Thanks, David, for your comments on my comments. Very interesting stuff. One minor point (I am also a Northern Hemispherian): Which birds are so difficult to identify in Europe and North America? Apart from maybe some Empidonax in North America and maybe some Phylloscopus, Acrocephalus and Hippolais in Eurasia/Africa I can’t think of many species that are that hard to ID there. “Hard” birds are certainly not the norm there.
Nikolas
