Siberian flying squirrel responses to high- and low-contrast forest edges

We examined responses of Siberian flying squirrels (Pteromys volans) to edges between nesting habitat (mature spruce forests), movement habitat (other forests, pine bogs), and open areas within their home ranges in southern Finland in 1996-2000. Radio-tracked squirrels (n = 146) were generally associated to edges when they were active at night. Compared to distances expected from the habitat pattern of their home range, squirrels occurred closer to high-contrast edges (of open areas) and low-contrast edges (nesting or movement forest types). Association with edges of open areas was more pronounced when squirrels were in movement habitat than in nesting habitat, possibly because of stronger channeling of movements in the former habitat. When in nesting habitat, squirrels responded more strongly to field edges than to recent clearcut edges, probably as a result of the presence of more deciduous trees on field edges, unlike clearcut edges. Responses to open areas were independent of spatial scale. However, responses to movement habitat from nesting habitat, and vice versa, were more pronounced over hundreds than tens of meters. Nesting cavities and dreys were generally located at random with respect to edges. We conclude that squirrel responses to edges of landscape attributes are diverse and depend both on spatial scale and edge contrast.