Anyone who’s been for a walk in the British countryside with an older relative will know the story of the grey squirrel. There used to be red squirrels all around these shores, but then the grey ones were brought over from North America in the 19th century and took over the place. Now they outnumber their red cousins by 15 to one. Furry bastards.
Researchers now have a better idea about why the grey squirrel has been so much more successful than native red squirrels. In short, they’re smarter.
As part of a study, published in the journal Animal Behaviour, scientists from Exeter and Edinburgh put red and grey squirrels through a series of trials. An easy test involved opening sealed containers to get to hazelnuts, while a more complex test meant the squirrels had to push and pull levers to get to the food.
The species were equally successful at the first task, but greys massively outperformed reds in the second. 91% of grey squirrels managed to get the food in the lever trial, compared to only 62% of reds. Now, it may be the case that this was a particularly dense batch of reds, but the researchers believe it demonstrates the greys squirrels’ “superior behavioural flexibility”.
“Many factors have been considered to explain why grey squirrels are more successful when they move into areas where red squirrels live,” said Dr Pizza Ka Yee Chow, from the University of Exeter’s Centre for Research in Animal Behaviour.
“These factors include disease resistance and the fact grey squirrels are bigger, but our research shows problem solving could be another key factor for the success of greys. This might be especially important for an invasive species like grey squirrels, as they have evolved elsewhere and have to adapt to their surroundings.”
The paper claims inferior foraging amongst the red population may lead to poorer fitness, and this could in turn harm survival and reproduction. It’s known that reduced breeding is a factor for the species’ decline. The study does note, however, that more research is needed to glean the scale of grey squirrels’ intelligence:
“It is not yet clear whether grey squirrels are born better problem-solvers, or whether they work harder because they’re an invasive species living outside their natural environment,” said Chow. “The current stage of our research is to look at this, and the results may give us more insight into the likely future of both species.”
It’s not all bad news for red squirrels. The research found that the species were quicker to switch up tactics after trying a method that didn’t work, and those that did succeed at the challenging task were quicker to repeat the method than greys.
The research could help conservation efforts to protect the red squirrel populations, which have been successfully reintroduced to areas in the Scottish Highlands.
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