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."
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.
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.
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.
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:
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 ą adoćčo 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.”