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Lifespan, longevity, and ageing

provided by AnAge articles
Maximum longevity: 20.6 years (captivity) Observations: Young females have an over 90% survival in the wild, though an increased mortality with age has been reported for both males and females after about 8 years of age (Loison et al. 1999). It has been reported that these animals live up to 24 years in captivity (David Macdonald 1985), which could be overestimated. Record longevity in captivity is 20.6 years (Richard Weigl 2005).
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Reproduction

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Bighorn sheep are perhaps best known for the head-to-head combat between males. Horn size is a symbol of rank, and the mass of the horns (as much as 14 kg) is used to a male's best advantage as he smashes into an opponent at speeds of 20 miles per hour. Combat has been observed to last for as long as 25.5 hours (with approximately 5 clashes an hour) until one of the males conceded. Males do not defend territories but rather engage in battles over mating access to a particular female. Male dominance status is determined by age as well as horn size, and homosexual activity often occurs in groups of males with the dominant animal behaving like a courting male and the subordinate playing the role of an estrous female. Ewes are seasonally polyoestrous and will accept several rams, often frequently, when in oestrus. Because of intense competition between males for females and the dominance hierarchy based on age and size (including the size of the horns), males do not usually mate until they are seven years old. Younger males will mate sooner if dominant rams in their group are killed.

Mating System: polygynous

Rutting season is in the autumn and early winter, and births take place in the spring. Mating for the desert bighorn, however, can last from July to December. Gestation lasts from 150-180 days, after which usually one, rarely two, young are born. Newborns are precocial and are able to follow their mothers at a good pace over the rocky terrain after the first week. Within a few weeks of birth, offspring form bands of their own, seeking out their mothers only to suckle occasionally. They are completely weaned by 4 to 6 months of age. Ovis canadensis females have been mated when 10 to 11 months old in captivity, but they generally do not breed until their second or third year in the wild.

Breeding interval: Bighorn sheep breed once yearly.

Breeding season: Mating occurs from July to December, with most activity concentrated in the fall rut.

Range number of offspring: 1 to 2.

Average number of offspring: 1.36.

Range gestation period: 5 to 6 months.

Range weaning age: 4 to 6 months.

Range time to independence: 4 to 6 months.

Range age at sexual or reproductive maturity (female): 1 (low) years.

Average age at sexual or reproductive maturity (female): 2-3 years.

Range age at sexual or reproductive maturity (male): 7 (high) years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous

Average birth mass: 4400 g.

Average number of offspring: 1.

Female bighorn sheep seek out protected areas to give birth to their lambs. They nurse the young for 4 to 5 months, with the lambs increasing from about 4 kg at birth to 25 to 35 kg at weaning (males generally weighing more). Lambs are capable of walking and following their mothers on precipitous terrain soon after birth. Males do not participate in parental care.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female); post-independence association with parents; extended period of juvenile learning

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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Behavior

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Bighorn sheep are very alert and have remarkable eyesight that allows them to judge distances accurately in jumping and locating footholds. They often watch other animals moving at distances of up to a mile away. Bighorn sheep probably also use chemical cues, as do most mammals, to distinguish reproductive states and may use visual cues to assess dominance among males. Bighorn sheep are less vocal than domestic sheep. The lambs bleat, and ewes respond with a gutteral "ba." At other times of the year, adults utter throaty rumbles or "blow" in fright. During the rut, the rams frequently snort loudly.

Communication Channels: visual ; acoustic ; chemical

Perception Channels: visual ; tactile ; acoustic ; chemical

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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Conservation Status

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Several populations may be threatened with eventual extinction, bighorn numbers are only one-tenth the population that existed when western settlers first began exploiting the Rockies. Their main threats are unregulated or illegal hunting, introduced diseases, competition from livestock, and continual human encroachment on their habitat. The subspecies O. c. auduboni of the Black Hills and adjacent areas has already become extinct. Bighorn sheep are incompatible with domestic sheep because they are susceptible to diseases of domestic livestock, including pneumonia, which is periodically responsible for large die-offs in bighorn sheep populations. Hunting has been prohibited or controlled since the early 1900's, but much illegal poaching still occurs. Hunting for trophies is particularly damaging to the cohesiveness of bighorn groups because it eliminates the dominant, breeding males. Recovery of numbers has been slow for these animals and their future is threatened unless further conservation measures are implemented. California bighorn sheep (O. c. californicus) are considered endangered under the U.S. Endangered Species Act.

US Federal List: endangered

CITES: appendix ii; no special status

IUCN Red List of Threatened Species: least concern

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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Benefits

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There are no known negative effects of bighorn sheep on humans.

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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Benefits

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Native Americans and early settlers prized bighorn meat as the most palatable of American big-game species. Native Americans also used the horns to fashion large ceremonial spoons and handles for utensils. The horns have also been popular for many centuries as trophies. Bighorn sheep may serve as an attraction for ecotourism ventures in parts of western North America.

Positive Impacts: food ; body parts are source of valuable material; ecotourism

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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Associations

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Bighorn sheep are important predators of grasses and shrubs in their native landscapes, they are also important sources of prey for large predators. Bighorn sheep are hosts for a number of parasites. Nematode lungworms, Protostrongylus stilesi and P. rushi, infect all bighorn sheep individuals and probably co-evolved with these sheep in North America. Most sheep do not experience any significant deleterious effects of lungworms.

Commensal/Parasitic Species:

  • Protostrongylus stilesi
  • P. rushi
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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Trophic Strategy

provided by Animal Diversity Web

Bighorn sheep are mainly diurnal, feeding intermittently throughout the day. Ovis canadensis canadensis is largely a grazer, consuming grasses, sedges, and forbs, but it will take some browse when preferred food is scarce (especially in winter). Desert bighorns (O. c. nelsoni) eat a variety of desert plants and get most of their moisture from the vegetation, although they still visit water holes every several days.

Plant Foods: leaves

Primary Diet: herbivore (Folivore )

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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Distribution

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Ovis canadensis is found in the Rocky Mountains from southern Canada to Colorado, and as a desert subspecies (O. c. nelsoni) from Nevada and California to west Texas and south into Mexico.

Biogeographic Regions: nearctic (Native )

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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Habitat

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Ovis canadensis canadensis inhabits alpine meadows, grassy mountain slopes and foothill country in proximity to rugged, rocky cliffs and bluffs. Bighorn sheep require drier slopes where the annual snowfall is less than about sixty inches a year, since they cannot paw through deep snow to feed. The winter range usually lies between 2,500-5,000 feet in elevation, while the summer range is between 6,000-8,500 feet.

Range elevation: 800 to 2500 m.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: desert or dune ; chaparral ; mountains

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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Life Expectancy

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Longevity depends on population status. In declining or stable populations, most sheep live over 10 years, with a maximum of 19 years. However in an expanding population with heavy reproduction, average life span is only 6 to 7 years. Females have been known to live up to 19 years and males to 14 but attaining these ages is rare. Even in areas where no hunting occurs, females rarely make it past 15 and males rarely live beyond 12. Juvenile mortality is variable and can be quite high, from 20 to 80%, averaging 5 to 30%. Between the ages of 2 and 6 there is relatively low mortality.

Range lifespan
Status: wild:
19 (high) years.

Typical lifespan
Status: wild:
6 to 15 years.

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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Morphology

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Males 119-127kg; females 53-91 kg. Rams typically measure 160-180 cm from head to tail, while ewes are approximately 150 cm. Bighorn sheep have double-layered skulls shored with struts of bone for battle protection. They also have a broad, massive tendon linking skull and spine to help the head pivot and recoil from blows. Horns may way as much as 14 kg, which is the weight of all the bones in a ram's body. The horns of a female are much smaller and only slightly curved. The horns of a ram can tell much about him such as his age, health, and fighting history. The desert subspecies, Ovis canadensis nelsoni, is somewhat smaller and has flatter, wider-spreading horns. The pelage of Ovis canadensis is smooth and composed of an outer coat of brittle guard hairs and short, grey, crimped fleece underfur. The summer coat is a rich, glossy brown but it becomes quite faded by late winter.

Range mass: 53 to 127 kg.

Range length: 150 to 180 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger; ornamentation

Average basal metabolic rate: 114.674 W.

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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
author
Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Associations

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The availability of escape territory in the form of rocky cliffs is important to bighorn sheep survival. If a sheep can reach a rocky outcrop or cliff, it is usually safe from the attack of wolves, coyotes, bears, Canada lynx, and mountain lions. Golden eagles (Aquila chrysaetos) may take some lambs.

Known Predators:

  • wolves (Canis lupus)
  • coyotes (Canis latrans)
  • bears (Ursus)
  • Canada lynx (Lynx canadensis)
  • mountain lions (Puma concolor)
  • Golden eagles (Aquila chrysaetos)
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Ballenger, L. 1999. "Ovis canadensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ovis_canadensis.html
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Liz Ballenger, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Associated Plant Communities

provided by Fire Effects Information System Animals
More info for the terms: shrubs, woodland

Bighorn sheep occupy a variety of plant communities ranging from alpine
meadows, woodlands, mixed-grass prairie, shrub-bunchgrass, and dry
pinyon-juniper (Pinus-Juniperus spp.) [2,7,14,25,27]. They avoid dense
forests [6].

Summer ranges of bighorn sheep in southeastern Oregon vary from
subalpine meadows or grasslands to sagebrush (Artemisia spp.)/grasslands
or shrublands. Winter ranges are usually shrub/grasslands and
shrublands. Communities dominated by trees or tall shrubs such as aspen
(Populus spp.), cottonwood (Populus spp.), fir (Abies spp.), pine,
juniper, mountain-mahogany (Cercocarpus spp.), squaw apple (Peraphyllum
ramosissimum), and cherry (Prunus spp.) may occur throughout both summer
and winter ranges [26].

On two bighorn sheep winter ranges in the upper Yellowstone River
Valley, vegetation types in which bighorns were observed included
bluebunch wheatgrass (Pseudoroegneria spicata), needle-and-thread (Stipa
comata), and Idaho fescue (Festuca idahoensis) grasslands; sagebrush
(primarily A. tridentata) and black greasewood (Sarcobatus vermiculatus)
shrublands; open Douglas-fir (Pseudotsuga menziesii) woodland; and the
vegetation mosaics associated with cliffs and draws [14]. Bighorn sheep
range in Glacier National Park includes bunchgrass communities dominated
by bluebunch wheatgrass, Idaho fescue, rough fescue (F. scrabrella), and
Saskatoon serviceberry (Amelanchier alnifolia); and seral vegetation of
subalpine fir (Abies lasiocarpa) habitat types [24].

Other plant species common on bighorn sheep range include bitterbrush
(Purshia tridentata), mountain muhly (Muhlenbergia montana), russet
buffaloberry (Shepherdia canadensis), bearberry (Arctostaphylos
uva-ursi), blue grama (Bouteloua gracilis), rabbitbrush (Chrysothamnus
spp.), bluegrass (Poa spp.), buffalograss (Buchloe dactyloides), western
wheatgrass (Pascopyron smithii), and sedges (Carex spp.) [2,7,11,24,25].
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Common Names

provided by Fire Effects Information System Animals
bighorn sheep
mountain sheep
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Conservation Status

provided by Fire Effects Information System Animals
Information on state- and province-level protection status of animals in the
United States and Canada is available at NatureServe, although recent changes
in status may not be included.
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Cover Requirements

provided by Fire Effects Information System Animals
More info for the terms: cover, shrub, shrubs

Escape terrain is an important habitat requirement for bighorn sheep.
Cliffs, rock rims, rock outcroppings, and bluffs with sparse cover of
trees or shrubs typify escape habitat, which provides both thermal and
hiding cover. While bighorn sheep are not always found in precipitous
mountain areas, ewes and lambs rely on these areas for escape cover,
especially during the lambing period [6,26,27].

Visibility is another important habitat component for bighorn sheep. It
allows for predator detection, visual communication, and efficient
foraging [4]. Bighorn sheep tend to forage in open areas with low
vegetation such as grasslands, shrublands, or mixes of these. They
avoid foraging on mild slopes with shrub or canopy cover in excess of 25
percent and shrubs 2 feet (60 cm) or higher. On steep slopes they have
been noted to travel through or bed in dense brush [26].
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Distribution

provided by Fire Effects Information System Animals
The former range of the bighorn sheep extended from the Northern Rocky
Mountains of Canada south to the mainland of Mexico and Baja California
[22]. It is now found in relatively isolated pockets in the Coast and
Cascade ranges and the Sierra Nevada, and in the Rocky Mountains south
of the Peace River to Mexico [6].
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Food Habits

provided by Fire Effects Information System Animals
More info for the term: forbs

Bighorn sheep primarily graze grasses and forbs, but eat other
vegetation depending on availability [6]. They prefer green forage and
move up- or downslope or to different aspects for more palatable forage.
Forage areas that provide a variety of aspects are preferable because
they provide green forage for longer periods [26].

Bighorn sheep eat sedges and a variety of grasses including bluegrasses
(Poa spp.), wheatgrasses, bromes, and fescues. Browse species include
sagebrush, willow (Salix spp.), rabbitbrush, curlleaf mountain-mahogany
(Cercocarpus ledifolius), winterfat (Kraschnennikovia lanata),
bitterbrush, and green ephedra (Ephedra spp.). Forbs include phlox
(Phlox spp.), cinquefoil (Potentilla spp.), twinflower (Linnaea
borealis), and clover (Trifolium spp.) [6,23].

Because of the dry climate, browse is the dominant food of the desert
bighorn sheep and includes desert holly (Atriplex hymenelytra),
honeysweet (Tidestromia oblongifolia), brittlebush or encelia (Encelia
spp.), hairy mountain-mahogany (C. breviforus), Wright silktassel
(Garrya wrightii), desert mallow (Sphaeralcea ambigua), Russian-thistle
(Salsola kali), false mesquite (Calliandra eriophylla), goatnut
(Simmondsia chinensis), white ratany (Krameria canescens), bursage
(Hyptis emoryi), mesquite (Prosopis glandulosa), catclaw (Acacia
greggii), ironwood (Olneya tesota), paloverde (Cercidium spp.),
pincushion (Mammillaria spp.), and saguaro (Carnegiea gigantea). Dry
grasses are eaten throughout the year and are an important food reserve,
especially near waterholes [6].
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bibliographic citation
Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat-related Fire Effects

provided by Fire Effects Information System Animals
More info for the terms: fire exclusion, prescribed fire, succession

Many bighorn sheep populations originally occurred in areas with
frequent fire intervals [19,24]. Bighorn sheep inhabiting the Salmon
River drainage of Idaho occupy a region where over 64 percent of their
habitat has burned since 1900 [24].

Fire exclusion for over 50 years has allowed plant succession to alter
many bighorn sheep habitats throughout North America [6,7]. Fire
exclusion, which has allowed conifers to establish on grasslands, has
decreased both the forage and security values on many bighorn sheep
ranges [7].

Fire is an important factor in creating habitats that are heavily used
by bighorn sheep [6,27]. Periodic burning keeps seral grasslands from
becoming dominated by coniferous trees [27]. In April 1987, a
prescribed fire was conducted on 235 acres (95 ha) of bighorn sheep
winter range in Custer State Park, South Dakota. Burning expanded
foraging habitat for bighorn sheep by curtailing encroachment of
pondersosa pine (Pinus ponderosa) onto mixed-grass prairie.

Burning may regenerate rangelands and enhance the production,
availability, and palatability of important bighorn sheep forage species
[27]. Bighorn sheep heavily utilized burned winter range the following
two winters after a September 1974 fire on the East Fork of the Salmon
River, Idaho [19]. Over 66 percent of the plants on this burned range
had been grazed by bighorn sheep. Utilization was consistently higher
on burned sites than on adjacent unburned sites for at least 4 years
after the fire [19].

Burning can increase visibility for bighorn sheep. Research has shown
that on burned sites bighorn sheep use areas more distant to escape
terrain than on adjacent unburned sites [27].

Fire can negatively affect bighorn sheep habitat when range condition is
poor and forage species cannot recover, when nonsprouting species that
provide important forage for bighorn sheep are eliminated, or when too
much area is burned and forage is inadequate until the next growing
season. Another potentially negative effect is when other species,
especially elk, are attracted to prescribed burns intended to benefit
bighorn sheep [19].
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bibliographic citation
Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Cover Types

provided by Fire Effects Information System Animals
More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

204 Black spruce
205 Mountain hemlock
206 Engelmann spruce - subalpine fir
208 Whitebark pine
210 Interior Douglas-fir
218 Lodgepole pine
220 Rocky Mountain juniper
230 Douglas-fir - western hemlock
237 Interior ponderosa pine
238 Western juniper
239 Pinyon - juniper
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Ecosystem

provided by Fire Effects Information System Animals
More info on this topic.

This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

More info for the term: shrub

FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES23 Fir-spruce
FRES26 Lodgepole pine
FRES29 Sagebrush
FRES30 Desert shrub
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands
FRES44 Alpine
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Plant Associations

provided by Fire Effects Information System Animals
More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the terms: forest, shrub, woodland

K003 Silver fir - Douglas-fir forest
K004 Fir - hemlock forest
K005 Mixed conifer forest
K010 Ponderosa shrub forest
K011 Western pondersoa forest
K012 Douglas-fir forest
K015 Western spruce - fir forest
K016 Eastern ponderosa forest
K018 Pine - Douglas-fir forest
K019 Arizona pine forest
K020 Spruce - fir - Douglas-fir forest
K021 Southwestern spruce - fir forest
K022 Great Basin pine forest
K024 Juniper steppe woodland
K023 Juniper - pinyon woodland
K028 Mosaic of K002 and K026
K029 California mixed evergreen forest
K031 Oak - juniper woodlands
K032 Transition between K031 and K037
K035 Coastal sagebrush
K037 Mountain-mahogany - oak scrub
K038 Great Basin sagebrush
K039 Blackbrush
K040 Saltbush - greasewood
K041 Creosotebush
K042 Creosotebush - bursage
K047 Fescue - oatgrass
K050 Fescue - wheatgrass
K051 Wheatgrass - bluegrass
K053 Grama - galleta steppe
K054 Grama - tobosa prairie
K057 Galleta - three-awn shrubsteppe
K058 Grama - tobosa shrubsteppe
K059 Trans-Pecos shrub savanna
K052 Alpine meadows and barren
K063 Foothills prairie
K064 Grama - needlegrass - wheatgrass
K065 Grama - buffalograss
K066 Wheatgrass - needlegrass
K067 Wheatgrass - bluestem - needlegrass
K068 Wheatgrass - grama - buffalograss
K069 Bluestem - grama prairie
K070 Sandsage - bluestem prairie
K074 Bluestem prairie
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Management Considerations

provided by Fire Effects Information System Animals
More info for the terms: competition, density

Bighorn sheep are very susceptible to diseases. Incidence of lungworm
infestation approaches 100 percent in some herds, although the level of
individual infection varies depending upon sheep and domestic livestock
densities, range conditions, climate, season, and age. Desert bighorn
sheep appear to have lighter infestations, possibly due to climate or
low density. A significant correlation exists between the intensity of
the lungworm infestation and the amount of precipitation in the spring
of the previous year. In Washington state both wild and captive bighorn
sheep have been successfully treated with the experimental drug
albendazole. Further research is needed to determine the feasibility of
treating remote populations [6].

The future of bighorn sheep depends on the preservation and improvement
of critical native ranges. Bighorn sheep are poor competitors with
other wild and domestic ungulates, and their range is diminishing.
The effect of domestic livestock grazing on bighorn sheep is
controversial and depends on the proximity and population size of
competing species. Domestic livestock have been reported to have little
deleterious effect if they do not graze on critical bighorn sheep winter
ranges. Nevertheless, extensive competition by livestock, especially on
public lands, persists and is one of the reasons for the decline in
density of bighorn sheep populations [6]. Elk (Cervus elaphus) and deer
(Odocoileus virginianus and O. hemionus) can also be serious competitors
with bighorn sheep on marginal habitat [6,18].

Human activities on bighorn sheep range are the most widespread threat
to bighorn sheep [4]. These activies reduce the number of bighorn sheep
by decreasing habitat, causing bighorn sheep to reduce or terminate
their use of prime habitat, stop migration, or split from large herds
into smaller herds [4,26]. Human activities responsible for declines in
sheep use of an area include hiking and backpacking, snow skiing, water
skiing, fishing, motorbiking, four-wheel-drive vehicle use, construction
and use of roads, urban development, and recreational development. When
bighorn sheep are pushed from prime to marginal habitat, mortality
usually increases and productivity decreases. Some herds have adapted
to human activity [26].
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Occurrence in North America

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AZ
CA
CO
ID
MT
NM
NV
ND
OR
SD

TX
UT
WA
WY

AB
BC
MEXICO

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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Predators

provided by Fire Effects Information System Animals
Golden eagles (Aquila chrysaetos) occasionally threaten bighorn sheep
lambs, but are rarely successful in taking one. Bighorn sheep are an
incidental food item in the diet of grizzly or black bears (Ursus
arctos, U. americanus) and wolverines (Gulo gulo), and are generally
eaten only as carrion. Wolves (Canis lupus), coyotes (C. latrans),
mountain lions (Felis concolor), and bobcats (Lynx rufus) are other
predators of bighorn sheep [6,26]. The number of bighorn sheep taken by
predators is usually of little consequence to healthy populations.
Predators are most effective when locations of escape terrain or water
limit sheep movement and allow predators to concentrate hunting efforts
[26].

Bighorn sheep are hunted by humans. Hunting has traditionally been for
rams only and is further restricted by a 3/4 or full horn curl policy.
In the last few years most states and provinces have adopted more
stringent horn curl regulations. While the overall trend has been for
more restrictive hunting seasons, in some cases local situations have
dictated either sex or 1/2 curl ram seasons [6].
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Preferred Habitat

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More info for the term: grassland

Bighorn sheep inhabit remote mountain and desert regions. They are
restricted to semiopen, precipitous terrain with rocky slopes, ridges,
and cliffs or rugged canyons [6,26]. Forage, water, and escape terrain
are the most important components of bighorn sheep habitat [26].

Winter range - Generally, bighorn sheep have two distinct, separate
summer and winter ranges [6]. Most of the year is spent on the winter
range, where the elevation is typically below 10,826 feet (3,300 m).
The aspect is usually south or southwest. Rams often venture onto the
more open slopes, although rugged terrain is always nearby. Desert
bighorn sheep rarely stray far from the base of a mountain and usually
are found on eastern aspects, where they use dry gullies. During
severe weather, if snow becomes unusually deep or crusted, bighorn sheep
move to slightly higher elevations where wind and sunshine have cleared
the more exposed slopes and ridges [6].

Spring range - The spring range is generally characterized by the same
parameters as the winter range. However, bighorn sheep begin to respond
to local greenups along streambanks and valleys. Bighorn sheep use
areas around saltlicks heavily in the spring. Preferred lambing range
is in the most precipitous, inaccessible cliffs near forage, and
generally has a dry, southern exposure [6].

Summer range - In the summer, bighorn sheep are mostly found grazing on
grassland meadows and plateaus above timber. In early summer south and
southwestern exposures are most frequently utilized; however, in the
case of the desert bighorn sheep the eastern aspect is preferred. By
late summer the more northerly exposures are preferred [6]. Snow
accumulation seems to be the principal factor that triggers bighorn
sheep to move from summer to winter ranges [26].

Water - Bighorn sheep obtain water from dew, streams, lakes, springs,
ponds, catchment tanks, troughs, guzzlers, and developed seeps or
springs [26]. Alkaline water is not suitable. Bighorn sheep spend most
of their time within 1 mile (1.6 km) of water but have been located as
far as 2 miles (3.2 km) from water. Water sources more than 0.3 mile
(0.5 km) from escape terrain or surrounded by tall dense vegetation are
avoided by bighorn sheep [26]. Desert bighorn sheep primarily utilize
ephemeral water sources. They may drink every day if water is nearby,
but may go without water for up to 14 days in the dry season. Since
water is one of the major limiting factors of desert bighorn sheep,
management agencies have installed cisterns and other water developments
in critical areas [6].
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bibliographic citation
Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Regional Distribution in the Western United States

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More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
16 Upper Missouri Basin and Broken Lands
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Taxonomy

provided by Fire Effects Information System Animals
The currently accepted scientific name for the bighorn sheep is Ovis
canadensis Shaw [6,13]. Subspecies are listed below [13].

Ovis canadensis subsp. canadensis (Rocky mountain bighorn sheep)
Ovis canadensis subsp. auduboni Merriam (Audubon's bighorn sheep)
Ovis canadensis subsp. californiana Douglas (California bighorn sheep)
Ovis canadensis subsp. cremnobates Elliot (Peninsular desert bighorn sheep)
Ovis canadensis subsp. mexicana Merriam (Mexican desert bighorn sheep)
Ovis canadensis subsp. nelsoni Merriam (Nelson's Peninsular bighorn sheep)
Ovis canadensis subsp. sierrae (Sierra Nevada bighorn sheep)
Ovis canadensis subsp. weemsi Goldman (Weem's desert bighorn sheep)
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Timing of Major Life History Events

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More info for the term: polygamous

Breeding season - Bighorn sheep are polygamous. Ewes are monesterous.
Rams of most subspecies rut in November and December. However, desert
bighorn sheep may rut for up to 9 months, with rutting reaching a peak
in August and September [6].

Age at sexual maturity - The age at which ewes attain sexual maturity is
quite variable and is dependent mainly on their physical condition [6].
Most bighorn sheep become mature at 2.5 years of age. Large-bodied rams
may reach sexual maturity within 18 months, but smaller rams may take as
long as 36 months. Very old ewes generally do not breed [6].

Gestation and lambing - The gestation period is 5.5 to 6 months. The
majority of ewes give birth to one lamb per year. Lambing of northern
bighorn sheep occurs between late April and late June, with most lambs
born before the end of May. Desert bighorn sheep ewes give birth
throughout the year; however, the peak is from January to April [6].

Development of lambs - Bighorn sheep lambs are precocious and within a
day or so climb almost as well as their mothers. Within 2 weeks lambs
can eat grass. They are weaned between 1 and 7 months. By their second
spring bighorn sheep are totally independent of their mother. Ewes
reach their adult weight by 4 to 5 years of age, while rams do not
achieve maximum weight until they are 6 or 7 years old [6].

Life span - Mortality is high for bighorn sheep 1 to 2 years of age,
drops to a relatively low rate for 2 to 8 years of age, then increases
to a maximum for those older than 8 to 9 years. Bighorn sheep that live
past 8 or 9 years may live to 15 to 17 years of age, but 10 to 12
years is more common [6].

Bighorn sheep are territorial. By 4 years of age, individuals have
established home ranges that are utilized throughout their life span [6].
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

U.S. Federal Legal Status

provided by Fire Effects Information System Animals
Nelson's Peninsular and Sierra Nevada bighorn sheep are listed as Endangered [28].
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Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Use of Fire in Population Management

provided by Fire Effects Information System Animals
More info for the terms: competition, fire regime, shrub

Prescribed fire can be useful tool in managing bighorn sheep habitat
[19]. Prescribed burning has been widely used to increase the quantity
and nutritional quality of bighorn sheep forage throughout North America
[7].

Prescribed crown fires conducted in winter in mature conifer stands
adjacent to escape terrain may provide an inexpensive solution to
maintaining or establishing bighorn sheep winter range. In areas where
the available bighorn sheep range is large and provides alternative and
distant wintering sites, fires should be prescribed or located in areas
that would minimize the stress on sheep. Early spring fires,
particularly on south and southwest aspects, may provide more spring
forage than would otherwise be available for bighorn sheep [27].
Burning immature forests and scrublands adjacent to bighorn sheep winter
range could also provide migration corridors between winter and summer
ranges [24].

Prescribed burning has been used to establish and maintain subalpine
bighorn sheep range in British Columbia. According to Bentz and Woodard
[2], burning provides an economical method of converting subalpine
forests, which are of low value to bighorn sheep, to earlier seral plant
communities. On the British Columbia range, bighorn sheep used burned
sites more than adjacent unburned sites.

Since both positive and negative effects can occur from burning bighorn
sheep range, a well-thought-out plan must be developed before fire is
considered for use on their range. Plans must consider the following:

1) condition of plants
2) plant response to burning
3) adjacent conifers (The possibility of creating more open range exists
if conifer stands or tall shrub fields occur next to currently used ranges.)
4) limiting factors (factors that may limit bighorn sheep populations
should be identified, and an evaluation made as to how burning will
effect these limiting factors)
5) lungworm (lungworm infections can possibly be altered by reducing
bighorn sheep concentrations; however, if burns are small and
concentrate bighorn sheep, results could be negative. If burns disperse
populations, the effects could be positive)
6) competition from other ungulates attracted to burns [19]

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".
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bibliographic citation
Tesky, Julie L. 1993. Ovis canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Bighorn sheep

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For other uses, see Big Horn (disambiguation).

The bighorn sheep (Ovis canadensis)[5] is a species of sheep native to North America[6] named for its large horns. These horns can weigh up to 14 kg (30 lb), while the sheep themselves weigh up to 140 kg (300 lb).[7] Recent genetic testing indicates three distinct subspecies of Ovis canadensis, one of which is endangered: O. c. sierrae. Sheep originally crossed to North America over the Bering land bridge from Siberia; the population in North America peaked in the millions, and the bighorn sheep entered into the mythology of Native Americans. By 1900, the population had crashed to several thousand, due to diseases introduced through European livestock and overhunting.[8]

Taxonomy and genetics

Ovis canadensis is one of three species of mountain sheep in North America and Siberia; the other two species being O. dalli, which includes Dall sheep and Stone's sheep, and the Siberian snow sheep, O. nivicola. Wild sheep crossed the Bering land bridge from Siberia into Alaska during the Pleistocene (about 750,000 years ago) and subsequently spread through western North America as far south as Baja California and northwestern mainland Mexico.[9] Divergence from their closest Asian ancestor (snow sheep) occurred about 600,000 years ago.[10] In North America, wild sheep diverged into two extant species—Dall sheep, which occupy Alaska and northwestern Canada, and bighorn sheep, which range from southern Canada to Mexico.[11] However, the status of these species is questionable given that hybridization has occurred between them in their recent evolutionary history.[12]

Subspecies

Former

In 1940, Ian McTaggart-Cowan split the species into seven subspecies, with the first three being mountain bighorns and the last four being desert bighorns:[9]

  • Rocky Mountain bighorn sheep, O. c. canadensis, found from British Columbia to Arizona.
  • Badlands bighorn sheep or Audubon's bighorn sheep, O. c. auduboni, occurred in North Dakota, South Dakota, Montana, Wyoming, and Nebraska. This subspecies has been extinct since 1925.
  • California bighorn sheep, O. c. californiana, found from British Columbia south to California and east to North Dakota. The definition of this subspecies has been updated (see below).
  • Nelson's bighorn sheep, O. c. nelsoni, the most common desert bighorn sheep, ranges from California through Arizona.
  • Mexican bighorn sheep, O. c. mexicana, ranges from Arizona and New Mexico south to Sonora and Chihuahua.
  • Peninsular bighorn sheep O. c. cremnobates, occur in the Peninsular Ranges of California and Baja California
  • Weems' bighorn sheep, O. c. weemsi, found in southern Baja California.

Current

 src=
Female Rocky Mountain bighorn sheep (O. c. canadensis) in Yellowstone National Park

Starting in 1993, Ramey and colleagues,[10][13] using DNA testing, have shown this division into seven subspecies is largely illusory. Most scientists currently recognize three subspecies of bighorn.[14][15] This taxonomy is supported by the most extensive genetics (microsatellite and mitochondrial DNA) study to date (2016) which found high divergence between Rocky Mountain and Sierra Nevada bighorn sheep, and that these two subspecies both diverged from desert bighorn prior to or during the Illinoian glaciation (about 315–94 thousand years ago).[16] Thus, the three subspecies of O. canadensis are:

In addition, two populations are currently considered endangered by the United States government:[18]

  • Sierra Nevada bighorn sheep (O. c. sierrae),
  • Peninsular bighorn sheep, a distinct population segment of desert bighorn sheep (O. c. nelsoni)

Description

 src=
A juvenile (lamb)

Bighorn sheep are named for the large, curved horns borne by the rams (males). Ewes (females) also have horns, but they are shorter with less curvature.[19] They range in color from light brown to grayish or dark, chocolate brown, with a white rump and lining on the backs of all four legs. Males typically weigh 58–143 kg (128–315 lb), are 90–105 cm (35–41 in) tall at the shoulder, and 1.6–1.85 m (63–73 in) long from the nose to the tail. Females are typically 34–91 kg (75–201 lb), 75–90 cm (30–35 in) tall, and 1.28–1.58 m (50–62 in) long.[20] Male bighorn sheep have large horn cores, enlarged cornual and frontal sinuses, and internal bony septa. These adaptations serve to protect the brain by absorbing the impact of clashes.[21] Bighorn sheep have preorbital glands on the anterior corner of each eye, inguinal glands in the groin, and pedal glands on each foot. Secretions from these glands may support dominance behaviors.[21]

Bighorns from the Rocky Mountains are relatively large, with males that occasionally exceed 230 kg (500 lb) and females that exceed 90 kg (200 lb). In contrast, Sierra Nevada bighorn males weigh up to only 90 kg (200 lb) and females to 60 kg (140 lb). Males' horns can weigh up to 14 kg (30 lb), as much as the rest of the bones in the male's body.[22]

Natural history

Ecology

 src=
Bighorn rams

The Rocky Mountains and Sierra Nevada bighorn sheep occupy the cooler mountainous regions of Canada and the United States. In contrast, the desert bighorn sheep subspecies are indigenous to the hot desert ecosystems of the Southwestern United States and Mexico. Bighorn sheep generally inhabit alpine meadows, grassy mountain slopes, and foothill country near rugged, rocky cliffs and bluffs.[22] Since bighorn sheep cannot move through deep snow, they prefer drier slopes, where the annual snowfall is less than about 150 cm (60 in) per year.[22] A bighorn's winter range usually lies at lower elevations than its summer range.[23]

Bighorn sheep are highly susceptible to certain diseases carried by domestic sheep, such as scabies and pneumonia; additional mortality occurs as a result of accidents involving rock falls or falling off cliffs (a hazard of living in steep, rugged terrain). Bighorns are well adapted to climbing steep terrain, where they seek cover from predators. Predation primarily occurs with lambs, which are hunted by coyotes, bobcats, lynxes, and golden eagles.

Bighorn sheep of all ages are threatened by bears, wolves, and especially cougars, which are perhaps best equipped with the agility to prey on them in uneven, rocky habitats.[19][24][25] They are considered good indicators of land health because the species is sensitive to many human-induced environmental problems. In addition to their aesthetic value, bighorn sheep are considered desirable game animals by hunters.

Bighorn sheep graze on grasses and browse shrubs, particularly in fall and winter, and seek minerals at natural salt licks.[24] Females tend to forage and walk, possibly to avoid predators and protect lambs,[26] while males tend to eat and then rest and ruminate, which lends to more effective digestion and greater increase in body size.[26]

Social structure and reproduction

 src=
A bighorn ram following a juvenile ewe

Bighorn sheep live in large herds, and do not typically follow a single leader ram, unlike the mouflon, the ancestor of the domestic sheep, which has a strict dominance hierarchy. Prior to the mating season or "rut", the rams attempt to establish a dominance hierarchy to determine access to ewes for mating. During the prerut period, most of the characteristic horn clashing occurs between rams, although this behavior may occur to a limited extent throughout the year.[27] Bighorn sheep exhibit agonistic behavior: two competitors walk away from each other and then turn to face each other before jumping and lunging into headbutts.[28] Rams' horns can frequently exhibit damage from repeated clashes.[24] Females exhibit a stable, nonlinear hierarchy that correlates with age.[29] Females may fight for high social status when they are integrated into the hierarchy at one to two years of age.[29]

Rocky Mountain bighorn rams employ at least three different courting strategies.[30] The most common and successful is the tending strategy, in which a ram follows and defends an estrous ewe.[30] Tending takes considerable strength and dominance, so ewes are more receptive to tending males, feeling they are the most fit. Another tactic is coursing, which is when rams fight for an already tended ewe.[30] Ewes typically avoid coursing males, so the strategy is not effective. Rams also employ a blocking strategy. They prevent a ewe from accessing tending areas before she even goes into estrus.[30]

Bighorn ewes have a six-month gestation. In temperate climates, the peak of the rut occurs in November with one, or rarely two, lambs being born in May. Most births occur in the first two weeks of the lambing period. Pregnant ewes of the Rocky Mountains migrate to alpine areas in spring, presumably to give birth in areas safer from predation,[31] but are away from areas with good quality forage.[31] Lambs born earlier in the season are more likely to survive than lambs born later.[32] Lambs born late may not have access to sufficient milk, as their mothers are lactating at a time when food quality is lower.[32] Newborn lambs weigh from 3.6 to 4.5 kg (8 to 10 lb) and can walk within hours. The lambs are then weaned when they reach four to six months old. The lifespan of rams is typically 9–12 years, and 10–14 years for ewes.[19]

Infectious disease

 src=
Skull

Many bighorn sheep populations in the United States experience regular outbreaks of infectious pneumonia,[33][34][35][36] which likely result from the introduction of bacterial pathogens (in particular, Mycoplasma ovipneumoniae,[37][38] and some strains of Mannheimia haemolytica)[39] carried asymptomatically in domestic sheep.[40] Once introduced, pathogens can transmit rapidly through a bighorn population, resulting in all-age die-offs that sometimes kill up to 90% of the population. In the years following pathogen introduction, bighorn populations frequently experience multiple years of lamb pneumonia outbreaks. These outbreaks can severely limit recruitment and likely play a powerful role in slowing population growth.[36]

Relationship with humans

 src=
A petroglyph of a caravan of bighorn sheep near Moab, Utah, United States, a common theme in glyphs from the desert southwest

Two hundred years ago, bighorn sheep were widespread throughout the western US, Canada, and northern Mexico. Some estimates placed their population at over 2 million. By around 1900, hunting, competition from ranching, and diseases had decreased the population to several thousand. A program of reintroductions, natural parks, and reduced hunting, together with a decrease in domesticated sheep near the end of World War II, allowed the bighorn sheep to make a comeback. In 2009, the California Department of Fish and Game issued 21 permits for the hunting of bighorn sheep, and 19 permits for the 2010–11 hunting season.[41]

Scouting

In 1936, the Arizona Boy Scouts mounted a statewide campaign to save the bighorn sheep. The scouts first became interested in the sheep through the efforts of Major Frederick Russell Burnham, the noted conservationist who has been called the "Father of Scouting".[42] Burnham observed that fewer than 150 of these sheep still lived in the Arizona mountains. He called George F. Miller, then scout executive of the Boy Scout council headquartered in Phoenix, with a plan to save the sheep. Burnham put it this way, "I want you to save this majestic animal, not only because it is in danger of extinction, but of more importance, some day it might provide domestic sheep with a strain to save them from disaster at the hands of a yet unknown virus."[43]

Several other prominent Arizonans joined the movement, and a "save the bighorns" poster contest was started in schools throughout the state. Burnham provided prizes and appeared in store windows across Arizona. The contest-winning bighorn emblem was made into neckerchief slides for the 10,000 Boy Scouts, and talks and dramatizations were given at school assemblies and on radio. The National Wildlife Federation, the Izaak Walton League, and the National Audubon Society also joined the effort.[43]

These efforts led to the establishment of two bighorn game ranges in Arizona: Kofa National Wildlife Refuge and Cabeza Prieta National Wildlife Refuge. On January 18, 1939, over 6,000 square kilometres (1,500,000 acres) of land were set aside and a civilian conservation corps side camp was set up to develop high-mountain waterholes for the sheep. The desert bighorn sheep is now the official mascot for the Arizona Boy Scouts.[43]

In culture

 src=
Bighorn sheep

Bighorn sheep were among the most admired animals of the Apsaalooka (Crow) people, and what is today called the Bighorn Mountain Range was central to the Apsaalooka tribal lands. In the Bighorn Canyon National Recreation Area book, storyteller Old Coyote describes a legend related to the bighorn sheep. A man possessed by evil spirits attempts to kill his heir by pushing the young man over a cliff, but the victim is saved by getting caught in trees. Rescued by bighorn sheep, the man takes the name of their leader, Big Metal. The other sheep grant him power, wisdom, sharp eyes, sure-footedness, keen ears, great strength, and a strong heart. Big Metal returns to his people with the message that the Apsaalooka people will survive only so long as the river winding out of the mountains is known as the Bighorn River.[44]

Bighorn sheep are hunted for their meat and horns, which are used in ceremonies, as food, and as hunting trophies. They also serve as a source of ecotourism, as tourists come to see the bighorn sheep in their native habitat.[45]

The Rocky Mountain bighorn sheep is the provincial mammal of Alberta and the state animal of Colorado and as such is incorporated into the symbol for the Colorado Division of Parks and Wildlife.[46]

Bighorn sheep were once known by the scientific identification "argali" or "argalia" due to assumption that they were the same animal as the Asiatic argali (Ovis ammon).[47] Lewis and Clark recorded numerous sightings of O. canadensis in the journals of their exploration—sometimes using the name argalia. In addition, they recorded the use of bighorn sheep horns by the Shoshone in making composite bows.[48] William Clark's Track Map produced after the expedition in 1814 indicated a tributary of the Yellowstone River named Argalia Creek and a tributary of the Missouri River named Argalia River, both in what is today Montana. Neither of these tributaries retained these names, however. The Bighorn River, another tributary of the Yellowstone, and its tributary stream, the Little Bighorn River were both indicated on Clark's map and did retain their names, the latter being the namesake of the Battle of the Little Bighorn.[49]

References

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Bighorn sheep: Brief Summary

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For other uses, see Big Horn (disambiguation).

The bighorn sheep (Ovis canadensis) is a species of sheep native to North America named for its large horns. These horns can weigh up to 14 kg (30 lb), while the sheep themselves weigh up to 140 kg (300 lb). Recent genetic testing indicates three distinct subspecies of Ovis canadensis, one of which is endangered: O. c. sierrae. Sheep originally crossed to North America over the Bering land bridge from Siberia; the population in North America peaked in the millions, and the bighorn sheep entered into the mythology of Native Americans. By 1900, the population had crashed to several thousand, due to diseases introduced through European livestock and overhunting.

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