Tails of I) New World white-tail, II) Colorado mule deer, III) Oregon black-tail, IV) Wyoming wapiti, V) British red deer.
Date 1909
Source Life-histories of northern animals : an account of the mammals of Manitoba
Author Ernest Thompson Seton, 1860-1946
Source: https://commons.wikimedia.org/wiki/File:Life_Histories_of_Northern_Mammals_(1909)_Cervidae_tails.png

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.