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Mule deer
Male in Wyoming
Female in Wyoming
Conservation status
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Cervidae
Genus: Odocoileus
Species: O. hemionus
Binomial name
Odocoileus hemionus
(Rafinesque, 1817)[2]

10, but some disputed (see text)

The mule deer (Odocoileus hemionus) is a deer indigenous to western North America; it is named for its ears, which are large like those of the mule. There are believed to be several subspecies, including the black-tailed deer.[1][3][4][5][6][7] However, some genetic studies have indicated that mule deer may have developed relatively recently through the interbreeding of white-tailed and black-tailed deer, which may have evolved from white-tailed deer thousands of years ago.[8][self-published source?] Unlike the related white-tailed deer (Odocoileus virginianus), mule deer are generally more associated with the land west of the Missouri River, and more specifically with the Rocky Mountain region of North America. Mule deer have also been introduced to Argentina.[3]


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 whitetails. 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. Black-tailed deer have also been introduced to Kauai, (Hawaii).

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 (male deer) 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).[9][10][11][12] 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 black-tailed 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.[13]

Seasonal behaviors[edit]

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 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. Mule deer females usually give birth to two fawns, although if it is their first time having a fawn, they often have just one.[14] 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.[14] For more information see the main article on deer.

Besides humans, the three leading predators of mule deer are coyotes, gray wolves and mountain lions. 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 would pose little threat to a strong, healthy mule deer. [10]


Mule deer consume a wide variety of plants, and their preferences vary widely geographically as well as seasonally, but they are primarily browsers on woody vegetation and eat relatively little grass. They readily adapt to agricultural products and landscape plantings.[15][16] In summer, mule deer chiefly forage on not only herbaceous plants, but also various berries (including blackberry, blueberry, salal, and thimbleberry). They also use grasses more than in winter.[16] Mule deer are known to forage in summer on California buckeye leaves, though they may be toxic.[17][dead link] In the United States Sierra Nevada range, mule deer depend on the lichen Bryoria fremontii as a winter food source.[18]:2:4

Mule deer grazing in Zion National Park
Buck grazing near Leavenworth, Washington
Doe grazing in Alberta, Canada

In winter, these deer forage on conifers (especially Douglas-fir, cedar, Taxus yews, juniper), and twigs of deciduous trees and shrubs (esp. aspen, willow, dogwood, serviceberry, and sage). In season, they eat acorns and apples. Over much of the species range, snow and ice cover many food sources and the food that is accessible grows slower. The deer's metabolism slows and individuals become less active to survive in an environment with less food. A large fraction of the deaths in a mule deer population occur in the winter, especially during the first year of life.[citation needed]

During the winter, mule deer often move down from mountains, where the snow is deeper and covers most of the food, into valleys with less snow. Sometimes, in response to perceived distress, concerned people create feeding programs. Such supplemental feeding efforts may be harmful if not properly implemented.[19]Supplemental feeding helps mule deer make it through a severe winter if the feeding is started early, long before the mule deer show signs of malnutrition or starvation. Effective feeding of mule deer requires a three- to four-month commitment because it has to be started before poor range conditions and severe weather cause malnourishment. It must be continued until range conditions can support the herd.[20]

Mule deer rarely travel far from water or forage, and often bed down within easy walking distance of both. Young generally forage together in family groups; older bucks tend to travel alone or with other bucks. Most actively foraging around dawn and dusk, they usually bed down in protected areas midday, 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.[citation needed]


The mule deer can be divided into two main groups: The mule deer (sensu stricto) and the black-tailed deer. The first group includes all subspecies, except O. h. columbianus and O. h. sitkensis, which are in the black-tailed deer group.[3] The two main groups have been treated as separate species, but they hybridize, and virtually all recent authorities treat the mule deer and black-tailed deer as conspecific.[1][3][4][5][7][21] It appears the mule deer evolved from the black-tailed deer.[7] Despite this, the mtDNA of the white-tailed deer and mule deer are similar, but differ from that of the black-tailed deer.[7] This may be the result of introgression, although hybrids between the mule deer and white-tailed deer are rare in the wild (apparently more common locally in West Texas), and the hybrid survival rate is low even in captivity.[6][7] Many claims of observations of wild hybrids are not legitimate, as identification based on external features is complicated.[6]


Distribution map of seven mule deer subspecies:
  Sitka black-tailed deer (O. h. sitkensis)
  Black-tailed deer (O. h. columbianus)
  California mule deer (O. h. californicus)
  Southern mule deer (O. h. fuliginatus)
  Peninsula mule deer (O. h. peninsulae)
  Desert mule deer (O. h. eremicus)
  Rocky Mountain mule deer (O. h. hemionus)

Some authorities have recognized O. h. crooki as a senior synonym of O. h. eremicus, but the type specimen of the former is a hybrid between the mule deer and white-tailed deer, so the name O. h. crooki is invalid.[3][22] Additionally, the validity of O. h. inyoensis has been questioned, and the two insular O. h. cerrosensis and O. h. sheldoni may be synonyms of O. h. eremicus or O. h. peninsulae.[21]

The 10 valid subspecies based on the third edition of Mammal Species of the World are:[3]


  1. ^ a b c Sanchez Rojas, G. & Gallina Tessaro, S. (2008). Odocoileus hemionus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 8 April 2009. Database entry includes a brief justification of why this species is of least concern.
  2. ^ "Odocoileus hemionus". Integrated Taxonomic Information System. Retrieved 23 March 2006. 
  3. ^ a b c d e f Wilson, D. E.; Reeder, D. M., eds. (2005). Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  4. ^ a b Ronald M. Nowak (7 April 1999). Walker's Mammals of the World. JHU Press. ISBN 978-0-8018-5789-8. 
  5. ^ a b Fiona Reid (15 November 2006). Peterson Field Guide to Mammals of North America: Fourth Edition. Houghton Mifflin Harcourt. ISBN 0-547-34553-4. 
  6. ^ a b c Heffelfinger, J. (March 2011). "Tails With A Dark Side: The truth about whitetail - mule deer hybrids". Retrieved 8 January 2014. 
  7. ^ a b c d e Valerius Geist (January 1998). Deer of the World: Their Evolution, Behaviour, and Ecology. Stackpole Books. ISBN 978-0-8117-0496-0. 
  8. ^ Gibson, Dan. "Columbian Blacktail Deer". Retrieved 8 January 2014. 
  9. ^ Petersen, David (Nov./Dec., 1985). "North American Deer: Mule, Whitetail and Coastal Blacktail Deer". Mother Earth News. Ogden Publications, Inc. Retrieved 4 January 2012.
  10. ^ a b Odocoileus hemionus, Animal Diversity
  11. ^ David Burnie (1 September 2011). Animal: The Definitive Visual Guide to the World's Wildlife. Dorling Kindersley Limited. ISBN 978-1-4053-6233-7. 
  12. ^ "Deer (Family Cervidae)". Retrieved 8 January 2014. 
  13. ^ "Sitka Black-tailed Deer Hunting Information". Alaska Department of Fish and Game. 2014. Retrieved 8 January 2014. 
  14. ^ a b Mule Deer Fact Sheet
  15. ^ Armstrong, David M (2014). "Species Profile: Deer". Colorado Division of Wildlife. Retrieved 8 January 2014. 
  16. ^ a b Alexander Campbell Martin; Herbert Spencer Zim; Arnold L. Nelson (1961). American Wildlife & Plants: A Guide to Wildlife Food Habits : the Use of Trees, Shrubs, Weeds, and Herbs by Birds and Mammals of the United States. Dover Publications. ISBN 978-0-486-20793-3. 
  17. ^ Hogan, C. Michael. "Aesculus californica". 
  18. ^ Lichens in relation to management issues in the Sierra Nevada national parks, McCune, B., J. Grenon, and E. Martin, L. Mutch, Sierra Nevada Network, Cooperative agreement CA9088A0008. Oregon State University, Corvallis, Oregon, and Sequoia and Kings Canyon National Parks, Three Rivers, California, [1]
  19. ^ "North American Mule Deer Conservation Plan". Western Association of Fish and Wildlife Agencies. 23 July 2004. Retrieved 7 January 2014. 
  20. ^ "Mule Deer in the West-Changing LandScapes, Changing Perspectives_Supplemental Feeding-Just Say No". Western Association of Fish and Wildlife Agencies. Retrieved 7 January 2014. 
  21. ^ a b George A. Feldhamer; Bruce C. Thompson; Joseph A. Chapman (21 October 2003). Wild Mammals of North America: Biology, Management, and Conservation. JHU Press. ISBN 978-0-8018-7416-1. 
  22. ^ Heffelfinger, J. (2000). "Status of the name Odocoileus hemionus crooki (Mammalia: Cervidae)". Proceedings of the Biological Society of Washington 113: 319–333. 

External links[edit]

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Mule_deer — Please support Wikipedia.
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The Denver Post
Tue, 12 Aug 2014 23:00:00 -0700

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Tue, 19 Aug 2014 09:18:45 -0700

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The Spokesman Review
Sun, 10 Aug 2014 00:07:30 -0700

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Colorado Public Radio

Colorado Public Radio
Fri, 08 Aug 2014 12:30:00 -0700

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Lewiston Morning Tribune (subscription)
Fri, 15 Aug 2014 00:20:09 -0700

Washington's largest deer herd will have to be reduced by hunting and winter feeding is planned for the survivors in the aftermath of wildfires torching the Methow Valley. Wildlife managers and some sportsman's groups already are taking steps to help ...
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Wed, 13 Aug 2014 17:33:45 -0700

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Wed, 13 Aug 2014 17:39:02 -0700

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