Elk [Wapiti, Cervus canadensis]

A wintering elk herd moving through Waterton Lakes National Park

Elk (also known as Wapiti, a Shawnee name meaning 'white rump') are an Old World deer species that originated in Eurasia and spread to North America, crossing the Bering Land Bridge during the ice age. North American elk were once considered a separate species, and the Eurasian red deer another species. Scientists now consider the North American Elk and Eurasian red deer to be the same, though distinctions between the two live on in the language. European red deer will interbreed with American elk, when penned together, and the offspring are fertile. Remnants of the elk population that moved easterly into North American from the Bering Land Bridge also moved westerly back into Asia, and there are existing populations in mountainous Central Asia that resemble, if not identical to, the North American elk. These Siberian elk, along with the American elk, are the only red deer subspecies where female deer are close to the male deer in size and also carry long neck manes identical to those of the males.

Elk weigh 230 to 450 kg (500 to 1,000 lbs.) and stand 0.75-1.5 m (2.5-5 ft.) high at the shoulder. Their antlers usually measure 1 to 1.5 m across, tip to tip. Males often weigh twice as much as females.

North American elk are the largest of the Red Deer, similar in size to, or slightly larger than, the Altai wapiti (Siberian elk) of Mongolia and southern Siberia, and the Tian-Shan wapiti. The American elk terminology is different from the European, as the males are called bulls, the females are called cows, and the offspring are calves, rather than stags, hinds, and fawns, respectively. The vocal apparatus and mating call of the elk is also different from that of the Red Deer, in that the elk "bugle" as opposed to "roaring". This is an adaptation to the more open (less thickly wooded) environment of the elk, allowing high-pitched sounds to travel further. Asian red deer and Asian wapiti-like red deer have mating calls that resemble both European red deer and American elk. Each subspecies is unique, and some calls start as a roar and end like a bugle.