The Eurasian beaver is a brown or black aquatic mammal that measures up to 120 centimetres in length. Its flat, oval-shaped, scaly tail is around 30 centimetres long and 13 centimetres wide. It has small eyes and ears, and webbed hind feet. Beavers warn each other of danger by slapping the water with their broad tails as an alarm signal.
Eurasian beavers live on the banks of slow-moving rivers and in lakes surrounded by deciduous forests. They can also be found in irrigation canals and shrubby wetlands. They are particularly widespread in Eastern Europe. Traces of beaver activity can sometimes be found in cities.
Eurasian beavers dig holes in steep banks, or build lodges out of branches and mud. These lodges can be up to 5 metres tall and have underwater entrances. In areas with low water levels, beavers construct dams from branches, stones and mud. They fell waterside trees and shrubs using their chisel-like incisors. Eurasian beavers feed on tree bark, twigs and shrubs, as well as aquatic and waterside plants, and prefer the wood of the aspen, willow, cherry and birch. They forage and work mostly at night. The normal litter size is two or three young. The young beavers are able to swim within one or two days of birth and are weaned at three weeks of age. Beavers live with their parents until they are about two years old and can live up to 24 years of age in the wild.