With contributions by Kevin Tolan
The Common Redpoll and Hoary Redpoll are now the same species: Redpoll. Photo credit: Kyle Tansley
If you’ve recently opened the eBird or Merlin apps, you might have noticed that your Hoary Redpoll has disappeared, or that other species suddenly have “Northern” or “American” in front of the name you’re familiar with. This isn’t a result of passing birding trends or slang. It’s actually a matter of scientific accuracy.
Each year, experts on the American Ornithological Society (AOS) North American Classification Committee carefully review proposals to split and lump species based on new scientific evidence, to make sure species are grouped based on the best available science. Splitting one species into two or lumping two (or more) into one typically calls for a new set of common names as well. The past few years have seen multiple common and scientific names change as a result of these re-classifications.
Also subject to change are the four-letter “alpha” codes that are commonly used as shorthand by biologists, and some birders, to denote species. Each code is derived from the species’ common name: for example, HETH for Hermit Thrush, BBWO for Black-backed Woodpecker, and, well, SORA for Sora. These codes are developed by the Bird Banding Laboratory and the Institute for Bird Populations primarily for fast data entry by biologists, but birders use them as well. You can even type an alpha code into eBird to quickly add it to a checklist. As common names change, alpha codes follow suit.
(By the way, the taxonomic changes outlined in this post are unrelated to potential future changes to eponymous common names: birds named after people. Proposals to change common names for non-taxonomic reasons, such as altering hyphenation, spelling, or capitalization or removing derogatory words, typically go through the same process of evaluation by AOS committees.)
Splits and Lumps
Common Redpoll (Acanthis flammea) CORE & Hoary Redpoll (Acanthis hornemanni) HORE →
Redpoll (Acanthis flammea) REDP
Sad to say, scouring winter finch flocks for an extremely pale Hoary Redpoll will no longer net you a new species. Genetic analysis has determined that the observable differences in color and bill size result from a single “supergene,” a cluster of linked genes that are inherited together and control multiple traits. A similar supergene separates the tan-striped and white-striped morphs of White-throated Sparrows. Given the major differences between the redpolls arise only from this supergene, the committee decided the redpolls are not separate enough to merit species status. Common, Hoary, and the European Lesser Redpoll have all been lumped into the mononymic “Redpoll”. Above, you’ll see Hoary is now in parenthesis as a type of Redpoll, instead of a species.
Cattle Egret (Bubulcus ibis) CAEG →
Western Cattle-Egret (Ardea ibis) WECE
This species arrived in the Americas from Africa in the late 19th century and has spread widely across North and South America. Now, Asian and African populations have been reclassified as separate species, with the African (and therefore their American descendent) populations classified as Western Cattle-Egret and the Asian population as Eastern Cattle-Egret. Note the new hyphenation!
The cattle-egrets have also been moved back into the main heron genus Ardea based on genetic evidence. A recent study found that cattle-egrets are “deeply nested” within the main heron genus Ardea, meaning they are more closely related to some large Ardea herons (like the Great Blue Heron) than those large herons are to other birds in Ardea (like the Great Egret). Keeping cattle-egrets in Bubulcus would mean splitting Ardea into two groups, which committee members wanted to avoid, so they voted to instead place cattle-egrets in Ardea.
Barn Owl (Tyto alba) BANO →
American Barn Owl (Tyto furcata) ABOW
Barn Owls are found on every continent except Antarctica. They were recently split into American Barn Owl (North and South America), Eastern Barn Owl (Australia and Southeast Asia), and Western Barn Owl (Africa, Europe, and western Asia).
Now that their name is American Barn Owl, two common points of confusion can be resolved. First, using the full name of American Barn Owl might clear up any confusion caused by “Barn Owl” and “Barred Owl” sounding similar. Second, this change resolves a conflict in alpha codes. Prior to 2024, Barn Owl and Barred Owl would both have received the code BAOW based on their common names. To clarify, each species instead received a unique code, BADO for Barred Owl and BANO for Barn Owl. Now, the renamed American Barn Owl gets the code ABOW, leading BAOW free for Barred Owl again.
You can use these codes to enter data into eBird, or as shorthand for your own notes, but using the full common name will always be the clearest way to talk to other birders!
House Wren (Troglodytes aedon) HOWR →
Northern House Wren (Troglodytes aedon) NHWR
House Wrens were split into three groups based on geography: Northern House Wren (North America to southern Mexico), Southern House Wren (southern Mexico through South America), and several island endemic species. The Northern House Wren keeps the original scientific name.
In the Caribbean, newly split species include the St. Lucia, Grenada, and St. Vincent Wrens. These species show morphological differences that helped them to adapt to local conditions, similarly to Darwin’s Galápagos Finches. These island species, with their limited ranges and small populations, are particularly vulnerable; hopefully their promotion to species status will spur further conservation efforts. Learn more about VCE’s work in the Caribbean.
Northern Goshawk (Accipiter gentilis) NOGO →
American Goshawk (Astur atricapillus) AGOS
The American Goshawk was split from Eurasian Goshawk. After this split, American Goshawks and Cooper’s Hawks were both moved to genus Astur, meaning the entire scientific name of American Goshawk has changed. This common name change makes American Goshawk and American Goldfinch competitors for the code AMGO. So, their codes are now AGOS and AGOL respectively. (We’ll miss you, NOGO and AMGO!)
Herring Gull (Larus argentatus) HERG →
American Herring Gull (Larus smithsonianus) AHGU
Herring Gull was split four ways into the American Herring Gull, European Herring Gull, Mongolian Gull, and Vega Gull. Fortunately for those of us who struggle with gull identification, the American Herring Gull is the only one of these species that regularly occurs in the lower 48.
Genus Name Changes
If you view the scientific names for species, you may have noticed some additional changes.
- Least Bittern from Ixobrychus to Botaurus
- Western Cattle-Egret from Bubulcus to Ardea (see above)
- American Goshawk and Cooper’s Hawk from Accipiter to Astur. In Vermont, Sharp-shinned Hawk now stands alone in Accipiter. In eBird, you can no longer report “Accipiter sp.” for birds that could be American Goshawks, Cooper’s Hawks, or Sharp-shinned Hawks. That category is now “Accipitrine hawk sp. (former Accipiter sp.)”. You can still report “Sharp-shinned/Cooper’s Hawk,” which is the more common ambiguity in most situations.
- Spruce Grouse from Falcipennis to Canachites
- Double-crested Cormorant from Phalacrocorax to Nannopterum
- Ruby-crowned Kinglet from Regulus to Corthylio
Other Bird Name Changes
No More Night Heron Hyphens
If you think that the inclusion or removal of a hyphen seems like an incredibly nitpicky detail, you’d be right! And yet, ornithologists have exchanged thousands of impassioned words on this very topic. Hyphens in common names sometimes indicate taxonomic relationships, like in whistling-ducks, golden-plovers, or, formerly, “night-herons,” which were thought to form a distinct evolutionary group within herons. The hyphen signified their unique status. However, genetic research has since revealed that Black-crowned and Yellow-crowned Night Herons are not closely related—they just look and behave alike. Since “night-heron” is not a meaningful taxonomic group, the hyphen was dropped. Now, they’re simply “night herons”, with no implied relationship beyond being herons active at night.
Taxonomies May Vary
There are multiple bird taxonomies, each of which has its own treatment of which species should be split or lumped, and what they should be called. In North America, the differences among these taxonomies are usually minor. The taxonomy in eBird follows the Clements Checklist, which itself usually follows the decisions of the AOS classification committees.
However, eBird will on rare occasions include taxonomic changes affecting North and South American birds that have not been accepted by AOS. For example, AOS rejected the proposed Herring Gull split because some committee members felt that the different populations still interbreed too much to be called different species, but additional research might lead them to re-assess the decision. Meanwhile, the reclassification of American Goshawk and Cooper’s Hawk into the genus Astur has not yet been assessed by AOS.
Efforts are underway to unify the major bird taxonomies to a single global consensus taxonomy thanks to the International Ornithologists’ Union Working Group Avian Checklists.
It might seem impossible to keep up with the ever changing state of bird taxonomy, but staying up-to-date helps birders better understand the birds we love. Newer discoveries, like the unexpected close relationship between parrots and falcons, are now reflected in their placement and ordering in your field guide. And, by keeping your records in eBird, you can enjoy the privilege of having these updates applied automatically to your life list. As a bonus, your eBird checklists help researchers build knowledge about bird distribution and abundance. For more information on birding in Vermont, check out the Vermont eBird portal.
Go Deeper
For more information on these changes, including changes for species not found in Vermont:
American Birding Association’s summary of the 2024 AOS Checklist supplement
