Oooh, Mike -- talk about a hard one. There have been reams of articles both here and abroad. One article gives several "sure-fire" ways of separating non-singing Bicknell's from Gray-Cheeked, the next article says, "yes, but..." First, Bicknell's are warm-toned rather than cold-toned, but so is one race of Gray-cheeked. However, a warm toned Gray-cheeked needs careful scrutiny. The way I understand it, the color of the lower mandible is diagnostic (hey, you have to be close) -- orange in Bicknell's and flesh-colored in Gray-cheeked. But there may be other subtle differences. What about call note? I have never heard that of Bicknell's -- is it distinquishable from Gray-cheeked? I for one will wait until I hear one singing, or see one on a high mountain in Maine or New Hampshire. (I tried this summer but the one thrush I saw was too low down in altitude and was cold-brown = Gray-cheeked!) Cheers, Gail Mackiernan