Wood mouse or long-tailed field mouse eating seeds fallen from a bird feeder. Wood mice feed on seeds, buds, fruits, insects, worms, centipedes, snails and fungi. During the winter, they often share nests, with up to four individuals per nest. They are agile climbers and are active at night. They nest below ground in a complicated burrow system, which is used by consecutive generations. They do occasionally nest above ground in holes in trees.