Best time to see: all year

Key facts

Beaver were hunted to extinction in the 16th century, but are now being reintroduced, including to Essex

They are nature's master engineers, creating small wetlands that enhance water quality and mitigate floods.

They occupy ditches, streams and small rivers wherever there are trees to provide material for their dams.

Recognition

The largest of the rodents, more than a metre from head to tail, and with brown fur and a broad flat tail.

Most often seen swimming low in the water with their nose up and tail flat on the water.

Their massive yellow teeth are used to fell trees to provide material for their dams and food in winter.

Lifecycle

They are nocturnal herbivores, feeding on aquatic plants, leaves and, in hard times, tree bark.

They build dams to create deep pools that protect the underwater entrances to their lodges and encourage wetland plants.

They live in small family groups, mating for life and producing up to 4 kits every year.