Big Horn Sheep 2011

Big Horn Sheep 2007

Yellowstone 2007

Big Horn Sheep Mother and Fawn 2007

Mother with Fawn 2007

Big Horn Sheep Female 2011

Female Yellowstone 2011

Yellowstone National Park, Blacktail Deer Plateau 2007 & Soda Butte 2011

They live in two worlds. For feeding they prefer the open meadows that support grasses and sedges, but for safety they are at home on steep slopes, rocky outcroppings and ledges. We saw them mainly in the Northern portion of the park between Gardiner and Black Deer Plateau. When they are high on a steep cliff you can really see how well they camouflage themselves against the dusty beige rocks and dirt.

Bighorn Sheep (Ovis canadensis) is a species of sheep in North America and Siberia with large horns which can weigh up to 30 lb (14 kg). Recent genetic testing indicates that there are three distinct subspecies of Ovis canadensis, one of which is endangered: Ovis canadensis sierrae.

The Bighorn Sheep originally crossed over the Bering land bridge from Siberia: the population in North America peaked in the millions, and the Bighorn Sheep entered into the mythology of Native Americans. However, the population crashed by 1900 down to several thousand. Conservation efforts (in part, due to the Boy Scouts) have restored the population.

Bighorn Sheep are named for the large, curved horns borne by the males, or rams. Females, or ewes, also have horns, but they are short with only a slight curvature. They range in colour from light brown to grayish or dark, chocolate brown, with a white rump and lining on the back of all four legs. Rocky Mountains bighorn females weigh up to 200 lb (90 kg), and males occasionally exceed 500 lb (230 kg). In contrast, Sierra Nevada bighorn females weigh about 140 lb (60 kg) with males weighing around 200 lb (90 kg). Males' horns can weigh up to 30 lb (14 kg), as much as the rest of the bones in the male's body.

Bighorn sheep graze on grasses and browse shrubs, particularly in fall and winter, and seek minerals at natural salt licks. Bighorns are well adapted to climbing steep terrain where they seek cover from predators such as coyotes, eagles, and cougars. They live in large herds, but do not have the strict dominance hierarchy of the mouflon: that is, they do not automatically follow a single leader ram, unlike the Asiatic ancestors of the domestic sheep.

Prior to the mating season or "rut", the rams attempt to establish a dominance hierarchy that determines access to ewes for mating. It is during the prerut period that most of the characteristic horn clashing occurs between rams, although this behavior may occur to a limited extent throughout the year. Ram's horns can frequently exhibit damage from repeated clashes. Bighorn ewes exhibit a six-month gestation. In temperate climates, the peak of the rut occurs in November with one, or rarely two, lambs being born in May. The lambs are then weaned when they reach 4-6 months.

Bighorn sheep are highly susceptible to certain diseases carried by domestic sheep such as scabies and pneumonia; additional mortality occurs as a result of accidents involving rock fall or falling off cliffs (a hazard of living in steep, rugged terrain).

Big Horn Sheep Range

Range Map

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