Eastern grey squirrel

These squirrels, originally from North America, were released in the UK by 19th century landowners. They are now very common and widespread, and are considered successful in displacing red squirrels in European woodlands. It was noted that they out-compete the native Red squirrels for food, feeding more at ground level and being able to digest acorns, which the reds can't. They also carry a deadly pox virus which does not affect them.