EDGE EFFECTS AND PATTERNS OF WINTER ABUNDANCE OF WOOD MICE APODEMUS SYLVATICUS IN SPANISH FRAGMENTED FORESTS

This paper analyzes the winter pattern of abundance of wood mice Apodemus syluaticus (Linnaeus, 1758) as related to the distance from forest edges in two Spanish fragmented forests. Mouse abundance was measured by means of pitfall traps located at a range of distances from forest edges in large forests, in small woodlots, and in the agricultural matrix surrounding both woodlots and forests (both close to forest edges and far from them). Mouse abundances were larger in forests than in croplands, and tended to become larger in woodlots and forest edges as compared to forest interior, and close to woodland as compared to far from it in the croplands surrounding forests. Overall, wood mouse distribution appeared as clearly affected by edge effects, the species behaving as a typical ecotonic, soft-edge species, as expected by its generalist habitat selection behaviour. The implications of this pattern of winter distribution are discussed in relation to the well-documented increased abundances of wood mice in fragmented forests, as well as to the potential negative effects of wood mouse populations on forest species through predation and exploitative competition.