Animal diversity is modest, as a result of factors including the island's small land area, the relatively recent age of the habitats developed since the last glacial period and the island's physical separation from continental Europe, and the effects of seasonal variability.
Great Britain also experienced early industrialisation and is subject to continuing urbanisation, which have contributed towards the overall loss of species.
A DEFRA (Department for Environment, Food and Rural Affairs) study from 2006 suggested that 100 species have become extinct in the UK during the 20th century, about 100 times the background extinction rate.
However, some species, such as the brown rat, red fox, and introduced grey squirrel, are well adapted to urban areas.

Rodents make up 40% of the mammal species.
These include squirrels, mice, voles, rats and the recently reintroduced European beaver.
There is also an abundance of European rabbit, European hare, shrews, European mole and several species of bat.
Carnivorous mammals include the red fox, Eurasian badger, Eurasian otter, weasel, stoat and elusive Scottish wildcat.
Various species of seal, whale and dolphin are found on or around British shores and coastlines.
The largest land-based wild animals today are deer.
The red deer is the largest species, with roe deer and fallow deer also prominent; the latter was introduced by the Normans.
Sika deer and two more species of smaller deer, muntjac and Chinese water deer, have been introduced, muntjac becoming widespread in England and parts of Wales while Chinese water deer are restricted mainly to East Anglia.
Habitat loss has affected many species.
Extinct large mammals include the brown bear, grey wolf and wild boar; the latter has had a limited reintroduction in recent times.

There is a wealth of birdlife, with 619 species recorded, of which 258 breed on the island or remain during winter.
Because of its mild winters for its latitude, Great Britain hosts important numbers of many wintering species, particularly waders, ducks, geese and swans.
Other well known bird species include the golden eagle, grey heron, common kingfisher, common wood pigeon, house sparrow, European robin, grey partridge, and various species of crow, finch, gull, auk, grouse, owl and falcon.
There are six species of reptile on the island; three snakes and three lizards including the legless slowworm.
One snake, the adder, is venomous but rarely deadly.
Amphibians present are frogs, toads and newts.
There are also several introduced species of reptile and amphibian.
Animal diversity is modest, as a result of factors including the island's small land area, the relatively recent age of the habitats developed since the last glacial period and the island's physical separation from continental Europe, and the effects of seasonal variability. Great Britain also experienced early industrialisation and is subject to continuing urbanisation, which have contributed towards the overall loss of species. A DEFRA (Department for Environment, Food and Rural Affairs) study from 2006 suggested that 100 species have become extinct in the UK during the 20th century, about 100 times the background extinction rate. However, some species, such as the brown rat, red fox, and introduced grey squirrel, are well adapted to urban areas.
Rodents make up 40% of the mammal species. These include squirrels, mice, voles, rats and the recently reintroduced European beaver. There is also an abundance of European rabbit, European hare, shrews, European mole and several species of bat. Carnivorous mammals include the red fox, Eurasian badger, Eurasian otter, weasel, stoat and elusive Scottish wildcat. Various species of seal, whale and dolphin are found on or around British shores and coastlines. The largest land-based wild animals today are deer. The red deer is the largest species, with roe deer and fallow deer also prominent; the latter was introduced by the Normans. Sika deer and two more species of smaller deer, muntjac and Chinese water deer, have been introduced, muntjac becoming widespread in England and parts of Wales while Chinese water deer are restricted mainly to East Anglia. Habitat loss has affected many species. Extinct large mammals include the brown bear, grey wolf and wild boar; the latter has had a limited reintroduction in recent times.
There is a wealth of birdlife, with 619 species recorded, of which 258 breed on the island or remain during winter. Because of its mild winters for its latitude, Great Britain hosts important numbers of many wintering species, particularly waders, ducks, geese and swans. Other well known bird species include the golden eagle, grey heron, common kingfisher, common wood pigeon, house sparrow, European robin, grey partridge, and various species of crow, finch, gull, auk, grouse, owl and falcon. There are six species of reptile on the island; three snakes and three lizards including the legless slowworm. One snake, the adder, is venomous but rarely deadly. Amphibians present are frogs, toads and newts. There are also several introduced species of reptile and amphibian.
Great Britain