Charlotte Bill's "confusing fall warbler" reminds me of a note in Roger
Tory Peterson's account of Pine Warbler in the 1947 edition of his
field guide. He quotes a colleague, " a museum tray of Pine Warblers
looks like a catch-all for the museum's ratty, discarded Warbler skins.
RTP also said in the same book, " If at the end of ten years of field
work you can say you know the fall Warblers you are doing well." He was
(Yeah, the book is old. I bought it from paper route money.)