Breeding occupancy and success of two hole-nesting passerines: the impact of fragmentation caused by forestry

We studied the distribution and the reproductive success of the pied flycatcher Ficedula hypoleuca and the redstart Phoenieurus phoenicurus in relation to forest patch size, edge type (clearcut vs natural), distance from the forest edge, and vegetation characteristics in a forest-dominated landscape. Breeding performances were recorded in up to 72 forest patches during 1992–1994 for birds breeding in nest-boxes. In the spring, breeding individuals of both species arrived earlier in large forest patches (> 1 ha) than in smaller ones. Pied flycatchers arrived earlier on clearcut edges than natural edges but in the redstart there was no preference for a particular edge type. The territory distance from the forest to open land edge did not affect the arrival dates of either species. In the case of the pied flycatcher, the proportion of unpaired males was highest in patches < 1 ha in size and in the case of the redstart this applied to patches < 5 ha in size. Pairing success was not related to the forest edge type or the nest's distance from the edge. Nest predation was not patch-size nor edge-related for either of the species, but in the combined data for both species nest predation was higher at clearcut edges than at natural edges. Clutch size, brood size and the survival of nestlings to the fiedgling stage (fledgling/egg. %) were independent of the patch size, edge type and nest's "distance from the forest edge.