RESPONSES OF BALD EAGLES TO HUMAN ACTIVITY DURING THE SUMMER IN INTERIOR ALASKA

Along narrow rivers, spatial restriction of human use based on wildlif e responses can effectively eliminate the entire river corridor from h uman use. Therefore, if river use by both wildlife and humans is a goa l, an alternative management strategy is necessary. We measured flush response rate and flush distance of breeding and nonbreeding Bald Eagl es (Haliaeetus leucocephalus) to recreational boating along the Gulkan a River in interior Alaska from 1989 to 1992. Eagle responses to our n onmotorized boat were governed by the context within which human-eagle encounters occurred. Flush response rate of nonbreeding eagles decrea sed as perch height and its distance from the river's edge increased, increased as the season progressed and as eagle group size increased, was lower for juveniles (20%) than other age classes (49-65%), and var ied with the existing level of human activity in geographic location ( P < 0.001 for all parameters). Flush distance of nonbreeding eagles in creased as the distance a disturbance was first visible to a perched e agle increased, as perch height and its distance from the river's edge increased, and as the season progressed. In contrast to flush respons e, flush distance was strongly associated with age and was greatest fo r adults, least for juveniles, and intermediate for subadults. Breedin g adults were much less likely to flush than nonbreeding adults, and f lushed at lesser distances. We recommend that along narrow wilderness rivers, the impacts of human activity on Bald Eagle populations be reg ulated with temporal, rather than spatial, restrictions.