The fifth edition of the A.O.U. Check-list (1957) states that the Glaucous-winged Gull (Larus glaucescens) breeds from western Alaska south to Copalis Rocks, Washington. In the southern part of its breeding range (Vancouver Island to Copalis Rocks) it is sympatric with the northernmost populations of the Western Gull (L. occidentalis) (Pearse, 1946; Jewett et al., 1953). In the summers of 1969–1971 several pairs of Glaucous-winged Gulls nested on Yaquina Head, Oregon (44°40'N, 124°05'W), 300 km south of the previously reported southernmost breeding colony for this species. Approximately 60 ± 10 pairs of Western Gulls also nested on Yaquina Head. In addition, three L. glaucescens were paired with L. occidentalis in the colony (Fig. 1). In 1971, six known hybrids were banded from a total of three nests.