ABA Species Update – August 25, 2025
ABA Species Update – August 25, 2025
Taxonomy is never static. Just as tectonic plates shift beneath our feet, bird classification evolves as researchers uncover new data. For birders, these updates can change how we keep our life lists, understand species ranges, and experience birds in the field.
The American Ornithological Society (AOS) has released its latest updates to the taxonomy of North American birds. Today, we’ll look at:
The two-way split of the Warbling Vireo
The four-way split of the Herring Gull
Several notable changes to Latin names
Warbling Vireo Split
A familiar springtime songster across much of North America, the Warbling Vireo has long been considered a single species. That has now changed:
Western Warbling Vireo (Vireo swainsoni)
Eastern Warbling Vireo (Vireo gilvus)
This split reflects new genetic and bioacoustic research. Though nearly identical in appearance, the two groups are reproductively isolated—a hallmark of cryptic species (taxa that look alike but are genetically distinct).
A key paper, Genetic, bioacoustics and morphological analyses reveal cryptic speciation in the warbling vireo complex(Carpenter et al., Zoological Journal of the Linnean Society, Vol. 195), revealed a deep east–west genetic divide dating back to the Pleistocene:
“We found a main west–east division for both mtDNA (cyt b) and microsatellites... The large genetic distances in mtDNA (4.0%) and abrupt split along the Great Plains suggest that the eastern genetic group was isolated in a separate glacial refugium from the two western genetic groups during the Pleistocene.”
How to Tell Them Apart
In most cases, geography is enough:
Observations in Boston = Eastern Warbling Vireo
Observations in Colorado = Western Warbling Vireo
In the Great Plains overlap zone, though, birders must rely on song:
Eastern: longer (2–3+ seconds), fast syllables, rising notes mid-song and again at the end
Western: shorter (<2 seconds), fewer/slower syllables, usually ending lower
Example recordings: Warbling Vireo – Xeno-Canto #1014885
Herring Gull Split
The once broad Herring Gull has now been divided into four distinct species:
American Herring Gull (Larus smithsonianus)
Vega Gull (Larus vegae)
European Herring Gull (Larus argentatus)
Mongolian Gull (Larus mongolicus)
This reflects genetic evidence, morphology, and distribution patterns. While field identification of large white-headed gulls can already be a challenge, these changes bring more precision—and complexity—to gull watching in North America.
Latin Name Updates
Several birds familiar to North American birders also received updated scientific names:
Spotted Dove (introduced in southern California): Streptopelia chinensis → Spilopelia chinensis
Cooper’s Hawk: Accipiter cooperii → Astur cooperii
American Goshawk: Accipiter atricapillus → Astur atricapillus
Bluethroat: Cyanecula svecica → Luscinia svecica
Fan-tailed Warbler: Basileuterus lachrymosus → Euthlypis lachrymosa
Final Thoughts
Taxonomic updates can be frustrating for some birders—especially when they mean adjusting life lists—but they also reflect the exciting reality that our understanding of birds continues to grow.
The Warbling Vireo split highlights how much remains hidden in plain sight, while the Herring Gull split underscores the complexity of widespread species. Add in the name changes, and it’s clear: birding is as dynamic as the natural world it celebrates.
Stay tuned for deeper dives into Pleistocene-era bird speciation, gull identification tips, and field ID guides for cryptic species. And let me know in the comments if you’d like a dedicated post on the Warbling Vireo songs or on the genetics of Pleistocene refugia.
References & Further Reading
Carpenter, A.M., Graham, B.A., Spellman, G.M., Klicka, J., & Burg, T.M. (2022). Genetic, bioacoustics and morphological analyses reveal cryptic speciation in the warbling vireo complex. Zoological Journal of the Linnean Society, 195(2).
Audubon Society: Eastern vs. Western Warbling Vireo Songs
Xeno-Canto: Warbling Vireo recordings
