Grey Squirrel (Sciurus carolinensis) Having been introduced from North America it is now one of the most frequently seen mammals. They build themselves a nest called a drey pretty high up in the trees usually in deciduous woodland. The nest is made of twigs and lined with dry grass, shredded bark, feathers and moss. They are most active at dawn and dusk searching for available food. They have a diet of acorns, hazelnuts, beechnuts, fungi, buds, leaves, shoots and flowers. They spend most of their time foraging and feeding on the ground rather than the trees. They are however very agile in the trees and can run along thin twigs and jump from tree to tree. They can leap for more than 6 metres (19ft 8 in).