The western gull (Larus occidentalis) is a large white-headed gull that lives on the west coast of North America. It was previously considered conspecific with the yellow-footed gull (Larus livens) of the Gulf of California. The western gull ranges from British Columbia, Canada to Baja California, Mexico.
Two subspecies are recognized, differentiated by the mantle and eye colouration. The northern subspecies L. o. occidentalis is found between Central Washington and Central California, has dark grey upperparts. The southern subspecies L. o. wymani is found between central and southern California has a darker mantle (approaching that of the Great black-backed gull) and has paler eyes on average. wymani has more advanced plumage development than occidentalis, and generally attains adult plumage by the third year.