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."