
The bighorn sheep is aptly named for the ram’s magnificent curved horns. During the breeding season rams use their horns in fierce – and sometimes deadly – combat with rival males. The bighorn sheep once inhabited a range from southwest Canada through California to northern Mexico. But today the bighorn is found wild in only a few areas as a result of habitat destruction, excessive hunting, and competition from domestic sheep for grazing land.
Habitat: The bighorn sheep is found on dry, remote mountain cliffs. Much of its habitat is high, rocky desert where it jumps from rock to rock. The bighorn associates in herds, usually of about 10 males or ewes with young of up to two years old. In the fall the rams join the herds of ewes to form groups of up to 100, and they move together to the lower valleys. In the spring they all move to the high slopes for summer grazing, although the males break off into all-male groups again. An adult bighorn is alert to danger even while grazing. At the slightest alarm, it snorts a warning to the others, and the herd bounds away to safety.
Food and Feeding: The bighorn feeds on various grasses, young plants, and leaves. During winter it eats woody plants. In desert areas it eats shrubs and cacti. Like all sheep, the bighorn digests its food in a four-chambered stomach, which allows it to eat even the toughest plants. The bighorn wanders as it feeds. Its route is determined by its search for food and water. It feeds mainly in early morning and evening. After grazing it chews the cud while resting in a location that offers a good view of the surrounding area.
Breeding: The mating season generally occurs between August and January, when the rams have joined the herds of ewes. Competition for the females is fierce between the older rams. They charge each other, crashing and licking horns during fights that may last for several hours and sometimes result in death. The ram with the largest horns usually wins the fight – and the female. Five to six months after mating, the pregnant ewe gives birth on a remote crag. Usually a single lamb is born, but sometimes there are twins. The lamb has a soft, light-colored coat and small horn buds. After a week the lamb follows the herd, staying constantly by its mother’s side. By the time it is weaned at five to six months old, it is nibbling grasses and leaves.
Key Facts: Sizes, Breeding, Lifestyle, and
Related Species:
Sizes:
Height to shoulder: 2 ½ -3
½ ft.
Length: 4-5 ft.
Weight: Male, 125-275 lb. Female, 75-150
lb.
Breeding:
Sexual maturity: 3-4 years
Mating season: Late fall to early winter
Gestation: 5-6 months
No. of young: 1, occasionally twins
Lifestyle:
Habit: Day-active; associates in herds.
Moves to high ground in winter
Diet: Grasses and leaves
Lifespan: About 15-20 years
Related Species: There are 8 species in
the genus. Dall’s sheep, Ovis dalli, is the only other species in North
America.
Distribution: Once widespread from Canada
to California and Mexico. Now found only in remote, wild mountainous areas
and in national parks such as Yellowstone.
Conservation: Habitat destruction, competition
with domestic livestock, disease, and excessive hunting have made the bighorn
sheep extinct over much of its former range.
Features of the Bighorn Sheep:
Rump: White patch characteristic of species.
Weaker animal turns rump to stronger animal to show submission.
Stomach: Four-chambered. Allows bighorn
to digest the high cellulose content of its diet. After swallowing, the
sheep regurgitates food and chews it as cud to break it down further before
swallowing for final digestion.
Coat: Coarse and short. Juvenile has woolly
coat like that of domestic sheep.
Hooves: Cloven. Spongy pads in center
give good grip on rocky surfaces.
Growth of Horns:
Two years: Horns have started to curl
away from head
Six years: Horns have begun to curl back on themselves
Twelve years: Ram will be socially dominant
with horns at full length. Growth rate slows
Did You Know:
When a ram’s long horns block his vision, he
rubs off the tips on a rock.
The bighorn’s steps measure approximately 18
inches when walking, 10 feet when bounding on level ground, and 16 feet
when bounding down a steep hill.
During the rutting season rams charge each other
at over 20 miles per hour. Their crashing horns can be heard over a mile
away.