The Sitka deer or Sitka black-tailed deer (Odocoileus hemionus sitkensis) is a subspecies of mule deer (Odocoileus hemionus), similar to the Columbian black-tailed subspecies (O. h. colombianus). Their name originates from Sitka, Alaska, and it is not to be confused with the similarly named sika deer. Weighing in on average between , Sitka deer are characteristically smaller than other subspecies of mule deer. Reddish-brown in the summer, their coats darken to a gray-brown in mid- to late August. They are also good swimmers, and can occasionally be seen crossing deep channels between islands. Their average lifespan is about 10 years, but a few are known to have attained an age of 15. Habitat and life patterns Sitka deer inhabit the coastal rainforests of northern British Columbia and southeastern Alaska. Their natural distribution included the Alexander Archipelago in Alaska and the adjacent mainland coast north to Yakutat. They were also introduced to Haida Gwaii (Queen Charlotte Islands) in the 1890s, Prince William Sound during 1917–1923, the Kodiak Island Archipelago in 1924 and 1930, Yakutat in 1924, and the Skagway and Haines area during the 1950s. Sitka deer can be both migratory and residential depending on their habitat; but during winter, they primarily reside in old or mixed-age forest growth below , except on the southern two-thirds of Kodiak Island, where forest cover is absent. The rut peaks in mid-November and fawns are born in early June; they weigh . Bucks can weigh up to and does can weigh . Diet Sitka deer primarily eat green vegetation. However, during the intense Alaskan winters, they also feed on woody vegetation and lichens. Sitka deer have no upper incisors, and digest vegetation through grinding plant material between their upper and lower molars. All Odocoileus species are ruminants, in that they have four-chambered stomachs which allow them to "ruminate" (rechew) their food, and contains bacteria specialized in breaking down cellulose. Since these bacteria are so specialized, they have tremendous difficulty digesting strange material and can die of starvation with their bellies full of food. Sitka deer feed on several plants, including Cornus, foam flower, trailing raspberry, fern leaf golden thread, Vaccinium, hemlock/cedar, and salmon berry bush. Population and hunting Sitka deer population fluctuate considerably due to the harsh Alaskan winters and are typically estimated using pellet surveys, DNA, photo traps and other methods. However, they are an abundant species that rapidly recovers from low populations,