Desert bighorns have a long lambing season. In the Mojave Desert it begins in December and ends in June. A few lambs are even born during the summer as well. Mating can last from July to December. Their gestation time lasts about 174 days. They will have from 1-3 lambs. The females will choose a steep and safe area for the birth and raising of the lambs. The lambs are able to quickly follow their mother after only a week. Within a few weeks the lambs gather in small bands of their own, and search out their mothers only to suckle. They are completely weaned by 4-6 months. A disease has been documented in Mojave and Sonoran desert bighorns which results in high death rates for lambs from pneumonia. This disease can continue for several years and results in large population declines.