Diets of nesting Bald Eagles, Haliaeetus leucocephalus, in western Washington

Abstract

We analyzed food remains collected at Bald Eagle (Haliaeetus leucocephalus) nests from three regions in Washington: San Juan Islands, Olympic Peninsula, and Puget Sound. Of 1198 items collected, 53% were birds, 34% were fish, 9% were mammals, and 4% were invertebrates. Fish were more abundant at nests in the San Juan Islands and Puget Sound than at nests on the Olympic Peninsula. Overall, mammals were not important; however, the Old World Rabbit (Oryctolagus cuniculus) was a common food species for eagles in the San Juan Islands. Forty-two prey items were identified during 212 hours of direct observations at three eagles nests. This allowed a comparison of prey delivered to nests with prey found beneath these nests and indicated that birds were over-represented in prey collections beneath nests and fish were over-represented in prey carried to nests. Two important Bald Eagle food items, the Glaucous-winged Gull (Larus glaucescens) and Old World Rabbits (Oryctolagus cuniculus) were analyzed for DDE and PCBs; the former showed detectable levels of both.