Officially these guys are Aphelocoma californica. Their common name is the California Scrub-Jay. They are in the family Corvidae.
Along the Pacific seaboard from Washington state to Baja California this is the “blue jay” that is a fixture in our backyards. They are assertive, inquisitive, and harsh vocalizers. They are omnivorous and eat a large variety of insects in the summer and acorns, nuts, and seeds in the winter. They will also eat rodents and the eggs or young of other birds as well as small amphibians. By their behavior you can tell they are definitely Corvids, much like small and colorful crows. You will often find them high in the trees being lookouts when not foraging on the ground.