Proposal (1044) to South American Classification Committee

Treat Formicarius destructus as a separate species from F. nigricapillus

Effect on SACC list

If this proposal passes, it will result in the elevation of the taxon destructus to full species, resulting in a monotypic F. nigricapillus and a monotypic F. destructus.

Background information

The current SACC note reads”

"1c. Areta & Benítez Saldívar (2025) provided vocal evidence for treating South American destructus as separate species. SACC proposal needed."

Areta & Benítez Saldívar (2025) summarized the situation as follows:

The Black-headed Antthrush (Formicarius nigricapillus) includes two allopatric subspecies: nominotypic nigricapillus in Costa Rica and Panama, and destructus in Colombia and Ecuador (Ridgway 1893; Hartert 1898; Wetmore 1972; Krabbe and Schulenberg 2003, 2020). Although the taxon nigricapillus was originally described as a full species by Ridgway (1893) and treated as such by some authors (Chapman 1917, Cory & Hellmayr 1924), it was often considered as a subspecies of the Black-faced Antthrush (F. analis) (Hartert 1902, Ridgway 1911). Conversely, the taxon destructus was originally described as a subspecies of F. analis by Hartert (1898) and was subsequently either considered as such (Hartert 1902), rarely afforded species-level status (Salvadori and Festa 1899; Howell and Dyer 2022), or most often considered as a subspecies of F. nigricapillus (Chapman 1917, Cory & Hellmayr 1924, Wetmore 1972, Krabbe & Schulenberg 2003).

New information

In Areta & Benítez Saldívar (2025), we assessed species limits in F. nigricapillus using vocal, plumage, and morphometric data, concluding that nigricapillus and destructus are better treated as two separate biological and recognition species. For more detailed explanations and discussions stemming from historical taxonomic references, please refer to the publication. What follows is a blend of selected copied and reorganized text and images from Areta & Benítez Saldívar (2025) with some minor adjustments to facilitate reading.

Songs: After discarding duplicates, Areta & Benítez Saldívar (2025) compiled a total of 57 songs of nigricapillus and 129 songs of destructus that were assessed aurally and through examination of spectrograms. The song of nigricapillus is a rapid series of around 25 clear, pulsated whistled notes that begins with a few more spaced notes that become mostly evenly paced with a slight rise in pitch halfway through the song and a relatively monotonous ending (sigmoid-like spectrographic contour; Fig. 1). The song of destructus is a very rapid eerie series of around 40 ventriloquial notes that fall and rise in pitch and decrease markedly in pace in the second half (smile-like spectrographic contour; Fig. 1). The vocalizations of nigricapillus and destructus have been described accurately in field guides, but the importance of their differences has not been fully realized. The song of nigricapillus was described as "a rapid, pulsating series of ca. 20 deep, resonant, whistled notes, the first 2-3 slower, more staccato, the next 6-8 rising in pitch, the last 10-12 on the same pitch, with the final 2 notes slower, the entire series lasting 4-5 sec" (Stiles and Skutch 1989, p. 287), while that of destructus "resembles that of Rufous-capped Antthrush, but shorter, an eerie, quavering glissando of about 30 notes in 3 sec, sliding upscale and slowing noticeably at the end; ventriloquial" (Hilty and Brown 1986, p. 417). The song of nigricapillus has been aptly likened to the shorter song of Thicket Antpitta Myrmothera dives ( Garrigues and Dean 2007; Vallely and Dyer 2018), a comparison that does not apply to the song of destructus.

The quantitative acoustic characterization evidenced that songs of both taxa are 100% diagnosable (n=21 nigricapillus, n=38 destructus). Acoustic data showed that 13 out of 15 variables differed significantly between nigricapillus and destructus, the differences in 10 of these 13 variables were very marked with non-overlapping mean ± SD, automatically indicating that they belong to statistically different populations. Taxon nigricapillus showed lower song peak frequency, longer mean note duration and mean interval between notes, fewer notes per song, slower pace, relatively even pace in the first and second halves of the song, lower peak frequencies of first, median, and final note, and longer duration of first, median, and final note. In contrast, destructus had higher song peak frequency, shorter mean note duration and mean interval between notes, more notes per song, faster pace, a marked deceleration in the second half of the song, higher peak frequencies of first, median, and final note, and shorter duration of first, median, and final note (Table 1). The songs of both taxa were clearly separated in multivariate space (Fig. 2A) and a cluster analysis also revealed two distinctive groups, unambiguously including all destructus samples clustered separately from all nigricapillus recordings (Fig. 2B).

The song of nigricapillus remains essentially identical through ca. 490 km across Costa Rica and into C Panama in our sample. t]The song of destructus also remains basically the same through its distribution, ca. 1130 km extending from NC Colombia to SW Ecuador. The diagnostic song types are separated by a gap of ca. 190 km between NW Colombia (Jardín Botánico del Pacífico, Chocó) and E Panamá (Nusagandi, Guna Yala), and exhibit no sign of intermediacy closer to their respective limits (Fig. 1). Further documented records are needed to properly understand the actual distributional gap between nigricapillus and destructus. The width of the gap is at least 190 km as shown by our song-recordings dataset, but possibly much smaller: birds seen, heard, and tape-recorded at Cuchilla del Lago on the Colombian side of the Serranía de Darién in the Cerro Tacarcuna (Renjifo et al. 2017) most likely represent the taxon nigricapillus. This would reduce the gap between nigricapillus (Cuchilla del Lago; see question mark in Figure 1) and destructus (Reserva La Bonga) to 100 km within Colombia. Unfortunately, the sound recordings were not available at the time of our writing and could not be assessed (J. Avendaño in litt.). Further fieldwork should clarify the extent of their allopatry and assess whether the Río Atrato and its formidable swamps act as a biogeographic barrier for these taxa (Haffer 1970, 1975, Renjifo et al. 2017). The Cerro Tacarcuna records, if confirmed to be nigricapillus (which seems very likely), would indicate that both taxa (nigricapillus and destructus) occur in South America.

Fig. 1. Plumage aspect, songs, and geographic distribution of songs of Black-capped Antthrush (Formicarius nigricapillus), and Black-hooded Antthrush (F. destructus) analysed in this study. Orange circles: F. nigricapillus (photo: ML-452131711, San Gerardo Biological Station, Costa Rica, by Mark Hebblewhite; song: ML-220516, Reserva Biológica Bosque Nuboso Monteverde, Costa Rica by D. L. Ross). Blue circles: F. destructus (photo: ML-121617911, Rio Silanche Bird Sanctuary, Ecuador by Nick Athanas; song: JIA-10, Reserva de Bosque Seco Lalo Loor, Ecuador by J. I. Areta). Circles with a central dot denote songs measured quantitatively; plain circles denote songs studied aurally (see Appendices 1 and S1); question mark (?) indicates unconfirmed sound recording of nigricapillus from Cerro Tacarcuna in Colombia. The differences in plumage (chestnut nape in nigricapillus, black nape in destructus), song, and morphometrics collectively support the recognition of nigricapillus and destructus as separate species.

Table 1. Acoustic parameters of songs of Black-capped Antthrush (Formicarius nigricapillus), and Black-hooded Antthrush (F. destructus). Values shown are mean ± SD [range], n= sample size. Asterisk denotes significant statistical differences in the Mann-Whitney non-parametric test (α<0.05), and plus symbol denotes non overlapping mean ± SD. See Appendix 1 for measured sound recordings.

Variable	F. nigricapillus (n=21)	F. destructus (n=38)
Bandwidth 90% (Hz)	205.35±56.37 [93.8-281.2]	207.93±38.45 [140.6-281.2]
Duration 90% (s)*	2.38±0.33 [1.74-3.00]	2.64±0.44 [1.92-3.88]
Peak frequency (Hz)*^+	1484.37±61.75 [1406.2-1593.8]	1689.91±61.7 [1546.9-1781.2]
Mean note duration (s)*^+	0.06±0.01 [0.05-0.09]	0.04±0.01 [0.02-0.07]
Mean interval between notes (s)*^+	0.08±0.01 [0.05-0.10]	0.04±0.01 [0.03-0.06]
Number of notes*^+	24.95±1.69 [22-29]	37.62±5.57 [28-52]
Sound density	0.56±0.06 [0.46-0.67]	0.6±0.08 [0.47 - 0.79]
Pace*^+	5.98±0.42 [5.44-6.96]	9.61±1.09 [7.76-11.81]
Pace change (second/first half)*^+	1.04±0.09 [0.88-1.19]	0.76±0.07 [0.63-0.93]
	(8.63±1.2/11.37± 1.08) [5.61-6.67/5.25-7.58]	(6.18±0.32/5.99±0.66) [6.82-11.46/9.02-12.82]
Peak frequency first note (Hz)*^+	1345.97±68.13 [1218.8-1500]	1650.24±93.23 [1406.2-1781.2]
Peak frequency median note (Hz)*^+	1412.91±47.54 [1312.5-1500]	1617.82±58.76 [1453.1-1781.2]
Peak frequency final note (Hz)*^+	1477.67±60.46 [1406.2-1593.8]	1703.12±69.11 [1546.9-1875]
Duration first note (s)*	0.04±0.02 [0.01-0.06]	0.02±0.01 [0.01-0.03]
Duration median note (s)*^+	0.09±0.02 [0.04-0.14]	0.12±0.03 [0.04-0.10]
Duration final note (s)*	0.14±0.04 [0.10-0.26]	0.11±0.03 [0.06-0.21]

*=non-parametric Mann-Whitney test P-value <.05

⁺=non-overlapping mean ± SD

Plumage: To characterize the external appearance of nigricapillus and destructus, Areta & Benítez Saldívar (2025) examined photographs of 37 museum specimens, including the holotypes of both taxa, and vetted 40 good-quality photographs on the citizen science platforms eBird (ebird.org) and iNaturalist (inaturalist.org). They found that nigricapillus exhibits chestnut-brown hindneck (sometimes extending to neck sides in a handkerchief or semicollar; Figure 1), and typically more chestnut-brown back (Fig. 1), whereas destructus exhibits all-black hindneck and neck sides (Fig. 1), and typically browner back. There is some variation in back colour of specimens (but not in the back-neck contrast that distinguishes taxa), with some nigricapillus being seemingly identical in colour to typical destructus (Chapman 1917, USNM specimens). In some nigricapillus individuals, the chestnut-brown hindneck is extensive and expands onto the sides of the neck creating a semicollar, which gives these individuals a capped aspect, that is less prominent in birds with less extensive chestnut-brown hindneck. On the other hand, all individuals of destructus show a hooded aspect, caused by its wholly black head, hind neck and neck sides (Fig. 1).

Fig. 2. Quantitative analyses of songs of Black-capped Antthrush (Formicarius nigricapillus), and Black-hooded Antthrush (F. destructus). (A) Plot of the first two principal components (PC1 vs. PC2) of the Principal Component Analysis. Ellipses depict 95% confidence intervals. (B) Dendrogram from the agglomerative hierarchical cluster analysis (UPGMA). Both methods consistently show that nigricapillus and destructus differ markedly in songs supporting their treatment as separate species. See Appendix 1 and S1 for songs measured.

Morphometry: based on a limited dataset (n=6 nigricapillus, n=9 destructus), Areta & Benítez Saldívar (2025) concluded that 1) bill length (exposed culmen) showed no overlap between taxa, with all individuals of nigricapillus having a longer bill than destructus, and therefore no overlap in mean ± SD values (Fig. 3a), 2) nigricapillus was longer winged than destructus, with exact overlap only in their extreme values, and no overlap in mean ± SD values (Fig. 3b), and 3) tail length was longer in nigricapillus than in destructus, but the difference was not statistically significant (two tailed t-test p=0.17) (Fig. 3c).

Fig. 3. Morphological measurements of Black-capped Antthrush (Formicarius nigricapillus), and Black-hooded Antthrush (F. destructus). Figure depicts median and quartiles on box plots. Asterisk denotes significant statistical differences in one-way ANOVA (α<0.05). The morphological differences in bill and wing length coupled to plumage differences give support to the treatment of nigricapillus and destructus as separate species. See Table 2 for sample sizes and data, and Appendix 2 and S2 for specimens measured and studied.

The differences in songs and plumage herein described can be readily appreciated in videos of free-ranging singing birds:

nigricapillus: https://macaulaylibrary.org/asset/608419951

destructus: https://macaulaylibrary.org/asset/316228641

Taxonomic assessment

The marked differences in vocalizations and morphology, and moderate but consistent plumage differences strongly supports the elevation of the taxon destructus to species-level, leading to the recognition of two allopatric and monotypic species, F. nigricapillus and F. destructus. Areta & Benítez Saldivar (2025) based their taxonomic conclusions on the recognition concept of species (Paterson 1985), whereas the same species would be recognized by applying the biological species concept (Mayr 1963; “isolation concept” fide Paterson 1985). The inferred level of discontinuity between nigricapillus and destructus is of such a magnitude that presumably any other modern species concept would recognise them as separate species, whether based on mating or other important attributes, phenotypic distinctiveness, presence of autapomorphies, or phylogenetic independence (Cracraft 1983, Mishler & Brandon 1987, Gill 2014, Areta et al. 2019, Winker 2021). Howell & Dyer (2022:27) wrote that "Differences in plumage and song indicate that Central American nigricapillus and South American destructus (Choco Antthrush) are best treated as separate species." A view that is amply supported by Areta & Benítez Saldivar (2025).

In terms of plumage, the differences between nigricapillus and destructus (Fig. 1) would be among the least conspicuous for two Formicarius species-level taxa, and comparable to (although less obvious than) those between F. moniliger and F. analis. They differ most notably by the presence of a rufous-chestnut fore-collar below the black throat in moniliger, whereas the black throat contacts the grey chest directly in the two subspecies groups of F. analis (Howell 1994, Vallely and Dyer 2018). However, less obvious plumage differences exist between the analis and hoffmanni subspecies groups within F. analis despite their noticeable vocal differences (Howell 1994) which are compatible with species-level differences in the genus (Krabbe and Schulenberg 2003, van Dort et al. 2023, Benítez Saldívar & Areta in prep.).

Common names

Most species in the genus Formicarius carry common English names that refer to plumage features. We propose to adopt the name Black-capped Antthrush for F. nigricapillus and Black-hooded Antthrush for F. destructus, which focus on one of the main plumage differences between them and retain a connection to the former Black-headed Antthrush used for the composite species. We find the proposed use of Black-hooded Antthrush for F. nigricapillus by Howell and Dyer (2022) to be misleading, as this taxon is capped rather than hooded. The smaller bill of destructus is difficult to appreciate in field conditions, and bill features do not seem useful to coin common names here. Finally, Choco Antthrush has been proposed for destructus (Howell and Dyer 2022); although a good name, there are other antthrushes in the Choco, and it loses the connection to the former Black-headed Antthrush name.

Voting and recommendations

Perhaps the best thing to do is to vote on three different aspects of the proposal:

A) Species limits: We recommend a YES vote to split F. destructus from F. nigricapillus.

B) English names: We recommend a YES vote to adopt the name Black-capped Antthrush for F. nigricapillus and Black-hooded Antthrush for F. destructus

C) Presence of nigricapillus in Colombia. A lingering question is whether the Cerro Tacarcuna records in Colombia should be provisionally considered to be nigricapillus until shown otherwise. For biogeographic reasons, we lean towards the maintenance of nigricapillus in the SACC list based on these records, as it seems unlikely for destructus to reach the Cerro Tacarcuna crossing the Atrato swamps. We recommend a YES vote to keep F. nigricapillus in the SACC list.

References

Areta JI, Depino EA, Salvador SA, Cardiff SW, Epperly K, Holzmann I (2019) Species limits and biogeography of Rhynchospiza sparrows. Journal of Ornithology 160:973-991

Areta, J.I., Benítez Saldívar, M.J. (2025). Species limits in the Black-headed Antthrush (Formicarius nigricapillus). J Ornithol https://doi.org/10.1007/s10336-025-02265-5

Chapman FM (1917) The Distribution of Bird-Life in Colombia. A Contribution to a Biological Survey of. South America. Bull. Amer. Mus. Nat. Hist., 36.

Cory CB, Hellmayr CE (1924) Catalogue of Birds of the Americas. Publications of the Field Museum of Natural History (Zoological Series). Volume 13, Part 3. Chicago.

Cracraft J (1983) Species concepts and speciation analysis. Curr Ornithol 1:159–187

Garrigues R, Dean R (2007) The Birds of Costa Rica. Zona Tropical, Comstock Publishing Associates, Cornell University Press.

Gill F (2014) Species taxonomy of birds: which null hypothesis? Ornithological Advances 131: 150–161

Haffer J (1970) Geologic-climatic history and zoogeographic significance of the Urabá region in northwestern Colombia. Caldasia 10: 603–636.

Haffer J (1975) Avifauna of northwestern Colombia, South America. Bonner Zoologische Monographien 7: 1–182.

Hartert E (1898) On a collection of birds from north-western Ecuador, collected by Mr. W. F. H. Rosenberg. Novitates Zoologicae 5: 477–505.

Hartert E (1902) Some further notes on the birds of north-west Ecuador. Novitates Zoologicae 9: 599–617.

Hilty SL, Brown WL (1986) A Guide to the Birds of Colombia. Princeton: Princeton University Press.

Howell SNG (1994) The specific status of black-faced antthrushes in Middle America. Cotinga 1: 20–25.

Howell SNG, Dyer D (2022). Costa Rica even richer than we thought? North American Birds 73: 22–33.

Krabbe NK, Schulenberg TS (2003). Black-headed Antthrush (Formicarius nigricapillus). In Handbook of the Birds of the World Alive (del Hoyo J, Elliott A, Sargatal J, Christie DA, de Juana E, eds). Lynx Edicions, Barcelona.

Krabbe NK, Schulenberg TS (2020). Black-headed Antthrush (Formicarius nigricapillus), version 1.0. In Birds of the World (del Hoyo J, Elliott A, Sargatal J, Christie DA, de Juana E, eds). Lynx Edicions, Barcelona. Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.blhant1.01

Mayr E (1963) Animal species and evolution. Harvard University Press, Cambridge

Paterson HEH (1985) The recognition concept of species. In: Vrba ES (ed) Species and speciation. Transvaal Museum Monograph, Pretoria.

Mishler BD, Brandon RN (1987) Individuality, pluralism, and the Phylogenetic Species Concept. Biology and Philosophy 2: 397–414

Renjifo LM, Repizo A, Ruiz-Ovalle JM, Ocampo S, Avendaño JE (2017) New bird distributional data from Cerro Tacarcuna, with implications of conservation in the Darién highlands of Colombia. Bulletin of the British Ornithologists´ Club 137: 46–66.

Ridgway R (1893) A revision of the genus Formicarius Boddaert. Proceedings of the United States National Museum 16: 667–686.

Ridgway R (1911) The Birds of North and Middle America: A Descriptive Catalogue. Part V. Bulletin of the United States National Museum 50.

Salvadori T, Festa E. 1899. Viaggio del Dr. Enrico Festa nell’Ecuador. XXI. Uccelli. Parte seconda - Passeres clamatores. Bollettino dei Musei di Zoologia ed Anatomia Comparata della R. Università di Torino 15 (362): 1–34.

Stiles FG, Skutch AF (1989) A Guide to the Birds of Costa Rica. Ithaca, NY: Cornell University Press.

Vallely AC, Dyer D (2018) Birds of Central America. Princeton University Press, Princeton and Oxford.

van Dort J, Patten MA, Boesman PFD (2023). Black-faced Antthrush (Formicarius analis), version 2.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.blfant1.02

Wetmore A (1972). The Birds of the Republic of Panamá. Volume 3. Passeriformes: Dendrocolaptidae (Woodcreepers) to Oxyruncidae (Sharpbills). Smithsonian Miscellaneous Collections 150(3). Smithsonian Institution, Washington, D.C., USA.

Winker K (2021) An overview of speciation and species limits in birds. Ornithology 138: 1–27 10.1093/ornithology/ukab006

Links to supplementary information:

https://static-content.springer.com/esm/art%3A10.1007%2Fs10336-025-02265-5/MediaObjects/10336_2025_2265_MOESM1_ESM.xlsx

https://static-content.springer.com/esm/art%3A10.1007%2Fs10336-025-02265-5/MediaObjects/10336_2025_2265_MOESM2_ESM.xlsx

Addendum:

Genetics: The coincidental break in plumage and vocalizations between F. moniliger and F. analis umbrosus (a representative of the hoffmanni group) were used as arguments to support the elevation of moniliger to species status (Howell 1994). More recently, phylogenetic data have shown that F. moniliger is sister to a clade including F. destructus as more closely related to F. analis (including representatives of the hoffmanni and analis subspecies groups) (Harvey et al. 2020). This distant relationship between moniliger and analis further reinforces the species-level split of F. moniliger and lends support to vocal differences as a useful tool to establish species limits in Formicarius. Although there are no available genetic data for nominotypic nigricapillus, the vocal distinctions between nigricapillus and destructus seem as or more marked than those between F. moniliger and F. analis of the analis and hoffmanni subspecies groups. In our paper we predicted that nigricapillus and destructus will exhibit levels of genetic differentiation tantamount to their vocal and morphological distinctions.

The Formicarius phylogenetic tree from Harvey et al. 2020:

Harvey MG, Bravo GA, Claramunt S, et al. (2020) The evolution of a tropical biodiversity hotspot. Science 370: 1343–1348.

Juan I. Areta and M. Juliana Benítez Saldívar, April 2025

Voting chart: https://www.museum.lsu.edu/~Remsen/SACCPropChart1044+.htm

Comments from Remsen:

“A. YES. Although playback trials would be nice, the degree of difference in the songs is consistent with species rank, and burden-of-proof falls on those who would treat them as subspecies.

“B. MAYBE, for all the good reasons outlined in the proposal, especially maintaining the connection between old and new names. Also, follows SACC guidelines (https://www.museum.lsu.edu/~Remsen/SACCEnglishNameGuidelines.pdf) for providing new names for both daughters in a parental split. After having looked through Macaulay photos of dozens of destructus, “hooded” seems especially appropriate for the extent of the black. The match between the scientific and English names for nigricapillus is helpful in remembering both. However, as for nigricapillus, a problem is that “capped” is typically used for cases in which the bird has a much more distinctive color patch on the top of the head, which is not really the case for nominate ruficapillus, despite the scientific name. Obviously, the scientific name reflects a pattern seen on specimens, but I think we need side-by-side photos of the specimens, if only as confirmation that the name is OK.

“C. YES, but somewhat reluctantly because the recordings are unavailable and because perhaps the Colombian national committee should have the say on this one. On the other hand, to propose that the records are not nigricapillus makes no biogeographic sense, and I agree with this statement in the proposal “Cerro Tacarcuna records in Colombia should be provisionally considered to be nigricapillus until shown otherwise.”

“Anecdote: puzzled by the name destructus, I looked at Jobling (online), and here is the derivation from Hartert’s 1898 description: ‘very much destroyed by the shot, but still quite recognizable, is so considerably smaller and darker brown above than typical analis that I do not hesitate to distinguish it subspecifically’.”

Comments from Lane: “I must admit this one was not on my radar (although I have seen, and heard, both taxa). The voices are much more distinct that I was expecting, and I think the results of the study presented are good.

“A) YES to splitting the two members of the complex as biological species.

“B) The two daughter species are not all that strongly differentiated by plumage, and really can't see F. nigricapillus having a distinctive black crown set off against the rest of the head (I suspect the name was coined because it was blacker-crowned than F. analis... and granted, I am looking at the poorly-lit Macaulay photos rather than specimens to make this statement), but unless we want to get derailed by another English name situation, I will go with the names suggested: Black-crowned and Black-hooded.

”C) YES to retaining both species in the SACC area due to the records from the border near Panama.”

Comments from Rasmussen (who has Robbins’ vote): “Re the suggestion that the presence of other antthrushes in the Choco makes Choco Antthrush for destructus less than a great name, I don't see the issue there. As far as I can see, destructus is the only antthrush in the majority of lowland Choco, and certainly it is the only one recognized as a species that is largely confined to the Choco (unless I'm missing something---please correct if so). Here are maps of the three other species in the region: 

“There are a smattering of Black-faced eBird reports for the Choco but no photos.

“Rufous-breasted is in the western Andes but not lowland Choco:

“Schwartz's Antthrush is also in the Andes, not the lowlands.

“All the others currently called antthrushes are either eastern slope or nowhere near the Choco.

“Thus, I'm voting for Choco Antthrush for destructus. I think Black-hooded is OK too.

“In the absence of something better, I'm still OK with Black-capped for nigricapillus, especially given the sci name.”

Additional comments from Remsen: “Terry Chesser graciously sent me photos of the USNM specimens of nigricapillus (1) and destructus (4). I have lightened up the originals, and done some cropping and rearranging so that the specimen of nigricapillus is always at the top, above the yellow line:

“Dorsal:

“Lateral:

Ventral:

“As noted by Terry, there does not seem to be much in the way of difference between the two in plumage, especially in how “capped” the two are. Of course, with only 1 nigricapillus, it’s tough to assess this, but I am backing off of the proposed English names and going with the names used by Howell and Dyer (2022), which have the additional advantage of already having been in print for 3 years. Also, as shown by Pam, destructus is “the” Antthrush of the Chocó. As much as I appreciate the logic of the proposed names, I am switching my vote on B to NO unless additional information indicates that nigricapillus has a ‘capped’ appearance.”

Comments from Terry Chesser: “If destructus is more closely tied to the Choco than any other antthrush, then I agree with Pam that Choco Antthrush is a perfectly good name. The name Black-hooded Antthrush, although suggested in the proposal for destructus, is also applicable to nigricapillus, and in my view is more appropriate for nigricapillus than Black-capped, which despite matching the scientific name doesn't seem to be particularly suitable (as others have noted). Black-headed or Black-hooded, yes, but not Black-capped, at least in the way that "capped" is typically used. A bonus is that Black-hooded for nigricapillus and Choco for destructus were used in 2022 by Howell and Dyer, so there's a bit of precedence there.”

Additional comments from Areta: “I find hooded for nigricapillus a terrible name. Look at photos of live birds in their habitat, and you´ll see how strikingly different is the hood of destructus (which gives it a bold hooded appearance) from the brown nape (and sometimes neck sides) of nigricapillus, which very often gives it a capped appearance (and if one would like to call this hooded, then it is obviously much, much, much less hooded than destructus, to the point that the name results in confusion, because one would be calling hooded the presumed sister species that is less hooded). Choosing a species name based on a feature that is more prominent in its sister species seems to be a bad choice to me.

“Note also that ALL the field guides (including the latest from Costa Rica by Howell and Dyer) have erred, and they have illustrated destructus instead of nigricapillus.

“Here some random nigricapillus photos:

https://macaulaylibrary.org/asset/622843058

https://macaulaylibrary.org/asset/622070151

https://macaulaylibrary.org/asset/613829664

https://macaulaylibrary.org/asset/601316591

https://macaulaylibrary.org/asset/452110921

https://macaulaylibrary.org/asset/153191961

“And some destructus:

https://macaulaylibrary.org/asset/205559781

https://macaulaylibrary.org/asset/184627131

https://macaulaylibrary.org/asset/121617911

https://macaulaylibrary.org/asset/76928221

“Anyway, I stand by the names we proposed in the paper.”

Comments from Gary Rosenberg (voting for Claramunt): “I vote YES with regard to Black-capped for nigricapillus and Black-hooded for destructus - as it has been demonstrated on looking at the photos that Nacho provided that nigricapillus is really visually more “black-capped” in comparison to destructus – with destructus having a more extensive black hood. Although seeing those differences in the field may be difficult. I personally would retain “Black-headed” for nigricapillus, but I guess that isn’t an option - we could use Black-headed and Choco Black-headed - or if retaining Black-headed is really against the rules, then using Black-capped for nigricapillus would be acceptable - it therefore would align with the scientific name. I am not against the idea of using “Choco” for destructus, but I don’t believe it is the only antthrush there - or at least it is a matter of semantics. In western Ecuador, “destructus” ALMOST overlaps with Rufous-breasted - the two are separated by elevation, but I would NOT be surprised if the two overlap (and I suspect they do overlap around Mindo) – nigricapillus and Rufous-breasted overlap in elevation in Costa Rica (I have seen the two on the same trail in Braulio Carrillo NP). Here is a more specific map of where Rufous-breasted occurs in Ecuador - therefore the idea that destructus is the only antthrush in the “Choco” is a bit misleading - in my opinion. One can make the argument that the “Choco” is not limited specifically to the lowlands but also includes the foothills. Furthermore, destructus does occur south along the slopes of the Andes in Ecuador south to about Guayaquil - south of the area generally described as the Choco - although the majority of the distribution is within the Choco for sure.

“I guess I prefer using Black-hooded for destructus, it is at least similar to “Black-headed” and as the authors say, retains that connection, but I would not have an issue with using Choco for destructus, as the majority of the bird’s range is in the Choco.”

Additional comments from Remsen: “I am flip-flopping back to YES on this one after seeing the photos for which Nacho provided the links. I am also strongly persuaded by his excellent point that using “hooded” for nigricapillus would be a bad idea given that “black-hooded” is more appropriate for its sister taxon.”

Comments from Josh Beck (guest vote):

“Essentially there are two good and suitable and relatively unproblematic names for destructus suggested/available (Black-hooded and Choco) and two slightly more problematic and less well received names suggested/available for nigricapillus (Black-capped and Black-hooded).

“Viewing this pragmatically, I don't think any of the proposed names are really going to cause any issues. This is not a group of birds where confusion reigns supreme or where there is such a diversity of species that we're entering into name soup. Formicarius are almost universally first detected and ID'd by voice and overlapping species are different enough from each other that subtle details of names aren't going to impact visual field ID either. Nor do I think someone working in a museum is likely to get thrown off the track by the common name Black-capped.

“I agree that Black-hooded for nigricapillus is suboptimal given that it is less hooded than destructus. I don't personally see nigricapillus as particularly capped (the contrast vs the cheek argument put forward earlier) but being pragmatic, this name is not going to cause a slew of mis-ID's in the field or mayhem in collections. Whatever your views of the cheek needing to contrast or not, nigricapillus does have black on the cap/crown and it aligns with the scientific name, so I am fine with Black-capped for nigricapillus. Further, I also think NACC should have priority on the naming of this one, so I'm not sure that this vote really matters but Black-capped is my vote for nigricapillus.

“For destructus I really think either Black-hooded or Choco serves just fine. I favor and vote for Black-hooded for two reasons:

1) Alignment with Black-capped and with the original name, Black-headed.

2) Given that at some point Black-faced Anthrush, F analis is likely going to be split, I think it's quite likely we'll end up with Amazonian and Central American Antthrush as common names and those will pair well with Mayan, so perhaps avoiding a geographic descriptor for destructus helps to keep a bit of name alignment not just now but also in a future split of Black-faced.”

Additional comments from Josh Beck (guest vote): “I had assumed that Black-headed would be too disagreeable.

“Without having requested a data dump from eBird to get precise numbers, a quick look at eBird and Macauley and XC shows that, as expected, both daughters are commonly observed. I would estimate destructus is a bit more commonly observed, perhaps a 60/40 split in data, give or take. For me this doesn't particularly impact a vote in this case but wanted to put the info out there in case it sways others. 

“I personally have no problem with Black-hooded and Black-capped but would prefer Black-headed and Black-hooded and am not worried about confusion here, so would vote for Black-hooded and Black-headed. I am actually quite catholic as well about which of the two carries which name. Black-headed for nigricapillus if it is viewed as more appropriate, or Black-hooded for nigricapillus if there is desire to align with Howell & Dyer's recent precedent.”

Comments from Andrew Spencer (voting for Naka): “I've also really been enjoying the discussion around these names! I've given myself a couple of days to think about these, and my initial gut reaction hasn't changed that much: I'm relatively ambivalent about the proposed names, but I am very against keeping the old name around (unless it's as compound names for both split species, which is probably overkill here). The fact that we have to even think about which one is better to use the old name for is especially a red flag for me that we should be retiring it if at all possible. If this was an instance where there was absolutely no acceptable options for one of the split species I might be more accepting of retaining the pre-split name, but I don't think that is the case here.

“On to the various names that people have proposed. I honestly think that the "capped" look of nigricapillus is, at best, very subtle. And for the times that it is most apparent, the "cap" looks very dark brown contrasting with the black elsewhere on the head, rather than truly "Black-capped". That being said, it would hardly be the first time a common name draws attention to a subtle plumage feature, and I prefer "Black-capped" over retaining the old name by many miles.

“’Black-hooded’ is ok for destructus. I'm also completely fine with ‘Choco’, but the symmetry of using plumage features for the two split species tilts my vote towards that for this bird as well.

“So, my official vote for now is to follow the names Nacho originally proposed. If that ends up not passing though, and we're spit-balling new names, what about using "Central American Antthrush" for nigricapillus, and then "Choco Antthrush" for destructus? At the moment there are no other antthrushes endemic or almost entirely limited to Central America (unless you consider the Yucatan part of Central America). When Black-faced Antthrush ends up getting split, the vocal type in Central America makes it well into Colombia, so contra what Josh says I think the name "Central American" works better for nigricapillus than it will for that eventual species.”