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How the North American bird list is changing in 2020

Mexican Duck is considered a full species once again, decades after being lumped with Mallard. Photo from The Crossley ID Guide: Eastern Birds by Richard Crossley (Wikimedia Commons)

This year’s changes to the official Check-list of North American Birds include the long-expected return of Mexican Duck to full species status, a so-called “lump” among crows, and recognition of new songbird species in Middle America.

Decisions made by the American Ornithological Society’s Committee on Classification and Nomenclature—North and Middle America from mid-April 2019 through mid-April 2020 are summarized in a new supplement published today by The Auk: Ornithological Advances.

The grassland bird currently known as McCown’s Longspur. Photo by Skip Russell/Flickr (Creative Commons)

One topic the new supplement does not address is an issue that has been on lots of birders’ minds in recent weeks: the practice of naming birds after people.

A year ago, the committee decided not to rename McCown’s Longspur, a bird found in short-grass prairies from southern Canada to northern Mexico. The bird is named after John P. McCown, a Confederate officer during the Civil War. In a 2019 proposal to rename the bird, Drexel University ornithologist Robert Driver said McCown was a man “who fought for years to maintain the right to keep slaves and also fought against multiple Native tribes” and therefore didn’t deserve to have a bird named for him.

At the time, Terry Chesser, the committee chair and an ornithologist at the U.S. Geological Survey and the Smithsonian, said that the committee values stability in common names, and that it “did not consider that changing the name of McCown’s Longspur in isolation (i.e., without placing McCown into the context of the many other people for whom birds are named, and without a general policy on such issues) was warranted.” (You can read the comments on the 2019 proposal from committee members here.)


The issue of eponyms or honorifics in bird names has come to the fore in recent weeks as the public reckoning over racial injustice has gained steam. We have seen changes announced for brands such as Aunt Jemima and Uncle Ben’s, the decision to remove the Confederate symbol from Mississippi’s state flag, and many more actions aimed at combating racism (or at least appearing to do so). Will the names we use for birds be next? 

Yesterday, I asked Chesser if his committee would revisit the longspur’s name or if it might go further and replace all avian eponyms, as some birders have suggested. “Regarding the McCown’s Longspur, amid a changed cultural landscape, the committee will be revisiting this issue with a new proposal,” he said.

Today, the committee published a statement about the longspur issue and updated guidelines for English bird names. The guidelines say that possible name changes will be considered on a case-by-case basis and that they won’t be replaced en masse. The new guidelines say, in part, “By itself, affiliation with a now-discredited historical movement or group is likely not sufficient for the NACC to change a long-established eponym. In contrast, the active engagement of the eponymic namesake in reprehensible events could serve as grounds for changing even long-established eponyms, especially if these actions were associated with the individual’s ornithological career. The NACC recognizes that opinions will often differ on how best to handle such situations, and the Committee strives to strike a balance that recognizes the principle of nomenclatural stability while respecting circumstances in which names should be reconsidered to reflect present-day ethical principles or to avoid ongoing harm.”


So, as Rachel Maddow would say, “watch this space.”

Here are the headlines from this year’s check-list supplement…

Hello again, Mexican Duck

The only notable split of a species found north of Mexico is the decision to separate Mexican Duck from Mallard. These birds were considered separate species until 1983, when they were lumped, but recent studies have argued that the ducks are indeed separate. This post from our friends at Rogue Birders explains the complicated relationships among the closely related Mallard, Mexican Duck, Mottled Duck, and American Black Duck.

The bulk of the Mexican Duck population lives in the interior plateau of central Mexico. Richard Crossley, in his Crossley ID Guide: Waterfowl, writes that fewer than 1,000 individuals occur in the United States. Those ducks that breed in the U.S. are found in southeastern Arizona, southern New Mexico, and west-central Texas.

The AOS also notes that “Non-breeding birds occur casually throughout the year north through much of Colorado and in Utah north to Great Salt Lake, west to the Lower Colorado River Valley, and east to the Lower Rio Grande Valley. Accidental west to San Luis Obispo County, California, north to Albany County, Wyoming, and east to southwestern Nebraska. Difficulties distinguishing this species from A. fulvigula [Mottled Duck] may be decreasing detection east of its usual range.”


Goodbye, Northwestern Crow

Genetic evidence from crows of the Pacific Northwest shows what many naturalists have long suspected: that Northwestern and American Crows are a single species that have varying body sizes. A study published this year by David Slager of the University of Washington found a 900-km-wide hybrid zone among the birds, which is more than seven times wider than the average widths of several other avian hybrid zones in North America.

The classification committee agreed with Slager’s research and lumped the Northwestern Crow into the wider American Crow species.

Terns across the ocean

For many years, the range of Royal Tern was said to cover the Pacific, Atlantic, and Gulf coasts of the Americas as well as the Atlantic coast of Africa. Recent research, however, has shown that the birds in Africa are a distinct species, and the committee accepted the split. America’s birds will keep the name Royal Tern, and Africa’s are now known as West African Crested Tern.


New birds in Middle America

In Mexico and Central America, the committee agreed to split Mayan Antthrush from the more widespread Black-faced Antthrush. The birds were separated based on differences in song, plumage, and genetics. Mayan Antthrush is found in Mexico, from the Caribbean slope from southern Veracruz, northern Oaxaca, Tabasco, Chiapas, and the Yucatan Peninsula, south to northern Honduras.

The committee also recognized that a tiny flycatcher known as Paltry Tyrannulet is in fact two species. One is now known as Guatemalan Tyrannulet, which is resident in the highlands of eastern Chiapas, Guatemala, and central El Salvador. The other is Mistletoe Tyrannulet, from the lowlands of southern Belize, eastern Guatemala, eastern Honduras, and Nicaragua (except the Pacific slope), throughout Costa Rica (except the dry northwest), Panama, and northwestern Colombia.

Proposals declined

The committee rejected several other proposals, including one that would have made the Great White Heron of southern Florida a full species, separate from Great Blue Heron.


“The Great White Heron was an interesting case and more-or-less split the committee,” says Chesser. “Most committee members who voted against the split considered there to be too much gene flow between GWH and GBH, whereas those who voted for it tended to cite evidence for assortative mating. It’s certainly a gray area with reasonable arguments on both sides. McGuire et al (2019), the paper on which the proposal was based, stated that deciding GWH’s species status ‘is difficult.’”

The committee also decided not to split a subspecies of Northern Saw-whet Owl found only on British Columbia’s Haida Gwaii archipelago into a full species.

“Although most committee members considered the Haida Gwaii owl proposal to be quite interesting, the committee voted unanimously not to split it,” says Chesser. “The committee considered it to be good subspecies rather than a species. Although the plumage differences are notable, these are not considered to be isolating mechanisms in owls and are characteristic instead of subspecies. Most members cited the lack of differences in vocalizations, which are known to be isolating mechanisms in owls.”


I’ll editorialize here to say that the lack of split among the owls is a bit of a bummer because it would have given Canada its first endemic bird species.

Other rejected proposals would have:

– Split Horned Lark into two or more species. This would have separated populations in the Americas from larks elsewhere in the world.

– Give a new common name to Olive Warbler, a bird that has very little olive in its plumage and is not a warbler. The proposal was to name it Ocotero, which is already commonly used throughout much of its range in Mexico and northern Central America.

– Removed “scrub” from the common names of our four scrub-jay species.  


To read about all of the changes to the North American checklist, download the supplement here

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Matt Mendenhall

Matt Mendenhall

Matt Mendenhall is the editor of BirdWatching magazine and You can reach him at [email protected].

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