Red squirrel. Artwork of a red squirrel (Sciurus vulgaris) eating a nut in a tree. Red squirrels are omnivorous rodents that live in woodlands across Eurasia. In Britain, populations are threatened by competition with the Eastern grey squirrel (Sciurus carolinensis) introduced from North America. The native British red squirrel has a striking red coat, but colours vary according to location and time of year.