1st class wildcat
Shy and nocturnal, and now confined to the wilder parts of Scotland, the wildcat resembles a tabby cat with prominent black stripes on the body and legs. Its tail is usually thicker and rounder-ended than a domestic cat's.

1st class water vole
A rat-sized animal with a chubby face and chocolate-brown fur, the water vole lives beside ponds, rivers and ditches, where it digs burrows in the banks and feeds on vegetation, roots and bark. It is found mainly in the lowlands of mainland Britain, usually in small colonies.

1st class sperm whale
Distinguishable by its blunt-ended head, this whale is normally found in deep waters to the west of Britain, but occasionally gets stranded in estuaries. After swimming at the surface for about 10 minutes, it can dive deep for half an hour to feed, mainly on squid.

1st class polecat
With its distinctive 'bandit' mask, the polecat is a solitary and predominantly nocturnal animal found in woodlands, farmland and wetland. Almost entirely carnivorous, it produces a strong musky scent when threatened. It is making a recovery across much of central and southern England, helped by reintroduction programmes.

1st class otter
Long and sleek with short legs and webbed feet, the otter is normally seen in or beside water, where it swims and dives in pursuit of fish, crabs and other aquatic food. It is most numerous in western counties and along the shores of Scotland's sea lochs, living alone or in a family group of a female and young.

1st class humpback whale
This big, black whale with white under its tail has knobbly flippers that are longer than those of any other whale. Seen mainly in summer off the west coast, it arches its back to dive and feeds by sieving small fish through an array of frilly plates in its upper jaw.

1st class dormouse
This golden-yellow mammal is the only British mouse with a thick, fluffy tail. Active among the branches of shrubs and trees, it feeds on flowers, fruits and insects. Found mostly in southern England, it is usually nocturnal and hibernates through the winter.

1st class greater horseshoe bat
Large and broad-winged, this bat has a distinctive cone-shaped nose-leaf which it uses for echo-location. Its wings and ears are pale brown, and its fur grey or buff, with a reddish tinge in older age. Found mainly in south-west England and south Wales, it hibernates in caves, cellars and mines from October to May.

1st class brown long-eared bat
Small but with enormous ears, this animal is found throughout mainland Britain, except in the extreme north, and is the bat most often found flying inside houses. It commonly lives in attics, hollow trees and bird boxes, and hovers to pick insects and spiders off trees.

1st class hedgehog
Britain's only spiny mammal is found throughout the UK. Nocturnal, it snuffles about in gardens, farmland and woodland, feeding on worms, beetles and other small prey. It rolls into a tight ball when alarmed, and hibernates for five to six months.