Not that uncommon, but very nearly impossible to spot in this case--I got lucky with a glimpse through the branches of one of the live-oaks in the backyard. My brain sent two conflicting signals back--"hummingbird" and "warbler." The warbler for general size and shape, the hummingbird because it had a big honkin' beak in proportion to its size, and was perched with its tail fanned when I caught the glimpse of it. Plus it had a buzzing call that was rather like the hummingbird.
ID seems straightforward--only other contender is Swainson's warbler, which isn't supposed to live in the canopy, and the buzzing shows up on the recording of the vireo's song.
So, that'd be a lifer!
