California Gull
Larus californicus
The California gull (Larus californicus) is a medium-sized gull, smaller on average than the herring gull but larger on average than the ring-billed gull, though it may overlap in size greatly with both.
Their breeding habitat is lakes and marshes in interior western North America from the Northwest Territories, Canada south to eastern California and Colorado. They nest in colonies, sometimes with other birds. The nest is a shallow depression on the ground lined with vegetation and feathers. The female usually lays 2 or 3 eggs. Both parents take turns feeding their chicks.
They are migratory, most moving to the Pacific coast in winter. It is only then that this bird is regularly found in western California.