Mule Deer

Mule Deer ( Odocoileus hemionus) are among the most widely distributed mammals in western North America, ranging from coastal islands off Alaska to Baja California, throughout the American deserts and mountains, and Great Plains from Texas to Canada. Mule Deer and the Black Tail Deer subspecies are highly adaptable to arid conditions and habitat fragmentation.

Mule deer grazing in Colorado

Mule Deer Size and Appearance: Mule deer stand 3 - 4' tall, 4.5 - 7' long, and average 120-250 pounds (trophy bucks can reach over 400 lbs). Mule deer can live 9-11 years in the wild. Traits Mule deer have exceptional smell, up to 1,000 x stronger than humans. They can detect water up to 2' below ground, a vital attribute in their oft-arid habitat. Mule deer eyes are located on the sides of their head, affording a 300-310 degree view. They have good night vision, but like many other members of the Cervidae family, display sub-par color vision, acuity, and sensitivity to motionless objects. Mule deer exhibit very good hearing, amplified by large, independently pivoting ears that can capture sound from all directions. Mule deer sport larger feet than their whitetail relatives, which offer better traction on rocky terrain and the ability to dig for underground water and snow covered food. Powerful haunches give the animal great leaping ability (8'), with running speeds over 40 mph that cover 50' per second over short distances.

Mule Deer vs White Tail Deer: Beyond geographic and ecological differences, the most salient distinctions between mule deer and whitetail deer are the size of their ears, tail color, and antler growth patterns. The mule deer has larger ears, a black-tipped tail, and smaller, bifurcated antlers. Mule deer antlers fork multiple times as they grow, sweeping out and up. Whitetails' branch from a single main beam and sweep out and forward. Diet Mule deer are primarily browsers, which procure most of their food from leaves and stems (vs. grazers, that feed on ground level vegetation like grass). Mule deer are also ruminates, which means they chew partially digested food (called cud) before final digestion. They have a relatively small rumen for their size, however, which limits their ability to process low-quality feed. To compensate, mule deer are more selective than larger ruminates such as elk and moose, who can feed with less discrimination.

Behavior: Mule deer are most active at dawn and dusk, with reduced activity in the high heat of the day to conserve energy and fluids. They move from high to low elevations at the onset of winter in colder climates, with more subtle patterns in arid and coastal climates. Mule deer are best known for stotting, a powerful stiff-legged jump with all four feet hitting the ground simultaneously. This distinct gait confuses predators, and enables the deer to quickly distance itself from threats while maintaining balance and vision over high brush.

Reproduction: Mating season peaks November - December as bucks round up females and battle for possession. Mating pairs remain together for several days, after which they'll absorb into small-medium co-ed groups for the balance of winter. Mule deer antlers are typically shed in February and begin re-growing almost immediately. Adolescent males shed a little later than prime stags. Winter groups disband with the onset of spring, and as calves are born April-June. Males will venture off alone or in small bachelor groups, while females raise fawns, sometimes in the company of other females. 1-3 fawns are born after a 200 day gestation period; first time mothers typically birth one, while older females often have two. Newborns weigh about 6 pounds, can stand within 12 hours, and have white spots that gradually fade over their first year.