The mule deer (Odocoileus hemionus) is a deer species native to western North America.
Mule deer prefer open grasslands and perk-lands, or forest edge ecosystems. The habitat varies largely due to the massive range of mule deer across western North America.
It is named for its ears, which are large like those of the mule.
The average lifespan for mule deer is from 8 to 10 years in the wild, while in captivity individuals may live up to 20 years.
The mule deer has a height from 80 to 106 cm (31 to 42 in) at the shoulders and a nose-to-tail length ranging from 1.2 to 2.1 m (3.9 to 6.9 ft).
Bucks weigh from 55 to 150 kg (121 to 331 lb), averaging around 92 kg (203 lb), while does weigh from 43 to 90 kg (95 to 198 lb), averaging around 68 kg (150 lb).
The color of the mule deer’s coat changes with the seasons, from short, reddish-brown in the summer, to longer, grayish-tan in the winter months. The rump patch may be white or yellow, while the throat patch is white. The white tails of most mule deer terminate in a tuft of black hairs.
Each spring, a buck’s antlers start to regrow almost immediately after the old antlers are shed. Shedding typically takes place in mid-February, with variations occurring by locale.
Mule deer forage for a wide variety of plants that differ with geographical ranges and seasonally depending on what resources are available. They are generally considered browsers, eating twigs and other vegetative parts of woody plants, but they also eat different grasses.
Mule deer have excellent hearing and eyesight that warns them of approaching dangers.
They flee with high jumps, leaping and landing on all four legs at once. Although this slows them down, it allows them to leave predators behind by quickly ascending steep slopes or jumping unpredictably over large obstacles.
Mule deer are social animals that typically stay in groups. They live in a multi-generation family of related females and their offspring. Bucks older than yearlings often group together or remain solitary. In late summer and autumn, mixed family groups form larger groups that stay together for protection throughout the winter. They break into smaller groups again by the next summer.
Some populations undertake long migrations between winter and summer ranges.
Mating season occurs in autumn when does come into estrus for a period lasting only several days. The gestation period is approximately 200 days, with fawns arriving in the spring; the young will remain with mothers throughout the summer and become weaned in the autumn. Mule deer females usually give birth to two fawns, although if it is their first time having a fawn, they often only have one.
Besides humans, the three leading predators of mule deer are coyotes, wolves, and cougars. Bobcats, Canadian lynxes, wolverines, American black bears, and brown bears may prey upon adult deer, but most often only attack fawns or infirm specimens or eat the deer after it has died naturally.
Mule deer populations have been restored since severe depletion by market hunting took place at the end of the 19th century.
The mule deer and the white-tailed deer are very similar in appearance. The most noticeable differences between white-tailed and mule deer are the size of their ears, the color of their tails, and the configuration of their antlers. The mule deer’s tail is black-tipped, whereas the whitetail’s is not. Mule deer antlers are bifurcated; they “fork” as they grow, rather than branching from a single main beam, as is the case with white-tails.