The bighorn sheep (Ovis canadensis) is a species of sheep native to North America.
They live in the western mountainous regions of North America, ranging from southern Canada to Mexico.
Bighorn sheep generally inhabit alpine meadows, grassy mountain slopes, and foothill country near rugged, rocky cliffs and bluffs.
There are three subspecies, which occupy separate geographical areas: the Rocky Mountain bighorn sheep (Ovis canadensis canadensis); the Sierra Nevada bighorn sheep (Ovis canadensis sierrae), and the desert bighorn sheep (Ovis canadensis nelson).
The lifespan of rams is typically 9–12 years, and 10–14 years for ewes.
The bighorn sheep is named for its massive, spiral horns, which in the male can reach lengths of over a meter (3.3 feet) and weigh up to 14 kilograms (30 pounds). Females also have horns, but they are shorter with less curvature.
Males typically weigh 58–143 kg (127–316 lb), are 91–104 cm (36–41 in) tall at the shoulder, and 180–200 cm (69–79 in) long from the nose to the tail.
Females are typically 34–85 kg (75–188 lb), 76–91 cm (30–36 in) tall at the shoulder, and 140–170 cm (54–67 in) long from the nose to the tail.
They range in color from light brown to grayish or dark, chocolate brown, with a white rump and lining on the backs of all four legs.
Male bighorn sheep have large horn cores, enlarged cornual and frontal sinuses, and internal bony septa. These adaptations serve to protect the brain by absorbing the impact of clashes.
They are relatives of goats, and have balance-aiding split hooves and rough hoof bottoms for natural grip. These attributes, along with keen vision, help them move easily about rocky, rugged mountain terrain.
Thanks to their amazing balance, bighorn sheep can stand on ledges that are only 5 centimeters (2 inches) wide.
They can bounce from ledge to ledge over spans as wide as 6 meters (20 feet).
They can move over level ground at 48 km/h (30 mph) and scramble up mountain slopes at 24 km/h (15 mph).
Bighorn sheep eat different foods depending on the season. During the summer, they subsist on grasses or sedges. During the winter they eat more woody plants, such as willow, sage and rabbit brush. Desert bighorn sheep eat brushy plants such as desert holly and desert cactus.
Bighorn sheep live in social groups but rams and ewes usually only meet to mate. Male-only bachelor herds usually contain 5 to 50 rams at one time. The females live in nursery herds, with 5 to 100 members, which include adult females and lambs of both genders.
It is during the mating season that the rams join the female groups and engage in fierce competition to establish access rights to ewes.
Bighorn sheep are perhaps best known for the head-to-head combat between males. Horn size is a symbol of rank, and the mass of the horns is used to a male’s best advantage as he smashes into an opponent at speeds of 32 kilometer (20 miles) per hour. Combat has been observed to last for as long as 25.5 hours (with approximately 5 clashes an hour) until one of the males conceded.
The strongest rams of the herd will mate with the females. Mating season is in the autumn and early winter.
Bighorn ewes have a six-month gestation after which usually one, rarely two, young are born. Newborns are precocial and are able to follow their mothers at a good pace over the rocky terrain after the first week. Within a few weeks of birth, offspring form bands of their own, seeking out their mothers only to suckle occasionally. They are completely weaned by 4 to 6 months of age.
Bighorn sheep of all ages are threatened by bears, wolves and especially cougars, which are perhaps best equipped with the agility to prey on them in uneven, rocky habitats. And also lambs are hunted by coyotes, bobcats, lynx and golden eagles.
Native Americans and early settlers prized bighorn meat as the most palatable of American big-game species. Native Americans also used the horns to fashion large ceremonial spoons and handles for utensils. The horns have also been popular for many centuries as trophies.
Two hundred years ago, bighorn sheep were widespread throughout the western US, Canada, and northern Mexico. Some estimates placed their population at over 2 million. By around 1900, hunting, competition from ranching, and diseases had decreased the population to several thousand.
Conservation efforts have restored the population. Today, there are about 70,000 bighorn sheep.
Bighorn sheep are not endangered, according to the International Union for Conservation of Nature.
The Rocky Mountain bighorn sheep is the provincial mammal of Alberta and the state animal of Colorado and as such is incorporated into the symbol for the Colorado Division of Parks and Wildlife.