Invasive Species: Grey Squirrel

Eastern grey squirrel
Sciurus carolinensis Gmelin, 1788
Sciuridae; Rodentia; Mammalia; Chordata
Wild in London Zoo
December 2009

Britain’s native squirrel is the red squirrel (Sciurus vulgaris). It is now only “common” (very much reduced in number) in far flung corners of Great Britain, including the northern portion of Scotland, Cumbria, Merseyside, Anglesey in North Wales, and Norfolk, as well as the Isle of Wight. Elsewhere in the UK and Ireland, the grey squirrel reigns supreme. They are as ubiquitous as rats in urban parks, suburban gardens, and other types of open space.

The eastern grey squirrel was first introduced into the UK in 1876 to a park in Cheshire in the northwest of England. The first Irish grey squirrels appeared in 1911. The spread was rapid, as grey squirrels are less picky in their food sources and habitat requirements, pushing the red squirrels to areas the greys would rather not go.



Eastern grey squirrel
Wild in Oxford Botanic Gardens
July 2008

Grey squirrels are a pest species, and are classed as such. Just like the brown/Norway rat (Rattus norvegicus) and black/ship rat (R. rattus), it is perfectly legal to kill them. In fact, according to the Wildlife and Countryside Act 1981 (God, it’s a long time since I’ve quoted British environmental legislature...), it is illegal to release a trapped grey squirrel. I haven’t kept on top of this legislature, it may have changed in the last five years (it’s been that long since I did UK Nature Conservation at uni? Crikey.). Obviously, humane dispatch is encouraged, as it should be with other animals classed as vermin.

What damage do grey squirrels do anyway? Apart from their direct responsibility for the exile of the red squirrel to tiny pockets of suitable habitat, which are ruthlessly defended by conservationists to prevent grey squirrels from becoming established, they are direct competitors with birds for food at bird tables, and cause damage to saplings and other plants by biting.