My Crittercam
My Crittercam › American bison

American bison field guide

Field Guide

Common nameAmerican bison
Scientific nameBison bison
FamilyBovidae (cattle, bison, antelope and goats)
SizeMature bulls can reach 5.5 to 6.5 ft (1.9 m) at the hump and 9 to 12.5 ft (2.7 to 3.8 m) long; cows are normally 5 ft (1.5 m) high and 7 to 10 ft (2.2 to 3.2 m) long.Smithsonian's National Zoo and Conservation Biology Institute
WeightBulls up to 2,000 pounds; cows up to 1,000 pounds (Yellowstone).National Park Service (Yellowstone National Park)
Lifespan15 to 20 years in the wild; up to 40 years recorded in captivity.Animal Diversity Web, University of Michigan
DietYellowstone bison: more than 90% grasses, sedges and other grass-like plants; forbs and browse usually under 5%.National Park Service (Yellowstone National Park)
Active whenPrimarily diurnal, especially early morning and late afternoon, with grazing periods between loafing and ruminating.NatureServe Explorer
RangeOnce Alaska to northern Mexico; now found on private and protected lands in areas of the western United States and Canada.Animal Diversity Web, University of Michigan
Conservation statusIUCN Red List: Near Threatened; NatureServe Global Rank G4. COSEWIC (Canada): Plains Bison Threatened, Wood Bison Special Concern.NatureServe Explorer

Field Marks

Habitat

Behavior

Winter

Questions

How big is a bison?

Bison are the largest land mammal in North America. Bulls weigh up to 2,000 pounds and cows up to 1,000 pounds.National Park Service (Yellowstone National Park)

Are bison dangerous to people?

Bison have injured more people in Yellowstone than any other animal. The park says to stay at least 25 yards (23 meters) away and never approach one for a photo.National Park Service (Yellowstone National Park)

How do I know a bison is upset?

Warning signs include bluff charging, head bobbing while staring, pawing, bellowing, or a raised tail. They mean you are too close and a charge is imminent: walk or run away at once.National Park Service (Yellowstone National Park) · U.S. Department of the Interior

How do bison eat in deep snow?

They swing their heads side to side to sweep snow off the grass. Large shoulder and neck muscles, the hump, power this motion.National Park Service (Yellowstone National Park) · U.S. Department of the Interior

Why do bison roll in the dirt?

This is wallowing. It deters biting flies, sheds molted fur, and during the rut bulls do it to show strength.National Park Service (Yellowstone National Park)

What is special about the Yellowstone herd?

Bison have lived in Yellowstone continuously since prehistoric times, but poaching cut the wild herd to about two dozen by 1902. That year the U.S. Army brought in 21 bison from two private herds, which later mixed with it.National Park Service (Yellowstone National Park)

What is the difference between plains and wood bison?

They are two subspecies of the same species. Wood bison average about 15% heavier, with a taller, more forward hump and woolly hair along the ribs.Smithsonian's National Zoo and Conservation Biology Institute · Alaska Department of Fish and Game

Are there wild wood bison in the United States?

Yes. In 2015, 130 wood bison were released along the Innoko River near Shageluk in Southwest Alaska.Alaska Department of Fish and Game

How many bison were there, and how many now?

Estimates before 1800 ranged from 30 to 100 million, falling below 1,000 by the 1890s. About 30,000 are in conservation herds and about 500,000 are managed as livestock.Smithsonian's National Zoo and Conservation Biology Institute

Is the bison the national mammal?

Yes. The American bison became the U.S. national mammal on May 9, 2016.U.S. Department of the Interior

Clips

Seen from above, a brown bison with its head lowered is below teal steel panels at the mouth of an alley, a rust-red rail in front, long shadows on the panels and a clear blue sky beyond.Tagged bison and a dark horn on fall working dayA dark-headed American bison bull with strands of hay across his head and shoulders stands behind a large round hay bale, a pipe fence beyond him.Big Joe the bison takes apart a round hay baleAn American bison walking head-on through falling snow, its face, hump and front legs caked white and its horn tips snowy, snowy conifers soft behind and a thin dark strip at the right edge.Face caked in snow, a bison plods through JanuaryAn American bison with snow caked over its face walks toward the camera through deep snow, its curved horns dark against a white background.Bison walks out of a whiteout in the TetonsA shaggy brown bison with curved horns stands in snow among dry shrubs at a conifer forest edge, facing the camera, under cut-off large yellow text and a red arrow pointing at its head.Wood bison herd found after being written offA herd of American bison walks right to left across a paved road, a smaller dark bison among them, with tall conifers and a partly cloudy blue sky behind.Bison herd takes over a Yellowstone roadA reddish-brown bison calf faces left in falling snow in front of its mother's dark, snow-flecked head and humped back, with cut-off overlay text at the left edge.A newborn bison calf in late spring snowDark bison bunched at the left edge of a flat snowfield, cut off by the frame, with a line of wolves strung out to their right below a band of broken snow, an abc7 logo, a date fragment, a credit line, a cropped white headline box reading Intense standoff between wolf pack and bison herd, and a black band down the right side.Bison herd and wolf pack face off in the snowA dark-faced American bison with short upcurved horns presses its snow-dusted muzzle into a deep drift, its shaggy brown shoulder filling the right edge, with the cut-off words Digging and ep Snow printed at lower left.Bison shovels deep snow with its foreheadClose-up of an American bison's dark, shaggy head in profile, snow caked over the brow and muzzle, one horn and one eye showing, a snow-crusted shoulder at left and a drift below.Snow-caked bison in a Yellowstone blizzard

On a fall working day at an Oklahoma ranch, the crew works a cow with failing sight on her own, then two bison bulls slip through a gate to join a third.

Big Joe, an American bison bull, rattles a tractor by hitting the round bale it carries, then tears the bale down and rolls the rest around his pen.

In a late-January snowfall in Yellowstone, an American bison plods toward the camera with its face, hump and forelegs caked white.

On a wind-scoured flat in the Tetons, a band of five or six bison walks slowly in from about 200 yards to full-frame range in the last hour of light, and one lies down in the snow at dusk.

A 1957 patrol flight finds about two hundred bison along the Nyarling River, the herd later measured as pure wood bison and used to seed nearly every recovered herd.

A dense column of American bison fills both lanes of a Yellowstone road and flows past a car, one big animal passing right beside the hood.

Two newborn bison calves, one perhaps born that same day, nurse beside their mothers in a Yellowstone snowstorm that buried ground already gone green.

In Yellowstone's Hayden Valley in late January, a bison herd stands bunched on the snow to protect its calves while a wolf pack waits beside it.

In a deep Wyoming snowfield, a bison plows the drift aside with its forehead to reach food buried under the snowpack.

In a Yellowstone blizzard, snow-caked bison clear drifts with their heads to reach buried grass until a lead cow takes the herd out of the valley.

Sources

  1. Bison, National Park Service (Yellowstone National Park)
  2. American bison, Smithsonian's National Zoo and Conservation Biology Institute
  3. Bison bison (American bison), Animal Diversity Web, University of Michigan
  4. Bos bison, American Bison, NatureServe Explorer
  5. Safety, National Park Service (Yellowstone National Park)
  6. Wood Bison, Alaska Department of Fish and Game
  7. 15 Facts About Our National Mammal: The American Bison, U.S. Department of the Interior