THE DIET OF HERRING-GULLS DURING THE NESTING PERIOD IN CANADIAN WATERS OF THE GREAT-LAKES

Although 11 families of fish and a minimum of 16 species were identified in the diet of Larus argentatus, 80% of the fish were of 2 exotic species, alewife Alosa pseudoharengus and rainbow smelt Osmerus mordax. The dietary importance of these two fish species reflected their relative abundance within a lake. Representatives of 8 orders of insects and 11 families of birds were also identified. The sexes probably have different foraging strategies. Although some food was scavenged, most was obtained alive. Dietary differences existed between colonies and between lakes, within and between years. -from Authors