North American elk (Cervus elaphus), also known as wapiti, once ranged across the continent. Wild populations now abide primarily in western montane regions, with the largest subspecies (Roosevelt elk) populating the Pacific Northwest coast. Elk enjoy summertime at high elevation but descend to lowland sites in the fall and winter for breeding and easier foraging. Strictly herbivorous with a diet of ferns, shrubs, lichen and grasses, they can be seen grazing in open meadows at dawn and dusk. Early September marks the beginning of breeding season, when male and female groups converge and bulls bugle and battle for breeding rights. The dominant male mates with all females of the herd while he thwarts the romantic advances of other bulls. In spring or early summer, wapiti migrate to high altitude grazing grounds where the females give birth. Twins are rare; most cows will birth a single calf, which is able to stand within 20 minutes. Daughters usually join their mothers' herds while sons are pushed off to graze their own pastures by the age of two.