All the recent discussion regarding the identification of winter loons made me reach for one of my favorite references. Kenn Kaufman's Advanced Birding provides thorough coverage on separating those challenging loons, not to mention grebes, jaegers, gulls, and more. This book consistently offers great tips for tough birds. This fall I was working at the Black Swamp Bird Observatory's bird banding research station. We captured a bird that had all of us a bit puzzled. A fall warbler looking very much like a Pine, but the soles of its feet were bright yellow. Perhaps the soles of a bird's feet are not THE most useful field mark for birders, but when you've got the bird in the hand this can be an important distinction. We turned to the Identification Guide to North American Birds, by Peter Pyle. This book is the "go to" reference for banders. Incidentally, not a bad book for birders to have on hand as well. The Pyle Guide, as it is commonly referred to, states that the blackish legs and feet of the Pine Warbler separate it from Blackpoll and Bay-breasted. Looking at the many field guides we had among us that day, not one showed a Pine Warbler with yellow on the soles of its feet. We ultimately decided to go with our instincts and the bird went down in the books as a Pine Warbler. Upon returning home, I reached for Advanced Birding and I admit, I was pleasantly shocked to find that it pointed out the fact that Pine Warblers may also have yellow soles. In the interest of full disclosure, I must admit that I'm married to the author of Advanced Birding. But the truth is, I was using the book and loving it long before I was in love with the author! Bird on..... Kim Kaufman ______________________________________________________________________ Ohio-birds mailing list, a service of the Ohio Ornithological Society. Our thanks to Miami University for hosting this mailing list. You can join or leave the list, or change your options, at: http://listserv.muohio.edu/scripts/wa.exe?LIST=OHIO-BIRDS Send questions or comments about the list to: [log in to unmask]