Stone Sheep

Ovis dalli stonei

Description

Stone sheep have sexual dimorphic horns, females have slender horns while males have massive, flaring, and curled horns. Males can grow to be 1.3-1.8 meters long and weigh 73-113 kg, which is 40% heavier than females (46-50 kg) that can grow to be 1.32-1.62 meters long. This species has a fine wool undercoat and stiff, long, hollow guard hairs. A stone sheep’s coat is usually grey to black in color while the inside of the ears appear to be white. The belly, rump patch and backs of the legs are white while the tail is black.

Habitat

This species can be found in western Canada and the United States. Populations can be seen in the mountain ranges of the northeast, central and southern Alaska as well as the Yukon Territory, the northwest corner of British Columbia and southwest of the Mackenzie River in the Northwest Territories. Stone sheep can survive in a variety of habitats including the arctic and sub-arctic regions but prefer alpine habitat upon mountain regions with sub-alpine grass and low shrub communities. Stone sheep require steep, rugged cliffs and outcrops with nearby open grass and meadows. They also prefer areas of light snowfall with strong winds in the winter that remove snow, exposing forage. Populations have distinct summer and winter ranges.

Feeding Behavior and Diet

This species is an herbivore, consuming only vegetation. Stone sheep graze for grasses and sedges. They can consume 50-120 species of vegetation in the summer. They will also consume lichens and mosses in small quantities. Feeding occurs in open grasses and meadows.

Reproduction

Stone sheep are polygynous, which means the males have multiple mating partners. Single lambs are produced annually (twins rarely occur) with a gestation period of 175 days, born in late May or early June. Ewes (females) remain in cliffs until young are strong enough to travel. Lambs are able to consume vegetation within two weeks but are not weaned for an additional 3-5 months. Females reach sexual maturity after 30 months but do not have their first lamb until they are 3-4 years old.

Months and Times of Activity

Summer and winter migrations correlate with temperature, snow depth, and vegetation conditions. Rams (males) live in bachelor bands and do not associate with females until late November and early December.

Special Features, Stories, Relationships

•    Stone sheep are a subspecies of Dall’s sheep.
•    Ovis dalli is the only species of thinhorn mountain sheep. The male’s horns after 4-5 years can become 8-10% of his body weight. The horns of a stone sheep can be used to determine age by counting the annuli (rings).
•    Males have a double layer of bone on their skulls to absorb heavy impacts or butting heads during breeding season. Clashing of horns from these battles can be heard a kilometer away.
•    Stone sheep use steep cliffs and outcrops to escape predators.
•    To read legends featuring this animal go to; http://www.firstpeople.us/FP-Html-Legends/CoyoteAndMountainSheep-PenDOreille.html

References

Gozdzik, A. 2001. "Ovis dalli" (On-line), Animal Diversity Web. Accessed November 04, 2014 at http://animaldiversity.ummz.umich.edu/accounts/Ovis_dalli/