WHITE-BROWED
[CAROLINA] WREN

That's how -- with brackets around "Carolina" -- Howell in A Guide to The Birds of Mexico and Northern Central America lists a common wren out in the scrub who looks a lot like, and calls, just like eastern North America's abundant Carolina Wren. Down here people wanting to add new species to their life lists identify it as the White-browed Wren, Thryothorus albinucha, but Howell's first scientific name for it is Thryothorus ludovicianus, which is the Carolina Wren's name.

Birds in our Yucatan population, well disjunct from North America's Carolina Wrens, have underparts much paler than typical Carolinas. But is that enough to declare ours as a separate species -- to add to your life list if you've already listed Carolina Wrens?

Howell doesn't give much guidance, and I don't worry about the matter either. I can tell you, however, that our Yucatan birds tend to be more woodsy and shy than North America's Carolina Wrens, not moving into the rafters of peoples' huts and not building in shrubs outside peoples' front doors, which is exactly what typical Carolinas would do if they were here.

If I were still compiling a life list and wanted to know the most current opinion on the matter I'd go to the American Ornithological Union's Checklist of North American Birds at http://www.aou.org/checklist/.