American Bison / Buffalo - adults and young in traffic, walking on road (Bison bison). Yellowstone National Park, Wyoming, USA. Males weigh up to 2000 pounds, heaviest land mammal in North America. Nearly went extinct by 1894 due to hunting prompting Congress to pass the National Park Protective Act which imposed stiff fines or imprisonment for bison poaching - Inhabits plains - prairies and river valleys and sometimes forests - Grazes on grasses-sedges and forbs and someti mes berries-lichens and horsetails - Native Americans used almost every part of the Bison - still used for human consumption today - Mates in the summer-Bull enters the matriarchal herd and displays 'flehmen' and 'tending behavior' - Flehmen consists of curling the lip back and extending the neck and is thought to enhance the sense of smell - Male 'tends' a female by remaining between her and the herd in an attempt to keep the cow isolated - Males threaten and can battle other contenders which can result in butting and horn-locking - Bison usually have a single calf after about nine months - Most young are weaned by late summer and some nurse up to seven months.