bighorn or Rocky Mountain sheep, wild sheep, Ovis canadensis, of W North America, formerly plentiful in mountains from SW Canada to N Mexico. Indiscriminate hunting, disease, and scarcity of food enormously reduced its numbers by the mid-20th cent., and in many areas of its former range it was exterminated. Since the late 20th cent., it has been reintroduced into parts of its former range, though its numbers and range remained greatly reduced compared to the early 1800s. The bighorn is a heavy, grayish brown animal, with a conspicuous whitish patch on its hindquarters; the male has heavy, curling horns, while the female has short, straight spikes. Two types of bighorn lives at high altitudes in the W United States (one restricted to the Sierra Nevada range) and a third type in desert regions. The similar Dall, or white, sheep, O. dalli, of Alaska, Yukon, and British Columbia, is white to slate-brown; the slate-brown type of British Columbia is also known as the Stone, or black, sheep. Bighorn sheep are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Artiodactyla, family Bovidae.
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