3 days ago
How red squirrels are fighting back against their grey cousins
Red squirrels are staging a comeback after being eliminated by their grey cousins, a study has suggested.
A resurgence in pine martens, the natural predator of squirrels, has had a greater impact on the greys, which are not native to the British Isles and do not know to fear them.
Red squirrels, which evolved alongside pine martens for centuries, can easily avoid the predators and become more wary when one is nearby, the study found, making the 'predator naive' greys easier prey.
The reds have started to thrive as a result, despite increasing numbers of wild squirrel hunters.
Red squirrels are native to the UK but have suffered significant population decline in recent decades because of the arrival of the larger grey variety from the US in the late 19th century.
They have been reduced to small populations in parts of the British countryside such as Scotland, Anglesey and the Isle of Wight as their shared habitat was overtaken by greys, which are indiscriminate in what they eat and able to reproduce at a faster rate.
Decline of pine martens
Pine martens have also suffered a catastrophic population decline in recent decades, but efforts to protect, reintroduce and nurture the species in Britain and Ireland has assisted red squirrels.
The study by the University of Galways laid wildlife cameras around the Irish countryside to monitor activity at feeding sites and discovered that red squirrels become wary in the presence of pine martens.
However, greys were more unaware of the signs and were therefore more likely to be killed.
Dr Emily Reilly, the study's lead author, told The Telegraph: 'Red squirrels would rarely even eat any food if a pine marten had been there in the last eight hours.'
'They slowly became less cautious but you could still see the effect even days after the pine marten visit.
'The grey squirrels do not have this response. This is most likely why their numbers have been decreasing since the pine marten has made a comeback.'
A total of 491 squirrel visits were recorded in the study, compared to 226 pine marten sightings detected by the cameras.
The data collected in western Ireland will probably apply to Britain, where pine marten numbers are also increasing, Ms Reilly said.
The study said: 'Following a pine marten visit to a feeder, red squirrels displayed a typical anti-predator response, exhibiting increased vigilance and decreased feeding.'
'There was no difference in the duration of the red squirrels' visits to a feeder, meaning red squirrels did not display a flight reaction in response to recent pine marten presence.'
The study is published in Royal Society Open Science.
