Whitetail deer are crepuscular, feeding mainly from before dawn until several hours after, and again from late afternoon until dusk. Bucks are polygamous although they may form an attachment and stay with a single doe for several days or even weeks until she reaches oestrus. Does are seasonally polyoestrous and usually come into heat in November for a short twenty-four hour period. If a doe is not mated, a second oestrus occurs approximately 28 days later. Mating occurs from October to December and gestation is approximately 6 and a half months.
Fawns are able to walk at birth and nibble on vegetation only a few days later.
They are weaned at approximately six weeks. Life span in the wild is 10 years, but whitetail deer have lived up to 20 years in captivity. They wave their tails characteristically from side to side when they are startled and fleeing. They are extremely agile and may bound at speeds of up to 30 miles per hour through tangled terrain in a forest. Whitetail deer are also good swimmers and often enter large streams and lakes to escape predators or insects or to visit islands.