(unless I'm missing something).
Thanks again
Yes, a newer book.
I too ran into this problem just a week ago or so, in Guanacaste - I am also an owner of a "Stiles & Skutch" (a
very wrinkly old copy) and I love it, but the taxonomy is now more than 20 years old. I found a (truly astonishing!) hummingbird when I was there, which matched "Fork-tailed Emerald" in the book; however, on my new Costa Rica
checklist (
Comité Científico Asociación Ornitológica de Costa Rica, 2009), this species doesn't exist.
I'm sure the taxonomic situation is more complicated than this, but for CR, it would seem that the species that S&S refers to as "Fork-tailed Emerald" has been split into Garden Emerald (
Chlorostilbon assimilis) and Canivet's Emerald (
C. canivetii). (According to some other checklists I have seen, the latter bird just assumes the "Fork-tailed Emerald" common name; still others lump these two taxa, along with quite a few others, as "Blue-tailed Emerald",
C.mellisugus).
As far as I can tell, the two species divide up nicely by range, with
C. canivetii being in the north (and beyond, through the remainder of Meso-america and into Mexico), and
C. assimilis being only on the South Pacific slope (and into Panama).