Copperheads are often in or near deciduous forest in hilly situations, usually in the vicinity of rock outcrops; they occur also on floodplains and at the edges of swamps in the south and in mesic situations near water in the arid west. Hibernation generally occurs in dens among rocks, or in caves, animal burrows, under objects, in hollow logs or stumps, or in similar sites. Usually copperheads are in areas with abundant surface cover such as rocks, logs, stumps, or leaf-litter. They are mainly terrestrial but sometimes climb into vegetation up to a few metres above the ground. In the east at least, gravid females select rocky areas that are more open and have warmer soil temperatures than those used by non-gravid individuals (Reinert cited by Ernst 1992).