A mature bull can reach 5.5 to 6.5 feet (1.9 meters) high at the hump and nine to 12.5 feet (2.7 to 3.8 meters) in length. Females are normally smaller, at 7 to 10 feet in length (2.2 to 3.2 meters) and 5 feet high at the hump (1.5 meters). Bison can weigh 1,800 to 2,400 pounds (816 to 1,088 kilograms). Male (bull) weighs up to 2,000 pounds, female (cow) weighs up to 1,000 pounds. May live 12–15 years, a few live as long as 20 years. Feed primarily on grasses and sedges. Mate in late July through August; give birth to one calf in late April or May. Can be aggressive, are agile, and can run up to 30 miles per hour. Bison are mostly active during the day and at dusk, but may be active through the night. They are social animals that often form herds, which appear to be directed by older females. Group sizes average about 20 bison during winter, but increase in summer to an average of about 200, with a maximum of about 1,000 during the breeding season (known as the rut) in July and August. Bison are sexually mature at age two. Although female bison may breed at these younger ages, older males (>7 years) participate in most of the breeding. During the rut mature males display their dominance by bellowing, wallowing, and engaging in fights with other bulls. The winners earn the right to mate with receptive females. Once a bull has found a female who is close to estrus, he will stay by her side until she is ready to mate. Then he moves on to another female. Following courtship, mature males separate and spend the rest of the year alone or in small groups. Group sizes decrease through autumn and into winter, reaching their lowest level of the year during March and April. Bison are grazing animals that feed on native prairie grasses mostly. They have a strong herd instinct and tend to graze and travel in large groups. Their mob-like behavior creates a heavy hoof action and substantial manure spreading which is very good for the rejuvenation of prairie and pasture grasses and an integral part of the ecology of open grassland soils. They have a very thick winter coat that sheds away to a slick seal-like undercoat during the summer months. They manage their hair growth, shedding and conditioning by creating wallows, which are large dust baths that they will roll around in. Wallows usually then remain free of vegetation since they are used often and by each animal. All bison are born orange and turn brown just about the time that they are old enough to survive without nursing milk from their mother. All males are called bulls and all females are called cows, and there is no difference between a bison and an American buffalo. The first explorers called them buffalo, not really knowing exactly what they were with the word le boeuf meaning cow, ox or beef in French helped to further confuse the naming. The only true buffalo that exist in the world are African Cape Buffalo and Water Buffalo, and water buffalo number in the hundreds of millions worldwide and are recently being introduced into human and pet foods in the US as “buffalo” further complicating things. Bison are now the U.S. National Mammal as of 2016. Bison have humps in order to anchor their unusually large heads. The large head is used as a snow plow to move snow drifts away from grass that they can smell 3-4 feet down under the snow. Their hair coat can be so thick as to create a snow and ice insulation on their backs that does not melt. They have very large guts (called rumen) that are capable of holding a 3 day quantity of food while it slowly digests and crates massive amounts of heat (like a compost pile) that keeps the animal warm during the coldest northern winters in the upper reaches of Canada and Alaska. Bison do not need or use any shelter.

Bison are year round grazers. They feed primarily on grasses, but will also consume flowering plants, lichens and woody plant leaves depending upon availability. To find grass in winter they sweep their heads from side to side to clear the snow. On average, bison ingest 1.6 percent of their body mass per day of dry vegetation. Bison require water every day as well. At the Smithsonian National Zoo, bison consume a diet of orchard grass hay and herbivore pellets. Yellowstone bison feed primarily on grasses, sedges, and other grass-like plants (more than 90% of their diets) in open grassland and meadow communities throughout the year. They also eat forbs (weeds and herbaceous, broad-leafed plants) and browse (the leaves, stems, and twigs of woody plants) through the year, but those usually comprise less than 5% of the diet. They typically forage for 9 to 11 hours daily. Bison are ruminants with a multiple-chambered stomach that includes microorganisms such as bacteria and protozoa to enable them to effectively digest plant material. Bison alternate between eating and ruminating, which is regurgitating partially digested food and chewing it again, to allow microorganisms to further break down plant material into volatile fatty acids and other compounds. Their large digestive tract allows them to digest lower quality foods with greater efficiency than other ungulates such as cattle, deer, or elk. All ruminant animals harvest and consume large quantities of forage in order to feed a wide variety of microbial “bugs” in their gut consisting of fungi, bacteria, protozoa and a variety of other microorganisms. The bugs then break down and digest forages in the first, second and third stomachs. The ruminant then digests this large assortment of bugs in the fourth chamber of their stomach. They ultimately digest this massive quantity of microorganisms and survive off these animal and plant proteins, meaning that ruminant animals are not actually vegetarians. In fact, there are no mammals that are actually vegetarians, despite the fact that they harvest plant materials as a source of food for these “bugs”. The “bugs” that feed off the plant material that the bison harvests to feed them are passed from adult to calf through saliva, whether it be licking on each other, or feeding in the same spot with saliva that drips out of the adult and is then consumed by the calf grazing side-by-side to its mother. This is one reason why it takes about 6 months for a calf to develop its own rumen capable of sustaining a whole biological grass-consuming factory in its stomach, and requires the animal proteins found in the milk in the meantime. 

Bison communicate through grunts to maintain contact with each other, and will snort to warn intruders. Male bison display their fitness by charging and butting heads with other bulls. They also bellow hoarsely, lower their heads, and paw the earth defiantly, but they rarely fight to the death. They have an excellent sense of hearing and smell, but cannot see very well, so an entire herd can stampede if it is startled. Bison have cloven hoofs, and can reach speeds of 30 miles per hour. Wolves and grizzly bears are the only large predators of adult bison. Dead bison provide an important source of food for scavengers and other carnivores. Bison will rub against trees, rocks, or in dirt wallows in an attempt to get rid of insect pests. Birds such as the magpie perch on a bison to feed on insects in its coat. The cowbird will also follow close behind a bison, feeding on insects disturbed by its steps. Bison are wild animals and will remain that way for a very long time. It takes 8,000-10,000 years to domesticate an animal, and not all animal species will allow themselves to be domesticated, such as the zebra. It is only because of modern technology that we are able to keep them fenced in using special wildlife fencing that is much taller than cattle fencing and quite expensive. The corral is more than twice as fortified as one that would be used for cattle and we have built it so that the animals cannot do damage to the workers or each other. As mentioned, they are very aggressive and can be very dangerous, and they never become tame or friendly. Bison can run 40 miles per hour, use their horns as weapons and can jump 5 feet from a standing position. Thomas Jefferson once tried to keep a bison at Monticello using 18th-century fencing technology and it lasted about 3 hours before the animal busted out and was gone. There are three types of modern bison worldwide. One life in Northern Europe is quite rare, smaller in stature, and called a wisent. The woods bison lives mostly in Canada and has a very small population worldwide. The most common bison is the plains bison which exists in both the US and Canada naturally. All bison at Virginia Bison Co. are plains bison. Bison are capable of breeding with beef cattle, and while this is not practiced anymore, it was a common way to build a small bison herd back before the 1970’s when bison were much more rare. One bison bull could be bred to beef cows and produce a 50% bison-cattle hybrid (called cattalo or beefalo), then that 50% hybrid could be bred to another bison to get a 75%, and after a few more breedings like this the farmer ended up with mostly bison genetics. Cross breeding bison and cattle only produces a difficult animal to handle without providing any of the low-fat and low cholesterol meat that you get from bison. This practice of cross-breeding for the past 100 years has resulted in a small percentage of cattle genetics that many bison carry today.

Females are sexually mature at 2 to 3 years of age. While males reach maturity around age three, they generally do not breed until six years of age. Mating season runs from late June through September, and gestation can last around 285 days. Breeding bulls will protect their chosen females and, with little time to eat, may lose more than 200 pounds during the breeding season. A single yellow-red calf will be born away from the herd in a secluded area. After a few days, the calf can keep up with the herd and follows its mother until the following spring. Calves are nursed for seven to eight months and are fully weaned by the end of the first year. Bison are seasonal producers (unlike cattle and sheep which can breed any month of the year) and go into a breeding season, called rutting, in mid-summer that usually ends around August. Any cows that do not get pregnant but are in good body condition can remain fertile into the early fall, so that sometimes we get calves born the following fall instead of spring like normal. Spring is natures regular cycle for calves to be born as that is when the grass is plentiful for cows to produce milk. Bison are much like deer and elk in their natural breeding and feeding cycles. Bison produce a small quantity of milk that is very thick, rich and sticky compared with cattle milk. It is impossible to milk bison due to the danger and stress on the cow and the quantity of milk produced makes this uneconomical to even consider. Buffalo mozzarella is made from water buffalo, but not bison. Due to the seasonality of bison breeding, the meats are all harvested in the fall and sold through the year frozen. There are feedlots around the country attempting to provide year-round fresh bison meat, but they are achieving this by harvesting some animals early, some animals late, taking advantage of the longer growth cycle of female bison in the feedlot, and playing feedlot grain mixture tricks. None of this is very cost effective and those high costs are being passed along to the consumer. Virginia Bison Co. has opted to maintain a natural seasonal flow in production and to have all meats flash frozen at the time of harvesting to be sold the following months frozen.