CONSTANT vigilance may be all that can save the 200 or so red squirrels living on Brownsea Island - one of the last remaining outposts of the species in England - from being lost.

Ecological experts this week warned that the native red squirrel faces extinction in the UK because of the spread of the more dominant North American grey squirrel.

Brownsea is one of the last secure outposts of the reds and Dorset Wildlife Trust wardens on the Poole harbour island will act swiftly to eject any greys that turn up.

It is feared red squirrels will soon become extinct from mainland Britain as they face the double-whammy of competition from the invasion of North American grey squirrels and outbreaks of parapox virus.

Reds have already been pushed to the margins of extinction in Britain following the 19th century introduction of the larger greys, which compete for food and are less affected by the parapox virus.

Brownsea is home to about 0.5 per cent of the UK's red squirrel population, and could be among the very last reserves for the species if experts from the Oxford University's Wildlife Conservation Research Unit are correct in their assessment that conditions for the reds in the UK are worsening.

Their report warns that unless there is large-scale control of greys and vaccination against disease, red squirrels will soon become extinct in England, Wales and Southern Scotland.

Nick Dear, of Dorset Wildlife Trust, said: "In areas of pine and coniferous trees the reds hold their own, and that is what Brownsea offers.

"If grey squirrels got onto the island with the virus and if we allowed them to stay, there would be a problem."

He added: "It is a man-made problem that the greys are in Britain, so it is up to us to help the red squirrels a bit."

First published: April 27