CHICAGO — October 20, 2026 — The 67th Supplement to the American Ornithological Society's (AOS's) Check-list of North American Birds , which published today in Ornithology, includes several significant updates to the classification of bird species found in North America, Central America, and the Caribbean.
A few highlights from the supplement include splits for Tringa semipalmata (Willet), Cistothorus palustris (Marsh Wren), Setophaga petechia (Yellow Warbler), and Turdus plumbeus (Red-legged Thrush). Also of note, Momotus mexicanus (Russet-crowned Motmot) has been split into two species, giving Guatemala its first endemic bird species, M. castaneiceps (Guatemalan Motmot); and Bubo virginianus (Great Horned Owl) has been split into four species, three of which are endemic to South America. American populations of two species, Ardea alba (Great Egret) and Numenius phaeopus (Whimbrel), have been split from their Old World counterparts, resulting in two new American endemics, A. egretta (American Egret) and N. hudsonicus (Hudsonian Whimbrel). We've gone through another "wrenaissance" this year, as one genus was added, one deleted, and the linear sequence was reordered for Troglodytidae.
The Check-list, first published in 1886, is updated in annual supplements from the AOS's North American Classification Committee (NACC). The Check-list and its supplements provide the taxonomic and nomenclatural foundation for bird research, conservation, management, and education throughout the region, and are relied on as the authority on avian biodiversity by government agencies, NGOs, scientists, and birders, among others. The NACC reviews proposals submitted annually for taxonomic and distributional updates to the Check-list of North American Birds.
