Friday, January 23, 2009

Black squirrels are rapidly wiping out grey ones in parts of Britain

Black 'super squirrels' that are rapidly wiping out their grey cousins in parts of Britain descend from one individual released nearly 130 years ago, it has emerged. The testosterone-fuelled black squirrels are faster, fitter, fiercely territorial and more aggressive, beating greys to food and mates. It is a subgroup of the same species of squirrel as greys but in some areas has already become the dominant variety. It could provide an even bigger threat to our native species of red squirrel, which had already been almost wiped out by greys. Until now it was not known whether the black squirrel was brought to Britain or was a result of a genetic mutation. But research published in Cambridge proved that the British variety is directly descended from the American black. It was introduced by accident in the 1880s when an American black squirrel escaped from the menagerie of an as yet unidentified landowner in the East, most likely in Bedfordshire. Dr Alison Thomas, professor of life sciences at Anglia Ruskin University, said: 'It had been argued that the black squirrel was the result of a genetic mutation caused by two grey squirrels mating and producing a black offspring. Finally we have quashed this. Genetic tests revealed the British black is a direct descendant of the American black. It took just one cheeky squirrel to escape a zoo and mate with a grey. Now there are tens of thousands in the UK.' Dr Thomas said the first black squirrel was sighted on the outskirts of Letchworth, Hertfordshire in 1912. The latest estimates show there could be as many as 25,000 black squirrels in the East of England. This is the biggest change in squirrel demographics since the last indigenous red squirrels almost disappeared 50 years ago as a result of the population explosion of the bigger and more aggressive greys. Grey squirrels, native to the east of North America, were first recorded in Britain in the 1820s, but systematic introduction began in 1876 when a pair were liberated in Cheshire. The prolific greys gradually displaced the native red species. By 1958 all red squirrels had vanished from Cambridgeshire - a county now overrun with black squirrels.


Origins of British Black squirrel discovered

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