Proposal (125) to South American Classification Committee

 

Split Notharchus hyperrhynchus from N. macrorhynchos

 

Effect on South American CL: This proposal would elevate a taxon to species rank that we currently treat as a subspecies on our baseline list.

 

Background: The hyperrhynchus subspecies group (consisting of named subspecies hyperrhynchus, cryptoleucus, and paraensis) of Notharchus macrorhynchos (the White-necked Puffbird) was formerly considered (e.g. Ridgway 1914, Cory 1919) to represent a separate species from nominate macrorhynchos. Peters (1948) lumped these forms (and swainsoni) without explanation, into a single wide-ranging, polytypic species. Most recent compilations (Meyer de Schauensee 1966, 1970; Sibley & Monroe 1990; Clements 2000) have followed suit, treating Notharchus macrorhynchos as a polytypic species consisting of five subspecies that ranged from Mexico to Argentina. The 7th Edition of the AOU Checklist (1998) recognized two subgroups within this species complex: a wide-ranging macrorhynchos group (consisting of the taxa hyperrhynchus, cryptoleucus, macrorhynchos, and paraensis), and a geographically disjunct subspecies swainsoni, which is restricted to the Atlantic Forest of southeast Brazil, eastern Paraguay and northeastern Argentina. In the 7th Volume of the Handbook of the Birds of the World, Rasmussen and Collar (2002) elevated swainsoni to separate species status (see SACC Proposal #124) and synonymized cryptoleucus of El Salvador and Nicaragua with hyperrhynchus. These authors recognize three subspecies of N. macrorhynchos as follows:

 

N. m. hyperrhynchus (Sclater 1856) - S Mexico south to N & NE Venezuela, and south to Colombia, Ecuador, E Peru, N Bolivia and W Brazil (E to Rio Tapajós and S to Mato Grosso).

 

N. m. macrorhynchos (Gmelin 1788) - extreme E Venezuela, the Guianas, and extreme N Brazil south to the Amazon.

 

N. m. paraensis (Sassi 1932) - lower Amazon Valley in Brazil (Pará east of the lower Rio Tapajós and into N Maranhčo).

 

Rasmussen and Collar (2002) noted that:

 

 "Races hyperrhynchus and paraensis markedly distinct from nominate, and together may constitute a separate species." In the Family Account, the same authors remark that "At the same time, however, it should be noted that the nominate race of the White-necked Puffbird in the Guianan region is also distinctive in appearance and possibly in song; thus, further study of the situation is required."

 

This situation has received surprisingly little attention from ornithologists or birders, given that plumage differences between hyperrhynchus/paraensis versus macrorhynchos are striking. The former group differs from the latter in having a much broader white forehead (white in nominate is restricted to a narrow frontlet), a broader white hind-collar, much less extensive black patches on the flanks, and a noticeably larger bill. These differences are well illustrated in HBW Volume 7. The subspecies paraensis is similar to hyperrhynchus in plumage characters, but has an even longer bill. The plumage differences between hyperrhynchus/paraensis and nominate macrorhynchos are of the same order as the differences between any of these three forms and N. tectus (Pied Puffbird), N. ordii (Brown-banded Puffbird),and N. pectoralis (Black-breasted Puffbird), and thus, are consistent with species-level plumage differences across the rest of the genus.

 

Vocal differences are even more pronounced, but no published quantitative analysis exists. In my experience, the songs of hyperrhynchus and paraensis are virtually identical and unvarying throughout their wide distributions. This song is described by Stiles and Skutch (1989) as "a long bubbling trill, at a constant pitch or rising slightly, then falling" and by Hilty (2003) from Iquitos, Peru as "a long, nasal, frog-like trill, prrrrrr (up to 15-20 seconds)". Ridgely and Greenfield (2001) describe it as "an evenly pitched monotonous trill that lasts 3-5 seconds, sometimes given by both members of a pair". These descriptions fit my own tape recordings of hyperrhynchus from Chiapas, Mexico; Pacific Slope of Costa Rica; and lowland E Ecuador; as well as my recordings of paraensis from Mato Grosso and Amazonas, Brazil. The song of nominate macrorhynchos is very different, and is described from SE Venezuela by Hilty (2003) as "a long series of rapid pree whistles (ca. 30 whistles in 8 seconds) on the same pitch". I have heard nominate birds giving a complex song that begins with a similar series of whistles (as described by Hilty) that then leads into a series of terminal couplets, recalling the songs of N. ordiiN. pectoralis and N. swainsoni. This song is not even remotely like the trill given by hyperrhynchus/paraensis. Rasmussen and Collar (2002) described the song of N. macrorhynchos (presumably the nominate form, although this is not explicitly stated) as being "a very high weak trill at variable speeds, usually descending, "ui-ui-uiwi-di-dik wi-di-dik wi-di-dik". Oddly, the first part of this description ("high weak trill") seems to refer to the song of hyperrhynchus/paraensis, whereas the transcription that follows sounds more like the song of nominate macrorhynchos. Hilty (2003) notes the vocal differences between the two groups as follows:

 

"Song (mid-morning) in Rio Grande, Bolívar, a long series of rapid pree whistles (ca. 30 in 8 sec) on same pitch. At dawn (Iquitos, Peru) a long, nasal, frog-like trill, prrrrrrrrr (up to 15-20 secs) on same pitch, given once every 2-5 minutes and by both sexes."

 

Unfortunately, Hilty obscured the significance of the differences by seemingly suggesting that they may reflect the difference between dawn songs and regular songs. I have taped hyperrhynchus and paraensis giving the trilled song at all hours of the day (including mid-day), and, conversely, I have heard the complex song of nominate macrorhynchos at dawn from atop canopy towers. Time of day has no bearing on the described vocal differences between these taxa.

 

Analysis: The plumage, biometric (possibly mainly bill length and depth), and vocal differences between nominate macrorhynchos and hyperrhynchus/paraensis are comparable to the differences between any of these three taxa and the other recognized species in the genus. The distributions of the two groups are seemingly parapatric in Venezuela (between hyperrhynchus and nominate) and in Brazil along the Amazon (nominate along north bank, paraensis along south bank), with no reported intergradation. I have no doubts that the vocal differences alone would act as isolating mechanisms between these taxa were they to come in contact, and the strong differences in distribution of black and white on the head and face of the two forms would seemingly also act to preclude recognition. Based on both vocal differences and morphological differences, I'm not even certain that macrorhynchos and hyperrhynchus/paraensis are one another's closest relatives. In song, distribution of black on the head/face, and in its smaller bill, nominate macrorhynchos is more reminiscent of N. ordii and N. pectoralis than of hyperrhynchus/paraensis.

 

The down side of all of this is the absence of any real published analysis of either vocal or morphological characters. However, qualitative descriptions of both types of characters are in the literature, as are good illustrations that reveal the plumage and bill size distinctions. The separation of hyperrhynchus/paraensis would also be consistent with the recognition of N. swainsoni as a separate species (as treated in Rasmussen & Collar 2002, and as proposed in SACC Proposal #124 that we follow).  N. swainsoni differs from the rest of the macrorhynchos complex to a similar degree (both vocally and morphologically) as does hyperrhynchus/paraensis from nominate, the main difference being that there is more published support for the former split.

 

This split would result in two species: a monotypic N. macrorhynchos; and a polytypic N. hyperrhynchus (to include N. h. paraensis).

 

Recommendation: I recommend a YES vote on splitting these two groups, in spite of the absence of any real published analysis. These taxa were originally considered separate species, and were subsequently lumped without published justification. I don't think undoing this unjustified lump should be held to a higher standard, but, in any case, a higher standard exists in the form of published qualitative descriptions of vocal, plumage and size differences. Weak as the published justification is, I believe that the distinctions behind it are sound and biologically significant. If this passes, I'll put together a short proposal suggesting an English name.

 

Literature Cited:

AMERICAN ORNITHOLOGISTS' UNION. 1998. The A.O.U. Check-list of North American Birds, Seventh Edition. American Ornithologists' Union. Washington D.C.

CLEMENTS, J. F. 2000. Birds of the world: a check-list, Fifth Edition. Ibis Publishing Company, Vista, California.

CORY, C. B. 1919. Catalogue of birds of the Americas. Publications of the Field Museum of Natural History, Zool. Ser. 13(2):608 pp.

HILTY, S. L. 2003. Birds of Venezuela. Princeton University Press, Princeton, New Jersey.

MEYER DE SCHAUENSEE, R. 1966. the species of birds of South American and their distribution. Livingston Publishing Co., Narberth, Pennsylvania.

MEYER DE SCHAUENSEE, R. 1970. A guide to the birds of South America. Livingston Publishing Co., Wynnewood, Pennsylvania.

PETERS, J. L. 1948. Checklist of birds of the world, vol. 6. Museum of Comparative Zoology, Cambridge, Massachusetts.

RASMUSSEN, P. C. AND N. J. COLLAR. 2002. Family Bucconidae (Puffbirds). Pp. 102_138 in: del Hoyo, J., Elliott, A., & Sargatal, J., eds. (2002). Handbook of the birds of the world, Vol. 7, Jacamars to Woodpeckers. Lynx Edicions, Barcelona.

RIDGELY, R. S., AND P. J. GREENFIELD. 2001. The birds of Ecuador. Vol. 2. Field Guide. Cornell University Press, Ithaca, New York.

RIDGWAY, R. 1914. The birds of North and Middle America. Bull. U. S. Natl. Mus., no. 50, pt. 6.

SIBLEY, C. G., AND B. L. MONROE, JR. 1990. Distribution and taxonomy of birds of the World. Yale University Press, New Haven, Connecticut.

STILES, F. G. AND A. F. SKUTCH. 1989. A guide to the birds of Costa Rica. Cornell University Press, Ithaca, New York.

 

Kevin Zimmer, May 2004

 

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Comments from Silva: "YES. The differences in plumage are very striking and as far as I know these two species do not present any evidence for intergradation when their ranges meet. Because they have been described as separate species and lumped without any adequate taxonomic review, I fully agree with the proposal in ranking these taxon as two distinct species."

 

Comments from Stiles: "[NO] This case is like the preceding with one crucial difference: none of the evidence has been published in detail. While I personally believe that Kevin is right, I feel that if we are to maintain our insistence on published evidence, available for independent evaluation (as we have on a number of similar occasions), I must vote NO. (If Kevin wants to do a short note with sonograms etc., might I recommend Ornitología Colombiana??)."

 

Comments from Robbins: "YES, Kevin presents a very cogent argument for treating hyperrhynchus as a species."

 

Comments from Jaramillo: "YES.  Instances such as this one are really difficult for me. We are dealing with taxa that were originally described as separate species, were lumped without published analysis, and current information strongly suggests that this undocumented lump was not a good decision. The full detailed analysis explaining why this split is a valid way to deal with these taxa is not published, but the available data seems pretty clear and I strongly suspect that Kevin is right in his analysis. The stickler in me says, vote NO, yet the pragmatists says vote YES. There are so many hundreds of these taxonomic issues in South America that need to be tackled. Some may only need a few days’ work to pull together some data and provide a note to a journal, but there are so few people willing to do this type of taxonomic cleaning up that it seems like many of these questions will not be resolved in many, many decades. I think I will forever be flipping back and forth on how to deal with these types of records, and I commend those that are much more clearly thinking and resolute in their stances. In this particular case, I am taking these verbal descriptions of voice as data, and they are published albeit in literature that was not peer reviewed. Even so they are something on which to anchor this decision, the original lump does not seem to be anchored on anything and that troubles me more than splitting with no published analysis, but some data. I do think that publishing in a venue such as Ornitología Colombiana is a superb way to get something on these issues in print."

 

Comments from Nores: "NO. Aunque Zimmer parece tener razón, no veo que hayan trabajos publicados que justifiquen la separación. Como este caso hay muchos otros en la misma situación."

 

Comments from Pacheco: "YES. Em minha primeira experiźncia sonora com a forma nominada de macrorhynchos ao norte do baixo Amazonas (Amapá), eu julguei que minhas gravaćões pudessem representar ordii; na medida em que, conhecia antes as vozes distintas de "macrorhynchos" paraensis de Carajás (sul do Pará). É possível (como sugerido por Kevin) que macrorhynchos seja - no escudo Guianense – o representante do grupo relictual ordii/swainsoni. Manter hyperrhynchus e macrorhynchos reunidos, como formas alopátricas de uma mesma espécie, é abonar uma decisčo inexata, arbitrária e anacrônica de Peters (1948), diante das informaćões agora disponíveis."

 

Comments from Remsen: "YES. My usual vote in cases such as this is "no" due to insufficient published information. However, the qualitative descriptions of voices that have been published combined with the absence of any published rationale for the original merger of a taxon ranked at species level by Ridgway and Cory."