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The Bison

Bison :: WLR:-   The American bison and the European wisent are the largest terrestrial animals in North America and Europe. Bison are good swimmers and can cross rivers over half a mile (1 km) wide. Bison are nomadic grazers and travel in herds. The bulls leave the herds of females at 2 or 3 years of age, and join a male herd which is generally smaller than the female herds. Mature bulls rarely travel alone. Both sexes get together for the reproductive season, towards the end of the summer. American bison are known for living in the Great Plains. Both species were hunted close to extinction during the 19th and 20th centuries, but have since rebounded. The American plains bison is no longer listed as endangered, but the wood bison is on the endangered species list in Canada.

Although superficially similar, there are a number of physical and behavioural differences between the American and European bison. The American species has 15 ribs, while the European bison has 14. The American bison has four lumbar vertebrae, while the European has five. Adult American bison are not as rangy in build, and have shorter legs. American bison tend to graze more, and browse less than their European cousins. Their anatomies reflect this behavioural difference; the American bison's head hangs closer to the earth than the European's. The body of the American bison is typically hairier, though its tail has less hair than that of the European bison. The horns of the European bison point through the plane of their faces, making them more adept at fighting through the interlocking of horns in the same manner as domestic cattle, unlike the American bison, which favours butting.  American bison are more easily tamed than their European cousins, and breed with domestic cattle more readily.

Wallowing is a common behavior of bison. A bison wallow is a shallow depression in the soil, either wet or dry. Bison roll in these depressions, covering themselves with mud or dust. Possible explanations suggested for wallowing behavior include grooming behavior associated with moulting, male-male interaction (typically rutting behavior), social behavior for group cohesion, play behavior, relief from skin irritation due to biting insects, reduction of ectoparasite load (ticks and lice), and thermoregulation.  In the process of wallowing, bison may become infected by the fatal disease anthrax, which may occur naturally in the soil.

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