Mule deer field guide

Field Guide

Common name	Mule deer
Scientific name	Odocoileus hemionus
Family	Cervidae (Deer family)
Size	Males: body length 126 to 168 cm, shoulder height 84 to 106 cm. Females: body length 125 to 156 cm, shoulder height 80 to 100 cm.Animal Diversity Web, University of Michigan
Weight	Bucks may weigh up to 350 lbs.; does rarely surpass 150 lbs.National Park Service
Lifespan	Usually 9 to 11 years in the wild; average lifespan in captivity 22 years.National Wildlife Federation · Animal Diversity Web, University of Michigan
Diet	Intermediate feeder: woody and herbaceous forage in approximate equal proportions, plus acorns, legume seeds and fleshy fruits.Animal Diversity Web, University of Michigan
Active when	Crepuscular; most often seen in the early morning and late evening.National Park Service
Range	Most of North America west of the 100th meridian, from 23 degrees to 60 degrees N; in the West from Canada to Mexico.Animal Diversity Web, University of Michigan · National Park Service
Conservation status	IUCN Red List: Least Concern. NatureServe: G5.Animal Diversity Web, University of Michigan · NatureServe

Field Marks

Large ears, about three-fourths the length of the head; named for them.National Wildlife Federation · National Park Service
Tail is thin and black-tipped, compared with the white-tailed deer.National Park Service · National Park Service
The white tails of most mule deer end in a tuft of black hairs, or less commonly in a thin tuft of white hairs.Animal Diversity Web, University of Michigan
Antlers are bifurcated: the tines fork and multiply from the main beam, a second tine forking into a 'Y'.National Park Service · National Park Service
Ears are lighter in color on the inside.National Park Service
When startled, moves in stiff-legged jumps with all four feet hitting the ground together (stotting).National Park Service

Habitat

Found in desert or dune, savanna or grassland, chaparral, forest and mountains.Animal Diversity Web, University of Michigan
Adapted to arid, rocky environments; found west of the Missouri River, especially in the Rocky Mountain region.National Wildlife Federation
Seasonal movements involve migrations from higher elevations (summer ranges) to lower winter ranges.Animal Diversity Web, University of Michigan
In Oregon, mule deer migrate, often long distances, to lower elevations to escape or minimize exposure to snow cover.USDA Forest Service
In western Colorado, shrinking habitat due to development, including increased oil and gas drilling, is a likely contributor to mule deer declines.National Wildlife Federation

Behavior

Stotting, a series of forward jumps with all four feet leaving the ground, is believed to help them see over thick vegetation and out-distance predators in rough terrain.National Park Service · National Park Service
Escapes predators by bounding rapidly uphill or by sudden unpredictable changes in direction.Animal Diversity Web, University of Michigan
Males can quickly detect and visually track another animal as far as 600 meters.Animal Diversity Web, University of Michigan
In summer, feeds on tender branch and leaf tips of trees, shrubs, and some grasses.National Park Service
Females live in clans related by maternal descent; males disperse as individuals or gather in groups of unrelated individuals.Animal Diversity Web, University of Michigan
Does spend time in a small herd, often with a few other does and their fawns.National Park Service
Breeding peak occurs mainly from late November through mid-December.Animal Diversity Web, University of Michigan
Between November and February (depending on the locality), bucks battle for the right to mate.National Wildlife Federation
During the rut, bucks compete for dominance and breeding rights by locking antlers.National Park Service
Average gestation length is 204 days; peak birth period is estimated from June 16th to July 6th; common litter size is two.Animal Diversity Web, University of Michigan
Fawns are spotted at birth and weigh approximately 5.5 pounds (2.5 kilograms); weaned at about 60 or 75 days.National Wildlife Federation
Fawns usually stay with the doe for the first full year.National Park Service
Antler growth begins in the spring; late each winter the antlers fall off.National Park Service
Predators include pumas, coyotes, bobcats, golden eagles, feral dogs, and black bears.Animal Diversity Web, University of Michigan
Red Desert to Hoback herd: one-way 150 miles from Red Desert winter ranges to the mountain slopes around the Hoback Basin; a 300-mile round trip.Wyoming Migration Initiative, University of Wyoming
Deer on the Red Desert to Hoback route spend 4 months of each year migrating. In 2016 Deer 255 went 242 miles from the Red Desert to Island Park, Idaho; at the time no deer had migrated such a great distance from winter range to summer range.Wyoming Migration Initiative, University of Wyoming · University of Wyoming

Winter

In winter, they depend heavily on browse from shrubs and twigs.National Park Service
Long, snowy winters deplete an adult's fat reserves; slogging through belly-deep snowpack month after month can starve fawns lacking those reserves.NASA Earthdata
During harsh winters, deer resort to nipping lichen from rock faces or chewing bark off trees.NASA Earthdata
Human-related disturbance can stress deer and cause them to expend unnecessary energy, which may increase winter mortality.USDA Forest Service
Long migration linking summer range to low-elevation winter range is thought to give Red Desert deer optimal fat gain over summer and fat conservation during winter.University of Wyoming

Questions

How big is a mule deer?

Bucks stand 3-3.5 feet at the shoulder and may weigh up to 350 lbs. Does average around 3 feet and rarely surpass 150 lbs.National Park Service

How do I tell a mule deer from a white-tailed deer?

Mule deer have large ears and a thin, black-tipped tail. Their antlers fork into a 'Y', and they bound with all four feet together.National Park Service

Why does a mule deer bounce on all four feet?

The gait is called stotting, a series of stiff-legged jumps with all four feet hitting the ground together. It is believed to let the deer see over thick vegetation and out-distance predators in rough terrain.National Park Service

What do mule deer eat?

They are intermediate feeders, eating woody and herbaceous forage in about equal proportions, plus acorns, legume seeds and fleshy fruits. In winter they depend heavily on browse from shrubs and twigs.Animal Diversity Web, University of Michigan · National Park Service

When are mule deer most active?

They are crepuscular feeders. They are most often seen in the early morning and late evening.National Park Service

How far do mule deer migrate?

Deer in Wyoming's Red Desert travel one-way 150 miles to the mountains around the Hoback Basin. In 2016 one doe, Deer 255, went 242 miles from the Red Desert to Island Park, Idaho.Wyoming Migration Initiative, University of Wyoming · University of Wyoming

When is the mule deer rut?

Breeding peaks mainly from late November through mid-December. Bucks compete for breeding rights by locking antlers.Animal Diversity Web, University of Michigan · National Park Service

How many fawns does a doe have?

The common litter size is two; the peak birth period is estimated at June 16th to July 6th. Fawns are spotted and weigh approximately 5.5 pounds at birth.Animal Diversity Web, University of Michigan · National Wildlife Federation

How do mule deer survive deep snow?

They gain fat in summer and fall and move to lower winter ranges. Long, snowy winters drain those reserves, and belly-deep snow can starve fawns.NASA Earthdata · Animal Diversity Web, University of Michigan

What hunts mule deer?

Predators include pumas, coyotes, bobcats, golden eagles, feral dogs, and black bears. Mountain lions rely heavily on robust mule deer populations.Animal Diversity Web, University of Michigan · National Park Service

Clips

A mule deer with large dark ears and snow on its head stands chest-deep in fresh snow facing the camera, a second deer half buried behind it to the right, a snow-buried iron bench at left, a snow-capped red shed and snow-laden conifers beyond, gray strips at both edges.

Mule deer chest-deep in four feet of new snow

A mule deer buck with slender antlers and large ears looks through square-mesh wire fencing from a rocky hillside, sagebrush in the foreground and blue sky above.

Mule deer buck clears a fence on a 150-mile trek

A Colorado mule deer stands chest-deep in a backyard, ears wide, after four feet of snow fell overnight in the March 2024 storm.

A mule deer buck clears a wire-wrapped fence rail in western Wyoming, one of more than 100 fences on a 150-mile migration out of the Red Desert.

Sources

Odocoileus hemionus (mule deer), Animal Diversity Web, University of Michigan
Mule Deer (Odocoileus hemoinus) - Jewel Cave National Monument, National Park Service
Mule Deer - Theodore Roosevelt National Park, National Park Service
Mule Deer - Wildlife Guide, National Wildlife Federation
Red Desert to Hoback Migration Assessment, Wyoming Migration Initiative, University of Wyoming
After 11 Years, Longest-Migrating Mule Deer Dies in Wyoming's Red Desert, University of Wyoming
Tracking survival among Idaho's mule deer, NASA Earthdata
Winter Range Closures - Ochoco National Forest, USDA Forest Service
Odocoileus hemionus - NatureServe Explorer, NatureServe