What Do Bison Eat?

Bison are herbivores that prefer grasses above all other plants. They eat big bluestem, buffalo grass, and other prairie grasses that dominate the plains. When grazing, a bison can consume up to 25 pounds of vegetation in a single day. Besides grasses, they eat forbs, wildflowers, and various shrubs including catclaw briar and inland ceanothus. In spring, they seek out fresh green shoots and new plant growth. During summer and fall, they focus on mature grasses and continue eating whatever vegetation is most abundant. Bison are not picky eaters and will consume nearly any plant available in their habitat. They eat both tall and short grasses, adapting their feeding to what grows in their area. Learn more about bison in Wyoming to see how they graze across different prairie types.

The foods bison eat shift dramatically throughout the year based on plant growth cycles. In spring, bison actively seek fresh new plant growth, eating new shoots and tender green vegetation. They take advantage of the lush grass after winter dormancy. Summer brings abundant food, so bison spend their time grazing on tall, nutritious grasses. They also eat violet bush clover and other forbs that are at their peak. As fall arrives, grasses become more mature and fibrous. Bison begin to store energy by eating more, preparing for the harsh winter months. Winter is the hardest season. When snow covers the ground, bison eat whatever dried vegetation they can reach or dig to find. They eat woody plants, bark, and any dried grasses still available. In deep snow, bison use their large heads to sweep away snow and expose vegetation beneath.

Bison diets vary across different parts of the United States based on local plant communities. In the Great Plains, bison eat the native prairie grasses that dominate the landscape. In South Dakota, where bison roam, they encounter different grass species and shrub communities than in Wyoming. The plants available determine what bison actually consume. In Utah and the surrounding western mountains, bison eat different vegetation than their plains cousins. Mountain habitats have different grasses and shrubs. In areas with mixed grassland and shrubland, bison eat more woody plants. In wetter prairie regions, bison find sedges and other water-loving plants. Desert and semi-desert bison eat drought-resistant plants. The key factor is that bison adapt to whatever plants grow in their specific region, making them well-suited to diverse North American habitats.

Bison grazing behavior is straightforward but effective. They walk slowly through grass while eating, moving steadily to find the best vegetation. Bison do not browse much, meaning they rarely eat leaves from trees or shrubs at height. Instead, they graze close to the ground, eating grasses and low-growing plants. A bison herd spreads out while grazing to access the most vegetation across a larger area. They do not overgraze a single spot when the herd is mobile. Bison have strong molars designed for grinding tough grasses and plant material. Their stomachs are specialized for digesting large amounts of fibrous plant matter. They spend most of the day eating, similar to cattle. Bison often eat in early morning and late evening when temperatures are cooler. During the heat of midday, they may rest and chew cud, a behavior that helps them digest their food more completely.

Newborn bison calves nurse from their mothers for several months, drinking rich milk that helps them grow quickly. Calves begin to nibble grass and plants within a few weeks of birth, starting to supplement their diet with vegetation while still nursing. By two months old, calves eat significant amounts of grass while continuing to nurse. As they grow, calves gradually transition to eating more plant matter and less milk. By around six to nine months old, young bison eat mostly vegetation like their parents, though nursing may continue longer. Calves stay close to their mothers while learning to forage and find the best plants to eat. The mother's experience guides calves to productive grazing areas. By their first winter, young bison eat independently but may still nurse briefly if available. Adult-sized teeth come in around two years, allowing younger bison to eat tougher, more mature vegetation.

Bison are wild animals and should not be fed by people. Do not offer bison grain, corn, hay, or any human food. Feeding wild bison causes them to lose their natural fear of humans and creates dangerous situations. Bison can weigh over 2,000 pounds and can seriously injure a person with little effort. In areas where bison live near ranches or farms, they must have access to natural grassland to meet their dietary needs. Bison do not thrive on grain or processed feeds alone, even though ranches may supplement. To support wild bison, protect natural prairie and grassland habitats. Remove fencing that blocks bison access to varied vegetation and seasonal grazing areas. Bison in national parks and protected lands have better access to diverse plants than in heavily managed areas. If you encounter bison, observe from a safe distance and never attempt to feed or hand them anything.

Bison share their grassland habitat with cattle and elk, but their diets differ in important ways. Cattle and bison both eat grasses, but bison prefer the shorter, drier grasses that cattle often avoid. Bison eat a wider variety of plants than cattle, including more shrubs and woody plants. This makes bison better adapted to harsher prairie conditions. Elk, which are browsers more than grazers, eat more woody plants and leaves than bison. Elk prefer trees and shrubs, while bison focus on ground-level vegetation. In the same prairie, bison eat the short grasses, elk browse the shrubs, and cattle eat the tall grasses. This difference means the three species can share habitat without competing heavily for the same food. Bison are more efficient at using tough, low-quality grasses than cattle. Their unique digestive system and strong jaws allow them to process fibrous prairie plants better. Visit wildlife to explore more about prairie herbivores and their diets.