Proposal (609) to South
American Classification Committee
Split Oxypogon into four species
Summary of morphological
differences
Collar & Salaman (2013) have recently proposed a re-evaluation of
species limits in the high elevation hummingbird genus Oxypogon, based largely on plumage differences and morphometrics.
Per their abstract: "Four distinct populations of Bearded
Helmetcrest Oxypogon guerinii (cyanolaemus in the Sierra Nevada de
Santa Marta, lindenii in the
Venezuelan Andes, guerinii in the
East Andes of Colombia, and stubelii
in the Central Andes of Colombia) were lumped without justification in the
1940s but are highly distinct in multiple plumage and morphometric characters.
Species rank is suggested for all four taxa, following species scoring
tests. We draw special attention to O. cyanolaemus
of the Sierra Nevada de Santa Marta, which has not been reported since
1946. It is recommended for the IUCN
criteria of Critically Endangered, although it may possibly already be extinct."
Discussion
I would urge committee members to look at any specimens available to
them and the plates in Collar & Salaman (2013) to understand further how
"off the scale" these birds are in their plumage differences for
current conspecifics. Sympatric or
parapatric forms in other genera, such as Phaethornis,
Eutoxeres, Colibri, Chalcostigma, Aglaiocercus, Lesbia, Heliangelus,
Chaetocercus, Chlorostilbon, Eriocnemis and Heliodoxa show lower morphological differentiation than these Oxypogon. The proposed split therefore adopts a
consistent treatment to those for other high elevation hummingbirds.
Vocal support
Collar & Salaman (2013)'s treatment is also supported by consistent
vocal differences between those populations for which sound recordings are
available, as set out and illustrated in their paper (although, as they note,
because voice is learned in hummingbirds, this may not be so significant). The Santa Marta form has gone unrecorded
since the 1940s despite searches, rendering vocal analysis incomplete. It would not seem appropriate to reject this
split on the basis of a lack of recordings of this population, which is perhaps
the most morphologically distinctive of them all.
Vernacular names
Collar & Salaman (2013) proposed recognising the following species
with the following English names:
• Blue-bearded
Helmetcrest Oxypogon cyanolaemus,
• White-bearded
Helmetcrest O. lindeni,
• Green-bearded
Helmetcrest O. guerinii and
• Buffy Helmetcrest O. stubelii.
These English names are certainly more interesting than Cory's names
(Blue-throated, Linden’s and Guerin’s and Stübel’s respectively). I would propose that if this proposal passes,
this should result in Collar & Salaman’s (2013) names being adopted. If there is support for using any of the
older names (or different names) and this proposal is accepted, then a separate
proposal can be produced on English names.
Reference
Collar, N.J. & Salaman, P. 2013. The taxonomic and conservation status of the Oxypogon helmetcrests. Conservación Colombiana 19: 31-38.
The paper can be accessed from this link:
http://www.proaves.org/birds-of-colombia-2013/?lang=en
Thomas Donegan,
December 2013
Comments
from Remsen: “YES, but
with reservations. I worry that voting
yes might imply an endorsement of the Tobias et al. scoring system, which has
not been adopted by anyone outside BirdLife International and HBW and has
generally been ignored by the scientific community. Nonetheless, Collar, Salaman, and Donegan have
good points on plumage – the differences among these taxa are typically
associated with species-level differences in almost every hummingbird genus. In a comparative approach based strictly on
plumage differences, I can’t think of any other genus in which males differ to
this degree yet are ranked as subspecies.
Peters lumped these four species without even a phrase of supporting
rationale, so I think burden-of-proof ought to be on a 1-species classification.”
Comments from Stiles: “YES, for reasons
expressed by Van, and the fact that all forms of Oxypogon are mountaintop birds that have probably been isolated for
a considerable time, and what with climate change in the offing, are likely to
remain so. No evidence of hybridization is evident, important in that we now
know that these forms do move about considerably in their respective ranges
following asynchronous blooming of Espeletia
species in particular.”
Comments from Pacheco “YES. Ainda
que igualmente considerando as ressalvas do Van, eu sou partidário de que o
tratamento em quatro táxons ao nível de espécie possui razoável suporte em
contraponto à adoção arbitrária de espécie politípica instituída por Peters.”
Comments from Nores: “NO. It seems to me, from their color
and distribution, that they are subspecies. Such particular color and crest and
shaggy patterns, with only subtle differences among the taxa, do not seem to be
consistent with species rank.”
Comments
from Zimmer: “YES. Using the yardstick provided by virtually
every other genus of hummingbird, the plumage distinctions noted are consistent
with species-level recognition. The fact
that they were described as distinct species and lumped without evidence by
Peters does, as Van notes, place the burden of proof on those who would favor
the current one-species treatment.”
Comments from Robbins: “YES. I agree that
the morphological differences among these taxa are as great or greater than
among recognized species in other hummingbird genera. So, to be consistent, I support recognition
of the four Oxypogon taxa as species.”