The Eurasian beaver

The Eurasian beaver C. fiber was once widespread in Europe and Asia, inhabiting the forest zones but also wooded river valleys reaching into the tundra and steppe zones. However, at the beginning of the 20th century only eight small populations with a total of 1200 beavers were left. The beaver was apparenrly exterminated from the south of his range, since Portugal, Spain, Grece, Turkey, Azerbaijian, and Iraq only sub-fossil founds have been recorded. The beavers subsequentely disapperared fron Italy and Britainin the 16th century. In most countries the last beaver was Kiled in the 19th century.

            The main cause for the near disapearence of beaver was, was without doubt, over-hunting. Beavers are easily located, especially in autumn when they fell trees and build or repair their lodges, dams and food caches, or during ice-cover winter. The beaver was mainly hunted for its fur (pelt), the chemical substance from its castor sacs ( castoreum, used as medicine and base aroma in perfume), and its meat.

Fortunately, a series of management measures led to remarkable recovery of the beaver. At first, starting in 1845 in Norway, hunting was prohibited in all countries which still retaind beaver populations, although in some cases (Finland, Sweden) the protection came too late. Subsequently. many beavers were translocated to restock vacant areas. The first reintroduction took place in Sweden in the 1920s. Later reintroductions translocations were conducted in (in chronological order) Norway, Russia, Latvia, Finland, Germany, Poland, Lithuania, Switzerland, Estonia, Mongolia, France, Austria, Netherlands, and Czech Republic. The early reintroductions were aimed at the re-establishment at a game species to be harvested for its fur. From the 1970s onwards, the animals were reintroduced more and more for ecological reasons, i.e. because of the significant impact beavers can have on their sunrroundings in being able to fell mature trees and modify water levels. Although a number of these reintroductions  failed because not enough animals were released, most gave rise to viable beaver population. However, because not much attention was paid to the origin of the founders, many translocations resulted in a mixture of beavers of geografical forms.

            Now the Eurasian beaver is slowly becoming restablished over much of its former range owing to two factors:) (1) the natural habitat is still present in some areas and (2) the beaver is so plastic that it can survive and reproduce in the cultivated landscape. The Eurasian beaver presently numbers an estimated 430 000 in Europe and Asia. In large parts of the continent, the munber of beavers is still increasing.(Bart A. Nolet and Frank Rosell “Comeback of the beaver Castor fiber: an overview of old and new conservation problems”)

 

 

 

 

The species belongs to the order Rodentia, suborder Sciuromorpha, Sciuroidae superfamily, family Castoridae, Castor gender and is the only representative of the family in Europe.

Beaver is a semi-aquatic, nocturnal and twilight animal, with multiple anatomical adaptations that allow him successful exploration of the aquatic environment. In water, the beaver has hydrodynamic position, propelling itself with their hind legs and tail.

The weight of an adult specimen of Eurasian beaver varies between 18 and 25 kg, and complet body length with tail is 70 - 100 cm.

Senses. Hearing and smell are well developed. The sight is poor, however, the beaver is able to distinguish colors.

Teeth. The incisors have open roots, are large and have continuing growing. The outer surface is covered by hard enamel, bright orange color.

The tail is used to swim, to maintain balance while moving on land and used for alarm signal. This is the place to store body fat for the winter and heat exchange.

Fur is composed of two types of hair, helps insulation. The small hair fur is soft, wavy and extremely thick and can reach 2 to 3 cm long. Instead, hair protector is strong, thick and long, reaching 5 to 6 cm long. The color of protection hair varies from black to gray, while the short hair is brown - reddish. To dive, a layer of air bubbles is retained in fur, improving the thermal insulation of the body. Beavers moult once a year during the summer.

Members. Front paws are agile, in contrast to those of the hind limbs. Are used for digging, to carry construction materials and sometimes to unwrap the food. During swimming, front legs are brought ​​under the chin.Hind feet toes membrane is especially adapted for swimming, and nails are used for daily grooming. A peculiarity is the presence of "double claw" to the second toe of the hind leg, used to clean fur.

Terrestrial locomotion. The beaver slow movements consist on diagonally coordinated movements. Rapid running movements consist of jumping on all members (gallop). Yet another type of locomotion is movement on both rear limbs.

Swimming. Various adaptations allow beaver to survive in water or moist environment of the lair. Automatically the nostrils gather and the ears close when the animal enters the water.

Digging. Beaver dig through alternative movements of the limbs. Specific activities are digging, pushing and throwing back.

Grooming. Like most mammals and birds, beaver grant time fur grooming.

Building shelters and dams. In the construction of permanent shelters, digging start under water, tunnel being dug rising up above the water level.

Material transport. The transport to the construction site is made by walking or swimming, grasping one end of the wood with incisors.Small pieces are transported either in the mouth or using its front paws.Beaver can carry over long distances thick branches.

Shelter. Along major rivers and affluents, whose sides allow excavation, the beavers arranged shelter in their bank.

Dam. High water levels contribute to better protection from enemies, so the beavers can dive and swim in underwater tunnel system.Because of these dams, the water level in the basin next to the the water remains constant feeding room and animals are able to accumulate food reserves near the entrance tunnels.

Food. They are strictly herbivorous animals. A large part of woody vegetation that beaver pull down is not used for food. Feeding is in close proximity to the water. Beaver prefer soft species, especially small size poplar and willow tree.

Reproduction. The beaver is monogamous, does not present sexual dimorphism. Mating takes place from January to March, in water. Gestation lasts 105 to 107 days. Dominant female in each family give birth between 2 to 5 cubs per year.

Biotope. The beaver has some "claims" regarding their structure and conformation of the banks, to the hydrological characteristics of the rivers and to the presence / quality of woody vegetation.

 

Main threats:

  • Regulated water courses and the execution of hydrotechnical works
  • Stragglers dogs
  • Poaching

           The course of rivers with streams are subject to hydrotechnical works. The most important hydrotechnical works with impact on species are construction of dams for accumulation lakes, concreting or paving banks, building waterfalls, dams with their maintenance works: unsilting, recalibration, etc.
           The presence of the dogs from stragglers or sheepfolds have a strong impact on beavers, especially during rearing of the young and winter when animal mobility is limited and can fall prey to them. Under normal conditions safety of beaver specimens is ensured in the aquatic environment, but remain very vulnerable on land where their movement is difficult.

Poaching on beaver occurs mainly in response to the damage the specimens of beaver produce in crops, orchards or on vegetation banks.They take place because of insufficient background information and awareness about the characteristics and importance of species in the ecosystem.So exemplary of beaver were caught with snares or other traps to protect crops. There have been isolated cases of killing the beaver because of lack of knowledge regarding the species.