Problem-solving could be key to grey squirrels' success, study finds

Research in UK shows invasive species bests native red squirrels in complex tasks

The ability to solve problems may explain why grey squirrels are thriving at the expense of native red ones in the UK, research suggests.

Wild greys and reds were presented with an easy task (opening a transparent lid) and a difficult version (a more complex process of pushing and pulling levers) to get hazelnuts.