Restoring Forest Raptors: Influence of Human Disturbance and Forest Condition on Northern Goshawks

Abstract

The Northern Goshawk (Accipiter gentilis) occurs throughout the Holarctic region in wooded environments. Changes in food supply and breeding habitat, along with human encroachment into otherwise suitable habitat, have negatively impacted the goshawk in some regions. Thus, conservation of the species requires coordinated planning to restore and manage both habitat and human activities in goshawk territories. Using our work in the Sierra Nevada (Lake Tahoe Basin) as a case study, we investigated why territories were abandoned and identified actions needed to reverse conditions negatively impacting goshawks that should lead to more successful goshawk conservation worldwide. We summarized all nesting records available on the goshawk in the Basin, quantified human activity levels within and near frequently and infrequently occupied territories, and described the forest structure and species composition of territories and related these parameters to goshawk territory occupancy. As we hypothesized, reproductive success was higher within frequently occupied territories. Human activity was twice as high within infrequently as compared to frequently occupied territories. There was a greater extent of all types of roads and trails within the infrequently occupied territories. Our findings, along with results from Europe, suggest that goshawk protection has been insufficient in some regions and actions that will reduce anthropogenic disturbance should be initiated, including reducing and re‐routing human activity, and reducing the extent of roads and trails within territories. We provide guidance on how to prioritize territories for restoration.