The initial deadline for comments on this topic is 10 March 2014, and is therefore later than for most other topics currently under discussion.
This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for non-passerines
Lynx Edicions and BirdLife International will soon publish 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 1 of the checklist (for non-passerines) will begin to be incorporated into the 2014 Red List update, with the remainder, and those for passerines (which will appear in volume 2 of the checklist), 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.
Tahiti Swiftlet Collocalia leucophaea and Marquesan Swiftlet C. ocista are being lumped as Aerodramus leucophaeus, following the application of criteria set out by Tobias et al. (2010).
Prior to the taxonomic change, C. leucophaea (BirdLife species factsheet), a resident of moist, forested, rocky valleys on Tahiti in French Polynesia (and probably only a vagrant to other islands) (Chantler and Driessens 2000), was listed as Vulnerable under criteria D1 and D2, on the basis that it has a tiny range, with the breeding population apparently restricted to one small island, where its very small population (fewer than 1,000 mature individuals) is thought to be stable.
This taxon was recorded in five valleys in 1971-1974 (Holyoak and Thibault 1984), and in six valleys (out of 39 visited) during the period 1986-1991 (Monnet et al. 1993). It was apparently never abundant in the 20th century (Holyoak and Thibault 1984); for example, in 1923 it was noted that two local hunters travelled for eight days through the valleys without seeing this species (Beck 1923). In 1997, a new breeding site, with c.30 nests, was found (P. Raust in litt. 1999, C. Blainvillain verbally 2000). A population of c.100 birds is monitored regularly in Papehue valley and appears to be stable (P. Raust in litt. 2007).
The rarity of this taxon is possibly linked to the introduction of the Common Myna Acridotheres tristis (Holyoak and Thibault 1984) (which is known to defend territories, tree hollows and other nesting sites from native birds), and Swamp Harrier Circus approximans (C. Blainvillain verbally 2000). Other introduced species may have a negative impact.
C. ocista (BirdLife species factsheet), a resident of forested areas on the Marquesas Islands in French Polynesia (Chantler and Driessens 2000), was listed as being of Least Concern, on the basis that it was not thought to approach the thresholds for Vulnerable under any of the IUCN Red List criteria. It is noted, however, that its population size has not been quantified, although it has been described as common (del Hoyo et al. 1999).
Following the taxonomic change, it is suggested that A. leucophaeus be listed as being of Least Concern, on the basis that it is not thought to approach the thresholds for Vulnerable under any of the IUCN Red List criteria.
Whilst the populations of the two lumped taxa are thought to be stable, any evidence of recent or future declines in their populations and habitats would likely warrant listing of the newly-defined species under a higher threat category.
Comments are invited and further information would be welcomed.
Beck, R. H. (1923) Ornithologie. Bull. Soc. Etud. Océan. Avril: 32-34.
Chantler, P. and Driessens, G. (2000) Swifts: a guide to the swifts and treeswifts of the world. Second Edition. Robertsbridge, U.K.: Pica Press.
del Hoyo, J., Elliott, A. and Sargatal, J. (1999) Handbook of the birds of the world, Vol 5: Barn-owls to Hummingbirds. Barcelona, Spain: Lynx Edicions.
Holyoak, D. T. and Thibault, J.-C. (1984) Contribution à l’étude des oiseaux de Polynésie orientale. Mem. Mus. Natl. Hist. Nat. Ser. A, Zool. 127: 1–209.
Monnet, C., Thibault, J. and Varney, A. (1993) Stability and changes during the twentieth century in the breeding landbirds of Tahiti (Polynesia). Bird Conserv. Int. 3: 261–280.
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.