Thank you all for your responses! The BT Blue imitating a Cerulean well enough to trick much more experienced birders than I is the reason I'm hesitant to bird by ear. The regional variations and each bird's interpretation of the song make things much more complicated for me. For instance, I have 6-8 Eastern Towhees living on my dog walking route. None of them have the same song, and they don't sound much like example recordings. There are hints of similarity, like the Towhee metallic reverberation and no other species has that, but so many warbler species have a rapid, complex, clear whistle song that I don't know if I'd ever be able to sort them all out. I do get frustrated when I *know* I'm standing in front of the tree a bird is singing from and I can't find the darn thing, but I'd rather not report something at all than to make a bad report. I guess I'll just have to wait til the fall migration when there are fewer leaves to see these birds you all hear. :) -Lisa