Mule deer facts for kids

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Mule deer
Mule deer male and female in Modoc County, California
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Cervidae
Genus: Odocoileus
Species: O. hemionus
Binomial name
Odocoileus hemionus
(Rafinesque, 1817)

Mule deer (Odocileus hemionus) is a species of deers. They are sometimes called black-tailed deer. They live in western North America. Their name was given to them because of their mule-like ears. There are many subspecies, including the black-tailed deer. Unlike the white-tailed deer, mule deer lives on land west of the Missouri River. They also live in the Rocky Mountains region of North America. Mule deer have been introduced to Argentina.

Description

Mule Deer Sulphur Springs Valley Arizona 2014
Small herd of mule deer in the Sulphur Springs Valley of southern Arizona
Stotting mule deer
Stotting mule deer
Mule Deer Trotting
O. h. eremicus, the desert mule deer. Female. New Mexico.

The most noticeable differences between white-tailed and mule deer are the size of their ears, the color of their tails, and the configuration of their antlers. In many cases, body size is also a key difference. The mule deer's tail is black-tipped, whereas the whitetail's is not. Mule deer antlers are bifurcated; they "fork" as they grow, rather than branching from a single main beam, as is the case with white-tails.

Each spring, a buck's antlers start to regrow almost immediately after the old antlers are shed. Shedding typically takes place in mid-February, with variations occurring by locale.

Although capable of running, mule deer are often seen stotting (also called pronking), with all four feet coming down together.

The mule deer is the larger of the two Odocoileus species on average, with a height of 80–106 cm (31–42 in) at the shoulders and a nose-to-tail length ranging from 1.2 to 2.1 m (3.9 to 6.9 ft). Of this, the tail may comprise 11.6 to 23 cm (4.6 to 9.1 in). Adult bucks normally weigh 55–150 kg (121–331 lb), averaging around 92 kg (203 lb), although trophy specimens may weigh up to 210 kg (460 lb). Does (female deer) are rather smaller and typically weigh from 43 to 90 kg (95 to 198 lb), with an average of around 68 kg (150 lb).

Unlike the whitetail, the mule deer does not generally show marked size variation across its range, although environmental conditions can cause considerable weight fluctuations in any given population. An exception to this is the subspecies the Sitka deer (O. h. sitkensis). This race is markedly smaller than other mule deer, with an average weight of 54.5 kg (120 lb) and 36 kg (79 lb) in males and females, respectively.

Seasonal behaviors

Mule Deer in Zion Canyon
Mule deer grazing in Zion National Park

In addition to movements related to available shelter and food, the breeding cycle is important in understanding deer behavior. The "rut" or mating season usually begins in the fall as does go into estrus for a period of a few days and males become more aggressive, competing for mates. Does may mate with more than one buck and go back into estrus within a month if they did not become pregnant. The gestation period is about 190–200 days, with fawns born in the spring, staying with their mothers during the summer and being weaned in the fall after about 60–75 days. Mule deer females usually give birth to two fawns, although if it is their first time having a fawn, they often have just one.

A buck's antlers fall off during the winter, to grow again in preparation for the next season's rut. The annual cycle of antler growth is regulated by changes in the length of the day. For a guide to identify the sex and age class of Rocky Mountain mule deer at various seasons see S1 File. For more information see the main article on deer.

The size of mule deer groups follows a marked seasonal pattern. Groups are smallest during fawning season (June and July in Saskatchewan and Alberta) and largest in early gestation (winter; February and March in Saskatchewan and Alberta).

Besides humans, the three leading predators of mule deer are coyotes, gray wolves, and cougars. Bobcats, wolverines, American black bears, and brown bears may prey upon adult deer, but most often only attack fawns or infirm specimens or eat the deer after it has died naturally. Bears and smaller-sized carnivores are typically opportunistic feeders, and pose little threat to a strong, healthy mule deer.

Diet and foraging behaviors

Mule Deer at Clearwater Pass 2
Doe grazing in Alberta, Canada

In 99 studies of mule deer diets, some 788 species of plants were eaten by mule deer, and their diets vary greatly depending on the season, geographic region, year, and elevation. The studies gave these data for Rocky Mountain mule deer diets:

Shrubs and trees Forbs Grasses and grass-like plants
Winter 74% 15% 11% (varies 0-53%)
Spring 49% 25% 26% (varies 4-64%)
Summer 49% 46% (varies 3-77%) 3% (varies 0-22%)
Fall 60% 30% (varies 2-78%) 9% (varies 0-24%)

The diets of mule deer are very similar to those of whitetail deer in areas where they coexist. Mule deer are intermediate feeders rather than pure browsers or grazers; they predominantly browse, but also eat forb vegetation, small amounts of grass, and where available, tree or shrub fruits such as beans, pods, nuts (including acorns, and berries.

Mule deer readily adapt to agricultural products and landscape plantings. In the Sierra Nevada range, mule deer depend on the lichen Bryoria fremontii as a winter food source.

Mule deer have also been known to eat ricegrass, gramagrass, bromegrass, and needlegrass, as well as antelope brush, bearberry, bitter cherry, bitterbrush, black oak, California buckeye, ceanothus, cedar, cliffrose, cottonwood, creek dogwood, creeping barberry, dogwood, Douglas fir, elderberry, fendlera, goldeneye, holly-leaf buckthrorn, jack pine, knotweed, kohleria, manzanita, mesquite, oak, pine, rabbitbrush, ragweed, redberry, scrub oak, serviceberry (including Pacific serviceberry), Sierra juniper, silktassel, snowberry, stonecrop, sunflower, tesota, thimbleberry, turbinella oak, velvet elder, western chokecherry, wild cherry, and wild oats. Where available, mule deer also eat a variety of wild mushrooms, which are most abundant in late summer and fall in the southern Rocky Mountains; mushrooms provide moisture, protein, phosphorus, and potassium.

Muledeerleavenworth
Buck grazing near Leavenworth, Washington

Humans sometimes engage in supplemental feeding efforts in severe winters in an attempt to avoid mule deer starvation. Wildlife agencies discourage most such efforts, which may cause harm to mule deer populations by spreading disease (such as tuberculosis and chronic wasting disease) when deer congregate for feed, disrupting migratory patterns, and causing overpopulation of local mule deer populations and overbrowsing of shrubs and forbs. Supplemental feeding efforts are appropriate when carefully conducted under limited circumstances, but to be successful, the feeding must begin early in the severe winter, before poor range conditions and severe weather cause malnourishment or starvation, and must be continued until range conditions can support the herd.


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