Short-Term Effects of Timber Harvest and Weather on Northern Goshawk Reproduction in Northern Idaho

Nesting habitat of the Northern Goshawk (Accipiter gentilis) in North America has been associated with the amount of mature, closed-canopy forest in the nesting area; however, few studies have experimentally tested the effects of timber harvest on goshawk reproduction. We tested the effects of clear-cutting within goshawk nesting areas on reoccupancy and nesting success for two years following treatments. We also included habitat and weather variables as potential covariates in our models. We found no treatment effects on goshawk reoccupancy, nesting success, or number of fledglings between harvested and unharvested nesting areas. Our models suggested goshawk breeding area reoccupancy was a function of the amount of potential nesting habitat available in the 170-ha area surrounding the nest; goshawks reoccupied breeding areas if they contained >39% potential nesting habitat following harvest. Nesting success was correlated with mean April precipitation and January daily temperatures. Our results suggested that, in the short term, goshawks were more likely to attempt nesting after disturbance if >39% of the 170-ha area around their nest was left in potential nesting habitat; however, our models suggested that once goshawks attempt nesting, nesting success was more likely to be a function of winter and spring weather.