{"elementGlobalId":102557,"circumscripConfidence":{"id":1,"circumscripConfidenceDescEn":"1 - Strong","circumscripConfidenceDescEs":"1 - Fuerte","circumscripConfidenceDescFr":"1 – Forte"},"classificationLevel":{"id":7,"classificationLevelNameEn":"Species","classificationLevelNameEs":"Especies","classificationLevelNameFr":"Espèce"},"classificationStatus":{"id":1,"classificationStatusDescEn":"Standard","classificationStatusDescEs":"Estándar","classificationStatusDescFr":"Standard"},"iucn":{"id":11,"iucnDescEn":"Least concern","iucnDescEs":"Menos preocupante","iucnDescFr":"Moins préoccupante","iucnCode":"LC"},"nameCategory":{"id":1,"nameCategoryDescEn":"Vertebrate Animal","nameCategoryDescEs":"Animal vertebrado","nameCategoryDescFr":"Animal vertébré","nameTypeCd":"A","nameTypeDesc":"Zoological"},"rankMethodUsed":{"id":4,"rankMethodUsedDescEn":"Expertise without calculation","rankMethodUsedDescEs":null,"rankMethodUsedDescFr":null,"rankMethodUsedExternalDescEn":"Ranked by inspection","rankMethodUsedExternalDescEs":null,"rankMethodUsedExternalDescFr":null},"formattedScientificName":"<i>Ovis canadensis</i>","scientificName":"Ovis canadensis","scientificNameAuthor":"Shaw, 1804","primaryCommonName":"Bighorn Sheep","relatedItisNames":"<i>Ovis canadensis</i> Shaw, 1804 (TSN 180711)","uniqueId":"ELEMENT_GLOBAL.2.102557","elcode":"AMALE04010","conceptRefFullCitation":"Wilson, D. E., and D. M. Reeder (editors). 1993. Mammal species of the world: a taxonomic and geographic reference. Second edition. Smithsonian Institution Press, Washington, DC. xviii + 1206 pp. Available online at: http://www.nmnh.si.edu/msw/.","conceptName":"<i>Ovis canadensis</i>","taxonomicComments":"Wehausen and Ramey (2000) examined variation in skull and horn characters in populations from the Great Basin north to British Columbia and Alberta and concluded that: (1) <i>O. c. auduboni</i> does not warrant recognition separate from <i>O. c. canadensis</i>; (2) populations of <i>O. c. \"californiana\"</i> in British Columbia and Washington are best treated as <i>O. c. canadensis</i>; (3) extirpated native populations of <i>O. c. \"californiana\"</i> in northeastern California, Oregon, northern Nevada, and southwestern Idaho should be included in <i>O. c. nelsoni</i> (recognizing that some transition to <i>O. c. canadensis</i> probably occurred along that northern boundary); and (4) <i>O. c. californiana</i> is restricted to the central and southern Sierra Nevada in California. However, the type locality of <i>O. c. californiana</i> is Yakima Co., Washington, a locality now assigned to <i>O. c. canadensis</i>; thus, the Sierra Nevada population is not part of <i>O. c. californiana</i>, but is either <i>O. c. canadensis</i> or a distinct subspecies with a different name. The evidence of Wehausen and Ramey (2000) that this population is fixed for a unique mtDNA haplotype would indicate the latter. Wehausen et al. (2005 and USFWS (2008) reviewed available taxonomic information and concluded that the Sierra Nevada population should be recognized as a distinct subspecies (<i>Ovis canadensis sierrae</i>).<br/><br/>The genus <i>Ovis </i>has been included in the genus <i>Capra </i>by some authors. Old World <i>O. nivicola</i> occasionally has been included in <i>O. canadensis</i>, but most authorities have regarded them as separate species (see Grubb, in Wilson and Reeder 1993, 2005).","roundedGRank":"G4","conservationStatusFactorsEditionDate":"2011-08-24","conservationStatusFactorsEditionAuthors":"Hammerson, G., and S. Cannings","primaryCommonNameLanguage":"EN","recordType":"SPECIES","elementNationals":[{"elementNationalId":164914,"classifConfidence":null,"nation":{"id":38,"nameEn":"Canada","nameEs":"Canadá","nameFr":"Canada","isoCode":"CA","region":"Canada"},"roundedNRank":"N4","elementSubnationals":[{"elementSubnationalId":366044,"subnation":{"id":61,"nameEn":"British Columbia","nameEs":"Columbia 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Data","dataSensitiveCategoryDescEs":null,"dataSensitiveCategoryDescFr":null,"nsStandardInd":true},"srank":"S4","speciesSubnational":{"elementSubnationalId":266403,"hybrid":false,"exotic":false,"native":true}}],"nrankReviewYear":2024,"nrank":"N4","speciesNational":{"elementNationalId":164914,"exotic":false,"native":true}},{"elementNationalId":165253,"classifConfidence":null,"nation":{"id":225,"nameEn":"United States","nameEs":"Estados Unidos","nameFr":"États-Unis","isoCode":"US","region":"United States"},"roundedNRank":"N4","elementSubnationals":[{"elementSubnationalId":310881,"subnation":{"id":35,"nameEn":"North Dakota","nameEs":"Dakota del Norte","nameFr":"Dakota du 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widespread in western North America from Canada to Mexico, although populations are much smaller than in the past. In some areas threatened by habitat changes resulting from fire suppression, interactions with feral and domestic livestock, and human encroachment; protected in some areas through adequate management.","grank":"G4","rankInfo":{"elementGlobalId":102557,"aooPercentGood":null,"enviromentalSpecificity":null,"intrinsicVulnerability":null,"longTermTrend":{"id":25,"longTermTrendDescEn":"Decline of 50-70%","longTermTrendDescEs":"Disminución del 50 al 70%.","longTermTrendDescFr":"Diminution de 50 à 70 %"},"numberEos":{"id":10,"numberEosDescEn":"21 - 80","numberEosDescEs":"De 21 a 80","numberEosDescFr":"De 21 à 80"},"numberGoodEos":null,"numberProtEos":{"id":14,"numberProtEosDescEn":"Many to very many (13 to >40) occurrences appropriately protected and managed","numberProtEosDescEs":"De varios a muchos casos (13 a >40) adecuadamente protegidos y controlados","numberProtEosDescFr":"De plusieurs à beaucoup d’occurrences (de 13 à >40) protégées et contrôlées convenablement"},"popSize":{"id":31,"popSizeDescEn":"10,000 - 100,000 individuals","popSizeDescEs":"De 10.000 a 100.000 individuos","popSizeDescFr":"De 10 000 à 100 000 individus"},"rangeExtent":{"id":35,"rangeExtentDescEn":">2,500,000 square km (greater than 1,000,000 square miles)","rangeExtentDescEs":">2.500.000 kilómetros cuadrados (más ","rangeExtentDescFr":">2 500 000 km carrés (plus de 1 000 000 miles carrés)"},"shortTermTrend":{"id":40,"shortTermTrendDescEn":"Relatively Stable (<=10% change)","shortTermTrendDescEs":"Relativamente estable (variación = <10%)","shortTermTrendDescFr":"Relativement stable (variation = <10 %)"},"threatImpactAssigned":{"id":5,"threatImpactAssignedDescEn":"High","threatImpactAssignedDescEs":"Alto","threatImpactAssignedDescFr":"Élevé"},"rangeExtentComments":"Range includes mountains and river breaks from southwestern Canada (southern British Columbia and southwestern Alberta) south through the Rocky Mountains, Sierra Nevada, and desert mountains of the southwestern United States to Baja California and the northwestern mainland of Mexico. Distribution is naturally fragmented in many areas due to discontinuity of habitat. Local extirpations and subsequent reintroductions from local or distant stocks have occurred in many parts of the range. For example, this species formerly ranged east to the badlands in western North Dakota and Black Hills of South Dakota; after extirpation there, individuals from non-native populations were introduced (Valdez and Krausman 1999).","areaOfOccupancy":null,"areaOfOccupancyComments":null,"numberEosComments":"Estimated in Demarchi et al. (1999a).","popSizeComments":"In 1991, the total population was estimated to be 70,840: Rocky Mountain-37,969; California-9816; and Desert-23,055 (Valdez and Krausman 1999). In 1992, End. Sp. Tech Bull. (17(3-8):6) reported that desert populations in the U.S. declined to 1171 by 1979 and to fewer than 400 in the early 1990s, and that 1500-2500 still occur in Mexico.","viabilityComments":null,"threatImpactComments":"Initial large declines were primarily the result of competition with domestic stock (e.g., cattle, sheep, burros), diseases and parasites introduced by domestic sheep, overhunting, and habitat loss (Cowan 1940; Buechner 1960; Sugden 1961; Stelfox 1971; Goodson 1982, Boyce et al. 1990, Valdez and Krausman 1999).  <br><br>DOMESTIC STOCK: In Idaho, introduced bighorns avoided cattle and were more sensitive to cattle presence than were established populations, based on previous studies (Bissonette and Steinkamp 1996). Decline of desert populations has been attributed destruction of habitat and competition with domestic livestock and other native and domestic species (e.g., may be limited through resource competition with burros; Seegmiller and Ohmart 1981).  <br><br>PARASITES AND DISEASE: Psoroptic scabies from domestic sheep devastated bighorn populations in the first half of the twentieth century (Boyce et al. 1990). The Peninsula ranges population (California and Baja California) has declined due to disease-caused low survival rate of juveniles (California Department of Fish and Game 1990). Many dieoffs (greater than 50% mortality over a few months) of herds have been reported over the last century; these are poorly understood, but seem to result from stress, which interacts with endemic lungworm infestations and lowers the animals' resistance to organisms such as PASTEURELLA bacteria. The animals subsequently die from acute bronchopneumonia (Ryder et al. 1992, Dunbar 1992, Schwantje 1988). See Bunch et al. (1999) for a general account of diseases and parasites affecting Bighorn Sheep. <br><br>HABITAT LOSS AND DEGRADATION: Loss and degredation of habitat, especially key winter forage sites, is a key threat (Valdez and Krausman 1999, Shackleton 1999, Krausman et al. 1999). Habitat degradation can occur through overgrazing by domestic stock, competition with exotic ungulates (e.g. Aoudad or Barbary, AMMOTRAGUS LERVIA), excessive off-road vehicle use, spread of rangeland weeds, and the usurpation of water sources (Simpson 1980, Valdez and Krausman 1999, Krausman et al. 1999). Fire suppression and resulting vegetation succession (encroachment of tall dense shrubland and forest) has been a major cause of habitat loss in Colorado and British Columbia (Davidson 1991, Cannings et al. 1999, Wakelyn 1987; see also Etchberger et al. [1989] for similar conclusion on the importance of fire in Santa Catalina Mountains, Arizona). Fragmentation of habitat reduces or eliminates genetic interchange among populations (Ramey 2000) and reduces the probability of recolonization following local extirpation; both these effects are especially of concern in small populations (fewer than 100 individuals), which are especially vulnerable to extirpation (Berger 1990).  <br><br>OTHER: The social behavior and predator evasion strategy may have contributed to their decline (Miller and Gaud 1989). Feral honey bees may interfere with sheep attempting to drink at artificial water sources (guzzlers) in desert environments (Boyce et al. 2003).<br><br><u>Bighorn Sheep - Peninsular Ranges</u><br><br><u>Threatened in the United States by habitat loss, degradation, and fragmentation resulting from urban and commercial development (including proposed and approved renewable energy projects), invasive non-native plants (e.g., tamarisk), fire suppression (allows development of unsuitable thick vegetation), increased fire frequency (in some areas this facilitates invasion by non-native plants), and off-highway vehicle (OHV) activity; disease (in some instances contracted directly or indirectly from introduced domestic livestock); low recruitment (still a problem despite a recent increase in the bighorn sheep population); nonadaptive behavioral responses associated with residential and commercial development; high predation rates (by mountain lions and others) coinciding with low bighorn sheep population numbers in some areas; effects of non-native (e.g., ornamental) toxic plants; and climate change, particularly the ongoing and predicted trend toward warmer and drier conditions (USFWS 1998, 2011). Populations in Mexico are regarded as not very threatened (USFWS 1998).</u><br><br><u>Responses of bighorn sheep to human activity range from cautious curiosity to immediate flight or abandonment of habitat, as well as disruption of normal social patterns and resource use (USFWS 2011). Responses depend on the type of activity, an animal's previous experience with humans, size or composition of the bighorn sheep group, location of the sheep relative to elevation of the activity, distance to escape terrain, and distance to the activity (USFWS 2000).</u><br><br><u>The apparent extirpation of a subpopulation near the United States-Mexico border (Recovery Region 9) in the 1980s may have been caused construction of Interstate 8 in the mid-1960s, railroad activity, livestock grazing, poaching, and fire suppression (Rubin et al. 1998).</u><br><br><u>Sierra Nevada Bighorn Sheep (</u><u><i>Ovis canadensis sierrae</i></u><u>)</u><br><br><u>\"Factors limiting Sierra Nevada bighorn sheep recovery include disease, predation, low population numbers and limited distribution, availability of open habitat, and potential further loss of genetic diversity due to small population sizes and inadequate migration between them. Since the vast majority of Sierra Nevada bighorn sheep habitat is publicly-owned land, loss of habitat has not been a limiting factor. However, management of bighorn sheep habitat (e.g., fire suppression) can result in habitat alterations and loss of key dispersal corridors connecting herds, which could be limiting factors.\" [Source: USFWS 2007]</u><br><br><u>Existing subpopulations are very small and are imminently threatened by mountain lion predation (USFWS 1999, 2000), which may need to be managed in some areas. As the numbers of Sierra Nevada bighorn sheep increase with recovery, the need for mountain lion control specifically for the benefit of Sierra Nevada bighorn sheep should be reduced and eventually eliminated (USFWS 2008). Continued suppression of fires in Sierra Nevada bighorn sheep range is a threat as habitat succession alters the abundance of suitable bighorn sheep habitat and increases bighorn sheep vulnerability to mountain lion predation (see USFWS 2008). </u><br><br><u>Although die-offs of bighorn sheep due to disease have occurred unrelated to domestic sheep (Miller et al. 1991: 534-540, cited by USFWS 2008)), a major contributing factor responsible for the decline of Sierra Nevada bighorn sheep populations over the years is thought to be the introduction of diseases by domestic livestock.  Clifford et al. (2007:18, cited by USFWS 2008) indicated concern regarding the probability of a respiratory disease case occurring from disease transmission between domestic sheep and Sierra Nevada bighorn sheep, especially in the northern part of bighorn sheep range. Domestic grazing allotments within the vicinity of Sierra Nevada bighorn sheep habitat should be reviewed and activities should be modified as necessary to prevent competition and contact between the domestic livestock (sheep and goats) and bighorn sheep.</u><br><br><u>Domestic livestock (sheep, goats, cattle) grazing practices that result in overgrazing or allow for contact between domestic sheep, domestic goats, and Sierra Nevada bighorn sheep is a threat. Domestic livestock could compete with Sierra Nevada bighorn sheep for forage at some level in designated critical habitat units (USFWS 2008).</u><br><br><u>Some population units require special management considerations or protection to address impacts from development activities, including road construction and maintenance within Sierra Nevada bighorn sheep habitat (USFWS 2008).</u><br><br><u>Patented mining claims occur within habitat used by the Sierra Nevada bighorn sheep, but the area of the claims is small. Mining activities and associated facilities threaten bighorn sheep by causing the loss of vegetation structure required for foraging activities; the destruction of habitats used for escape, bedding, lambing, or connectivity between ranges; and the disturbance due to ongoing mining activities. Disturbance could modify bighorn sheep behavior or cause them to flee an area (USFWS 2008).</u><br><br><u>It remains unclear how significantly Sierra Nevada bighorn sheep may be affected by human disturbance. Increases in human uses of bighorn sheep habitat, including recreational activities such as rock and ice climbing, mountaineering, ski touring, hiking, camping, pack station establishment, snowmobiling, and off-road vehicle use may cause detrimental disturbance to Sierra Nevada bighorn sheep in some areas (USFWS 2008). Impacts to the habitat could occur through trampling and reduced vegetation structure due to grazing by pack animals (USFWS 2008). </u><br><br><u>Management actions to protect Sierra Nevada bighorn sheep habitat from catastrophic, naturally occurring events may be necessary. Events such as wildfires and avalanches could temporarily destroy large areas that provide summer or winter foraging habitat (USFWS 2008).</u>","shortTermTrendComments":"Recent trends seem more or less stable; some increases are apparently offset by local dieoffs.  Some sources conclude that numbers of Rocky Mountain bighorn sheep are increasing, whereas others cite declines due to habitat loss and disease (Risenhoover et al. 1988). Population on east slope of Sierra Nevada has increased in recent decades due to reintroduction program (California Department of Fish and Game 1990). (California and Baja California) has declined (California Department of Fish and Game 1990). A die-off occurred in Canyonlands National Park/Glen Canyon NRA and vicinity in the 1980s (Park Science, Summer 1993).  Penisular range population declined between 1971 and 1991 in the United States, but is relatively stable in Mexico (USFWS 1998).","longTermTrendComments":"Long-term trend is a great decline: from approximately 150,000-200,000 before 1800 (Seton's 1929 estimate of 2 million or more is considered an order of magnitude too high, Demarchi 1976, Valdez and Krausman 1999) to very few thousand at the turn of the century. Numbers are not available for the total population at this time, but in 1915, there were only 1775-3400 Rocky Mountain Bighorns in Canada (Miller 1916). Protection from hunting and some habitat protection helped populations over the next few decades, but devastating dieoffs occurred as more and more domestic sheep (and their exotic diseases) were introduced onto western ranges in the early 1900s (Goodson 1982). The number of domestic sheep in 11 western states increased to approximately 28 million in 1920 and remained high until 1945 (Goodson 1982). After 1945, however, domestic sheep numbers declined and this allowed an energetic program of reintroductions and habitat enhancement to begin to turn the trend around. By 1960, populations in the contiguous United States had increased to 15,200-18,000 (Buechner 1960). Since 1960, populations of Rocky Mountain and California Bighorns have generally increased: 1975-30,667; 1983-37,035; 1993-48915 (Gilchrist (1998). In 1991, the total population (Rocky Mountain, California, and Desert Bighorns) was estimated to be 70,840 (Valdez and Krausman 1999).","inventoryNeeds":"Determine current total abundance.","numberProtEosComments":"Protected in many National Parks; many reserves have been established specifically for the species.<br><br>USFWS (2008) designated as critical habitat for subspecies <i>sierrae </i>approximately 417,577 acres (168,992 hectares) in Tuolumne, Mono, Fresno, Inyo, and Tulare counties, California.","protectionNeeds":"Protect habitat from domestic livestock damage; protect populations from excessive hunting. Desert populations exhibit more movement between isolated patches of habitat than previously thought; consequently corridors between traditional habitats should be given conservation consideration (Bleich et al. 1990).","otherConsiderations":null,"intrinsicVulnerabilityComments":null,"enviromentalSpecificityComments":null},"animalCharacteristics":{"elementGlobalId":102557,"majorHabitat":{"id":3,"majorHabitatDescEn":"Terrestrial","majorHabitatDescEs":"Terrestre","majorHabitatDescFr":"Terrestre"},"nonMigrant":false,"localMigrant":true,"longDistanceMigrant":false,"mobilityMigrationComments":"Populations other than those in low deserts typically migrate between an alpine or montane summer range and a lower elevation winter range (Shackleton et al. 1999). Some may occupy as many as five separate ranges during a year (Geist 1971). This vertical migration is probably a response to the increasing abundance of nutritious, new vegetative growth at higher elevations as spring and summer progress (Shackleton et al. 1999). The downward migration is motivated by snow accumulation in the high elevation summer ranges (Shackleton et al. 1999).<br><br><u>Bighorn Sheep - Peninsular Ranges</u><br><br><u>\"This population...exhibits a metapopulation structure, and requires habitat necessary to accommodate movements of males (rams), and more rarely females (ewes), between ewe  groups (subpopulations)\" (USFWS 2011).</u><br><br><u>In the San Jacinto Mountains, fixed-kernel home range sizes averaged 25 square kilometers for males and 20 square kilometers for females (DeForge et al. 1997). Home range size depends on forage quantity and quality, season, sex, and age of the animal, and on the location of required resources such as water, forage, escape terrain, and lambing habitat (USFWS 2000). In many populations, home range size is smaller in summer thatn in winter, presumably because movement away from permanent water sources is more restricted in the hotter months (see sources cited in USFWS 2011).</u><br><br><u>\"The gregarious and philopatric (faithful to natal home range) behaviors of ewes limit their dispersal and exploratory abilities relative to those of rams\" (USFWS 2011). Young learn seasonal movement patterns from their mothers. Adult males are more vagile than females and young, and they often move among groups of females. Young maleseventually begin to follow older males and may adopt their traditional travel routes.</u><br><br><u>In the Peninsular Ranges, movement of radio-collared females between female groups is rare, although inter-group movement does occasionally occur (Rubin et al. 1998).</u><br><br><u>Sierra Nevada Bighorn Sheep (</u><u><i>Ovis canadensis sierrae</i></u><u>)</u><br><br><u>Seasonal migrations revolve primarily around avoidance of deep snow in winter.</u><br><br><u>Individuals tend to show a high level of philopatry to their seasonal home ranges, though long-distance dispersal to new areas sometimes occurs.</u><br><br><u>Maximum diameters of annual home ranges for females in the Mount Warren/Mount Gibbs, Wheeler, and Baxter herds ranged from 6.35 to 16.75 km); males from the Mount Warren/Mount Gibbs, Wheeler, and Sawmill herds ranged from 8.9 to 59.4 km (Sierra Nevada Bighorn Sheep Recovery Program 2004).</u>","foodHabitsComments":"Diet is diverse and variable. Bighorn sheep are primarily grazers of grass and forbs, but the diet can also include significant amounts of shrubs (Miller and Gaud 1989, Krausman et al. 1999, Shackleton et al. 1999). Diet changes seasonally. Access to mineral lick may be important for Rocky Mountain and desert bighorns, especially in spring (Shackleton et al. 1999, Krausman et al. 1999).","animalPhenologyComments":"During the day, feeding alternates with rest-rumination periods. Daily activity may vary seasonally; often feeding peaks in early morning and at dusk. In winter, feeding periods are longer.","colonialBreeder":false,"length":185,"width":null,"weight":150000,"animalPhenologies":[{"animalCagPhenologyId":101895,"animalPhenology":{"id":3,"animalPhenologyDescEn":"Diurnal","animalPhenologyDescEs":"Diurno","animalPhenologyDescFr":"Diurne","displayOrder":3},"adult":true,"immature":true}],"animalFoodHabits":[{"animalCagFoodHabitsId":103529,"foodHabits":{"id":4,"foodHabitsDescEn":"Herbivore","foodHabitsDescEs":"Herbívoro","foodHabitsDescFr":"Herbivore","displayOrder":4},"adult":true,"immature":true}]},"occurrenceDelineations":[{"eoSpecsDetailId":1590,"locationUseClass":{"id":1,"locationUseClassDescEn":"Not applicable","locationUseClassDescEs":"No se aplica","locationUseClassDescFr":"Sans objet","displayOrder":1},"eoSpecGroupName":"Bighorn Sheep","subtypes":"Lambing range, Summer range, Winter range","inferredExtentDistance":null,"inferredExtentNotes":null,"minimumEoCriteria":"Evidence of historical presence, or current and recurring presence, in a given area. Such evidence minimally includes reliable observation and documentation of more than one individual in appropriate habitat where the species is evidently established and breeding.","mappingGuidance":null,"separationBarriers":"None.","separationDistanceUnsuitableHabitatat":null,"separationDistanceSuitableHabitatat":null,"altSeparationProcedure":"Occurrence separations should be based on populations that exhibit specific migration patterns, or on appropriate resource agency management units, rather than on specific prescribed distances.","separationJustification":"Rams especially may travel extensively between winter and summer ranges. Unsuitable habitat: open water, wetlands, thick forests, and other areas without grass understory.","versionDate":"2004-09-23","versionAuthor":"Hammerson, G., and S. Cannings","versionNotes":null,"lastModified":"2021-03-05T23:39:52.336408Z"}],"plantCharacteristics":null,"elementManagement":{"elementGlobalId":102557,"eoManagementGroupName":null,"stewardshipOverview":null,"impacts":null,"restorationPotential":null,"siteConservationPlansConsidered":"In the southwestern U.S., Berger (1990) found that populations with fewer than 50 individuals are not viable; all such populations went extinct within 50 years.","managementMethods":"See Douglas and Leslie (1999) for a general discussion of Bighorn Sheep management; and see Smith and Krausman (1988) for a discussion of management of desert populations. <br><br>Management needs for the Rocky Mountain population: identification of seasonal ranges and migration corridors and identification of factors limiting range expansion; improvement of ranges by vegetation manipulation (burning, clearing); protection of ranges from human encroachment; avoiding contact between bighorn and domestic livestock Risenhoover et al. 1988). Smith et al. (1991) presented a habitat evaluation procedure for the Rocky Mountain population. <br><br>See California Department of Fish and Game (1990) for brief comments on management activities relating to Peninsular Range (California) population; recovery of this population with require compatible grazing programs by BLM, USFS, and private landowners.","monitoringMethods":"Full censuses are difficult and costly. Lamb:ewe ratios are the best indicators of population status and need to be monitored regularly (Douglas and Leslie 1999).","managementProgramContacts":null,"monitoringProgramContacts":null,"managementResearchPrograms":null,"managementResearchNeeds":"Research into habitat requirements is important, and much work remains to be done in assessing habitat suitability and capability, and modeling habitat on a landscape scale. Continued studies of diseases are vital, as is research into population and metapopulation dynamics and population genetics (Douglas and Leslie 1999).","biologicalResearchNeeds":null,"additionalTopics":null},"occurrenceViabilities":[{"eoRankSpecsDetailId":104064,"eoRankSpecsGroupName":null,"locationUseClass":{"id":1,"locationUseClassDescEn":"Not applicable","locationUseClassDescEs":"No se aplica","locationUseClassDescFr":"Sans objet","displayOrder":1},"excellentViability":null,"goodViability":null,"fairViability":null,"poorViability":null,"viabilityJustification":"Use the Generic Guidelines for the Application of Occurrence Ranks (2008).<br>The Key for Ranking Species Occurrences Using the Generic Approach provides a step-wise process for implementing this method.","versionDate":null,"versionAuthor":null,"versionNotes":null,"lastModified":"2020-05-14T02:21:51.177704Z"}],"references":[{"id":1151804,"citation":"American Society of Mammalogists (ASM). 2025. 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The Sierra Nevada population is listed as Endangered under the U.S. Endangered Species Act (see pop. 3) (USFWS 1999, 2000).<br/><br/>Mexican populations are included in CITES Appendix 2.","completeDistribution":true,"synonyms":[],"infraspeciesList":[{"infraspeciesId":102472,"uniqueId":"ELEMENT_GLOBAL.2.102472","formattedScientificName":"<i>Ovis canadensis sierrae</i>","scientificName":"Ovis canadensis sierrae","primaryCommonName":"Sierra Nevada Bighorn Sheep","nsxUrl":"/Taxon/ELEMENT_GLOBAL.2.102472/Ovis_canadensis_sierrae"},{"infraspeciesId":102097,"uniqueId":"ELEMENT_GLOBAL.2.102097","formattedScientificName":"<i>Ovis canadensis canadensis</i>","scientificName":"Ovis canadensis canadensis","primaryCommonName":"Rocky Mountain Bighorn Sheep","nsxUrl":"/Taxon/ELEMENT_GLOBAL.2.102097/Ovis_canadensis_canadensis"},{"infraspeciesId":102585,"uniqueId":"ELEMENT_GLOBAL.2.102585","formattedScientificName":"<i>Ovis canadensis mexicana</i>","scientificName":"Ovis canadensis mexicana","primaryCommonName":"Desert Bighorn Sheep","nsxUrl":"/Taxon/ELEMENT_GLOBAL.2.102585/Ovis_canadensis_mexicana"},{"infraspeciesId":105707,"uniqueId":"ELEMENT_GLOBAL.2.105707","formattedScientificName":"<i>Ovis canadensis nelsoni</i>","scientificName":"Ovis canadensis nelsoni","primaryCommonName":"Desert Bighorn Sheep","nsxUrl":"/Taxon/ELEMENT_GLOBAL.2.105707/Ovis_canadensis_nelsoni"},{"infraspeciesId":100041,"uniqueId":"ELEMENT_GLOBAL.2.100041","formattedScientificName":"<i>Ovis canadensis</i> pop. 2","scientificName":"Ovis canadensis pop. 2","primaryCommonName":"Bighorn Sheep - Peninsular Ranges Population","nsxUrl":"/Taxon/ELEMENT_GLOBAL.2.100041/Ovis_canadensis_pop_2"}],"ebarId":null,"ebarCanadianScope":false,"ebarGlobalScope":false,"ebarKbaGroup":"Mammals","caGeneralStatusId":"GS001460"},"speciesCharacteristics":{"elementGlobalId":102557,"reproductionComments":"The timing of the mating season varies throughout the range. Bighorns in southwestern deserts have an extended season encompassing several months (Krausman et al. 1999), but the season is relatively later and shorter elsewhere, generally November in the northern part of the range (Shackleton et al. 1999), November-December in some southern California mountains (DeForge (1980). Gestation lasts about 175 days (Geist 1971, Shackleton et al. 1999). Lambing generally peaks in March in desert populations (Rubin et al. 2000), May (occasionally April or June) in the remainder of range (Krausman et al. 1999, Shackleton et al. 1999). Litter size is 1, rarely 2 (Geist 1971, Turner and Hansen 1980).Young are weaned in 4-6 months. Females first breed usually in second year in south, third year in north; occasionally in first year in some areas (Krausman et al. 1999, Shackleton et al. 1999); fecundity generally declines only slightly after eight years of age (Caughley 1977).<br><br>In the mating season, mature males battle over access to females through vigorous head butting contests, but during most of the rest of the year they live amiably in small bands apart from the females.","ecologyComments":"Gregarious, but for most of the year adult males live apart from females/young (Shackleton et al. 1999, Krausman et al. 1999). Among mature males, older males (up to an age of not more than 10 years) generally dominate younger males during the breeding season; males older than 10 years decline rapidly in condition. In western Arizona, January-June home range of adult females was 19-27 sq km (Seegmiller and Ohmart 1981). Male annual home range up to 37 sq km in Nevada (Leslie and Douglas 1979). <br><br>Carrying capacity for bighorn can be reduced through grazing by other ungulates (cattle, burros, etc.). In the Santa Catalina Mountains of southern Arizona, not limited by forage quantity or quality (Mazaika et al. 1992). <br><br>Contact with a stray domestic sheep is believed to have resulted in the death (through bacterial pneumonia) of entire reintroduced herd of 65 in Warner Mountains, California (California Department of Fish and Game 1990). In some areas, lungworm infections may predispose bighorn to respiratory infection by opportunistic bacteria; lungworm life cycle involves gastropod intermediate host. <br><br>In desert, can survive 10 or more days in summer without drinking; may meet water needs in part by eating barrel cacti (Warrick and Krausman 1989). <br><br>PREDATION: Probably live in groups primarily to reduce predation (Shackleton et al. 1999). Coyotes may be a significant predator on young in some areas, killing up to 80% of the year's lambs (Hebert and Harrison 1988, Harper 1984, Hass 1989). Cougars can be important predators as well (Harrison and Hebert 1988, Krausman et al. 1999), and can have significant impacts on remnant or transplant herds (Krausman et al. 1999). Direct losses to predation are not generally as important as the fact that predation has forced females and young to use less productive habitats in and near escape terrain (Festa-Bianchet 1988, Demarchi et al. 1999a).","habitatComments":"Bighorn sheep occur in mesic to xeric, alpine to desert grasslands or shrub-steppe in mountains, foothills, or river canyons (Shackleton et al. 1999, Krausman et al. 1999). Many of these grasslands are fire-maintained (Geist 1971, Erickson 1972). Suitable escape terrain (cliffs, talus slopes, etc.) is an important feature of the habitat. In winter, Rocky Mountain Bighorns spend as much as 86% of their time within 100 meters of escape terrain (Oldemayer et al. 1971, Erickson 1972), and usually stay within 800 meters of escape terrain throughout the year (Pallister 1974). Mineral licks are more important in the range of Rocky Mountain Bighorn than in the range of \"California\" Bighorn, presumably because the soils in the range of the former are generally lower in mineral content (Van Dyke 1978). Distribution is correlated with low precipitation levels, especially in winter and spring. Elevation varies considerably, both geographically and seasonally, from as low as 450 meters to over 3,300 meters (Shackleton et al. 1999). <br><br>Winter ranges of northern populations are relatively snow-free because of light snow, steep south aspect, and/or high winds; bighorns generally avoid snow deeper than 30 centimeters (Stelfox 1975). The solar heat on south aspects also reduces cold stress on sheep (Shackleton et al. 1999). <br><br>In the north, bighorn sheep usually are not dependent on free-standing water, getting water instead from succulent vegetation in the summer and snow or ice in the winter (Van Dyke 1978). However, in some southwestern deserts they may be dependent on access to free water during summer (Turner 1979, Turner and Weaver 1980, Seegmiller and Ohmart 1981).<br><br><u>Bighorn Sheep - Peninsular Ranges</u><br><br><u>Habitat includes steep slopes and cliffs, rough and rocky topography, and sparse vegetation (Monson and Summner 1980), \"with use of alluvial fans and washes, and valley floors depending on environmental conditions and dispersal requirements\" (USFWS 2011; see also Monson and Sumner 1980 and USFWS 2000). Females about to give birth \"seek secluded sites with shelter, unobstructed views, and steep terrain, ...while rams may be found in less steep or rugged terrain\" (USFWS 2011). In the Peninsular Ranges, bighorn sheep generally stay elevationally below the pinyon pine-juniper and chararral vegetation zones (USFWS 2011). Vegetation of occupied habitat often includes </u><u><i>Agave deserti </i></u><u>(agave)-</u><u><i>Fouquieria splendens </i></u><u>(ocotillo), </u><u><i>Opuntia </i></u><u>spp. (cholla)-</u><u><i>Cercidium floridum </i></u><u>(palo verde), and </u><u><i>Larrea tridentata </i></u><u>(creosote)-</u><u><i>Prosopis </i></u><u>spp. (palo verde-mesquite). Bighorns use open areas and generally avoid areas where visibility is obstructed by thick vegetation.</u><br><br><u>Valley floors provide important linkages between adjacent mountainous regions and allow bighorn sheep access to resources (e.g., forage, water, lambing habitat) in neighboring areas; these lowlands also allow gene flow to occur between subpopulations (USFWS 2011). Bighorns may forage or access water on gentle terrain (e.g., alluvial fans and washes) but may travel quickly through valley floors to reach  nearby mountains (Simmons, in Monson and Sumner 1980). Reproductive females may make heavy use of the food resources on alluvial fans and washes, and these areas can be important in summer and during droughts, when nutritious forage is scarce elsewhere (Andrew 1994).</u><br><br><u>North-facing slopes provide cooler refuges during the hottest weather, and south-facing slopes may be used on cold winter days (Andrew 1994).</u><br><br><u>In summer, bighorn sheep may congregate around water sources; most sheep stay wihtin 3-5 km of water (see USFWS 2011). They may abandon areas where no standing water exists. Above-average rainfall and cooler temperatures may allow bighorns to occupy habitats that may be abandoned during droughts (USFWS 2011).</u><br><br><u>Suitable habitat exists as a narrow north-south continuum from the San Jacinto Mountains all the way to the U.S.-Mexico border (Rubin et al. 2009).</u><br><br><u>Sierra Nevada Bighorn Sheep (</u><u><i>Ovis canadensis sierrae</i></u><u>)</u><br><br><u>Sierra Nevada bighorn sheep inhabit open areas where the land is rocky, sparsely vegetated, and characterized by steep slopes and canyons.. Habitats range from alpine to Great Basin sagebrush scrub. They prefer open ground and areas with good access to steep, rocky terrain (escape habitat) and so generally avoid forests, thick brush, and large expanses lacking precipitous escape terrain. In summer, most live at higher elevations (10,000-14,000 feet; 3,050-4,270 meters) in subalpine and alpine areas. Females occur largely in alpine environments, whereas males often are at somewhat lower elevations in subalpine habitats. In winter, they occupy high-elevation, windswept ridges if forage is available and tend to inhabit south-facing slopes where snow melts more readily, or they migrate to lower elevations in sagebrush-steppe areas to avoid deep snow and to find forage. Low-elevation winter ranges provide an important source of high quality forage early in the growing season. Reproductive female select steep, rugged slopes and canyons for lambing. Sources: McCullough and Schneegas (1966), Wehausen (1980), USFWS (2007, 2008).</u><br><br><u>USFWS (2008) determined that primary constituent elements (habitat features) for Sierra Nevada bighorn sheep include: (1) Non-forested habitats or forest openings within the Sierra Nevada from 4,000 feet (1,219 meters) to 14,500 feet (4,420 meters) in elevation with steep (greater than or equal to 60 percent slope), rocky slopes that provide for foraging, mating, lambing, predator avoidance, and bedding and that allow for seasonal elevational movements between these areas.  (2) Presence of a variety of forage plants as indicated by the presence of grasses (e.g., </u><u><i>Achnanthera </i></u><u>spp.; </u><u><i>Elymus </i></u><u>spp.) and browse (e.g., </u><u><i>Ribes </i></u><u>spp.; </u><u><i>Artemisia </i></u><u>spp., </u><u><i>Purshia </i></u><u>spp.) in winter, and grasses, browse, sedges (e.g., </u><u><i>Carex </i></u><u>spp.) and forbs (e.g., </u><u><i>Eriogonum </i></u><u>spp.) in summer. (3) Presence of granite outcroppings containing minerals such as sodium, calcium, iron, and phosphorus that could be used as mineral licks in order to meet nutritional needs.</u><br><br><u>Johnson et al. (2007) used resource selection probability functions to identify important winter and summer habitat characteristics, and to generate predictive models of habitat use in unoccupied ranges. \"Characteristics of topography and vegetation were significant in describing bighorn sheep winter habitat use, and only topographic characteristics were significant in describing summer habitat use. Habitat models were used to determine the amount of winter and summer range within each herd unit, the connectivity of seasonal ranges, areas at risk of contact with domestic sheep, and to simulate the effects of prescribed fire on bighorn sheep habitat.\"</u>","generalDescription":"Upper pelage varies from dark brown to pale tan, with a whitish underside. Tail is short.  is tan or reddish brown in summer, grayish brown in winter. Mature male has massive horns that form a C-shaped curl. Horns of adult female are shorter and more slender, forming a half curl at most. 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