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Wisent |
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| Bison bonasus (Linnaeus, 1758) |
The wisent (pronounced /ˈviːzənt/), or European bison (Bison bonasus), is a bison species and the heaviest surviving land animal in Europe. A typical wisent is about 2.9–3.0 m (9.5 ft) long and 1.8–2.2 m (5.9–7.4 ft) tall, and weighs 300–920 kg (660–2000 lb). It is typically smaller than the related American bison (Bos bison), and has shorter hair on the neck, head, and forequarters, but longer tail and horns. Wisent are now forest-dwelling. They have few predators (besides humans) with only scattered reports from the 1800s of wolf and bear predation. Wisent were first scientifically described by Carolus Linnaeus in 1758. Some later descriptions treat the wisent as conspecific with the American bison. It is not to be confused with the aurochs, the extinct ancestor of domestic cattle.
In 1996 the IUCN classified the wisent as an endangered species. In the past it was commonly killed to produce hides and drinking horns, especially during the Middle Ages.
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About 2000 years ago, wisent lived throughout most of Europe - from Britain in the west, to Siberia in the east, and from Spain in the south, to Sweden in the north. Wisent lived not only in forests but also roamed grasslands.
In Western Europe, wisent became extinct by the 11th century, except in the Ardennes, where they lasted into the 14th century. The last wisent in Transylvania died in 1790.
In the east, wisent were legally the property of the Polish kings, Lithuanian grand dukes and Russian czars. King Sigismund I of Poland instituted the death penalty for poaching a wisent in the mid-16th century. Despite these measures, and others, the wisent population continued to decline over the following four centuries. The last wild wisent in Poland was killed in 1919 and the last wild wisent in the world was killed by poachers in 1927 in the Western Caucasus. By that year fewer than 50 remained, all in zoos.
In order to help manage this captive population, Dr. Heinzel Heck commenced the first studbook for a non-domestic species; first as a card index from 1923 with a full publication in 1932.1
Wisent were reintroduced successfully into the wild, beginning in 1951. They are found living free-ranging in forest preserves like Western Caucasus and Prioksko-Terrasny Nature Reserve in Russia and Białowieża Forest in Poland and Belarus.
Free-ranging herds are found in Poland, Lithuania, Belarus, Ukraine, Romania, Russia, Slovakia, Latvia, Kyrgyzstan and since 2006 in Moldovacitation needed. There are plans to re-introduce two herds in northern Germanyclarification needed and in Oostvaardersplassen Nature reserve in Flevoland (Netherlands). Zoos in 30 countries also have quite a few animals. There were 3,000 individuals (as of 2000), all descended from only 12 individuals. Because of their limited genetic pool, they are considered highly vulnerable to diseases like foot and mouth disease.
Wisent have lived as long as 28 years in captivity although in the wild their lifespan is shorter. Productive breeding years are between four and 20 years old in females and only between six and 12 years old in males. Wisent occupy home ranges of as much as 100 square kilometers and some herds are found to prefer meadows and open areas in forests.
Wisent can cross-breed with American bison. The products of a German interbreeding program were destroyed after World War II. This program was related to the impulse which created the Heck cattle. The cross-bred individuals created at other zoos were eliminated from breed books by the 1950s. A Russian back-breeding program resulted in a wild herd of hybrid animals which presently lives in the Caucasian Biosphere Reserve (550 individuals in 1999).
There are also wisent-cattle hybrids. Cattle and wisent can hybridise fairly readily, but the calves cannot be born naturally (birth is not triggered correctly by the first-cross hybrid calf, and they must therefore be born by Caesarian section). In 1847 a herd of wisent-cattle hybrids named żubroń was created by Leopold Walicki. The animal was intended to become a durable and cheap alternative to cattle. The experiment was continued by researchers from the Polish Academy of Sciences until the late 1980s. Although the program resulted in a quite successful animal that was both hardy and could be bred in marginal grazing lands, it was eventually discontinued. Currently the only surviving żubroń herd consists of just a few animals in Białowieża Forest, Poland.
Three sub-species have been identified:
The modern herds are managed as two separate lines - one consisting of only Bison bonasus bonasus (all descended from only seven animals) and one consisting of all 12 ancestors including the one Bison bonasus caucasicus bull. Only a limited amount of inbreeding depression from the population bottleneck has been found, having a small effect on skeletal growth in cows and a small rise in calf mortality. Genetic variability continues to shrink. From five initial bulls, all current wisent bulls have one of only two remaining Y chromosomes.
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