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BC Conservation Data Centre: Species Summary


Ovis dalli
Thinhorn Sheep

 
Scientific Name: Ovis dalli Nelson, 1884
English Name: Thinhorn Sheep
 
Classification / Taxonomy
Scientific Name - Concept Reference: 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/.
Classification Level: Species
Species Group: Vertebrate Animal
Species Code: M-OVDA
Kingdom Phylum Class Order Family
Animalia Craniata Mammalia Artiodactyla Bovidae
   
Conservation Status / Legal Designation
Global Status: G5 (Apr 2016)
Provincial Status: S4 (Feb 2015)
BC List: No Status
Provincial FRPA list:   
Provincial Wildlife Act:
COSEWIC Status:
SARA Schedule:
General Status Canada: 4 - Secure (2005)
   
Ecology & Life History
General Description:
Global Reproduction Comments: Monestrous. Breeds November-December. Gestation lasts 5.5-6 months. Usually single young is born late April-late June; most births before end of May (peak in May in central Alaska). Young are able to travel with mother within 24 hours, weaned in 3-5 months. Most females breed at 1 year. Females may not breed every year, especially in low quality habitats. Males physiologically mature as early as second year, but generally are precluded from breeding until several years old by older males.
Global Ecology Comments: Gregarious. Up to 19-23 individuals per sq km on northern winter ranges. Adult bands are segregated by sex. Largest bands are composed of females and young; males are more solitary (Lawson and Johnson 1982). Mortality of young may be 40-50% by end of first winter in populations near carrying capacity. Severe winters may cause population declines. Wolf predation may limit some populations. Maximal annual rate of increase for unhunted populations is 11-18%. Generally does not compete with other native ungulates, but feral horses may compete. See Bowyer and Leslie (1992).
Migration Characteristics:
(Global / Provincial)		 
    Nonmigrant:
    Local Migrant:
    Distant Migrant:
    Within Borders Migrant: 		Y /
Y /
N /
na /
Global Migration Comments: Migrates to higher elevations in spring, to lower elevations in fall. Exhibits high degree of fidelity to seasonal home ranges. Some populations do not migrate between seasonal ranges.
Habitats:
(Type / Subtype / Dependence) 		Alpine/Tundra / Krummholtz / Facultative - frequent use
Alpine/Tundra / Tundra / Facultative - frequent use
Forest / Conifer Forest - Dry / Facultative - occasional use
Forest / Conifer Forest - Mesic (average) / Facultative - occasional use
Grassland/Shrub / Grassland / Facultative - frequent use
Grassland/Shrub / Meadow / Facultative - frequent use
Grassland/Shrub / Shrub - Logged / Facultative - occasional use
Grassland/Shrub / Shrub - Natural / Facultative - occasional use
Other Unique Habitats / Avalanche Track / Facultative - frequent use
Rock/Sparsely Vegetated Rock / Cliff / Obligate
Rock/Sparsely Vegetated Rock / Rock/Sparsely Vegetated Rock / Obligate
Rock/Sparsely Vegetated Rock / Talus / Obligate
Global Habitat Comments: Typically in semiopen, precipitous terrain with rocky slopes, ridges, and cliffs or rugged canyons; dry mountainous terrain, subalpine grass-low shrub communities. Attracted to mineral licks. In winter, attracted to areas with little or no snow cover. Females rely on precipitous mountain areas for escape cover during lambing period (Lawson and Johnson 1982).
Food Habits: Herbivore: Adult, Immature
Global Food Habits Comments: Eats mainly grasses (fescues), sedges, and forbs in summer. Willow, horseweed (Erigeron), and alpine fireweed important in spring and summer. Relishes horsetail and Richardson's saxifrage. Woody plants important in winter. Uses mineral licks high in calcium-phosphate or calcium-magnesium.
Global Phenology: Diurnal: Adult, Immature
Global Phenology Comments: Little nocturnal activity (Lawson and Johnson 1982).
Provincial Phenology:
(1st half of month/
2nd half of month)
Colonial Breeder: N
Length(cm)/width(cm)/Weight(g): 153/ / 90000
Elevation (m) (min / max): Global: 
Provincial: 
   
 
Distribution
Endemic: N
Global Range Comment: Extensive areas of Brooks and Alaska ranges in Alaska, Kenai Peninsula, and MacKenzie and Rocky mountains in western Canada (Yukon and Northwest Territories south to Peace River in British Columbia); many southern populations are isolated.
 
Authors / Contributors
Global Information Author: Hammerson, G.
Last Updated: Nov 23, 1993
Provincial Information Author:
Last Updated:
   
References and Related Literature
Bowyer, R. T., and D. M. Leslie, Jr. 1992. Ovis dalli. Am. Soc. Mamm., Mammalian Species No. 393:1-7.
Dalle-Molle, J., and J. Van Horn. 1991. Observations of vehicle traffic interfering with migration of Dall's sheep, OVIS DALLI DALLI, in Denali National Park, Alaska. Can. Field-Nat. 105:409-411.
Demarchi, R.A., and C.L. Hartwig. 2004. Status of Thinhorn Sheep in British Columbia. B.C. Minist. Water, Land and Air Prot,.Biodiversity Branch, Victoria, BC. Wild. Bull. No. B-119.

Georgiadis, N. J., P. Kat, H. Oketch, and J. Patton. 1991. Allozyme divergence within the Bovidae. Evolution 44:2135-2149.
Hoefs, M. and I.M. Cowan. 1980. Ecological investigations ofa population of Dall Sheep-Ovis dalli dalli (Nelson). 81 pp.
Hoefs, M., and M. Bayer. 1983. Demographic characteristicsof an unhunted Dall sheep (OVIS DALLI DALLI) population in southwest Yukon, Canada. Can. J. Zool. 61:1346-1357.
Jones, J. K., Jr., R. S. Hoffman, D. W. Rice, C. Jones, R. J. Baker, and M. D. Engstrom. 1992a. Revised checklist of North American mammals north of Mexico, 1991. Occasional Papers, The Museum, Texas Tech University, 146:1-23.
Kraus, F., and M. M. Miyamoto. 1991. Rapid cladogenesis among the pecoran ruminants: evidence from mitochondrial DNA sequences. Systematic Zoology 40:117-130.
Lawson, B., and R. Johnson. 1982. Mountain sheep. Pages 1036-1055 in Chapman, J. A., and G. A. Feldhamer, eds. Wild mammals of North America. Biology, management, and economics. Johns Hopkins Univ. Press, Baltimore.
Murphy, E. C., F. J. Singer, and L. Nichols. 1990. Effects of hunting on survival and productivity of Dall sheep. J. Wildl. Manage. 54:284-290.
Whitaker, J. O., Jr. 1980. The Audubon Society field guide to North American mammals. Alfred A. Knopf, New York. 745 pp.
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/.
 

Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.

Suggested Citation:

B.C. Conservation Data Centre. 1993. Species Summary: Ovis dalli. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 8, 2026).