Jeff Kingery writes: "1a and 1b are both Western Kingbirds. Western is the only one of the
gray-headed/yellow-bellied kingbirds with a truly *black* tail. In 1a
the breast looks much paler than the head. If this were a Cassin's, the
breast would be about as dark as the head. In 1b you can see the
diagnostic white outer webs on the outermost tail feathers."