Mule Deer | Odocoileus hemionus

Mule Deer
Copyright Darren Choate

Mule Deer

Odocoileus hemionus

Mule deer are one of the West’s most prized big game animals. They get their nickname from their oversized ears, which resemble that of a mule’s. Over the years there’s been quite a debate regarding exactly how many mule deer subspecies there are, and where these subspecies live. At one time there were thought to be 11 distinct subspecies. Today taxonomists generally recognize eight. Although generally no longer recognized, two subspecies, the burro, and Inyo mule deer, still have their proponents.

The subspecies are:

Rocky Mountain Mule Deer (Odocoileus hemionus hemionus) is the most common subspecies, having the largest home range and being the most populous. It ranges roughly from the southern edge of the Northwest Territories down through British Columbia, Alberta, Saskatchewan, and western Manitoba through the western Dakotas, Montana, Idaho, and eastern Washington, then south through western Oregon and northwestern California, Nevada, Utah, Wyoming, Colorado, and the northern and central portions of Arizona and New Mexico. Its tentacles have also spread into portions of western Nebraska, Oklahoma, and Texas. It is the largest of the mule deer subspecies.

California Mule Deer (O. h. californicus) is found only in California, ranging roughly from the Sierra Nevada mountains west to the Pacific Ocean. Along the northern and western borders of its range, it interbreeds with the Columbia blacktail. These deer are characterized by smaller bodies and antlers than the Rocky Mountain muley, with antlers that often achieve only a forked-horn shape.

Southern Mule Deer (O. h. fuliginatus) is found along the southern California coast, from roughly Los Angeles County south into Baja California. It is about the same size as the California mule deer, but usually much darker.

Inyo Mule Deer (O. h. inyoensis) is a disputed subspecies, calling only the area in and closely adjacent to Inyo County, California, on the eastern slope of the Sierra Nevada mountains, home. Many taxonomists call this deer a version of the California mule deer.

Burro Deer (O. h. eremicus) is thought by many to be a form of the desert mule deer. Its range is the extreme southeastern desert of California and southwestern desert of Arizona, ranging down into northern Sonora, Mexico, and the extreme northeastern corner of the Baja peninsula. It is a small deer, and lighter in color than other subspecies.

Desert Mule Deer (O. h. crooki) has the second-largest distribution of all the mule deer subspecies. It ranges from the deserts of southeastern Arizona, southern New Mexico, and West Texas down hundreds of miles into Sonora, Mexico. It is a large-boned and long-legged deer, but thin through the withers. It lives in some of the harshest habitats imaginable, with little water and scant forage.

Columbia Blacktail (O. h. columbianus) is found in a narrow coastal band stretching from north-central California up through Oregon, Washington, and British Columbia, as well as on Canada’s Vancouver Island. It lives in a  variety of habitats in this area, ranging from dry chaparral to oak/grassland to the densest, thickest, and wettest coastal rain forests. These deer have a more reddish coat than other mule deer subspecies, shorter ears, and an all-black tail.

Sitka Blacktail (O. h. sitkensis) lives only on British Columbia’s Queen Charlotte Island, and the coastal mainland of Alaska and the state’s many islands, the most famous of which is Kodiak but also includes the Admiralty, Baranof, Chicagof, and Prince of Wales Island in southeast Alaska. Sitka deer have short, blocky bodies, short, thick antlers, and a cinnamon-brown coat.

Two other small subspecies of mule deer are sometimes referred to as well. These are the Tiburon Island and Cedros Island mule deer, although many people believe they are members of the desert and southern subspecies, respectively.

In my life, I’ve been fortunate enough to observe and hunt all the different mule deer subspecies. Growing up in southern California, I hunted the California, Southern, Burro, and Inyo subspecies regularly, finally traveling far enough north to hunt the Columbia blacktail. During college, I began making trips to northeastern California and many other western states to pursue the Rocky Mountain mule deer. Finally, I hit the extremes, hunting both the desert mule deer in Arizona and old Mexico, and living in Alaska for many years, the Sitka blacktail. Over the past 30 years, I’ve not missed hunting at least one mule deer subspecies annually. Those experiences have given me a deep appreciation for each subspecies, as well as the challenges they present.

Today, all populations of mule deer subspecies are under pressure. In some areas, increased predation from wolves and mountain lions has contributed to declining numbers. In areas affected by drought, a lack of water both affects a deer’s health and concentrates animals where predators – both animal and human – can efficiently hunt them. Habitat loss from increased human development is another major issue. In future years it will take continued vigilance from sportsman’s groups to help ensure that all mule deer subspecies populations remain healthy and strong.


Size

  • Varies by subspecies. A large Rocky Mountain mule deer can weigh upwards of 300 lbs., though 200 pounds is average, and stand 3 ½ feet high at the shoulder and be up to 7 feet long, nose to tail. Tails are between 5-7 inches long. Does are smaller.

Antlers

  • All mule deer subspecies have bifurcated antlers, which means they fork off the main beam; both continue to grow and fork again from there. Nontypical points can also occur.

Diet

  • Mule deer are primarily browsers, not grazers, with a majority of their diet comprised of forbs (weeds) and browse (leaves and twigs of woody shrubs). Deer digestive tracts differ from cattle and elk in that they have a smaller rumen in relation to their body size, so they must be more selective in their feeding. Instead of eating large quantities of low-quality feed like grass, deer must select the most nutritious plants and parts of plants. Because of this, deer have more specific forage requirements than larger ruminants.

Lifespan

  • Can reach 9-11 years in the wild and much older in captivity, though the average age in hunted populations is less than five years.

Fast Facts

  • Although mule and blacktail deer are the same species, the mule deer’s mitochondrial DNA, which is passed down through the maternal line, is very close to that of the whitetail deer, and not of the more primitive and ancestral blacktail deer. Consequently, the mule deer is apparently a rather recent form that arose from hybridization of female whitetail and male blacktail deer.
  • Mule deer have no upper teeth, only a hard palate.
  • Some biologists estimate that a mule deer’s sense of smell is up to 1000 times stronger than a human. Research suggests that a mule deer can detect human odor at up to a half mile away. They can detect water that is up to two feet below ground.
The author with a magnificent Colorado mule deer buck taken on a muzzleloader hunt.