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Beaver, Eurasian (Castor fiber)

Architects of the natural world, beavers are back in Britain after centuries away.

Scientific name: Castor fiber

Family: Castoridae


With brown fur, a long, flat, muscular tail, webbed feet and huge orange teeth, the beaver is distinctive. Weighing up to 30kg, it is the largest rodent in Europe.

Where and how to spot

Hunted to extinction around five hundred years ago, beavers were officially reintroduced to the UK in 2009 at Knapdale, Argyll as part of a Scottish government trial. However, these were not the first to return. A few years earlier, beavers were discovered on the River Tay, having either escaped from captivity or been illegally released. In 2010, a similar situation occurred on the River Otter, Devon, with a population of unknown origin becoming established. Several other beavers have since been released on the river as part of a government-sanctioned trial. Another reintroduction trial was launched in the Forest of Dean in summer 2018, with two beavers released into a large enclosure from which their impact on the local environment will be studied.

Fresh water surrounded by woodland is ideal beaver habitat, providing them with both food and shelter. As crepuscular animals, your best chance of seeing a beaver is at dawn or dusk. It’s much easier to see signs of their presence, however, with felled trees, stripped branches and dams all clear evidence that beavers are in the area.


Beavers are herbivorous and do not eat fish. Their diet is made up of aquatic plants and grasses, as well as the bark, twigs and leaves of trees.

Behaviour and breeding

Beavers live in small family groups and are thought to mate for life. Typically, two to four young, known as kits, are born each year. Youngsters will stay with their family for around two years, before leaving to find territories of their own. A typical beaver will live for around seven to eight years.

Animal architects, beavers build dams to restrict water flow and create ponds of still, deep water. Within these ponds, they will construct lodges in which they live, safe from predators. Beavers use their huge teeth to fell trees and divide them up into smaller branches, which are dragged into place to build dams. Lodges are comprised of sticks and branches held together with mud, which also provides insulation. These building activities can have a significant impact on the environment in which the beavers live.

Threats and conservation status

The Scottish government has formally recognised beavers as a native species, meaning the populations at Knapdale and on the River Tay are here to stay. The trial in Devon is ongoing, while research is underway concerning possible reintroductions in Cornwall, Kent and Wales. Opinions have been divided regarding the species’ return. Known as ‘ecosystem engineers,’ it is thought beavers can provide several environmental benefits, including flood prevention and the creation of more diverse habitats that benefit a host of other wildlife. However, concerns have also been raised about the potential for arable land to be flooded due to beaver activity.

Did you know?

  • Beavers can hold their breath for up to 15 minutes. They are able to close their nose and ears while underwater and even have inner lips behind their teeth to prevent their mouth filling with water while gnawing wood.
  • As rodents, beavers are related to rats and mice, but are much larger. An adult beaver can weigh as much as 1,500 house mice!
  • Beaver lodges are often built with a type of ‘chimney’ to regulate temperature.