Larus californicus, commonly known as the California Gull, is native to North America. It is predominantly found in the western United States and Canada, including areas around the Great Basin, Rocky Mountains, and the west coast, extending to parts of Mexico during the non-breeding season.

The California Gull typically inhabits areas with open water and adjacent flat open spaces such as lakes, marshes, coastal regions, and reservoirs. During the breeding season, it prefers freshwater and saline lakes in steppe and prairie environments with limited vegetation.

Larus californicus occupies a diversified ecological niche, feeding on fish, insects, and other invertebrates, and often foraging in agricultural fields. It plays a role in controlling insect populations and acts as both a predator and scavenger, adaptable to various environments and food sources.