Typically, male deer gather a harem during the breeding season. Deer mate during the autumn, and the doe usually gives birth to one or two fawns in the spring. Before rutting season, bucks rub their antlers against trees in an effort to remove the soft, hairy skin called velvet that covers growing antlers. During breeding season, the bucks use their mature antlers as weapons in fights for the favor of females. They also use them to fend off predators.
Deer are fast runners and swimmers.
They can often run as fast as 40 mph. When frightened, a deer may remain motionless, waiting for the danger to pass. Deer typically feed on herbs, bark, leaves, twigs, and sprouts, although they may also eat moss, lichens, some forms of grass and fungi. Unless killed by hunters, predators, disease, or famine, a wild deer may live up to 20 years.