Forest Characteristics of Northern Goshawk Nest Stands and Post-Fledging Areas in Oregon

The role of old-growth forest as a component of nesting habitat for northern goshawks (Accipiter gentilis) and the effect of timber harvest has come under increased scrutiny in the western United States. We examined the importance of selected elements of old-growth forest as nesting habitat for goshawks by comparing forest structure around 22 nests with 2 sets of random points. Comparisons were made at 6 spatial scales, from the nest stand up to a 170-ha post-fledging area (PFA). Goshawks nested more frequently in stands with dense canopy, late forest structure (i.e., trees >53 cm dbh, canopy closure >50%), and rarely in stands with mid-aged forest structure. Despite the occasional occurrence of goshawk nests in younger, more open-canopied stands, these conditions were less preferred than dense canopy, late forest structure. Late forest structure was more abundant within circles of 12 ha and 24 ha around nests than around random points. At the PFA scale, forest structure around nests was dominated by dense-canopied forest, always contained wet openings, and nests were positively associated with dry openings. Our findings support recent management recommendations for northern goshawks in the western United States, which call for maintaining the PFA in forest conditions intermediate between the high foliage volume and canopy cover of nest stands and more open foraging habitats. These conditions would provide nest sites for goshawks and habitat for a variety of prey species that inhabit late or early seral stage forest.