Archived 2016 topics: Vermilion Flycatcher (Pyrocephalus rubinus) is being split: list P. rubinus as least concern, P. dubius as Critically Endangered (Possibly Extinct) or Extinct and P. nanus as Vulnerable or Endangered?

This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for passerines

Lynx Edicions and BirdLife International will soon publish the second volume of the HBW-BirdLife Illustrated Checklist of the Birds of the World, building off the Handbook of the Birds of the World series, and BirdLife’s annually updated taxonomic checklist.

The new Checklist will be based on the application of criteria for recognising species limits described by Tobias et al. (2010). Full details of the specific scores and the basis of these for each new taxonomic revision will be provided in the Checklist.

Following publication, an open and transparent mechanism will be established to allow people to comment on the taxonomic revisions or suggest new ones, and provide new information of relevance in order to inform regular updates. We are also actively seeking input via a discussion topic here regarding some potential taxonomic revisions that currently lack sufficient information.

The new Checklist will form the taxonomic basis of BirdLife’s assessments of the status of the world’s birds for the IUCN Red List. The taxonomic changes that will appear in volume 2 of the checklist (for passerines) will begin to be incorporated into the 2016 Red List update, with the remainder to be incorporated into subsequent Red List updates.

Preliminary Red List assessments have been carried out for the newly split or lumped taxa. We are now requesting comments and feedback on these preliminary assessments.

Vermilion Flycatcher Pyrocephalus rubinus is being split into P. rubinus, P. dubius and P. nanus, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, P. rubinus was listed as Least Concern on the basis that it did not approach the threshold for Vulnerable under any criteria. P. rubinus (as now defined following the taxonomic change) is found through much of the neotropics, from southern U.S.A. to Argentina. The pre-split population was numbered in the range of 5,000,000-50,000,000 individuals (A. Panjabi in litt. 2008), and it is highly likely that the split will not have significantly affected this estimate. Any declines that may be occurring in this species is not thought severe enough to warrant listing as Vulnerable, and so it is proposed that this species be listed as Least Concern.

P. dubius was last seen in 1987 (Vargas 1996). It was endemic to the island of San Cristóbal in the Galápagos islands, and despite the pre-split species being previously ‘fairly common’ on San Cristóbal at the start of the 1900s (Snodgrass and Heller 1904) the species has been considered extirpated from the island for some time (Wiedenfeld 2006, Merlen 2013). If it is confirmed as extinct this would represent the first recorded extinction of a Galápagos endemic bird species (Carmi et al. 2016). The cause of the decline of the species is not known, and appears to be unrelated to the presence of introduced predators (Wiedenfeld 2006). It is likely that this species is now Extinct, but we welcome any comments as to whether this species may persist anywhere, to decide whether this species be formally listed as Extinct or whether it be listed as Critically Endangered (Possibly Extinct).

P. nanus was originally found throughout the Galápagos Islands, apart from San Cristóbal. However, there have been reported declines, with the taxon possibly extinct on Floreana and Santa Fe (see Wiedenfeld 2006, Merlen 2013, Carni et al. 2016) and in serious decline on Santa Cruz (Wiedenfeld 2006, Merlen 2013). The cause of the decline, however, is not understood. It may be related to parasites, disease, changes in land use or the application of pesticides (Wiedenfeld 2006, Merlen 2013), but may not be a results of introduced predators such as rats and cats because it has disappeared from islands without introduced predators and persists on other islands where these predators have been introduced (Wiedenfeld 2006). As this species may now be relatively rare across many islands (e.g. the population on Santa Cruz may not number more than 36 individuals [Wiedenfeld 2006]) it is unlikely that the global population numbers more than 10,000 mature individuals, and possibly no more than 2,500 mature individuals. It is therefore proposed that this species be listed as Vulnerable under criterion C2a(i), but with further information about population sizes on each island where it is found it may qualify as Endangered.

Comments are invited on these proposed categories and further information would be welcomed, particularly regarding the potential extinction of P. dubius.

References:

Carmi, O., Witt, C.C., Jaramillo, A. and Dumbacher, J.P. 2016. Phylogeography of the Vermilion Flycatcher species complex: multiple speciation events, shifts in migratory behavior, and an apparent extinction of a Galápagos-endemic bird species. Mol. Phyl. & Evol. 102: 152–173.

Merlen, G. 2013. Gone, gone…Going: The fate of vermilion flycatchers on Darwin’s Islands. Pp. 180-188. In: Galapagos Report 2011-2012. GNPS, GCREG, CDF and GC. Puerto Ayora, Galapagos, Ecuador.

Snodgrass, R. E. and Heller, E. 1904. Papers from the Hopkins-Stanford Galapagos Expedition, 1898 – 1899, XVI, birds. Proceedings of the Washington Academy of Sciences 5: 231-372.

Tobias, J. A., Seddon, N., Spottiswoode, C. N., Pilgrim, J. D., Fishpool, L. D. C. and Collar, N. J. 2010. Quantitative criteria for species delimitation. Ibis 152: 724–746.

Vargas, H. 1996. What is happening with the avifauna of San Cristóbal? Noticias de Galápagos 57: 23–24.

Wiedenfeld, D.A. 2006. Aves, The Galapagos Islands, Ecuador. Check List 2(2): 1–27.

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One Response to Archived 2016 topics: Vermilion Flycatcher (Pyrocephalus rubinus) is being split: list P. rubinus as least concern, P. dubius as Critically Endangered (Possibly Extinct) or Extinct and P. nanus as Vulnerable or Endangered?

  1. James Westrip (BirdLife) says:

    Based on available information, our preliminary proposal for the 2016 Red List would be to list:

    P. rubinus as Least Concern.

    P. nanus as Vulnerable under criterion C2a(i).

    P. dubius as Extinct.

    There is now a period for further comments until the final deadline of 28 October, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from the initial proposal.

    The final 2016 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

Comments are closed.