Aspects of the Ecology of Urban-Nesting Bald Eagles (Haliaeetus leucocephalus) in South-Coastal British Columbia

Abstract

Bald Eagle (Haliaeetus leucocephalus) populations throughout North America have increased considerably since the ban of DDT in 1972 and eagles now inhabit suburban areas in large numbers. To better understand the ecology of urban populations living in south-coastal British Columbia, we compared nest-site characteristics, reproductive rates, and diets of more than 150 breeding pairs of rural-, suburban- and urban-nesting eagles in the Greater Vancouver area. Three-quarters of the nests were located within 230 m of buildings and roads, or within 31 m of a potential source of disturbance. Urban eagles nested in live, taller trees that were close to the edges of patches, whereas rural eagles used shorter trees and occasionally human-made structures such as transmission towers. Eagles at nests located close to patch edges and in areas with greater human land use had higher reproductive rates than those at isolated nests or in remote rural habitat. Waterfowl and gulls (family Laridae) were common in the diet across the study area, but urban eagles also used alternative sources such as C-O sole (Pleuronichthys coenosus), Bufflehead (Bucephala albeola), and Band-tailed Pigeon (Patagioenas fasciata). Eagles in the Vancouver area have adapted to human-altered landscapes; management strategies should focus on maintaining edge habitat, monitoring population expansion in urban areas, and protecting nest sites.