Whitetail deer are inhabitants of forests, wooded river valleys, and other habitats with considerable vegetative cover. They spend the day bedded down in the brush and begin to move about in the evening, singly or in small groups, browsing on tender shoots and leaves. Whitetail deer can be found throught Central and North America except in arctic areas, and in northern South America. When alarmed, they jump through the brush while raising their tail, exposing a conspicuous white flag on its underside. They quickly disappear into dense vegetation.
Whitetail bucks begin to grow antlers in the spring. By late summer the velvet is coming off, and the antlers are usable. The bucks use their antler racks for sparring and wrestling, to establish dominance for the rut. During the rut, a buck will follow and guard a single female until she is mated. By mid to late winter, the antlers will have fallen off.
Does give birth to a single fawn or twins in mid to late spring. For the first weeks of life, fawns stay hidden in tall vegetation. Their mothers return to them periodically during the day and night to let them nurse, then move off to feed. The fawns have nearly no scent at this stage of life to protect them from predators. After a month, the fawns are strong enough to accompany their mothers.
Unregulated hunting of whitetail deer with firearms dramatically reduced their numbers in the early 20th century. After commercial hunting was banned and recreational hunting regulated, whitetail numbers have rebounded. With the absence of large predators to control their numbers, they commonly overbrowse their range, leaving poor quality fodder and herds of starving, parasite riddled deer. Large deer numbers pose a hazard to humans driving motor vehichles, as deer often stray onto roads at twilight or night when visibility is poor, and then freeze in place when they see a vehicle approaching. The resulting collisions cause significant damage to cars and can imperil human drivers and passengers. Whitetail deer often wander into towns and cities, where they become a nuissance by eating gardens and ornamental plants. With humans and deer in frequent contact, people are occasionally attacked by bucks in rut or does protecting their fawns. Whitetail deer also host ticks that carry diseases such as lime disease that can threaten humans if the human is bitten by an infected tick.