The 51st Supplement to the AOU Check-list was published in The Auk in late July, and now it has been posted online as well (in pdf form). This supplement lists changes approved by the checklist committee in 2009 and 2010. Since the ABA usually follows the lead of the AOU, these changes will likely be reflected on that list as well. The big news is that the checklist is now a little longer because several species have been split. Here are a few of the changes.
Winter Wren and Pacific Wren: Winter Wren (Troglodytes troglodytes) was formerly considered to be a single species with a range covering the northern hemisphere. However, the species is now being broken into multiple species on the basis of genetics and vocalizations. The Eurasian populations will keep the name Troglodytes troglodytes. The eastern North American population will become Winter Wren (Troglodytes hiemalis), and the western population will become Pacific Wren (Troglodytes pacificus). The research behind this split has been covered at Biological Ramblings and in two parts at Earbirding: part 1, part 2. David Sibley has posted draft range maps for the two wren species. This split is my one armchair lifer from the changes in this supplement.
Black Scoter: The Eurasian and North American populations were split. The Eurasian population will be called Common Scoter (Melanitta nigra), while the North American population will retain the English name Black Scoter with a new scientific name (Melanitta americana).
Eastern and Mexican Whip-poor-will: Whip-poor-will was split into two species on the basis of vocalizations, genetics, and morphology. The eastern population becomes Eastern Whip-poor-will (Caprimulgus vociferus) and the western population becomes Mexican Whip-poor-will (Caprimulgus arizonae). You can read more about this split at Earbirding. David Sibley has posted draft range maps for the two Whip-poor-will species.
Several other splits concern species with ranges entirely outside of the continental United States. Eight species were added due to new records within with AOU checklist area. In addition to species-level splits, there are changes to the English and scientific names for multiple species, as well as rearrangement of the taxonomic order for some families and genera.
The AOU was busy revising warbler taxonomy over the past year. The genus Vermivora has been divided into Vermivora and Oreothlypis. Bachmann's, Blue-winged, and Golden-winged Warbler will remain in Vermivora (with the Blue-winged Warbler's scientific name changing to Vermivora cyanoptera). Tennessee, Orange-crowned, Nashville, Virginia's, Colima, Lucy's, Flame-throated, and Crescent-chested Warblers move to Oreothlypis. Oreothlypis will sit between Vermivora and Parula on the checklist. Another warbler genus, Seirus, is also being split. Ovenbird will remain by itself in Seirus, and Northern and Louisiana Waterthrush will form a new genus, Parkesia.
Here is the full revised North American checklist.