Mule Deer Reproduction For the Mule Deer the females are ready to mate when they are 1 ½ years of age. Near mating season the deer will release secretions from sweat glands on their legs for intra-species communication (Desert USA). The Mule Deer is a deer indigenous to Western North America, it is named for its ears which are large like those of of the Mule. This species is relatively calm outside of the breeding season, which is called “rut.” When rut begins, the females become receptive to mating and the males fight for dominance. The Bucks will also develop antlers and will fight with other males during the breeding season to win mating privileges (Desert USA). Mule Deer are more associated with the land west of the Missouri River and more specifically the Rocky Mountain Region of North America. During rut the male deer are increasingly aggressive, and the most dominant male breeds with the most females. Mule Deer - Reproduction The mating season, also known as the rut, begins in late fall and continues into February. Behavior of the Mule Deer. Reproduction of the Mule Deer As the rut begins males become increasingly aggressive and more active. Outside of breeding season, herds are relatively peaceful. For the males they may be mature enough for it, but they have to win their opportunity and that often takes many years before they are successful.