California Gull

The California Gull is a medium-large gull breeding primarily around interior lakes and wetlands of the western United States and Canada, wintering along the Pacific coast. It shows the classic gray-backed gull pattern, intermediate in size between Ring-billed and Herring Gull, and is historically notable for a legendary event in which flocks of these gulls helped save early Utah settlers' crops from a locust infestation.

Adult mantle feathers are medium gray, slightly darker than Ring-billed Gull but paler than Lesser Black-backed or Great Black-backed Gull, contrasting with white head and underparts. Outer primary feathers are black with white tips and typically two white mirrors. Immature birds show mottled brown-gray feathers, progressing over three to four years toward the clean adult gray-and-white pattern, with darker, more solidly gray-brown tones than the checkered pattern of Ring-billed Gull immatures. The bill in adults often shows a black-and-red spot pattern near the tip, a useful feature alongside feather tone for identification.

Sexes look alike, with males averaging larger. This species takes three to four years to reach full adult plumage, an intermediate maturation period between the three-year Ring-billed Gull and four-year Herring Gull. Nonbreeding adults show brownish streaking on the head and nape, molting to a cleaner white head for breeding. A complete post-breeding molt replaces flight feathers, generally completed before or during the winter period.

Breeds colonially on islands in large interior lakes, marshes, and reservoirs across the western United States and southwestern Canada, notably including the Great Salt Lake region. Outside the breeding season it moves primarily to the Pacific coast, foraging along beaches, harbors, and estuaries, though some individuals remain in interior areas near open water or agricultural fields.

California Gulls forage on a wide variety of food including fish, insects, invertebrates, and human refuse, and are notably significant insect predators around interior lakes, historically credited with controlling locust outbreaks that threatened early agricultural crops in the Great Basin region. Nests are built on the ground in colonies on islands within lakes and reservoirs, offering protection from mammalian predators, with both parents sharing incubation and chick-rearing. Its call is similar to other large gulls, a series of wailing and mewing notes. Conservation status is IUCN Least Concern.