The habitat requirements of hazel grouse ( Bonasa bonasia) in managed boreal forest and applicability of forest stand descriptions as a tool to identify suitable patches

Abstract

We evaluated preferences of habitat variables by hazel grouse ( Bonasa bonasia) in an intensively managed boreal landscape in south-central Sweden. We surveyed 71 forest patches that varied in tree age, tree species composition, structure and field layer, as described by ordinary forest stand data. They were surveyed during autumn and spring for 2 years. A distinct difference in habitat quality, measured as amount of vertical cover and development of the field layer, was found among patches occupied during spring, patches occupied during only autumn and unoccupied patches. We found that the existing nation-wide forest stand data are adequate to select habitat patches to maintain hazel grouse in managed forested landscapes. However, the stand data would be improved if parameters concerning field-layer type, alder and field-layer cover were added. We used the results of an earlier study to predict hazel grouse occurrence in our studied patches. Unthinned middle-aged (20–69 years) or old (>90 years) stands rich in deciduous trees (5–40%), including alder, and with a rich field layer were the most often occupied patches. Moreover, the low density of hazel grouse in this landscape, compared to hazel grouse densities in less intensively managed landscapes, clearly showed the influence of forestry on the species.