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. The current Key deer population is an estimated 25O to 3OO animals. Both have permanent fresh water and extensive pineland habitat.
Habitat selection varies with season, time of day, and the sex and age to the animal.
Pinelands, hardwood hammocks, recent clearings, roadsides and grassy areas are used for feeding. Burned-over pinelands produce new growth which is browsed extensively for 6 months or more. Hammocks and mangrove swamps are used for cool retreats during the day. The greatest current impact on Key deer is the loss of habitat to development. Anticipated future population growth implies a further loss of habitat.