Mule deer

Mule Deer[1]
Male and female
Conservation status

Least Concern (IUCN 3.1)[2]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Cervidae
Subfamily: Capreolinae
Genus: Odocoileus
Species: O. hemionus
Binomial name
Odocoileus hemionus
(Rafinesque, 1817)
Subspecies

11 ssp., see text

The mule deer (Odocoileus hemionus) is a deer whose habitat is in the western half of North America. It gets its name from its large mule-like ears. The black-tailed deer is considered by some a distinct species though it is classified as a subspecies of the Mule Deer. Unlike its cousin, the white-tailed deer, mule deer are generally more associated with the land west of the Missouri River. The most noticeable differences between whitetails and mule deer are the color of their tails and configuration of their antlers. The mule deer's tail is black tipped. Mule deer antlers are bifurcated, or "fork" as they grow rather than branching from a single main beam (as with white-tails). Each year a buck's antlers start to grow in spring and are shed after mating season from mid-January to mid-April. Mule deer bucks have somewhat more prominent ears than females. Instead of running, mule deer move with a bounding leap (stot), with all four feet coming down together.

The mule deer is the largest of the Odocoileus genus, standing, on the average, 40–42 inches (100–110 cm) at the shoulders and stretching 80 inches (200 cm) or so nose to tail. An adult buck will weigh from 150–300 pounds (68–140 kg) on the hoof, with does averaging 125–175 pounds (57–79 kg). The occasional trophy-sized mule deer buck may weigh in around 500 pounds (230 kg).[1] The Mule Deer does not show marked size variation across its range as does the White-tailed Deer.

Contents

Seasonal behaviors

In addition to movements related to available shelter and food, the breeding cycle is important in understanding deer behavior and personality. 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 do not settle. 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. A buck's antlers fall off during the winter, to grow again in preparation for the next season's rut. For more information see main article on deer.

There are several non-human predators of mule deer. Gray Wolves and Cougars are the main predator of adult deer. Bobcats, Coyotes, American Black Bears and Grizzly Bears less commonly prey on adult deer, though commonly attack fawns.[3]

Foraging

In summer, it chiefly forages on not only herbaceous plants, but also various berries (including blackberry, blueberry, salal, and thimbleberry). Mule deer are known to forage in summer on California Buckeye leaves, even though there is some evidence of that plant's toxicity.[4]

Mule Deer grazing in Zion National Park
Mule Deer buck in Rocky Mountain Arsenal National Wildlife Refuge
A Mule Deer doe grazing near the Devon Lakes

In winter, it forages on conifers (especially twigs of Douglas fir, cedar, Taxus yews, aspen, willow, dogwood, serviceberry, juniper, and sage). In season, it eats acorns and apples. Over much of its range, snow and ice cover many food sources and the food that is accessible grows slower. Its metabolism slows and it becomes less active to survive in an environment with less food. A large fraction of the deaths in mule deer population occur in the winter, especially with during the first year of life.

During the winter, most mule deer must move down from mountains, where the snow is deeper and covers most of the food, into the valleys, where there is less snow. Sometimes, in response to perceived distress, concerned people create feeding programs. Such supplemental feeding efforts may be harmful if not properly implemented.[5]

Mule deer prefer to eat high amounts of fresh grass and populations tend to move up or down with those of their preferred foods. Mule deer rarely travel far from water or forage, and tend to bed down within easy walking distance of both. Young mule deer tend to forage together in family groups while bucks tend to travel alone or with other bucks. Most actively foraging around dawn and dusk, they tend to bed down in protected areas mid-day, but will also forage at night in more open agricultural areas, during full moons, or when pressured by hunters. Repeated beds will often be scratched level, about the size of a washtub. Temporary beds will seem little more than flattened grassy grounds.

Subspecies

Line notes

  1. ↑ ITIS: O. hemionus Taxonomy
  2. ↑ Sanchez Rojas, G. & Gallina Tessaro, S. (2008). Odocoileus hemionus. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 8 April 2009. Database entry includes a brief justification of why this species is of least concern.
  3. ↑ Odocoileus hemionus, Animal Diversity
  4. ↑ C.Michael Hogan (2008) Aesculus californica, Globaltwitcher.com, ed. N. Stromberg
  5. ↑ http://www.dfg.ca.gov/wildlife/hunting/deer/docs/NAMuleDeerConsPlanFinal.pdf

References

Mule deer enjoy the open range and grasslands available to them in Paradise Valley (Montana)

External links