A grey squirrel in Northumberland Park, North Shields.
The eastern gray squirrel (Sciurus carolinensis), also known as the grey squirrel depending on region, is a tree squirrel in the genus Sciurus. It is native to eastern North America, where it is the most prodigious and ecologically essential natural forest regenerator. Widely introduced to certain places around the world, the eastern gray squirrel in Europe, in particular, is regarded as an invasive species.