Bighorn Sheep

Occurring in suitable mountainous habitat across their extensive range, individual bighorn sheep populations tend to remain localized rather than mixing together.

Bighorn sheep are the most common wild sheep in North America. They are excellent climbers and are often found on rocky outcrops or high cliffs. They seek refuge in steep areas from cougars and other predators that are not agile enough to keep up with their sure-footed prey.

Bighorns are named after the males' massive spiral horns, which may be up to 1.1 m (3.5 ft) long. The females have smaller, less curved horns.

Bighorn sheep is found on high mountain pastures in summer, when groups of males or females with young graze independently on grass and herbage. In winter, they form mixed herds and move to lower pastures.

Flocks of bighorn sheeps can contain up to 100 individuals. They head up to high meadows in summer, then retreat to the valleys when the winter snows come. Male bighorns tend to live in separate groups from the ewes and lambs. Horn size plays a key part in the social structure of these sheep. Males with the largest horns are unchallenged, but where two males are well-matched in horn size, they will battle for their place in the social hierarchy of the herd. Living in a mountainous region, bighorn sheep are very agile, proving extremely sure-footed, and able to climb and jump without difficulty. Ewes prefer to mate with rams with large horns and refuse the courtship of others. Females have exceptionally short horns.

A more unusual characteristic of this species is that they are strong swimmers.

Ewes produce 1 or 2 lambs, born after a gestation period of about 6 months, and are assiduous in care of the young.

Distribution: Distribution centred on the Rocky Mountains in North America, extending from British Columbia and Alberta, western Canada, down to eastern parts of Baja California.

Habitat: Alpine meadows and rocky cliffs.

Weight: 45 - 135 kg (99 - 297 lb).

Length: 160 - 210 cm (63 - 83 in), including tail.

Maturity: Females about 2.5 years; males about 3 years, but often do not breed until they are older.

Gestation Period: About 175 days; weaning occurs at 4 - 6 months.

Breeding: 1 - 3 young born in spring.

Food: Herbivorous, grazing mainly on grass, but also on herbs and other small plants.

Lifespan: Up to 14 years.

Status: Lower risk.

Female horns

These are far less developed than those of the male, slimmer and carried above the top of the skull.

Male horns

The horns of the male are massive, growing backwards and then curling forwards below the level of the top of the head.

Coat

The brownish colouration on the body varies between different populations.

Young bighorn sheep will lie down to avoid predators such as eagles.

HORN GROWTH

The horns grow gradually in the male, and a second curl may start to develop in individuals from about eight years old.