The type of blue jay we see in Sunnyvale are the Western Scrub Jay. Robin-sized, but large strong bill and long tail make it appear larger. Head, wings, and tail blue (conspicuous when it glides in a long, undulating flight). Their back is dull brown; underparts light gray. No crest; dusky face mask. White throat offset by incomplete blue necklace. 11-13 inches long.
They are assertive, vocal and inquisitive. You’ll often notice scrub-jays silhouetted high in trees, on wires, or on posts where they act as lookouts. In flight seems underpowered and slow, with bouts of fluttering alternating with glides.
Voice Call is loud, throaty jayy? or jree? In flight, a long series of check-check-check notes.
http://birds.audubon.org/birds/western-scrub-jay
http://www.allaboutbirds.org/guide/western_scrub-jay/id
