Field guide to the most commonly encountered mammals and birds

Here, we provide some basic information regarding commonly observed species (plus some others about which we have had queries).  

Feel free to contact us by email if you have any questions regarding species you have encountered on the site.

For more information about mammals, we recommend the Mammal Society's species hub, here, and MammalNet here. For birds, excellent resources are available from the RSPB (here) and the BTO (here).


Common UK Mammals All UK Mammals Common UK Birds All Species All Deer

Eurasian Beaver

 (C) Patricia van Casteren (shared under a CC BY-NC-ND 2.0 license)

Scientific name: Castor fiber

Family: Castoridae

Appearance: The Eurasian Beaver is one of the largest species of rodent and is most likely to be seen in water. The colour of the fur can vary from a light-chestnut brown to dark blackish-brown across its geographical range but in Great Britain they are most commonly a mid-brown. They are thickset with large heads with a flattened top and small eyes and ears. The tail is flattened and scaly and distinguishes the beaver from any species with which it is likely to be confused such as an otter, water vole or mink.

Size:  Head and body 75-90 cm; Tail 28-38cm; Weight 12-38 kg

Natural history: The Eurasian Beaver was once a widespread and common animal in Britain but was hunted to extinction by the 16th century for its fur and for ‘castoreum’ a musk-scented secretion widely used in the making of perfume. Escapes of captive animals and small-scale reintroductions mean that the beaver is once again present in several locations across Great Britain.

Beavers are largely nocturnal but are occasionally seen during the day. They are active throughout the year feeding on a variety of aquatic and herbaceous plants in spring and summer and bark in winter. Eurasian Beavers form monogamous pairings and litters of (usually) 2-3 kits are born in late spring or early summer. The kits are born fully furred and with their eyes open, they can swim within hours of birth and are weaned at around 2-3 months.