Natural Histories

photograph of a Sunda Pangolin

Mule Deer

Odocoileus hemionus


The fur ranges from a brown-gray, dark and light ash-gray to brown and even a reddish coloration with a white throat patch and a white or yellow rump patch. Some individuals have a dark dorsal line from the pack to the tip of the tail; all mule deer have a tuft of black hairs on the tip of their white tail. This species has a unique V-shaped dark mark between the eyes that extends upward; it is especially noticeable in males. Male mule deer grow antlers on an annual cycle mediated by day length.  Males typically have larger chest girth, neck circumference, weight (45-150 kg), body and head length, cranial breadth, shoulder height (84-106 cm) and hoof length. Females generally weigh between 43 and 75 kg with a shoulder height of about80-100 cm.


Mule deer are found in western North America, they are not found east of southwestern Saskatchewan, central North and South Dakota, Nebraska, Kansas, and western Texas. This species may be found in over sixty varieties of habitat including California woodland, chaparral, Mojave Sonoran desert, Interior semi desert shrub woodland, the Great Plains, the Colorado Plateau shrubland and forest, the Great Basin, the Sagebrush steepe, the Northern mountain and the Canadian boreal forest.

Feeding Behavior and Diet

This species is a small ruminant, having difficulty digesting highly fibrous roughage and therefore depends on succulent forage. Because nutritious forage is in poor supply most of the year, mule deer have a annual cycle of metabolic rates. During the summer mule deer have a higher metabolic energy flux to accommodate the abundant high energy forage and food intake, also allowing for fat storage. During the winter mule deer have a lower metabolic energy flux due to the intake of low quantities of poor-quality forage. During rut (mating season), male mule deer decrease their food intake and only browse leaves and twigs of trees and shrubs. Mule deer eat succulent green leaves, acorns, legume seeds and fleshy fruits (berries and drupes).


Breeding season occurs in late November through mid-December. Mule deer are polygynous, where males mate with multiple females. The breeding system of this species is a tending-bond type, a dominant male tends a female until mating or displacement by another male occurs. Dominance is largely decided by size; the largest males have the largest antlers. Most females do not mate until their second year. Two hundred four days after mating, females give birth to an average of two young; most births occur between mid- June to early July. Young are weaned between 5 and 16 weeks after birth.

Months and Times of Activity

Individuals use the same winter and summer home ranges each year. Migrations associated with decreasing temperatures occur from higher elevations in the summer to lower elevations in the winter. Southwestern populations migrate as a response to rainfall patterns.

Special Features, Stories, Relationships

•    Mule deer have a social system consisting of clans of females, and individual or sometimes unrelated groups of males. Clans of females all maternally related and act as the defenders of resources. During winter and spring months, female clans and male groups are structured by dominance hierarchies.
•    Mule deer are very good swimmers.
•    Children’s book featuring this animal: FRECKLES by Brian Wolf


Misuraca, M. 1999. "Odocoileus hemionus" (On-line), Animal Diversity Web. Accessed November 04, 2014 at