This gull was at first thought to be a particularly bleached out second-winter Glaucous Gull (by virtue of the yellow eye). But a couple of observers have noted that Glaucous has a pretty parallel-sided bill, whereas this bird has the narrow-base bulging-tip structure of the Western and Glaucous-winged Gull. Hybrids have been suggested, both Herring x Glaucous-winged and Glaucous x Glaucous-winged.