Odocoileus hemionus

Pelage is reddish or yellowish brown in summer, more grayish brown in winter. Ears are large and may move independently. Males have antlers that branch into separate equal beams that fork into two tines (white-tailed deer has only one main beam). Upper side of tail white with a black tip or all black or brown. Juveniles have spotted pelage.

Mule deer occupy many types of habitats in mountains and lowlands, including various forests and woodlands, forest edges, shrublands, grasslands with shrubs, and residential areas. They are often associated with successional vegetation, especially near agricultural lands, but in southeastern Alaska they use old growth forests almost exclusively in winter and spring (Schoen and Kirchhoff 1990). Mule deer are scarce or absent in portions of the Mohave and Sonoran deserts, particularly where permanent water is absent during the summer dry season (Rautenstrauch and Krausman 1989). In southern Arizona, mean distance of mule deer from permanent water in July was less than 3 km (most females averaged less than 2 km) (Hervert and Krausman 1986); in early and late summer mule deer averaged 1.1-1.2 km from permanent water (compared to about 1.3 km for random locations) (Ordway and Krausman 1986). In winter, mule deer tend to be on warmer slopes or other areas with minimal snow cover. Snow depth in excess of 25-30 cm can impede movement, and snow depths greater than 51-60 cm discourage continuous occupation (Loveless 1967, Gilbert et al. 1970). Populations in Hawaii occur in moderately dry native and introduced forest.

In Nevada, mule deer inhabit most areas above the Lower Sonoran Life-zone; Hall (1946) observed that areas heavily grazed by domestic sheep have far fewer deer than those utilized only by cattle (possibly a result of competition for browse).

In northern Arizona, mule deer live in areas vegetated by yellow pine, buckbrush, snowberry, and aspen; elsehere in Arizona they inhabit chaparral and more xeric habitats, except those in the far southwestern portion of the state (Hoffmeister 1986). Deer that occur in yellow pine and spruce-fir habitats in spring and summer migrate to lower elevations (pinyon-juniper) for winter (Hoffmeister 1986).

In southern Arizona, mule deer used and preferred mountainous vegetative associations, but males also used nonmountainous associations (Ordway and Krausman 1986).

A survey along the lower Colorado River (California-Arizona border) in 1910 yielded no evidence at all of mule deer, but in earlier years deer apparently were numerous "both in the river bottom and back through certain desert ranges, where there are springs which the deer could visit regularly for water" (Grinnell 1914). In 1902 deer were said to be common on both sides of the river near Cibola (Grinnell 1914).

Home range size may be 30-240 hectares or more; directly correlated with availability of food, water and cover. Deep winter snows are major factor limiting population size in Pacific Northwest (Schoen and Kirchhoff 1990). Predators include: mountain lions; coyotes; dogs.

See Hatter and Janz (1994) for information on apparent demographic changes associated with wolf control on northern Vancouver Island.

Mule deer males use glands on their forehead to apply scent marks to trees. These scent posts communicate the presence and physiological status of the deer and seem to be important in the social and reproductive biology of the species.

Mule deer mate in autumn, often mainly late November to mid-December. Gestation lasts about 203 days Births occur in late spring, mostly in May-June in much of the range, sometimes as late as July or August. Litter size is 1-2, depending on age and condition of female. Fawns are born with spotted pelage and initially stay hidden. They lose their spots generally by late summer or early fall. Weaning begins at about 5 weeks, usually completed by 16 weeks. Males usually first breed at 2 years, males at 3-4 years.