A MARKED decline in red squirrel numbers now puts it at high risk of extinction, a study has found — but an Island expert believes ours are bucking the trend.

Red squirrels, which are found on the Isle of Wight but in few other areas of the UK, are among the species which face severe threats to their survival, the first major review of British mammals for more than 20 years revealed.

Helen Butler, of the Wight Squirrel Project, said she was surprised by the findings.

"We are doing our own big survey of corridors, woods, gardens, and we have got so much data to show they are thriving over here. We have had so many babies reported lately.

"We have always estimated 3,500 red squirrels on the Island, but this figure was based on woodland, and now they are using gardens and towns, so we estimate the actual figure will come out as much higher." A lot of the success is thanks to people feeding the red squirrels in their gardens. People should use sunflower seeds, corn on the cob, pine nuts, and fruit, and leave it in a safe place that can't be reached by larger animals.

The study, led by the Mammal Society and commissioned by government agency Natural England, examined 1.5 million records of mammals across Britain including data from "citizen science" reports and local wildlife groups.

It found that at least one in five British mammals is at high risk of extinction in the face of threats such as disease and loss of their natural habitat. Also at high risk are wildcats and grey long-eared bats.

Populations of nine species, including hedgehogs, water voles, hazel dormice and even rabbits, have declined in the last 20 years, the study of 58 native, "naturalised", introduced and reintroduced species, showed.

Hedgehog numbers have fallen by two-thirds since the previous estimate in 1995, and water vole populations are thought to be just a 10th of what they were in the 1990s.

There is better news for some species, such as otters, whose range has expanded since the banning of pesticides which poisoned their river homes, and pine martens, polecats and badgers are recovering.

Mammals face a range of threats, including loss of habitat such as ancient woodland, the presence of invasive species, and diseases.