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Home/Species/ Thinhorn Sheep

Ovis dalli

Nelson, 1884

Thinhorn Sheep

G5Secure Found in 9 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
Least concernIUCN
Identity
Unique IDELEMENT_GLOBAL.2.101667
Element CodeAMALE04020
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassMammalia
OrderArtiodactyla
FamilyBovidae
GenusOvis
Other Common Names
Dall's Sheep (EN) Mouflon de Dall (FR)
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/.
Taxonomic Comments
Grubb (in Wilson and Reeder 2005) did not recognize kenaiensis as a valid subspecies.
Conservation Status
Rank MethodExpertise without calculation
Review Date2016-04-04
Change Date1996-11-19
Range Extent Comments
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.
Threat Impact Comments
Population decline in southwestern Yukon was attributed to impact of feral horses (Hoefs and Bayer 1983). Dalle-Molle and Van Horn (1991) noted that, in some circumstances, vehicle traffic may interfere with seasonal migrations.
Ecology & Habitat

Habitat

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).

Ecology

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).

Reproduction

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.
Terrestrial Habitats
Grassland/herbaceousAlpineBare rock/talus/screeCliff
Other Nations (2)
CanadaN4
ProvinceRankNative
Yukon TerritoryS4Yes
British ColumbiaS4Yes
Northwest TerritoriesS4Yes
United StatesN5
ProvinceRankNative
AlaskaS5Yes
Roadless Areas (9)
Alaska (9)
AreaForestAcres
Boston BarChugach National Forest53,617
College FiordChugach National Forest1,130,818
Johnson PassChugach National Forest152,508
Kenai LakeChugach National Forest213,172
Kenai MountainsChugach National Forest306,600
Nellie JuanChugach National Forest713,697
ResurrectionChugach National Forest224,615
Roaded DonutChugach National Forest968
Twenty MileChugach National Forest198,775
References (14)
  1. American Society of Mammalogists (ASM). 2025. Mammal Diversity Database (Version 1.13) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.10595931. Online. Available: https://www.mammaldiversity.org/
  2. Bowyer, R. T., and D. M. Leslie, Jr. 1992. Ovis dalli. Am. Soc. Mamm., Mammalian Species No. 393:1-7.
  3. Bradley, R.D., L.K. Ammerman, R.J. Baker, L.C. Bradley, J.A. Cook. R.C. Dowler, C. Jones, D.J. Schmidly, F.B. Stangl Jr., R.A. Van den Bussche and B. Würsig. 2014. Revised checklist of North American mammals north of Mexico, 2014. Museum of Texas Tech University Occasional Papers 327:1-28. Available at: http://www.nsrl.ttu.edu/publications/opapers/ops/OP327.pdf
  4. 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.
  5. Georgiadis, N. J., P. Kat, H. Oketch, and J. Patton. 1991. Allozyme divergence within the Bovidae. Evolution 44:2135-2149.
  6. Hoefs, M. and I.M. Cowan. 1980. Ecological investigations ofa population of Dall Sheep-Ovis dalli dalli (Nelson). 81 pp.
  7. 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.
  8. 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.
  9. Kraus, F., and M. M. Miyamoto. 1991. Rapid cladogenesis among the pecoran ruminants: evidence from mitochondrial DNA sequences. Systematic Zoology 40:117-130.
  10. 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.
  11. 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.
  12. Whitaker, J. O., Jr. 1980. The Audubon Society field guide to North American mammals. Alfred A. Knopf, New York. 745 pp.
  13. 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/.
  14. Wilson, D. E., and D. M. Reeder (editors). 2005. Mammal species of the world: a taxonomic and geographic reference. Third edition. The Johns Hopkins University Press, Baltimore. Two volumes. 2,142 pp. [As modified by ASM the Mammal Diversity Database (MDD) at https://www.mammaldiversity.org/index.html]