European Beaver

The European beaver or Eurasian beaver (Castor fiber) is a species of beaver, which was once widespread in Eurasia, where it has been hunted both for fur and for castoreum, a secretion of its scent gland believed to have medicinal properties. It still occurs as far as China and Mongolia.^[2][4]

Contents 1 Physiology 1.1 Physical characteristics 2 Differences from North American beaver 3 Range 3.1 Mainland Europe 3.2 Scandinavia 3.3 Great Britain 4 Ecology 5 Gallery 6 References 7 External links

Physiology

Physical characteristics

The fur colour of European beavers varies geographically. Light, chestnut-rust is the dominant colour in Belarus. In Russia, the beavers of the Sozh River basin are predominantly blackish brown, while beavers in the Voronezh Reserve are equally distributed between brown and blackish-brown.^[2]

European beavers on average weigh 18 kg, the largest specimen on record having weighed 31.7 kg.^[2]

Differences from North American beaver

Although superficially similar to the North American beaver, there are several important differences. European beavers tend to be bigger, with larger, less rounded heads, longer, narrower muzzles, thinner, shorter, and lighter underfur, narrower, less oval-shaped tails, and have shorter shin bones, making them less capable of bipedal locomotion than the North American species. European beavers have longer nasal bones than their American cousins, with the widest point being at the end of the snout for the former, and in the middle for the latter. The nasal opening for the European species is triangular, unlike that of the North American race which is square. The foramen magnum is rounded in the European beaver, and triangular in the North American. The anal glands of the European beaver are larger and thin-walled with a large internal volume compared to that of the North American breed. Finally, the guard hairs of the European beaver have a longer hollow medulla at their tips. Fur colour is also different. Overall, 66% of European beavers have pale brown or beige fur, 20% have reddish brown, nearly 8% are brown and only 4% have blackish coats. In North American beavers, 50% have pale brown fur, 25% are reddish brown, one fifth are brown, and 6% are blackish.^[2]

The two species are not genetically compatible. North American beavers have 40 chromosomes, while European beavers have 48. Also, more than 27 attempts were made in Russia to hybridize the two species, with one breeding between a male North American beaver and a female European resulting in one stillborn kit. These factors make interspecific breeding unlikely in areas where the two species' ranges overlap.^[2]

Range

The European (or Eurasian) beaver is recovering from near extinction, after depradation by humans for its fur and castoreum decimated populations to an estimated 1,200 by the early 20th century.^[5] In many European nations, the beaver went extinct but reintroduction and protection has led to gradual recovery to approximately 639,000 individuals by 2003.^[6]

Mainland Europe

In Romania, beavers became extinct in 1824, being reintroduced in 1998, along the Olt River, spreading to other rivers in Covasna County.^[7]

Beavers have been re-introduced in Bavaria and the Netherlands and are tending to spread to new locations.^[8] After being reintroduced in the Biesbosch in 1988, the Dutch population has spread considerably (supported by additional reintroductions), and can now be found in the Biesbosch and surrounding areas, along the Meuse in Limburg, and in the Gelderse Poort and Oostvaardersplassen.

Scandinavia

In Sweden the beaver had been hunted to extinction by the end of the nineteenth century. Between 1922 and 1939 approximately eighty individuals were imported from Norway and introduced to nineteen separate sites within the country.

Norwegian beavers also played an important role in reintroducing the locally extinct animal to Finland, but there the population also includes a substantial number of C. canadensis of Canadian origin. (The North American Beavers were imported to Finland in 1937, when it was not yet known that C.canadensis was a different species from the European beaver.)

In Denmark, the beaver was reintroduced to the wild in western Jutland in 1999^[9] and in Arresø, northern Zealand, in 2009^[10] after it was hunted to extinction c. 1000 AD. The reintroduced beavers were caught in the river Elben in Germany. As of 2009^[update], the Danish population of beavers was estimated to be 100—120 individuals.^[11]

Great Britain

The beaver became extinct in Great Britain in the sixteenth century: Giraldus Cambrensis reported in 1188 (Itinerarium ii.iii) that it was to be found only in the Teifi in Wales and in one river in Scotland, though his observations are clearly secondhand. The last reference to beavers in England dates to 1526.^[12]

In 2001 the Wildwood Trust with Kent Wildlife Trust imported two families of European beaver from Norway to manage a wetland nature reserve. This project pioneered the use of beaver as a wildlife conservation tool in the UK. The success of this project has provided the inspiration behind other projects in Gloucestershire and Argyll. The Kent beaver colony live in a 130-acre (0.53 km²) fenced enclosure at the wetland of Ham Fen. Subsequently the population of beaver has been supplemented in 2005 and 2008. The beaver continue to help restore the wetland by rehydrating the soils.^[13]

Six European Beavers were released in 2005 into a fenced lakeside area in Gloucestershire.^[14]

In 2007 a specially-selected group of four Bavarian beavers were released into a fenced enclosure in the Martin Mere nature reserve in Lancashire.^[15] It is hoped that the beavers will form a permanent colony, and the younger pair will be transferred to another location when the adults begin breeding again.^[16] The progress of the group will be followed as part of the BBC's Autumnwatch television series.

A colony of beavers is established in a large enclosure at Bamff, Perthshire.^[17]

A beaver living wild was confirmed in Scotland in early 2007 and was captured. It may have been released illegally.^[18]

In 2005, the Scottish Government turned down a licence application for unfenced reintroduction. However, in late 2007 a further application was made for a release project in Knapdale, Argyll.^[19] This application was accepted, and the first beavers were released on the 29th May 2009.^[20][21] This inital release into the wild of 11 animals received a set back during the first year with the disappearance of two animals and the illegal shooting of a third. However, the remaining population was increased in 2010 by further releases.^[22] The Scottish charity Trees for Life plans to reintroduce beavers in the Scottish Highlands.^[23][24]

With the exception of the Knapdale animals, all the beavers in the United Kingdom today are in semi-enclosed sites and not fully released into the wild. A 2009 report by Natural England, the Government’s conservation body, and the People's Trust for Endangered Species recommended that beaver be reintroduced to the wild in England.^[25]

Ecology

Beaver are a keystone species helping support the ecosystem of which they are a part. They create wetlands which increase biodiversity and provide habitat for many rare species such as water voles, otters and water shrews. They coppice waterside trees and shrubs so that they re-grow as dense shrubs which provide cover for birds and other animals. Beaver dams trap sediment and improve water quality; recharge groundwater tables and increase cover and forage for trout and salmon.^[25]

Beaver ponds have been shown to have a beneficial effect on trout and salmon populations, in fact many authors believe that the decline of salmonid fishes is related to the decline in beaver populations. A study of small streams in Sweden that found that brown trout were larger in beaver ponds compared with those in riffle sections, and that beaver ponds provide habitat for larger trout in small streams during periods of drought.^[26] These findings are similar to several studies of beaver effects on fish in North America. Brook trout, coho and sockeye salmon were significantly larger in beaver ponds than those in un-impounded stream sections in Colorado and Alaska.^[27][28] In addition, research in the Stillaguamish River basin in Washington state, found that extensive loss of beaver ponds resulted in an 89% reduction in coho salmon smolt summer production and an almost equally detrimental 86% reduction in critical winter habitat carrying capacity.^[29]

In Poland in May and June 2010 after major flooding, the Polish government and local authorities held beavers responsible for causing the flooding and demanded the culling of 150 beavers.^[30]

Gallery

Skull of a beaver (Castor)

Eurasian beaver

Large beaver dam

Beavers in captivity

References

External links

• Media related to Castor fiber at Wikimedia Commons

• Data related to Castor fiber at Wikispecies