Low Low High

Alternative 2 Alternative 3 Snow Mesa More than one contact every year; Disease Contact every 1.9 years; Disease potential every potential every 3.2 years; Overlap. 7.6 years; 0.5 mile separation. Table Contact every 2.1 years; Disease potential every Contact every 2.1 years; Disease potential every 8.2 years; 0.5 mile separation. 8.4 years; 0.5 mile separation. Miners More than one contact every year; Disease Contact every 1.7 years; Disease potential every potential every 3 years; Overlap. 6.8 years; 0.5 mile separation. Ouray N/A Contact every 1.9 years; Disease potential every 7.6 years; 0.65 mile separation.

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. Photo: Domestic sheep leaving the allotments in mid-September 2014.

Overall, under Alternative 2, the Snow Mesa and Miners Allotments present the highest potential for physical contact due to overlap with domestic sheep grazing and the S-22 bighorn herd’s CHHR. Allotment boundary modification under Alternative 3 doubles the number of years between bighorn contact with the allotments and the potential for subsequent disease potential but contact rates and the disease potential expressed in years remains high. See Table 14.

The third allotment, Table Allotment, has 0.5 miles of separation from the S-22 CHHR for both alternatives with similar contact rates and disease potential expressed in years. These rates are comparable high.

The Ouray Allotment is not considered as part of Alternative 2. As part of Alternative 3, the boundary change will result in moving domestic sheep grazing within 0.65 miles of the S-53 CHHR. This grazing shift results in a high level of risk of physical contact and subsequent disease potential with the S-53 herd.

All three allotments considered under Alternative 2 and all four allotments in Alternative 3 have a high risk rating. There is no single allotment 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.

-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 (Current Conditions) 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 (Continued Grazing with Boundary Modification) provides for a lower amount of risk of physical contact than Alternative 2, but 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.

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 models assumptions, especially those related to foraying rates and distances. In contrast to the Payette National Forest’s Hells Canyon, 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 how the Risk of Contact Tool predictions for bighorn contact with an allotment might relate to actual physical contact between individual 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 sub herd 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 1990’s reduced the population from an estimated 125 down to a low of 30 by 2001. 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. In this herd instance, it has taken over 20 years for the herd to slowly recover helping to support 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 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 die off. Poor lamb survival in S-22 and S-53 is an

52 indication that a less deadly strain is present which results in lamb mortality but not adult mortality. 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 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-53.

-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 grazing season, 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 full and complete 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

53 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 Appendix 7.

-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 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 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 on and outside 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 which 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

54 these goats, potentially introducing disease to the herd and thereby affecting bighorn populations in the landscape.

-There is uncertainty regarding the connectiveness of the individual sub herds within RBS-22 itself and other bighorn herds. The individual sub herds within RBS-22 are combined as 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 movement more 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. Photo: Domestic sheep in the hanging valley within the Table Allotment. Continental Divide and S-22 CHHR in the background.

LITERATURE CITED

Bear. G.D. and G.W. Jones, 1973. History and distribution of bighorn sheep in Colorado. Colorado Parks and Wildlife Research Report. 232 pp.

Beecham, J.J., C.P. Collins, and T.D. Reynolds 2007. Rocky Mountain bighorn sheep (Ovis Canadensis): a technical conservation assessment. USDA Forest Service, Rocky Mountain Region.

Besser et al. 2012a. Survival of Bighorn Sheep (Ovis Canadensis) Commingled with Domestic Sheep (Ovis aries) in the Absence of Mycoplasma ovipneumoniae. Journal of Wildlife Diseases 48(1), 2012, pp. 168-172.

Besser et. al. 2012b. Causes of pneumonia epizootics among Bighorn Sheep, Western United States, 2008-2010. Emerging Infectious Diseases. Vol. 18, No. 3, March 2012.

Besser et. Al. 2014. Epizootic Pneumonia of Bighorn Sheep following Experimental Exposure to Mycoplasma ovipneumoniae. PLos IBE 9(10):e110039. Doi:10:1371/journal.pone.0110039.

Cassirer. E., R.K. Plowright, K.R. Manlove, P.C. Cross, A.P. Dobson, K.A. Potter, and P.J. Hudson. 2013. Spatio – temporal dynamics of pneumonia in bighorn sheep. Journal of Animal Ecology 82:518- 528.

Colorado Parks and Wildlife. 2013. Bighorn Sheep Management Plan for RBS-22, Central San Juan Bighorn Sheep Herd (Data Analysis Unit 22 and Game Management Units S22, S36, S52 and S53.

Ferrero and Diamond. 2013. Personal Communication. Colorado Parks and Wildlife.

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. 92-101.

George, J. L., D.J. Martin, P.M. Lukacs and M.W. Miller. 2008. Epidemic Pasteurellosis in a Bighorn Sheep Population Coinciding with the Appearance of a Domestic Sheep. Journal of Wildlife Diseases. 44:388-403

George, J. L., R. Kahn, M.W. Miller, and B. Watkins. 2009. Colorado Bighorn Sheep Management Plan 2009 – 2019. Colorado Division of Wildlife Special Report. 88 pp.

Martin, K.D., T.J. Schommer, and V.L. Coggins. 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 10:72-77.

Schommer, T., and M. Woolever. 2001. A process for finding management solutions to the incompatibility between domestic and bighorn sheep. USDA Forest Service, Washington, DC. 62 pp.

USDA Forest Service. 2007. Forest Service Manual 2600: Chapter 2670, Threatened, Endangered and Sensitive Plants and Animals, Supplement Number 2600-2007-1, June 8, 2007.

USDA Forest Service. 2010a. Supplemental to the Forest Plan Biological Evaluation and Conservation Assessment for the Rocky Mountain Bighorn Sheep. Rio Grande National Forest.

USDA Forest Service. 2011a. USDA Forest Service, Bighorn Sheep Analysis for NEPA Documents letter R-1, 2, 3, 4, 5 and 6. Joel D. Holtrop, Deputy Chief, Washington Office, Washington D.C. (August).

USDA Forest Service. 2011b. USDA Forest Service, Bighorn Sheep Analysis for NEPA Documents letter, Glenn Casamassa, Action Deputy Regional Forester, Rocky Mountain Region, Denver, CO. (September).

USDA Forest Service. 2013. Bighorn Sheep Risk of Contact Model. USDA Forest Service, Intermountain Region. Prepared by USDA FS Bighorn Sheep Working Group and Critigen.

Wild Sheep Working Group, 2012. Recommendations for Domestic Sheep and Goat Management in Wild Sheep Habitat. Western Association of Fish and Wildlife Agencies.

APPENDIX 1: 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.

ALTERNATIVE 2 (Current Boundary)

S-22 San Luis Peak Herd – Annual Contact Rates via Foray Alternative 2 Allotment Prb of Prb of Single Single All Rams All Ewes Herd Ram Ewe Ram Ewe Contact Contact Contact Rate Snow This allotment intersects the CHHR polygon and is therefore not included in the Mesa analysis. Herd Contact Rate is 1.0. Table 0.055516 0.032530 0.007827 0.000487 0.187868 0.022445 0.210314 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 Prb of Prb of Single Single All Rams All Ewes Herd Ram Ewe Ram Ewe Contact Contact Contact Rate Snow 0.028394 0.009299 0.004003 0.000139 0.152136 0.010043 0.162180 Mesa Table 0.03632 0.019257 0.005122 0.000288 0.194645 0.020798 0.215443 Miners 0.03983 0.012549 0.005616 0.000188 0.213409 0.013553 0.226962

S-36 Bellows Creek Herd – Annual Contact Rates via Foray Alternative 2 Allotment Prb of Prb of Single Single All Rams All Ewes Herd Ram Ewe Ram Ewe Contact Contact Contact Rate Snow 0.028988 0.010009 0.004087 0.000150 0.065397 0.004353 0.069751 Mesa Table 0.020247 0.006187 0.002854 0.000093 0.045678 0.002693 0.048372 Miners 0.045154 0.010873 0.006366 0.000163 0.101868 0.004729 0.106598

APPENDIX 2: 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.

Alternative 3 (Modify Boundary)

S-22 San Luis Peak Herd – Annual Contact Rates via Foray Alternative 3 Allotment Prb of Prb of Single Single All Rams All Ewes Herd Ram Ewe Ram Ewe Contact Contact Contact Rate Snow 0.075647 0.0619868 0.010666 0.0009298 0.2559921 0.042770 0.298763 Mesa Table 0.055343 0.0324075 0.007803 0.0004861 0.1872837 0.022361 0.209644 Miners 0.097351 0.0651398 0.013726 0.0009770 0.3294384 0.044946 0.374384 Ouray 0.044260 0.0211083 0.006240 0.0003166 0.1497785 0.014564 0.164343

S-53 Bristol Herd – Alternative 3 Annual Contact Rates via Foray Allotment Prb of Prb of Single Single All Rams All Ewes Herd Ram Ewe Ram Ewe Contact Contact Contact Rate Snow 0.028394 0.009299 0.004003 0.000139 0.152136 0.010043 0.162180 Mesa Table 0.036135 0.019155 0.005095 0.000287 0.193615 0.010043 0.214303 Miners 0.025110 0.012549 0.003540 0.0001882 0.134540 0.013553 0.148093 Ouray 0.045379 0.028527 0.006398 0.0004279 0.243144 0.03081 0.273954

S-36 Bellows Creek Herd – Annual Contact Rates via Foray Alternative 3 Allotment Prb of Prb of Single Single All Rams All Ewes Herd Ram Ewe Ram Ewe Contact Contact Contact Rate Snow 0.023244 0.008025 0.003277 0.000120 0.052438 0.000349 0.055930 Mesa Table 0.020025 0.006124 0.002823 0.000091 0.045176 0.002664 0.047840 Miners 0.029853 0.007188 0.004209 0.000107 0.067348 0.003127 0.070475 Ouray 0.032972 0.006431 0.004649 0.000096 0.074386 0.002797 0.077184

APPENDIX 3: RAM FORAY PROBABILITY MAPS OF EACH SUB HERD for ALTERNATIVE 2.

The illustration below proved a display produced by the Risk of Contact Tool that illustrates individual bighorn ram CHHR for each of the 3-subherds, distribution of summer source habitat, domestic sheep allotments under Alternative 2 and estimated rates of ram contact extending out from the CHHRs. Blue being that area with the highest foray probability with yellow being the lowest.

APPENDIX 4: RAM FORAY PROBABILITY MAPS OF ALL THREE SUB HERDS 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 3-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 being that area with the highest foray probability with yellow being the lowest.

APPENDIX 5: RAM FORAY PROBABILITY MAPS OF EACH SUB HERD 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 3-subherds, distribution of summer source habitat, domestic sheep allotments under Alternative 3 and estimated rates of ram contact extending out from the CHHRs. Blue being that area with the highest foray probability with yellow being the lowest.

APPENDIX 6: RAM FORAY PROBABILITY MAPS OF ALL THREE SUB HERDS 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 3-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 being that area with the highest foray probability with yellow being the lowest.

Alternative

APPENDIX 7 - Project Design Criteria 1 2 3

HERDING, HERD ACCOUNTABILITY (STRAY MANAGEMENT) AND DOMESTIC SHEEP TRAILING  Random on-site compliance monitoring of these project design criteria will be conducted by the N/A   Forest Service.

 At least one herder is required to be with the sheep. The main flock will never be left unattended, except at night and short periods when the herder is within sight distance of the herd accomplishing other tasks in the immediate area. A herder must remain in the camp during the night.  It is the permittees responsibility to describe the allotment boundaries to their herders. Sheep will not be herded or allowed to graze north of trails 787 and 803 (Continental Divide Trail and Miners Creek) or south of FDR 532 (Crystal Lakes Road). Some initial difficulties with herd management can be expected due to domestic sheep learned grazing pattern habits and utilization.  Permittees will notify the FS of the exact day and approximate time when domestic sheep are entering and trailing off the allotment (i.e. at the Shallow/Miners Creek staging area leading to the McKenzie Stock Driveway). A count-on/count off inventory will be required as a condition of operation and will be completed jointly by FS personnel and the permittees.  Extensive efforts will be made by the permittees to remove every authorized domestic sheep from the allotments following the grazing season. All sheep must be accounted for (dead or alive) as they enter and exit the allotments at the end of the season. Special attention should be given to accounting for domestic sheep at all times. If sheep are unaccounted for, diligent efforts will be made to locate them as quickly as possible.  Permittees will be required to respond to reports of stray domestic sheep within 24 hours. The Snow Mesa domestic sheep are the only permitted domestic sheep trailing from Creede to South Fork; it is assumed that all reported strays belong to the permittees. A full report (verbal or written) will be provided to the Forest Service on time, date and action taken to resolve the matter; within 4 days of stray notification.  When trailing domestic sheep on/off the McKenzie stock driveway or on main pasture moves, the permittees/herders will make a sweep over the route traveled to locate any strays that may have been left behind. This pass will be conducted between 1 and 3 days after the move occurred. Domestic sheep will be kept in a tight group during trailing on and off the allotment with a minimum of two herders. The main area of concern is from the Crystal Lake Basin to Shallow/Miners Creeks.  Tight grouping while trailing through the Wagon Wheel Gap area from the Pool Table road to Blue Creek is recommended to prevent contact with bighorn in S36. It is preferred that domestic sheep do not overnight in the Wagon Wheel Gap area.

ADDITIONAL PROJECT DESIGN CRITERIA RELATED TO DOMESTIC SHEEP AND BIGHORN  Any bighorn sheep having the potential to come in contact with domestic sheep will be hazed by the N/A   herders to prevent contact from occurring. Special emphasis will be taken on the northern and southern most boundaries of the allotments and while in the Wagon Wheel Gap area.  The permittees will contact the Ranger District range personnel as soon as possible if bighorn sheep come into contact with domestic sheep. The Forest Service will then inform Colorado Parks and Wildlife.  Sick bighorn sheep or carcasses must be reported immediately to the district office.  A protocol specific to these allotments will be developed between the FS, Colorado Parks and Wildlife and the permittees in the instance of pending or confirmed contact between bighorn and domestics.

Alternative

APPENDIX 7 - Project Design Criteria 1 2 3

SALTING

 Every effort will be made to prevent bighorn access to the domestic sheep salting locations. N/A   Leaving available salt or excess salt residue in the soil or on rocks or tubs presents a salt source that may attract bighorn and may even train bighorn to follow domestic sheep bands in search of salt.  It is preferred that only block salt be used. If salt blocks are used, they must be kept with the domestic sheep at all times. Salt blocks will not be left behind when the domestic sheep are moved. If loose salt is used, it will be kept in a container and kept with the domestics at all times.  See Heritage Resources in this same table for additional salting information.  Salt blocks and loose salt in containers will be placed on rocky knolls, well-drained sites, or in timber where excessive trampling will not destroy plant growth. Salt or supplement will not be placed closer than ¼ mile to designated trails, streams, springs, water developments, or other wetlands without prior approval of the Forest office. HERDER EDUCATION  It is of utmost importance that the permittees spend as much time as necessary teaching the N/A   herders the requirements attached to the grazing permit, AOI, and all of the applicable project design criteria included here. Annual operating instructions and Project Design Criteria will be provided in English and in Spanish concerning proper management practices, so that this information can be passed on to Spanish-speaking herders (if applicable). Ultimately, it is the permittees responsibility to ensure compliance is being achieved. PERMITTEE MONITORING  Permittees are responsible for monitoring the following: livestock numbers; pasture entry and exit N/A   dates; and allotment entry and exit dates. This information will be kept in written format and will be made available to the Forest Officer upon request. The Forest Officer may provide a reporting form for the permittee’s use and may specify a due date for its return to the Ranger District Office. LIVESTOCK GRAZING MANAGEMENT AND HERDING DOG  Livestock will be herded and distributed across the allotment in order to achieve proper grazing N/A   utilization of key forage species.  Livestock grazing will be managed in riparian areas and willow carrs (a wetland willow thicket) to maintain or achieve mid-seral or higher condition to provide cover and forage for prey species within Canada lynx habitat (Ruediger et al. 2000).  Livestock protection dogs (LPD’s) and herding dogs are used at the discretion of the livestock owner under appropriate state and county laws and regulations.  The Forest Service will post signs at trailheads (where practical) giving public notice of the presence of LPD’s and working dogs in the analysis area.

SHEEP BEDDING  Sheep will be on new bed grounds every night and moved to fresh feed daily in accordance with the N/A   grazing schedule.

 Sheep will be bedded no closer than 100 feet from the herder’s camp.

 Sheep bedding will not be allowed within 300 yards of any running stream, spring, lake, or designated trails. There may be some exceptions due to topography on the allotment, but these will be approved in advance by the Forest Officer.

Alternative

APPENDIX 7 - Project Design Criteria 1 2 3

HERDER CAMPS  Sheep herder camps will be moved every 5 to 10 days and regularly rotated on an annual basis. By N/A   changing camps each year, bed grounds will be used only once every several years.  Camps will be placed at least 200 feet from live water.  Camps will be kept clean and garbage packed out.  Camps will be placed at least 200 feet from designated trails.  Sheepherders will not be allowed to excavate campsites.  All fires built for any purpose by the permittee and/or herder will not be left unattended and will be completely extinguished. Each camp must be equipped with a serviceable shovel and axe. Other restrictions may be required during periods when the Forest enacts “fire restrictions”. Those restrictions will be identified in the particular “fire restriction order”. DISPOSAL OF DEAD LIVESTOCK  Death by Illness or Unknown Causes. When permitted sheep die from disease, or any other cause, N/A   the carcass must be moved to a location greater than 200 feet from water, out of view of trails, and away from any areas of significant public use, and away from herder camps, within 24 hours of discovery or notification by Forest Service personnel. SOILS AND WETLANDS  Minimize livestock concentrations on sensitive soils, wetlands and riparian areas through herding, N/A   and salt or supplement placement. ANIMAL DAMAGE CONTROL  Animal damage management activities will be conducted in accordance with both Federal N/A   regulations and state law. Requests for assistance will be done in compliance with the current Animal and Plant Health Inspection Service Animal Damage Management Plan.  Predator control (i.e., black bears, mountain lions, bobcats and coyotes) will be conducted following the correct state, Wildlife Services, and Forest Service procedures.

NOXIOUS PLANTS/INVASIVE SPECIES  Any hay, straw, or other feeds used on the allotment will be either certified as being free of noxious N/A   plants (also called noxious weeds), or will consist of heat-treated pelletized feeds.

 Permittees will make every effort to ensure that livestock do not contribute to the transport of noxious plants onto the allotment(s). ACCESS AND TRAVEL MANAGEMENT  Some travel-ways are closed to vehicular use or have restricted seasons. Permittees are required N/A   to abide by all Forest road and trail restrictions and closures. Written approval from the district ranger is required prior to driving off road.

HERITAGE RESOURCES

Alternative

APPENDIX 7 - Project Design Criteria 1 2 3

 Range managers and archaeologists will work with the permittee(s) and the herders to move sheep N/A   and camps away from 5ML302, 5Ml303, and 5ML662. Sites 5ML302, 5ML303, 5ML662, 5ML663, 5ML664, 5ML679, 5ML680 and 5ML684.1 will be monitored every five years for grazing and recreation impacts.  Salt locations should be moved on a continual basis and located in areas of low site potential and far from significant heritage resources. Range managers will coordinate with archaeologists to select the most optimal locations for the protection of unidentified cultural resources. To mitigate the effects of erosion stemming from livestock grazing on unidentified and potentially significant cultural resources, Forest Service range personnel must report substantial erosion to the Heritage Program Manager.  To mitigate the effects of erosion stemming from livestock grazing on unidentified and potentially significant cultural resources, Forest Service range personnel must report substantial erosion to the Heritage Program Manager.  If any new actions are planned, such as spring developments, water haul sites or new fence or if grazing patterns change or livestock numbers increase, additional cultural resource assessment is required to determine if additional survey is needed prior to implementation.  All persons associated with operations under this authorization must be informed that any objects or sites of cultural, paleontological, or scientific value such as historic or prehistoric resources, graves or grave markers, human remains, ruins, cabins, rock art, fossils, or artifacts shall not be damaged, destroyed, removed, moved, or disturbed. If in connection with operations under this authorization any of the above resources are encountered, the proponent shall immediately suspend all activities in the immediate vicinity of the discovery that might further disturb such materials and notify the Rio Grande National Forest authorized officer of the findings. The discovery must be protected until notified in writing to proceed by the authorized officer (36 CFR 800.110 & 112, 43 CFR 10.4).

APPENDIX 8: RISK ASSESSMENT PROCESS – FOUR STEP OUTLINE

Factors Considered in the Risk Assessment Process - August 19, 2011 Washington Office National Direction on addressing potential implications of disease transmission from domestic sheep/goats to bighorn sheep. (USDA Forest Service 2011a).

“The relationship between bighorn sheep population viability and domestic sheep grazing on National Forest System lands continue to be an important wildlife and range management issue facing the Forest Service on western rangelands. Where management objectives include maintenance or enhancement of bighorn sheep populations, the potential for disease transmission from domestic sheep/goats to bighorn sheep must be addressed. To meet these objectives, forests must conduct a bighorn sheep risk assessment. Our viability analyses should be based upon current scientific information and coordination with States taking into consideration state wildlife plans.” (USDA Forest Service 2011a).

The following 4-step outline (Bighorn Sheep Analysis for NEPA Documents 2011) for conducting an analysis for bighorn sheep viability was used to assist in helping to determine qualitative risk between domestic sheep and bighorn on the Snow Mesa Allotments.

1. Gather applicable data and information from appropriate sources.

 In all NEPA analysis regarding bighorn sheep viability, coordinate with state fish and game agencies and consider state wildlife management plans for bighorn sheep.

 Identify seasonal bighorn sheep occupied habitats (to infer Core Herd Home Range areas).

 Completed – The CHHR used by the Risk of Contact Tool for the Snow Mesa Analysis was produced by representatives of both the Rio Grande NF and by Colorado Parks and Wildlife personnel based upon professional knowledge and verified sightings and surveys.

 Completed - Coordination with CPW Terrestrial Biologists and District Wildlife Managers has occurred throughout the risk analysis process. Both the Colorado Bighorn Sheep Management Plan (George et al 2009) and the Final Bighorn Sheep Management Plan for the Central San Juan’s Bighorn Sheep Herd (RBS-22) were reviewed and considered for this analysis.

 Consider objectives for critical/core and non-critical/core herds.

 Completed - Based on the Final Bighorn Sheep Management Plan, the Central San Juan Herd is identified as a Tier 2, secondary 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 comprised of one or more interconnected herds that are native or have resulted from translocations. (George et. al. 2009). RBS-22 encompassed native bighorn 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).

2. Assess spatial and temporal overlap of bighorn sheep core herd home ranges with domestic sheep allotments, use areas, and driveways using, but not limited to:

 Maps showing suitable (occupied and unoccupied) bighorn sheep habitat (including suitable source bighorn sheep summer habitat).

 Maps showing habitat connectivity between bighorn sheep Core Herd Home Ranges and domestic sheep allotments, use areas, and driveways (if information is available).

 Distances between bighorn sheep Core Herd Home Ranges and domestic sheep allotments, use areas and driveways (if information is available).

 Completed – Based on the Model, all areas surrounding the CHHR were assigned to one of three habitat classes – source (suitable) habitat, connectivity areas and non-habitat. The criteria for source habitats include factors such as escape terrain, horizontal visibility, water sources, lambing areas, and summer range. 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 those criteria and are located more than 350 meters from source habitat. All habitat areas can be quantified within a radius consisting of one-kilometer bands surrounding the CHHR.

 The proportion of rams/ewes within the bighorn sheep population that foray (travel) outside of the CHHR and the distances they foray.

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 and back to its herd’s CHHR. This life-history trait can put bighorn sheep at risk of contact with domestic sheep, particularly when source habitats are well connected and overlap with domestic sheep use areas, even when domestic sheep use is outside of CHHR areas.

 Completed – Because foray information is lacking for bighorn sheep herds on the Rio Grande NF, this analysis uses the default value in the Risk of Contact Model. This default value is 14.1% for rams and 1.4% for ewes, indicating that any given ram and ewe has a 14.1% and 1.5%, respectively, of making a foray during the summer season outside of the CHHR. Based on known bighorn sheep preferences for each of the three habitat classes, the model estimates the proportion of rams and ewes reaching each one kilometer band outside of the CHHR. The model estimates this proportion out to 35 kilometers (21 miles) which incorporated the extent of most forays throughout the western United States. This risk of contact between dispersing bighorn sheep and domestic sheep is related to the number of bighorn sheep in a herd (particularly rams), proximity of domestic sheep allotments to a bighorn sheep CHHR, distribution of bighorn sheep

suitable source habitat across the landscape, and frequency and distance in 1 km bands of bighorn sheep forays outside of the CHHR (USDA Forest Service, Risk of Contact Model).

Four separate Game Management Units or subpopulations make up the Central San Juan’s Bighorn Herd. The four sub populations consist of S-22 (San Luis Peak), S-53 (Bristol Head), S-36 (Bellows Creek) and S-52 (Rock Creek). Of these sub populations, S-22 is within the boundary of the Snow Mesa and Miners Creek Allotments. A disease event originating in S-22, could then spread throughout the entire Central San Juan’s Herd due to the interconnecting habitat among the four sub populations.

The number of bighorn in the Central San Juan’s Herd is estimated at 250 individuals (Colorado Parks and Wildlife 2013). Because herd sex ratio information is lacking for bighorn sheep herds on the Rio Grande NF, this analysis uses the default value of 35:65 for rams and ewes as built into the Risk of Contact Model. Based on this information, the Model then estimates the probability and rate of contact to the allotments. The results of this analysis for the Snow Mesa Allotments on an allotment and sub population basis are displayed within the Assessment of Risk of Physical Contact between Rocky Mountain Bighorn Sheep and Domestic Sheep in the Snow Mesa Sheep Allotment Grazing Landscape document.

3. Assess likelihood and rate of contact based on spatial and temporal overlap between allotments and bighorn sheep herds.

 Completed - Likelihood of Contact

The Risk of Contact Model provides the probability that forays will intersect a given allotment and the total annual rate of contact to the allotment. 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 pose a higher likelihood of BHS contracting respiratory disease from domestic sheep, returning to the CHHR and initiating a disease outbreak in the CHHR. The Model represents the best available science regarding potential disease transmission and resultant long-term viability of bighorn sheep herds. Interpretation of the model is based on a range of probabilities of effective contact (i.e. a contact resulting in a disease transmission), and a subsequent herd-level outbreak, given cohabitation of bighorn sheep and domestic sheep in an open allotment.

On the RGNF, four herds are still experiencing lingering effects (low lamb recruitment) of past disease events dating back to the mid 1990’s. Of the four herds, only one is demonstrating slight recovery from dramatic die-off-nearly 20 years ago (S-36 Bellows Creek). The other three herds are stagnant or continue to decline in numbers reaching the point that herd persistence is unlikely (<30 animals). Numerous occurrences of bighorn sheep herds experiencing a dramatic die-off followed by lengthy periods of poor lamb recruitment are documented in the literature (Foreyt 1990, Besser et. al 2012a and George et. al 2008).

Local information suggests that disease outbreaks of every 32 years or less would result in a bighorn sheep population that is constantly being exposed to ongoing disease transmission and resultant outbreaks. Initially, the population would most likely suffer an all age die-off followed by low lamb recruitment for an extended period of time. The herd may slowly start to rebuild by the end of the first two decades following the initial die-off but will soon (<32 years) experience another disease outbreak resulting in a cycle of dramatic die-offs followed by slow population rebuilding. The population would likely be extirpated as a result of consistent exposure to disease in time. A disease event occurring within a Rio Grande NF bighorn herd every 32 years or less would result in a High Risk to bighorn sheep long term viability and a Low Probability of Population Persistence and Viability as evidenced from several local herds.

4. Identify management practices with the goal of separation between domestic and bighorn sheep where necessary to provide for Forest-wide bighorn sheep viability.

In this instance, implementing effective management practices with the goal of separating domestic and bighorn sheep is unlikely. Bighorn (CHHR) and domestic sheep (Snow Mesa and Miners Allotments) currently overlap both spatially and temporally. Source (suitable) bighorn habitat within the allotments is well connected.

This analysis utilizes recent disease transmission 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 Central San Juan’s Herd as a whole. For this analysis, we assume a moderate probability that a contact will result in a disease transmission event. In this case, a moderate probability is defined as 0.25%, or 1 out of every four contacts. We believe that this is a conservative estimate given the recent literature published on this subject (Besser et. al. 2012a and b). Based on these assumptions, the disease intervals for the allotments could range from approximately 3 years to 8.4 years (Table 14 Risk Assessment Document). Bighorn sheep on the allotments as a whole are expected to be continually exposed to potential disease transmission risk.

Effectiveness of management practices designed to reduce risk of association are not proven and should not be solely relied upon to achieve effective separation, particularly for high risk situations in which direct overlap between domestic and bighorn sheep is occurring.

“Where viability assessments indicate a high likelihood of disease transmission and a resulting risk to bighorn sheep population viability across the forest, the goal of spatial and/or temporal separation between domestic sheep/goats and bighorn sheep is the most prudent action we can use to manage risk of disease transmission” (USDA Forest Service 2011a).