Bighorn Sheep Fact File
The most prominent feature of a bighorn sheep is its namesake big horns. These spiral around on the side of the head. Both males and females possess these horns but those on males are bigger. A males horns may reach 1m (3.3ft) long measuring around the outside curve.
At the end of the body is a short tail which measures 7-15cm (2.75-6in) long.
Their summer coat is made up of glossy brown guard hairs which sit over a crimped grey underfur. This fades during winter. On the rump is a pale patch of fur.
They have a cloven hoof which is an adaptation to help with climbing across rocks and jumping. These hooves have a rough bottom to help with grip.
There is variability in their size depending on the subspecies and where they live. Six subspecies are currently recognized.
On average they measure 1.5-1.8m (5-6ft) long and weigh 55-125kg (120-280lbs). At the shoulder they stand 81-101cm (32-40in). Males are larger than females.
Bighorn sheep are herbivores. They graze on grasses, sedges and forbs.
Those in desert areas are well adapted. They will feed on desert plants from which they can obtain most of their moisture which is supplemented by visits to waterholes.
Their food is regurgitated as cud and chewed a second time before it is digested.
Wild 8-9 years
North America is the native home of the bighorn sheep. Here they live in Canada, Mexico and the United States.
They can be found in the western regions of Canada and the United States along with northern areas of Mexico.
Two populations have been introduced to parts of British Colombia which were not originally part of their range.
These adaptable animals make their home in a wide range of habitats including grassland, rocky areas and deserts. Most populations live in different areas over winter and summer.
Due to their climbing abilities they can survive on near-vertical bluffs or cliffs.
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Prior to the breeding season the males will fight for dominance and mating rights. These aggressive fights see males rise up on their hind legs and hurl themselves at one another. They will aim their horns at the opponent and bash these together. This is repeated until one concedes and walks away. They have a thick, bony skull to help prevent injury.
Young are most often born during spring. Typically females give birth to a single lamb, though twins are possible, after a six month gestation period. For the first week after birth the young remain hidden before joining their mother in the herd.
The lambs will be nursed for four to six months.
A common cause of death for the lambs is malnutrition as mothers may stop milk production if they do not have enough fat for themselves to survive winter.
Sexual maturity is reached for females at 2 years old and 6 months old for males.
Females usually first breed at 3-4 years old while males will not breed for the first time at 7-8 years old when their horns have reached full curl and they can successfully compete for dominance.
Outside of the breeding season the rams and ewes live separately. Rams form bachelor groups which grow larger during the breeding season. Most herds consist of around 12 members.
They are mostly active by day but may also be active during moonlit nights.
Bighorn sheep are able to run at speeds of up to 48km/h (30mph).
Predators and Threats
Humans caused major population declines for the bighorn sheep starting in the 1800s. Threats they faced include overhunting, habitat loss and introduced diseases.
Poaching continues to be a threat from people who want them as trophies.
While overall the population is considered least concern some subspecies are considered endangered.
Another threat is food competition with domestic animals such as sheep and cows.
They have many names including the bighorn sheep, mountain sheep or American bighorn sheep.
Males are known as rams and females are known as ewes.
The horns of a male may weigh as much as the rest of the bones in their body combined.
Bighorn sheep are close relatives of goats.
Rocky mountain bighorn sheep are the state animal of Colorado.
They have growth rings on their horns which can help to determine the age of a bighorn sheep.
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