Dall Sheep ram at the Alaska Zoo in Anchorage, Alaska.
The Dall Sheep (originally Dall's Sheep, sometimes called Thinhorn Sheep), Ovis dalli, is a wild sheep of the mountainous regions of northwest North America, ranging from white to slate brown and having curved yellowish brown horns. Edward William Nelson ( May 8, 1855 - May 19, 1934) was an American naturalist and ethnologist. There are two putative subspecies: the northern Dall Sheep proper (Ovis dalli dalli) which is almost pure white, and the more southern Stone Sheep (also spelled Stone's Sheep) (Ovis dalli stonei), which is a slaty brown with some white patches on the rump and inside the hind legs.
Research has shown that the use of these subspecies designations is questionable. Complete colour integradation occurs between white and dark morphs of the species with intermediately coloured populations, called Fannin's Sheep (Ovis dalli fannini), found in the Pelly Mountains and Ogilvie Mountains of Yukon Territory. The Pelly Mountains are a Mountain range in the Yukon, Canada.  Mitochondrial DNA evidence has shown no molecular division along current subspecies boundaries, although evidence from nuclear DNA may provide some support.  Also at the species level current taxonomy is questionable because hybrdization between Ovis dalli and Ovis canadensis has been recorded in recent evolutionary history. 
The latter half of the Latin binomial dalli is derived from William Healey Dall (1845-1927), an American naturalist. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. In Elementary algebra, a binomial is a Polynomial with two terms the sum of two Monomials It is the simplest kind of polynomial except for a monomial William Healey Dall, ( August 21, 1845 - March 27, 1927) was a great American naturalist and a prominent malacologist The common name Dall Sheep or Dall's Sheep is often used to refer to the species Ovis dalli. An alternative use of common name terminology is that Thinhorn Sheep refers to the species Ovis dalli, while Dall's Sheep and Stone's Sheep refer to subspecies Ovis dalli dalli and Ovis dalli stonei.
The sheep inhabit the subarctic mountain ranges of Alaska, the Yukon Territory, the Mackenzie Mountains in the western Northwest Territories, and northern British Columbia. The Subarctic is a region in the Northern Hemisphere immediately south of the true Arctic and covering much of Alaska, Canada and Alaska ( Аляска Alyaska) is a state in the United States of America, in the northwest of the North American continent Yukon (ˈjuːkɒn is the westernmost and smallest of Canada's three territories. The Mackenzie Mountains are a Mountain range forming part of the Yukon - Northwest Territories boundary between the Liard and Peel rivers The Northwest Territories (ˌnɔrθˌwɛstˈtɛrɨtɔriz ( NWT or NT; French, les Territoires du Nord-Ouest) is a territory British Columbia (ˌbrɪtɨʃ kəˈlʌmbiə ( BC) ( (la Colombie-Britannique C Dall sheep are found in relatively dry country and try to stay in a special combination of open alpine ridges, meadows, and steep slopes with extremely rugged ground in the immediate vicinity, in order to escape from predators that cannot travel quickly through such terrain.
Male Dall Sheep have thick curling horns. The females have shorter, more slender, slightly curved horns. Males live in bands which seldom associate with female groups except during the mating season in late November and early December. Lambs are born in May.
During the summer when food is abundant, the sheep eat a wide variety of plants. During the winter diet is much more limited and consists primarily of dry, frozen grass and sedge stems available when snow is blown off, lichen and moss. Many Dall Sheep populations visit mineral licks during the spring and often travel many miles to eat the soil around the licks.
The primary predators of Dall Sheep are wolves, coyotes, black bears, and grizzly bears; golden eagles are predators of the young. The grey wolf or gray wolf ( Canis lupus) also known as the timber wolf or simply wolf, is a Mammal of the order Carnivora The coyote (kaɪˈoʊti ˈkaɪoʊt ( Canis latrans) also known as the prairie wolf, is a Mammal of the order Carnivora The American Black Bear ( Ursus americanus) is the most common Bear Species native to North America. The Brown Bear ( Ursus arctos) is an Omnivorous Mammal of the family Ursidae, distributed across much of northern Eurasia and The Golden Eagle ( Aquila chrysaetos) is one of the best known birds of prey in the Northern Hemisphere
Dall Sheep can often be observed along the Alaska Highway at Muncho Lake and at Sheep Mountain in Kluane National Park and Reserve, as well as near Faro, Yukon (Fannin's Sheep). The Alaska Highway (also known as the Alaskan Highway, Alaska-Canadian Highway, or ALCAN Highway) was constructed during World War II and connects Kluane National Park and Reserve are two units of Canada's national park system located in the extreme southwestern corner of Yukon Territory Faro is a small Town in the central Yukon, Canada, formerly the home of the largest open pit Lead - Zinc mine in the world as well as