PREDATORY pine martens could reverse the spread of invasive grey squirrels in Scotland, a study concludes.

Research involving academics from Scotland, Ireland and America in three Scottish regions has found red squirrels thrive in areas where pine martens are present, but their grey cousins do not.

It is thought that grey squirrels lack “caution” when pine martens are sharing their habitat, making them easier to catch.

The results, based on work carried out over three years in the Borders, Highlands and Central Scotland using monitored animal feeders, are published in the scientific journal Proceedings of The Royal Society – B.

Dr Emma Sheehy of Aberdeen University said: “Where pine marten activity was high, red squirrels took longer to use the feeders, which suggests red squirrels modify their behaviour to be more cautious when their natural predator is around.

“This type of behaviour is to be expected from species that have co-evolved together. On the other hand, no such caution was identified in the grey squirrel population, which suggests they may be easier prey to find, and much more susceptible to predation by pine martens.

“This is a really interesting result, and contradicts the ‘landscape of fear’ theory which suggests grey squirrels are avoiding pine martens rather than being heavily preyed upon.

“Our evidence that, in addition to their intrinsic value, pine martens provide an ecosystem service by suppressing invasive grey squirrel populations is good news for both red squirrel conservation efforts and the timber growing industry, due to the detrimental impact of the invasive grey squirrel on both.

“The pine marten is already heavily suppressing grey squirrel populations where they are well established, and presumably this influence will spread as the pine marten’s range expands southwards through Scotland and into the North of England but this is likely to be a slow and very gradual process.”