Field Guide/Mammals/Mule Deer

Odocoileus hemionus (Mule Deer)

Family: Deer (Cervidae) Size: Mule deer weigh from 94.71 to 330.4 lbs (43-150 kg). Their body length ranges from 49.6 to 66.1 inches (126-168 cm) in males, and 42.9 to 61.4 inches (125-156 cm) in females. Shoulder height ranges from 33 to 41.7 inches (84-106 cm) in males, and 31.5 to 39.4 inches (80-100 cm) in females. Description: The mule deer’s coat color ranges from dark brown gray, dark and light ash-gray to brown and even reddish. Their rump is either white or yellow, while the throat patch is white. Generally, they have a white tail that ends in a tuft of black hairs, but occasionally a tail that ends in a tuft of white hair. Some mule deer have a dark line running down the back to the top of the tail. A distinguishing feature of the mule deer is their dark V-shaped mark, which extends from a point between the eyes upward and laterally. Similar Species: Mule deer can be distinguished from other subspecies by their tail that is white and tipped black. Their antlers also branch dichotomously rather than one main beam with vertically rising prongs. Range: Mule deer can be found throughout western North America from Alaska and Western Canada through the Rocky Mountains and Western Plains States of the United States south to the Peninsula of Baja California, Cedro Island, Tiburon Island and Northwestern Mexico. The southernmost distribution reaches central Mexico. Habitat: Mule deer can be found in a variety of habitats due to their high ability to adapt to different environments. Some habitats include: mountains, deserts, semi deserts, temperate forests, open ranges, grasslands, and fields. Diet: Mule deer are classified as intermediate eaters. They commonly eat green leaves, twigs, acorns, legume seeds, and fleshy fruits, including berries and drupes. Activity: Mule deer generally limit their daily movements to isolated home ranges. They do not hibernate, however they tend to move to lower elevations during the winter due to temperature changes. Most mule deer establish home ranges and use the same winter and summer homes in consecutive years. Reproduction: The mule deer’s breeding season occurs from late November through mid-December. The average gestation period is 204 days. The common litter size is 2. The young are fully weaned at 16 weeks, and full development occurs at about 49 months of age in males and 37 months of age in females. Lifespan: Average lifespan is 22 years. Notes: Mule deer have an annual cycle of antler growth. This growth is based on changes in day length. Mule deer also have excellent hearing and binocular vision. They are unable to detect motionless objects, however are very sensitive to moving objects. Mule deer have both positive and negative economic importance for humans. Their positive economic importance is that due to their large population, mule deer are of great interest to hunters. They are able to support hunting during two or three weeks in the fall. The mule deer’s negative economic importance for humans is that they heavily browse Douglas fir and Ponderosa pine trees, both of which are important for commercial timber. In terms of conservation of mule deer, the most pending threat in the wild is the spread of Chronic Wasting Disease (CWD). Currently CWD is more prominent at the local or regional level. The IUCN Red List of Threatened Species lists mule deer as a “least concern” species.

Mule deer