アメリカオオセグロカモメ Larus occidentalis

Large, stocky gull with a stout bill. Adults have rather dark gray upperparts and bright pink legs. Takes four years for immatures to progress from mostly brown to fully white and gray adult plumage; intermediate plumages are often mottled and messy. Starts to develop dark gray back in second year. At all ages, look for overall stocky shape and large bill. Strictly coastal, occurring along beaches and bays along the Pacific coast. Commonly seen around coastal towns and cities, but almost never ventures inland. Identification is muddied by frequent hybridization, especially with Glaucous-winged Gull at the northern end of its range. Hybrids can show any mix of intermediate traits; some are best left unidentified.