A Plains Bison.
|Common Name||American buffalo|
The American Bison is a species from the Bison genus. Their range once roughly comprised a triangle between the Great Bear Lake in Canada's far northwest, south to the Mexican states of Durango and Nuevo León, and east along the western boundary of the Appalachian Mountains.
A bison has a shaggy, long, dark brown winter coat, and a lighter weight, lighter brown summer coat. As is typical in ungulates, the male bison are slightly larger than the female. The heads and forequarters are massive, and both sexes have short, curved horns that can grow up to 2 feet (61 cm) long, which they use in fighting for status within the herd and for defense.
Range and population
Despite being the closest relatives of domestic cattle native to North America, bison were never domesticated by native Americans. Later attempts of domestication by Europeans prior to the 20th century met with limited success. Bison were described as having "wild and ungovernable temper"; they can jump 6 feet (1.8 m) vertically, and run 35–40 mph (56–64 km/h) when agitated. This agility and speed, combined with their great size and weight, makes bison herds difficult to confine as they can easily escape or destroy most fencing systems, including most razor wire.
There are approximately 500,000 bison in captive commercial populations (mostly plains bison) on about 4,000 privately owned ranches. Under the IUCN Red List Guidelines, commercial herds are not eligible for consideration in determining a Red List designation, therefore the total population of bison calculated in conservation herds is approximately 30,000 individuals and the mature population consists of approximately 20,000 individuals. Of the total number presented, only 15,000 total individuals are considered wild bison in the natural range within North America (free-ranging, not confined primarily by fencing).
American bison live in river valleys, and on prairies and plains. Typical habitat is open or semi-open grasslands, as well as sagebrush, semi-arid lands and scrublands. Some lightly wooded areas are also known historically to have supported bison. Bison will also graze in hilly or mountainous areas where the slopes are not steep. Though not particularly known as high altitude animals, bison in the Yellowstone Park bison herd are frequently found at elevations above 8,000 feet and the Henry Mountains bison herd is found on the plains around the Henry Mountains, Utah, as well as in mountain valleys of the Henry Mountains to an altitude of 10,000 feet.
Bison are migratory and herd migrations can be directional as well as altitudinal in some areas. Bison mate in late spring and summer in more open plain areas. During fall and winter, bison tend to gather in more wooded areas. During this time, bison partake in horning behaviors. They will rub their horns against trees, young saplings and even telephone poles. Aromatic trees like cedars and pine seem to be preferred. Horning appears to be associated with insect defense as it occurs most often in the fall when the insect population is at its highest.
Bison are herbivores, grazing on the grasses and sedges of the North American prairies. So they eat prairie plants
Social behavior and reproduction
Female bison live in maternal herds which include other females and their offspring. Male offspring leave their maternal herd when around three years old and will either live alone or join other males in bachelor herds. Male and female herds usually do not mingle until the breeding season. However female herds may also contain a few older males. During the breeding season, dominant bulls maintain a small harem of females for mating. Individual bulls "tend" cows until allowed to mate, by following them around and chasing away rival males. The tending bull will shield the female's vision with his body so she will not see any other challenging males. A challenging bull may bellow or roar to get a female's attention and the tending bull has to bellow/roar back. The most dominant bulls mate in the first 2–3 weeks of the season. More subordinate bulls will mate with any remaining estrous cow that has not mated yet. Male bison play no part in raising the young.
Bison herds have dominance hierarchies that exist for both males and females. A bison's dominance is related to its birth date. Bison born earlier in the breeding season are more likely to be larger and more dominant as adults. Thus bison are able to pass on their dominance to their offspring as dominant bison breed earlier in the season. In addition to dominance, the older bison of a generation also have a higher fertility rate than the younger ones. Cows nurse their calves for at least 7 or 8 months but most calves seem to be weaned before the end of their first year.
Bison have been observed to display homosexual behaviors, males much more so than females. In the case of males, it is unlikely to be related to dominance but rather to social bonding or gaining sexual experience.
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Bison mate in August and September; gestation is 285 days. A single reddish-brown calf nurses until the next calf is born. If the cow is not pregnant, a calf will nurse for 18 months. Bison cows are mature enough to produce a calf at 3 years of age. Bison bulls may try to mate with cows at 3 years of age, but if more mature bulls are present, they may not be able to compete until they reach 5 years of age. Bison have a life expectancy of approximately 15 years in the wild and up to 25 years in captivity.
Bison mate in late spring and summer in more open plain areas. During fall and winter, bison tend to gather in more wooded areas. During this time, bison partake in horning behaviors. They will rub their horns against trees, young saplings and even utility poles. Aromatic trees like cedars and pine seem to be preferred. Horning appears to be associated with insect defense as it occurs most often in the fall when the insect population is at its highest. Cedar and pines emit an aroma after bison horn them and this seems to be used as a deterrent for insects.
A bison wallow is a shallow depression in the soil, which is used either wet or dry. Bison roll in these depressions, covering themselves with dust or mud. Past explanations and current hypotheses suggested for wallowing behavior include grooming behavior associated with shedding, male-male interaction (typically rutting behavior), social behavior for group cohesion, play behavior, relief from skin irritation due to biting insects; reduction of ectoparasite (tick and lice) load; and thermoregulation.
While often secure from predation due to their size and strength, in some areas, bison are regularly preyed upon by wolves. Wolf predation typically peaks in late spring and early summer, with attacks usually being concentrated on cows and calves. Observations have shown that wolves more actively target herds with calves than those without. The length of a predation episode varies, ranging from a few minutes to over nine hours. Bison display five apparent defense strategies in protecting calves from wolves: running to a cow, running to a herd, running to the nearest bull, running in the front or center of a stampeding herd, and entering water bodies such as lakes or rivers. When fleeing wolves in open areas, cows with young calves take the lead, while bulls take to the rear of the herds, to guard the cows' escape. Bison typically ignore wolves not displaying hunting behavior. Wolf packs specializing in bison tend to have a greater number of males, as their larger size compared to the females allows them to wrestle their prey to the ground more effectively. Healthy, mature bulls in herds rarely fall victim to predators. The grizzly bear can also pose a threat to calves and sometimes old, injured or sick adult bison.
Dangers to humans
Bison are among the most dangerous animals encountered by visitors to the various U.S. and Canadian national parks and will attack humans if provoked. They appear slow because of their lethargic movements but can easily outrun humans—bison have been observed running as fast as 40 miles per hour (64 km/h).
Between 1980 and 1999, more than three times as many people in Yellowstone National Park were injured by bison than by bears. During this period, bison charged and injured 79 people, with injuries ranging from goring puncture wounds and broken bones to bruises and abrasions. Bears injured 24 people during the same time frame. Three people died from the injuries inflicted—one person by bison in 1983, and two people by bears in 1984 and 1986.
Buffalo hunting (hunting of the American bison) was an activity fundamental to the Plains Indian tribes of the United States, which was later adopted by American professional hunters, leading to the near-extinction of the species around the year 1890. It has since begun to recover.
Range history of bison in North America
The first thoroughfares of North America, except for the time-obliterated paths of mastodon or muskox and the routes of the Mound Builders, were the traces made by bison and deer in seasonal migration and between feeding grounds and salt licks. Many of these routes, hammered by countless hoofs instinctively following watersheds and the crests of ridges in avoidance of lower places' summer muck and winter snowdrifts, were followed by the Indians as courses to hunting grounds and as warriors' paths. They were invaluable to explorers and were adopted by pioneers. Bison traces were characteristically north and south, but several key east-west trails were used later as railways. Some of these include the Cumberland Gap through the Blue Ridge Mountains to upper Kentucky. A heavily used trace crossed the Ohio River at the Falls of the Ohio and ran west, crossing the Wabash River near Vincennes, Indiana. In Senator Thomas Hart Benton's phrase saluting these sagacious path-makers, the bison paved the way for the railroads to the Pacific.
- In the United States, the American bison is a popular symbol in the Great Plains states.
- The American Bison is the state animal of Oklahoma.
- By 1770 they had disappeared from America east of the Mississippi.