August 22, 2006
Gray Squirrel Virus Wiping Out Reds
By Jeremy Lovell
LONDON (Reuters) - Britain's native red squirrels, already in headlong retreat, are being wiped out not just by competition for resources with non-indigenous gray squirrels but from a virus the grays carry, research showed on Monday.
The squirrel poxvirus is harmless to the grays but kills reds within two weeks of contact, said the researchers from Newcastle University and Queen Mary, University of London among others.
In the absence of a vaccine, they proposed killing gray squirrels that enter the few and rapidly shrinking areas in Britain where red squirrels are still found.
"It is vital we get this disease under control, especially as it is now threatening to spread across the border to Scotland with severe consequences for red squirrel conservation there," said Peter Lurz of Newcastle University's Institute for Research on Environment and Sustainability.
"We are not trying to wipe out the gray squirrel but as conservationists we have a duty to look after the red squirrel as it is a protected, native species.
The disease entered the country with the gray squirrels when they were brought into Britain 100 years ago from America to curb the red population -- traces of which can be found dating back at least 10,000 years.
The grays have been devastatingly effective -- although until now it has been attributed to their simply muscling the smaller reds out of the way.
In 1940, reds covered most parts of Britain. But by 1998 they had been squeezed back primarily to the Isle of Wight in the south and Scotland, outnumbered 66 to 1.
The researchers said that unless action was taken promptly, even the few remaining reds could be wiped out in some areas within a decade.
"Given that the gray squirrel is an introduced species, and therefore the disease has occurred as a consequence of human action, the onus is very much on us to look for practical solutions to control the disease and protect red squirrels from (it)," said Tony Sainsbury, lecturer in wild animal health at the Zoological Society of London.
"Our work concludes that targeted control is the most viable way forward.