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SPECIES PROFILE
American Bison (Bison bison)
Bison
IUCN STATUS
Near Threatened
CONSERVATION STATUS
Near Threatened
CLASS
Mammalia
GEOGRAPHICAL RANGE
Historically across the Great Plains; largest free-roaming herds now in Yellowstone NP and Badlands NP
DIET
Herbivore
HABITAT
Grasslands, prairies, and open meadows; formerly ranged across the entire Great Plains; free-roaming herds now only in national parks
🔬 Classification
PHYLUM
Chordata
CLASS
Mammalia
ORDER
Artiodactyla
FAMILY
Bovidae
GENUS
Bison
📋 Description
SIZE
Bulls 800–1,000 kg, shoulder height 1.8 m; cows 360–540 kg
COLORATION
Dark brown shaggy coat on the head, neck, and forequarters; lighter hindquarters; massive humped shoulder; both sexes bear short curved horns
ADAPTATIONS
Massive shoulder muscles support a heavy skull for snow-plowing; can run at 55 km/h despite their bulk; highly mobile migratory herds
🌿 Ecology
HABITAT
Grasslands, prairies, and open meadows; formerly ranged across the entire Great Plains; free-roaming herds now only in national parks
DIET
Herbivore
GEOGRAPHIC RANGE
Historically across the Great Plains; largest free-roaming herds now in Yellowstone NP and Badlands NP
REPRODUCTION
Rut July to August; single rust-coloured calf born May; calves can run within hours of birth
DIET DETAILS
Grasses and sedges grazed by sweeping the head side to side; may paw through snow in winter to reach buried vegetation
⚠️ Threats & Conservation
PRIMARY THREATS
Historical commercial slaughter reduced population from 30–60 million to fewer than 1,000 by 1889; still threatened by brucellosis management, habitat limits, and hybridisation
💡 Interesting Facts
1
American Bison are the national mammal of the United States; the Yellowstone herd is the largest wild bison population in the country and the only herd continuously wild since prehistoric times.
2
Bison can run at 55 km/h and jump nearly 2 metres vertically despite weighing up to a tonne — tourists underestimate their speed and agility more than any other Yellowstone animal.
🔭 Sighting Guide
📍 BEST PLACES TO SIGHT
Hayden Valley in Yellowstone National Park, WY, has the most reliable and accessible free-roaming Bison herds
Badlands National Park near Interior, SD, has a free-roaming Bison herd in mixed-grass prairie
Theodore Roosevelt National Park near Medora, ND, has Bison herds in the North Dakota Badlands
🗓️ BEST TIME TO SIGHT
July and August for dramatic rut behaviour; September and October when bulls are active; year-round in Hayden Valley, Yellowstone.
🎯 SIGHTING TIPS
Year-round. Hayden Valley and Lamar Valley in Yellowstone have free-roaming herds visible daily; rut in late July and August.
