The dominant ram earns the right to mate with the females. Mating season, called the rut, is in the autumn. Males are not usually strong enough to mate until they are at least 3 years old.
Female bighorns are pregnant for about 175 days, or about 25 weeks. They usually have only one lamb at a time. In the spring, the young are born on high ledges that protect them from predators.
Lambs are dependent on their mothers for the first four to six months of their lives, though they can walk almost as soon as they are born. The mortality rate for lambs is quite high. On average, 5 to 30 percent of lambs don’t make it to adulthood, according to ADW, though sometimes the death rate can be as high as 80 percent.
Rams typically don’t mate until they are around 7 years old. They can live from 10 to 19 years in the wild.