The mountainous terrain in the northern third of the province is home to British Columbia’s approximately 12,250 Thinhorn Sheep (Ovis dalli).
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About the size of domestic sheep, these hardy animals are called “thinhorns” because the horns of the males, or rams, are more slender and sharply pointed than those of the more familiar Bighorn Sheep of southern British Columbia and the western United States.
There are two subspecies of Thinhorn Sheep with strongly contrasting colouration:
- The pure white Dall’s Sheep (Ovis dalli dalli), and
- The almost black Stone’s Sheep (Ovis dalli stonei)
Dall’s Sheep have golden-yellow horns that often flare more widely than the horns of Stone’s Sheep.
Thinhorn rams are larger than the ewes (females) and have much larger horns:
- Rams stand about 90 cm high at the shoulder
- Weigh up to 110 kg, and
- Have horns as long as 122 cm from base to tip
The rams’ amber-coloured horns are roughly triangular in cross-section and grow throughout life, although they grow most during the first six to eight years. The horns grow rapidly in summer and slowly in winter, and the difference produces prominent rings or “annuli” that show the animal’s age.
The slender horns of ewes grow slowly and never get more than about 25 cm long. The rings on a ewe’s horn are a less accurate reflection of age than the rings of a ram’s horns because they are so close together.
Thinhorn sheep are found in mountainous regions of northwestern North America and occupy some of the most expansive, rugged and picturesque landscapes on the continent.
Dall’s Sheep’s range extends into the Tatsenshini River region in the extreme northwestern corner of British Columbia. Only 200 to 300 Dall’s Sheep winter in this area, but a few Yukon animals may also summer there. Bennett Lake, about 80 km west of Atlin, is the approximate boundary between Dall’s and Stone’s Sheep in northwestern British Columbia.
Almost the complete global population of Stone’s Sheep occurs in British Columbia. Here, they are distributed along the interior side of the Coast Range from the Yukon border to the vicinity of Mount Edziza and Spatsizi parks in the Stikine drainage and eastward into the Cassiar, Omineca, Muskwa, and northern Rocky Mountain ranges. The Pine River valley is the approximate dividing line between Thinhorn and Bighorn Sheep in British Columbia. Recent genetic research has shown that over 90% of the global population of Stone’s sheep live in B.C. (Sim et al 2016 and 2018).