Proposal (169) to South American Classification Committee

Split Santa Marta Nightjar (Caprimulgus heterurus) from Little Nightjar (Caprimulgus parvulus)

Background

The taxon Caprimulgus (?parvulus) heterurus was originally described by Todd, 1915, as a distinct species:

Setopagis heterurus Todd, 1915, Proceedings of the Biological Society of Washington, 28, p.81. (La Tigrera, Santa Marta, Colombia.)

Cory (1918:135) continued to recognise "S. heterurus" as a distinct species. Footnote b reads: "Resembling S. parvulus (Gould), but under parts less rufescent and male with white areas of wings and tail decidedly more extensive covering both webs of the terminal portion of the three outer pairs of rectrices."

Then, Peters (1940: 202) merged heterurus as a subspecies of parvulus, with no discussion or explanation.

Davis (1978). argued for the re-separation of heterurus from parvulus on the basis of calls.

Cleere (1999: 354) stated: "Birds of Santa Marta region (N. Colombia) have been considered a separate species, C. heterurus, again on the basis of vocal differences, but these are normally considered insufficiently marked to justify such a split."

However, Hilty (2003: 380) stated: "Birds of e Peru, s Brazil, and Argentina are surely a separate species] (song very different)."

Cleere (loc. cit.) describes the song of parvulus as "warbled 'dop, dro-dro-dro-dro-dro'"; song of heterurus is "deeper, evenly pitched 'pik, gobble-gobble-gobble-gobble-gobble'."

I have inserted below a wav file that contains the songs of both C. parvulus and C. heterurus. [can't get this to work yet - Remsen]

Anyone who listens to these songs cannot doubt that, of themselves, they strongly suggest we are dealing with two distinct species. It is surprising that Cleere (1999: 348) splits (I believe correctly) Caprimulgus ekmani Hispaniolan Nightjar from Caprimulgus cubanensis Cuban Nightjar citing solely "notable differences in voice".

In recent years, it has been widely recognised that vocal differences are likely to serve as the chief method of reproductive isolation among nocturnal families, such as owls and nightjars.

Finally, in terms of biogeography, the extreme separation between heterurus, whose distribution is: COLOMBIA <Northeast: north base of Santa Marta Mts.: La Tigrera below Minca; east of Santa Marta; Catatumbo lowlands: Cucutá, VENEZUELA <west Zulia; coastal. cordillera. In Aragua. Distrito Federal & Miranda; probably also Carabobo & interior cordillera; locally from west Apure: San Camilo. Hato Cedral. El Frio; south Cojedes: Hato Piñero; east to west Sucre: Embalse de Turumiquire; northeast Bolívar: Upata. and parvulus of PERU humid lowlands east of Andes, BOLIVIA Non-Amazonian lowlands & Valle zone in Beni Santa Cruz. Chuquisaca. Tarija (lfR+), BRAZIL<South of Amazon: Amazonas east to Pará &. Maranhão; Goiás Piauí & Bahia south through São Paulo Mato Grosso to Rio Grande do Sul>, PARAGUAY <Alto Chaco; elsewhere{uR+}>(lcR+uR+), URUGUAY(uR+), ARGENTINA <North Catamarca southeast through Córdoba to north Buenos Aires>(luR+)

argues against conspecificity.

RECOMMENDATION: Caprimulgus heterurus (Todd 1915) Santa Marta Nightjar should be recognised as a species distinct from Caprimulgus parvulus Gould 1837 Little Nightjar.

REFERENCES:

Cleere, N. (1999) CAPRIMULGIDAE(Nightjars),in del Hoyo, Elliott & Sargatal (eds.), Handbook of the Birds of the World, 5, Lynx Edicions, Barcelona.

Cory, C. B. (1918) Catalogue of Birds of the Americas, pt.2, no.1..

Davis, L. I. (1978). "Acoustic evidence of relationship in Caprimulginae". Pan American Studies 1: 22-57

Hilty, S L.(2003) Birds of Venezuela, Christopher Helm, London.

Peters, J.L. (1940) Checklist of Birds of the World, 4, Harvard University Press, Cambridge, Mass.

John Penhallurick, March 2005

Addendum from Nigel Cleere:

"The person responsible for 'lumping' heterurus with parvulus was P. Schwartz 1968, Condor 70, pp. 223 - 227. In my opinion, he seemed to ignore the differences in plumage and vocalisations, which today are increasingly being used to recognise Caprimulgid species.

“I am currently preparing a new, annotated checklist of the Caprimulgidae and C. heterurus is certainly a taxon that I will suggest is valid.

Addendum from Remsen: I just checked Schwartz's paper (which you can get at http://elibrary.unm.edu/sora/Condor/files/issues/v070n03/p0223-p0227.pdf). Because Schwartz was a leader in redefining species limits of Neotropical birds based on voice, I was puzzled by the comments above. It turns out that Schwartz had recordings of heterurus but evidently not of nominate parvulus, which does not occur in Venezuela. He wrote under his justification of re-elevating parvulus to species rank: "There is no doubt that the more important of the two factors is the voice. Unfortunately, we know nothing of the voice of C. anthonyi [which Peters had lumped with parvulus]. For those who may be interested, the songs of both C. parvulus heterurus and C. cayennensis cayennensis have been published in a recording: 'Bird Songs of the Tropics," Naturaleza Venezolana No. 1, Instituto Neotropical.)" Under his discussion of heterurus, the only form in Venezuela, there is no mention of voice, although he knew the bird from many places in Venezuela. So, this implies to me that he assumed that heterurus, which in his assessment of the degree of morphological differences from nominate parvulus warranted only subspecies rank (in contrast to anthonyi), sounded like the nominate bird.

“It should also be added that heterurus is not a Santa Marta endemic, but rather is found from N Colombia east across N and C Venezuela. I have also asked Nigel Cleere for comments on English names. As noted above, his forthcoming list splits heterurus -- confirmed by email from him of 3/14/05: "I believe that Proposal 169 is a good split and I had recently told John that I will also treat C. heterurus as a valid species in a new Caprimulgidae checklist that I am currently preparing."

Comments from Nores: "YES, aunque todavía no está muy claro el tema de las vocalizaciones. C. parvulus a esta latitud emite un canto muy sonoro que en español suena como "choglí-glo glo glo glo" y en inglés sería "choglee-glau glau glau glau", que no parece coincidir con la descripción que hace Cleere y cita Penhallurick."

Comments from Stotz: "YES. Note on this, that I tape recorded heterurus in Roraima, Brazil, so its range is even wider than just the Santa Marta region. I really think we need to think about a better name, since 'Santa Marta xxx' I think otherwise is used for species restricted to the Santa Martas. I don't have a good idea."

Comments from Stiles: "NO. This is an interesting case.. appears to be a perfect example of the necessary data existing but not being published. To my mind, the vocal descriptions given could be used as evidence either way, given the differences in orthography and pronunciation by speakers of different languages - at least, saying the transliterations of a given song in Spanish vs. English produces different sounds to my ear! When the sonograms are published with a decent analysis (as well as more detailed info on morphology), I will almost surely vote YES but until then, just showing sonograms to the committee doesn´t cut it.. so, NO for now. Get on the stick, John!!"

Comments from Zimmer: "YES. Gary's point is well-taken, but I would argue that what should make this case (and many others) an exception to the "publish first" rule is that the current status quo is based on a Peters lump that in itself was not based on any published analysis or rationale. Would I like to see a peer-reviewed analysis before splitting? Absolutely. But to require such a published analysis is to give greater substance to Peters' many unjustified lumps. It is a pet peeve of mine that some editors and reviewers, themselves unfamiliar with the birds in question, demand the most rigorous of quantified analyses before signing off on a paper splitting two taxa into separate species, when the same taxa, described as separate species, were lumped without justification or comment by Peters. When the status quo is achieved through a reversal of the original status without analysis or even comment, I would argue that almost any evidence (published or not) that favors a return to the original treatment should carry more weight. In this case, I think the vocal differences are clear and are likely more important to the question of reproductive isolation (or lack thereof) than any lack of plumage distinctions. The burden of proof should be on those that would change the original status of heterurus and parvulus."

Comments from Robbins: "[NO]. Although I have no doubt that heterurus should be recognized as separate species from parvulus, I would like to hear a recording of the former before voting (I note that our web site still does not have the .wav file available; as I evaluate this record on 3 July 2005). Until that information is available I vote "no".

Comments from Pacheco: "YES. Eu me alinho ao posicionamento de Zimmer, neste caso e possivelmente em vários outros. O táxon heterurus foi arbitrariamente reunido com parvulus sem justificativas. Se atualmente há evidências (eu considero sobretudo os dados de Stotz obtidos em Roraima) de que ambos sejam espécies plenas, o desmembramento deve ser a "medida automática". Na minha opinião, a [re] subordinação de heterurus = a parvulus é que deveria ser prioritariamente antecedida por uma análise publicada."

Comments from Jaramillo: "YES - I agree with most of what Kevin mentions on this record, and records like it. However, I am going a bit on faith here and I am not comfortable with that. Can the .wav file be e-mailed directly to us, so we can hear it? I know parvulus from the south quite well, so hearing heterurus will be interesting."

Additional comments from Stiles: "With respect to the Caprimulgus heterurus question and Kevin's comments, I think that we should arrive at a clearer consensus. Kevin points out that C. parvulus and heterurus should be considered distinct species on the basis of voice and morphology, and that the split overturns one of the many unjustified Peters lumpings. While I agree on both points, the fact remains that the critical evidence has not been published in a peer-reviewed journal. The fact remains that Peters has been the standard for a couple of generations now and that many lists worldwide, including those of Meyer de Schauensee for the Neotropics, have followed Peters. When I joined SACC, I understood that changes to this standard should not be adopted without explicit published evidence, and I have voted (hopefully consistently) in this sense thereafter - often against my own better taxonomic judgment. It seems worth noting that Peters was not totally arbitrary, but was following the biogeographic species concept of Hellmayr and others, including Zimmer, which was in vogue in the early twentieth century (a reaction to the excessive splitting of Sharpe and others earlier). With better knowledge of the birds in the field than was available to Peters, it is now evident that many of his judgments in this sense were wrong - but the evidence against has not been published in detail, except for passing references and such in field guides and family books a la Helm. Certainly we have much better information today than was available to Peters et al., but if it is unpublished, hence unreviewed, we could be accused of using Petersian arbitrariness - against Peters.  So the question is this: do we or don´t we insist on full publication of the evidence before endorsing a split in such cases, or should we follow our own best judgments (or those of the committee with personal experience of the birds in question)?

"This brings up a further question: how much evidence is required? Are genetic studies, such as those of John Penhallurick, based upon a single-gene analysis, adequate? Or do we require two or more independent studies (or at least, two or more genes to be sequenced?) In such cases the evidence looks good, as far as it goes, but is independent confirmation required - especially as genetic distances are often not an infallible guide (especially at the species level) and deep divisions are not always reliably diagnosed by a fast-evolving gene like cytochrome b?"

New Comments from Robbins: "I just received a wav. file of Caprimulgus [parvulus] heterurus. After hearing that taxon for the first time (it is quite distinct from the nominate form), I change my vote to a "yes" for recognizing it as a species."

Comments from Remsen: "NO. Although I have little doubt that heterurus merits species rank, I do think that we should adhere to rigorous standards and require, minimally, some published comparative sonograms."

More comments from Robbins: "A good question posed by Gary is if we are willing to accept unpublished data for making decisions. Although in general I agree that we should wait (especially involving issues such as generic & familial relationships) until results are published. However, in the case of Caprimulgus heterurus and other caprimulgids, we all recognize voice is the key clue for species' limits. Thus, the decision is generally straightforward. In this case, the voice of both nominate parvulus and heterurus are published on at least the revised "Voices of the New World Nightjars & Allies" (Hardy et al., 1989). I realize that some may consider that "gray" literature, but as Kevin and I demonstrated in our documentation of the voice of dimidiata being extremely similar to other Syndactyla, citing voice-based publications is invaluable for understating authors' rationale for proposed changes."