THE EFFECT OF MATRIX ON THE OCCURRENCE OF HAZEL GROUSE (BONASA-BONASIA) IN ISOLATED HABITAT FRAGMENTS

The aim of this study was to determine the effect of matrix on the occ urrence of hazel grouse (Bonasa bonasia) in habitat fragments. The stu dy was conducted in two kinds of landscape: (1) an agricultural landsc ape, where the censused forest habitat fragments were surrounded by fa rmland, and (2) in an intensively managed forested landscape, where th e censused habitat fragments were surrounded by nonhabitat coniferous forest. Occupied and unoccupied habitat fragments in the agricultural landscape differed significantly in distance to the nearest suitable c ontinuous habitat, with hazel grouse occurring only in habitat fragmen ts closer than 100 m from continuous forest. In the intensively manage d forest landscape, the effect of isolation was less evident, but ther e might be a threshold around 2 km. Effects of isolation occurred over much shorter distances when the surrounding habitats consisted of far mland than when it was forested habitats. The size of the habitat frag ments was important in both landscapes, with larger habitat fragments more often containing hazel grouse.