What is Mule deer?
{{Taxobox | name = Mule deer | fossil range = | status = LC | status_system = iucn3.1 | image = MuleDeer ModocCounty.jpg | image_width = 200px | image_caption = Mule deer male and female in [[Modoc County, California]] | regnum = [[Animal]]ia | phylum = [[Chordate|Chordata]] | classis = [[Mammal]]ia | ordo = [[Artiodactyla]] | familia = [[Cervidae]] | genus = ''[[Odocoileus]]'' | species = '''''O. hemionus''''' | binomial = ''Odocoileus hemionus'' | binomial_authority = ([[Constantine Samuel Rafinesque-Schmaltz|Rafinesque]], 1817) | range_map = }} The '''mule deer''' (''Odocileus hemionus'') is a [[species]] of [[deer]]. 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]].<ref name=Walker>Novak, R. M. (1999). ''Walker's Mammals of the World.'' 6th edition. {{ISBN|0-8018-5789-9}}</ref><ref name=Reid>Reid, F. A. (2006). ''Mammals of North America.'' 4th edition. {{ISBN|978-0-395-93596-5}}</ref><ref name=hybrid>Heffelfinger, J. (Ver. 2, March 2011). ''[http://www.coueswhitetail.com/coues_biology/hybrids.htm Tails with a dark side: The truth about whitetail–mule deer hybrids.] {{Webarchive|url=https://web.archive.org/web/20101122111506/http://www.coueswhitetail.com/coues_biology/hybrids.htm |date=2010-11-22 }}''</ref><ref name=DeerEvolution>Geist, V. (1998). ''Deer of the world: their evolution, behaviour, and ecology.'' {{ISBN|978-0-8117-0496-0}}</ref> 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 species|introduced]] to [[Argentina]]. The mule deer's favorite food is new plants that grow in the spring. They eat a large number of their yearly calories during spring feeding. Because spring comes later in colder places, the mule deer [[migration|move from warmer to colder]] places so they spend the mos