“Taxonomy” refers to the classification of living organisms (as species, subspecies, families, etc.) based on their characteristics, distribution, and genetics. There are multiple taxonomies for birds around the globe. Projects at the Cornell Lab of Ornithology—including eBird, Merlin, Birds of the World, and the Macaulay Library—use the eBird/Clements Checklist of Birds of the World. The eBird/Clements taxonomy is the backbone of all bird information available through Cornell Lab projects.
Our understanding of species is constantly changing. Every year, some species are “split” into two or more, while others are “lumped” from multiple species into one, as we gain a better understanding of the relationships between birds. The eBird/Clements Checklist is updated annually to reflect the latest developments in avian taxonomy. “Taxonomy Time” is an opportunity to celebrate the many scientific advances in ornithology made over the past year—some of them thanks to your eBird data!
The 2025 update includes 40 species gained because of splits and 18 species lost through lumps, resulting in a net gain of 22 species and a new total of 11,167 species worldwide. There were no newly-described species during this year’s taxonomy update.
Submit all Not Submitted checklists by 26 October, so Cornell can implement taxonomic changes to all your lists. All checklists will be updated on October 28.
Among North American species, the following changes will be made:
Whimbrel
Whimbrels occur on almost all continents. Whimbrels in the Americas will be renamed Hudsonian Whimbrels.
Warbling vireo
The long-awaited split of Warbling Vireo has finally arrived: Eastern Warbling Vireo (Vireo gilvus) and Western Warbling Vireo (V. swainsoni). The breeding range splits roughly at the Rocky Mountains and breeding habitats differ somewhat, with Western Warbling Vireo occurring in mountain forests—especially riparian forest adjacent to pines—while Eastern Warbling Vireo is a bird of lowland watercourses from the Great Plains eastward, usually in areas with cottonwoods, willows, and other riverside vegetation. The songs differ substantially. Compared to Eastern, Western averages shorter- and smaller-billed, darker-crowned, and shorter tailed. These combined with the more colorful plumage may invite confusion with Philadelphia Vireo, but warbling-vireos never have dark lores, and their yellow is never brightest on the center axis of the body below.
Yellow warbler
Another big North American split, Yellow Warbler will be divided into:
- Northern Yellow Warbler (Setophaga aestiva)—the migratory northern population that breeds in shrubland and riparian habitats across Canada, the United States, and northern Mexico.
- Mangrove Yellow Warbler (S. petechia)—the resident southern population that lives year-round in mangroves along the coasts of Mexico, Central America, and northern South America, and on the fringes of Caribbean islands.
To see information on all worldwide splits and lumps, go to https://ebird.org/news/2025-taxonomy-update or https://www.aba.org/check-list-redux-2025/
