Mule deer are polygynous, having a tending-bond type breeding system, and mating within groups from late November through mid-December.
The mule deer is a polygynous species, having a tending-bond type breeding system.
Courtship and mating occur within the group and the breeding peak occurs mainly from late November through mid-December.
The breeding period is mediated by decreasing day length through the action of gonadotropins on Leydig cells, thus producing androgens. Androgens induce secondary ossification, accelerate maturation, induce behavioral changes that result in shedding antler velvet, and aid in the maintenance of osteoblasts and osteocytes to maintain antlers in hard bone condition. Withdrawal of androgens at the end of the breeding season permits resorption of bone at the pedicel-antler junction and antler shedding.