Contrary to their name these gulls are the state bird of Utah. They are migratory birds move to the Pacific coast in winter. That is only then this bird is regularly found in California.
California gulls nest in colonies. The female usually lays 2 or 3 eggs. Both parents are very responsible and feed their youngsters.
When I was leaving Bear River refuge I saw a lot of dead fish and gulls who were feeding on them. I guess fish died because it's getting hot and water in Bear river is getting more shallow and very warm. The desert stories sometimes are sad.