Russet-naped Wood-Rail (Aramides albiventris) Costa Rica 2014 © Corey Finger / Macaulay Library
By Jack Hruska
In July, the American Ornithologists’s Union Committee on Classification and Nomenclature of North and Middle American Birds (NACC) releases the annual “Check-list Supplement” with the latest decisions regarding species designations. These designations either result in the ‘splitting’ of separate populations into ‘new’ species, or the ‘lumping’ of populations into one. This summer, the NACC approved several new splits, adding a whopping six species to Central America’s ever-growing avifauna. Of these, four are endemic to Central America. The list now exceeds 1200 species, highlighting the region’s status as a biodiversity hotspot. Listed here is a review of those splits and other recent taxonomic changes.
Splits
Plain Wren (Cantorchilus modestus): a vocally charismatic wren found across a variety of habitats from southern Mexico to central Panama, split into three species, all found in Central America. Two are regional endemics. A combination of vocal, morphological, and genetic data informed this decision. For more more details of this split, see the recent review written by César Sanchez.
- Cabanis’s Wren (Cantorchilus modestus)—Found from southern Mexico, mostly along the Pacific, to northern Costa Rica. An isolated population also occurs in the pine forests of Belize.
- Canebrake Wren (Cantorchilus zeledoni)—Larger and overall more gray in appearance; endemic to the Caribbean slope from southeastern Nicaragua through Bocas del Toro, Panama.
- Isthmian Wren (Cantorchilus elutus)—Similar plumage to Cabanis’s, but subtle differences in song; endemic from southwestern Costa Rica to central Panama. A contact zone may occur in central Costa Rica. eBirders, particularly in zones of contact, are encouraged to upload checklists with precise localities and recordings of these species.
Green Violetear (Colibri thalassinus): Widespread in the Neotropics and emblematic of highlands throughout its range, the Green Violetear has now been split into two species. Little is known of the vocal differences, so if you have a chance to record their songs, please upload the recordings in your eBird checklists. For more information on the differences between the two species, refer to a review written by John van Dort.
- Mexican Violetear (Colibri thalassinus)—Found from central Mexico through northern Nicaragua; it exhibits a blue patch on the breast that is lacking in the Lesser Violetear.
- Lesser Violetear (Colibri cyanotus)—The Lesser Violetear is found from the highlands of Costa Rica to Bolivia.
Gray-necked Wood-Rail (Aramides cajaneus): A widespread species from Mexico to Argentina, the boisterous Gray-necked Wood-Rail has been split into two species.
- Russet-naped Wood-Rail (Aramides albiventris)—Found from Mexico to the Caribbean slope of Costa Rica; not to be confused with the similarly named Rufous-necked Wood-Rail.
- Gray-cowled Wood-Rail (Aramides cajaneus)—Found from the Pacific coast of Costa Rica to Argentina. It lacks the rusty patch on the back of the head characteristic of its northern relative.
Whether albiventris and cajaneus come into contact in Costa Rica is not known. eBirders can help document the exact ranges of the two species, with photographs and voice recordings submitted on eBird lists with clearly defined localities.
Blue-crowned Motmot (Momotus momota): An iconic member of the Neotropical avifauna, the taxonomy and species delimitations has long been a contentious issue. The Blue-crowned Motmot has been split into five species, with just two in Central America.
Lesson’s Motmot (Momotus lessoni) Honduras 2016 © Oliver Komar / Macaulay Library
- Lesson’s Motmot (Momotus lessoni)—Occurring from central Veracruz to western Panama; distinguished by its diagnostic WHOOP whoop!, although it has been known to give a single whoop on occasion.
- Whooping Motmot (Momotus subrufescens)—Occurring from central Panama to northwestern Peru, the Whooping Motmot is characterized by a single whoop.
A better understanding of potential areas of contact in central Panama is desired. eBirders in this area are highly encouraged to submit photographs and recordings with their precisely located checklists.
Three-striped Warbler (Basileuterus tristriatus): based on genetic and vocal data, the widespread highland species has been split into three, two of which are found in Central America.
- Costa Rican Warbler (Basileuterus melanotis)—Endemic to the Talamancan highlands of Costa Rica and western Panama; vocally distinct, lacking a ‘rising song’ typical of other populations.
- Tacarcuna Warbler (Basileuterus tacarcunae)—Endemic to the Cerro Azul/Cerro Jefe area, the San Blas Mountains, and Cerro Tacarcuna within Panama; closely related to the Three-banded Warbler (Basileuterus trifasciatus) of South America.
Not adding to the Central American total yet, Leach’s Storm-Petrel (Oceanodroma leucorhoa) was also split into three: Townsend’s Storm-Petrel (Oceanodroma socorroensis), Ainley’s Storm-Petrel (Oceanodroma cheimomnestes), and Leach’s. While the latter is regular off the Pacific coast of Central America, there are as yet no documented records of Townsend’s and Ainley’s, but both breed off the coast of northwestern Mexico, and should be watched for.
Other changes
The Black-mandibled Toucan (Ramphastos ambiguus) is now called the Yellow-throated Toucan, but it maintains the scientific name.
Restricted to the Darién in Panama, the Choco Sirystes (Sirystes sibilator) is now recognized as a full species and given the scientific name Sirystes albogriseus.
The genus Porzana has been split into several genera, and thus the enigmatic Yellow-breasted Crake (Porzana flaviventer) is now called Hapalocrex flaviventer.
Similarly, the antbird genus Cercomacra has been split. For this reason, the Dusky Antbird (Cercomacra tyrannina) is now called Cercomacroides tyrannina.
The Black-capped Swallow (Notiochelidon pileata) and White-thighed Swallow (Notiochelidon tibialis) are now placed within the genus Atticora, and are Atticora pileata and Atticora tibialis, respectively.
The greenlet genus Hylophilus was found to be polyphyletic. The Tawny-crowned Greenlet (Hylophilus ochraceiceps), Golden-fronted Greenlet (Hylophilus aurantiifrons), and Lesser Greenlet (Hylophilus decurtatus) are now called Tunchiornis ochraceiceps, Pachysylvia aurantiifrons, and Pachysylvia decurtata, respectively.
In order to emphasize their distant relation to ‘true finches’, the four “Brush-Finch” species are now renamed as “Brushfinch”, removing the hyphen and capitalization of the “F” (e.g., Chestnut-capped Brushfinch).
Check out these hyperlinks to view the AOU supplement, and the proposals with comments made by the committee. All of these changes have now been incorporated by eBird (following the Clements Checklist taxonomy), and are now reflected in all submitted eBird checklists.
Happy birding!