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.
Blue-headed Fantail Rhipidura cyaniceps is being split into R. cyaniceps, R. sauli and R. albiventris, following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, Rhipidura cyaniceps (BirdLife species factsheet) was listed as Least Concern as it was not considered to approach any of the thresholds for listing as Vulnerable under any of the criteria. The pre-split species was characterised as common in most of its range and inhabited a wide range of wooded habitats from sea level to 2,400m (Boles 2016).
R. cyaniceps (as defined following the taxonomic change) is found on Luzon and Catanduanes, R. sauli is restricted to the island of Tablas, and R. albiventris is found on Ticao, Masbate, Panay, Guimaras and Negros.
Both the new nominate R. cyaniceps and R. albiventris are suggested to be listed as Least Concern, as following the changes they still do not appear to approach the thresholds for listing as Vulnerable under any of the criteria.
Tablas Fantail R. sauli has a newly calculated extent of occurrence of only 950km2. If the species occurs at roughly similar densities to those recorded for R. albiventris on Negros Island (115-220 inds/km2 [Evans et al. 1993]) then the population is estimated at 20,000-49,999 individuals. On the island of Tablas roughly 4% of tree cover appears to have been lost within the last 15 years (Hansen et al. 2013), from which a minor, slow ongoing population decline in the species is inferred.
Consequently R. sauli is suggested to be listed as Least Concern, as although the species has a restricted range it is not considered severely fragmented or to occur at a limited number of locations*, there is not believed to have been or to be a significant population reduction, and the population is considered likely to be relatively large. If there is evidence that this species occurs at much lower densities than were recorded for R. albiventris on Negros then the species may be Near Threatened, as it may approach the thresholds for listing as Vulnerable under criterion C2a(ii).
Comments are invited on these proposed categories and further information would be welcomed.
*Note that the term ‘location’ defines a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the taxon present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat (IUCN 2001, 2012).
Boles, W. (2016). Blue-headed Fantail (Rhipidura cyaniceps). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/59142 on 6 October 2016).
Evans, T. D., Dutson, G. C. L. & Brooks, T. M. eds. 1993 Cambridge Philippines Rainforest Project 1991 Final Report. ICBP Study Report No. 54. Cambridge: BirdLife International
Hansen, M. C., P. V. Potapov, R. Moore, M. Hancher, S. A. Turubanova, A. Tyukavina, D. Thau, S. V. Stehman, S. J. Goetz, T. R. Loveland, A. Kommareddy, A. Egorov, L. Chini, C. O. Justice, and J. R. G. Townshend. 2013. High-Resolution Global Maps of 21st-Century Forest Cover Change. Science 342: 850–53. Data available on-line from:http://earthenginepartners.appspot.com/science-2013-global-forest. Accessed through Global Forest Watch on 6th October 2016. www.globalforestwatch.org
IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. Gland, Switzerland and Cambridge, UK: IUCN Species Survival Commission.
IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN.
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.