Diet and Foraging Behavior of Ring-Billed Gulls Breeding at Dog Lake, Manitoba

Ring-billed Gulls (Larus delawarensis) breeding at Dog Lake, Manitoba, were almost exclusively terrestrially based in their foraging efforts. Major food items in late May to early June were earthworms and grain that were obtained by foraging behind farm cultivating implements. Insects increased in importance as the season progressed, particularly for female gulls. Gulls obtained insects by foraging along lakeshore ridges (mayflies) or behind haying implements (grasshoppers). Males obtained birds and mice in the latter part of the season by foraging behind haying implements. Chick diet (from late June to late July) closely paralleled that of adults.