Squirrels are active all year round and do not hibernate. A squirrel lives in a nest known as a ‘drey’, comprising of a ball of interwoven twigs, lined inside with soft materials including moss, leaves, grass and fir. Dreys are usually located in the fork of a branch tight against the tree trunk, around two-thirds of the way up the tree.
Grey squirrel dreys are often bigger and untidier than those of red squirrels, whose dreys they may take over. They will sometimes also create ‘nests’ inside the roof cavities of buildings.
The grey squirrel has adapted from the mixed broadleaved woodlands of North America to our lowland mixed broadleaf woodlands, which provide an abundant, diverse diet but, importantly, which have no natural predators other than foxes. However, there is growing evidence that when pine marten populations increase, those of grey squirrels decrease. They are equally at home in large woodlands, parks, farmland, suburban and urban areas.
Grey squirrels do not thrive in purely coniferous habitats, needing to retain their weight throughout the winter which is not possible on a diet of cones. However, they will live in conifers if other food sources are available.
Grey squirrels are opportunistic feeders eating any kind of fruits, seeds, fungi, eggs and fledglings, buds and bark from trees. They have even been seen to eat grey squirrel carcasses from road kills. Greys are better able to eat unripe acorns, hazel nuts and other foods than reds.