Beaver, Beaver

They are the second-largest rodent in the world (after the capybara). Their colonies create one or more dams to provide still, deep water to protect against predators, and to float food and building material. The North American beaver population was once more than 60 million, but as of 1988 was 612 million. This population decline is due to extensive hunting for fur, for glands used as medicine and perfume, and because their harvesting of trees and flooding of waterways may interfere with other land uses. Nowak, Ronald M. 1991. pp. 364367.

Beavers also build canals to float build materials that are difficult to haul over land. They use powerful front teeth to cut trees and plants that they use for building and for food. In the absence of an existing pond a Beaver has to construct a dam before building his lodge. First they place vertical poles and then fill between the vertical poles with a crisscross of horizontally placed branches. They fill in the gaps between the branches with a combination of weeds and mud until the dam holds back sufficient water to surround the lodge.

This creates a loud "slap," audible over great distances above and below water. This noise serves as a warning to beavers in the area.

Beavers are slow on land, but good swimmers that can stay under water for as long as 15 minutes. (Wilson, 1971) Rarely does a frightened beaver attack a human.

Genetic research has shown the European and North American beaver populations to be distinct species and that hybrid is unlikely. Beavers are closely related to squirrels (Sciuridae), agreeing in certain structural peculiarities of the lower jaw and skull. In the Sciuridae the two main bones (tibia and fibula) of the lower half of the leg are quite separate, the tail is round and hairy, and the habitats are arboreal and terrestrial. In the beavers or Castoridae these bones are in close contact at their lower ends, the tail is depressed, expanded and scaly, and their habitats are aquatic. Although superficially similar to each other, there are several important differences between the two species. 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 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 fomer, and in the middle for the latter. The nasal opening for the European species is triangular, unlike that of the American race which is square. The foramen magnum is rounded in the European beaver, and triangular in the American. The anal glands of the European beaver are larger and thin-walled with a large internal volume compared to that of the 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 American beavers,50% have pale brown fur, 25% are reddish brown, 20% are brown and 6% are blackish.

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 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.

However, the beaver is now being re-introduced throughout Europe. Several thousand live on the Elbe, the Rhone and in parts of Scandinavia. A thriving community lives in northeast Poland, and the European Beaver also returned to the Morava River banks in Slovakia and the Czech Republic. They have been reintroduced in Scotland, Bavaria, Austria, The Netherlands, Serbia (Zasavica bog), Denmark (West Jutland) and Bulgaria and are spreading to new locations. 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 second hand. In October 2005, six European beavers were reintroduced to Britain in Lower Mill Estate in Gloucestershire; in July 2007 a colony of four European beavers was established at Martin Mere in Lancashire, and a trial re-introduction occurred in Scotland in May 2009. Feasibility studies for a reintroduction to Wales are at an advanced stage and a preliminary study for a reintroduction of beavers to the wild in England has recently been published.

During the early 19th century, trapping eliminated this animal from large portions of its original range. However, through trap and transfer and habitat conservation it made a nearly complete recovery by the 1940s. Beaver reintroduction in British Columbia was facilitated by Eric Collier as recounted in his book Three Against the Wilderness.

The actions of beavers for hundreds of thousands of years in the Northern Hemisphere have kept these watery systems healthy and in good repair, although a human observing all the downed trees might think that the beavers were doing just the opposite.

PMID 12576209 Claudius Aelianus comically described beavers chewing off their testicles to preserve themselves from hunters, which is not possible because the male beaver's testicles are inside its body.

As a national symbol, the beaver was chosen to be the mascot of the 1976 Summer Olympics held in Montreal with the name "Amik" ("beaver" in Ojibwe). The beaver is also the symbol of many units and organizations within the Canadian Forces, such as on the cap badges of the Royal 22 e Rgiment and the Canadian Military Engineers. Toronto Police Services, London Police Service, Canadian Pacific Railway Police Service and Canadian Pacific Railway crest bears the beaver on their crest or coat of arms.

They were then shipped back to Great Britain and France where they were made into clothing items. Widespread hunting and trapping of beavers led to their endangerment. Eventually, the fur trade declined due to declining demand in Europe and the takeover of trapping grounds to support the growing agriculture sector. A small resurgence in beaver trapping has occurred in some areas where there is an over-population of beaver; trapping is done when the fur is of value, and the remainder of the animal may be used as feed. In the 1976/1977 season, 500,000 beaver pelts were harvested in North America. Nowak, Ronald M. 1991. pp. 638.

Source: Wikipedia > Beaver