Mule DeerOdocoileus hemionusWhere and when to see them

The mule deer is a native western North American deer named for its large, mule-like ears. It occurs across a wide range of landscapes, from dry shrublands to mountain forests. Along the Columbia River, mule deer are especially associated with the open slopes, grasslands, and shrub-steppe of the drier interior. Black-tailed deer, generally classified as subspecies of mule deer, occupy wetter landscapes toward the Pacific coast. Although the species is widespread, individual populations can be affected by habitat loss, drought, severe winters, and disease.

Size

Adults are approximately 1.2–2.1 m long and 80–110 cm tall at the shoulder.

Weight

Adults generally weigh 45–150 kg, with males larger than females.

Lifespan

Typically about 9–11 years in the wild, although some individuals live longer.

Status

Least Concern

Mule deer are often most active around dawn and dusk, although they may feed or travel during daylight. They spend resting periods chewing cud in sheltered bedding sites. Females commonly form groups with their young, while males often gather in separate groups outside the breeding season. During the autumn rut, males compete for access to females through displays, pursuit, and sometimes antler clashes. Some populations migrate between higher summer ranges and lower winter ranges, while others remain relatively local. When alarmed, mule deer may use a stiff-legged bounding gait called stotting, lifting all four feet from the ground together. Fawns initially rely on concealment and remain quietly bedded while their mothers feed nearby.

• Their common name refers to their oversized ears.
• Males shed and regrow their antlers each year.
• Spotted fawns blend into patches of light and shade.
• Mule deer have a four-chambered stomach and chew cud.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

Mule deer use shrub-steppe, grassland edges, open woodland, forest clearings, and mountainous terrain. In the Columbia River basin, suitable habitat includes sagebrush slopes, rocky draws, and patches of riparian vegetation. They benefit from a mixture of feeding areas and nearby cover for resting and escaping disturbance. River margins can provide water, forage, and sheltered travel routes, but mule deer are not confined to the shoreline. Seasonal habitat use varies with snow cover, plant growth, and local conditions.

Mule deer are ruminant herbivores that feed heavily on shrubs, leaves, and other woody browse. They also eat flowering herbaceous plants and some grasses, particularly when new growth is nutritious. Their diet shifts seasonally, with fresh green vegetation important in spring and more woody browse used during winter. In the Columbia basin, foods can include bitterbrush, sagebrush, and the leaves and shoots of riparian shrubs.

Common name

Mule Deer

Scientific name

Odocoileus hemionus

Animal group

Mammals

Size

Adults are approximately 1.2–2.1 m long and 80–110 cm tall at the shoulder.

Weight

Adults generally weigh 45–150 kg, with males larger than females.

Lifespan

Typically about 9–11 years in the wild, although some individuals live longer.

Status

Least Concern

Identification

Look for very large ears, a grayish-brown winter coat or warmer brown summer coat, and a pale rump. Typical interior mule deer have a narrow, black-tipped tail, unlike the broad white underside displayed by a fleeing white-tailed deer. Adult males usually have antlers that fork into paired branches rather than having most tines rise from a single main beam. Coastal black-tailed forms have a much darker tail, so tail appearance varies within the species.