Attempts to save the red squirrel on the UK mainland are a waste of money, a scientist has said.
Red squirrels are in decline on the UK mainland, but not on islands
Funding should focus on protecting populations found on islands such as the Isle of Wight, said Stephen Harris from the University of Bristol.
He said past experience showed efforts to eradicate grey squirrels, which compete with the reds for food and habitat, had little impact.
Professor Harris made his comments in an article for BBC Wildlife magazine.
"Conserving rare or vulnerable species on islands is not a new concept," the founder of the Mammal Research Unit wrote.
"[The UK] is not short of large, accessible islands where it would be simpler and cheaper to conserve red squirrels. It would be more effective in the long term to establish these as red squirrel reserves."
Grey squirrels, introduced to the UK at the turn of the 20th Century, were originally thought to be more aggressive and drove the reds from suitable habitat.
However, more recent research revealed that greys were better at digesting acorns, but ate hazelnuts before moving on to acorns, thus depriving red squirrels of their preferred food.
The biggest problem now is a virus that is spread by grey squirrels but kills red ones, accelerating the native species decline.
In April, the Heritage Lottery Fund awarded the Northumberland Wildlife Trust £600,000 to set up nature reserves to protect dwindling numbers in Cumbria, the Yorkshire Dales and Merseyside.
A Conservative member of the Scottish Parliament has also suggested that bounties should be paid for the shooting or trapping of grey squirrels.
MSP Murdo Fraser said such measures would help preserve the numbers of the indigenous animal.
Although the animals were under threat from their larger grey cousin in the UK, Professor Harris said red squirrels were very common in other parts of the world.
"While their decline on mainland Britain has been very sad, as a global conservation issue it hardly registers."
Sophie Stafford, editor of BBC Wildlife magazine, hoped Professor Harris' comments would help focus minds on conservation efforts.
She said: "[His] arguments will undoubtedly encourage heated debate, but it is through this kind of innovative thinking that we can find solutions to some of Britain's most challenging conservation issues."