Species – Eurasian beaver (Castor fiber)
Habitat: Woodland, slow moving river valley bottoms, floodplains.
Description: Large rodent with robust body, short neck and limbs. Large, flattened, scale-covered tail. Webbed hindfeet. Distinct from smaller coypu and muskrat due to shape of tail. Large incisor teeth covered in orange enamel.
Size: 74-90cm; tail length 28.5-38cm; hindfeet length 16-18cm.
Lifespan: Average lifespan 7-8 years, can be up to 25 years.
Origin and distribution: Once deemed extinct in Great Britain but there have been reintroductions in certain areas including Scotland, Devon, Cornwall and Kent.
Diet: Rhizomes, pond weeds, grasses, water lilies, ferns and leaves in summer. Bark from aspen, willow, poplar and alder in winter. Caches food on bottom of watercourse near lodge in winter in harsh environments.
General Ecology: Tend to use natural holes or burrow into the bank. Entrance below water level, leading to a nest chamber. Bank burrows normally 1.5-2m high above the entrance. When burrows and bank lodges are unavailable true lodges are constructed entirely from woody debris, soil and twigs.
Small family groups comprise of a monogamous adult pair, young-of-year and sometimes young of the previous year. Group sizes increase with population density. Territory size varies with habitat, density and season. Generally 3km but can vary from 0.5-12.8km.
Predators in Europe include wolves, wolverine, lynx and red fox.
Breeding: Monogamous breeding takes place between December and April. Pregnancy lasts 103-108 days. Litter size between 1-6 young between May and June. Individuals are sexually mature at 2 years old, but unlikely to breed successfully until they reach 3 years old.
Conservation Status: The Eurasian beaver is deemed by the IUCN as endangered in Scotland and not assessed in the rest of Great Britain. Since the recent reintroductions the population numbers are rising with the Mammal Society’s study in 2018 indicating there are now 168 individuals. Current threats are due to socio-economic interests as beavers can drastically alter the rivers they live in, which can result in land belonging to farmers flooding and causing crops to fail.