THE DIET OF BALD EAGLES, HALIAEETUS-LEUCOCEPHALUS, WINTERING IN THE LOWER GREAT-LAKES BASIN, 1987-1995

Observations of wintering Bald Eagles (Haliaeetus leucocephalus) from the lower Great Lakes basin feeding on identifiable food items provide an indication of winter diet for this population. Overall, 47% of 339 feeding observations were on carcasses of White-railed Deer ((Odocoil eus virginianus), 23% on fish, 11% on other mammal species, 10% on off al and human garbage, and 9% on birds. Only 35% of food items were of aquatic origin. Diet composition varied significantly by region, and e agle age. Garbage and offal formed 39% of feeding observations for imm atures, but only 17% for adult eagles. Two-thirds of our observations were in the upper St. Lawrence River. where deer carcasses on the ice accounted for 62% of feeding records. Contaminant exposure could be re latively low for wintering eagles feeding on prey of terrestrial origi n compared to those feeding on aquatic mammals, ducks, gulls and fish.