Bucks usually have antlers by their second year, and eight points by the fifth. Possibly most of the available plant species are used at one time or another. The selection of some food plants changes seasonally, probably reflecting availability and nutritional needs. Other plants are browsed almost continuously resulting in their stunting and near extirpation. Breeding occurs all year but peaks in September and October.
Territorial activity seems limited to defending a receptive doe from other bucks.
Bucks with full racks are generally the earliest breeders and exclude yearling males and those with lesser racks. May. Key deer have a relatively low reproductive rate, averaging 1.O8 fawns per adult doe annually. Male fawns outnumber females, but the sex ratio changes until adult females outnumber males 2.38 to 1. Longevity records are 8 years for males and 17 years for females. Adult females form loose matriarchal groups with one or two generations of offspring, while bucks feed and bed together during the non-breeding season only.