This visitor to my backyard bird feeder today looks like some kind of warbler to me, but I can't find an exact match in my bird book. Possibly it's a pine warbler, but the yellow patch is considerably smaller than the bird book suggests. The bird's about the size of a chickadee, maybe a tad larger, but noticeably smaller than a sparrow. Can any of you eagle-eyed birdwatchers identify it? Click on the photos for larger versions.