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.
Bar-bellied Cuckooshrike C. striata is being split into C. striata, C. panayensis and C. dobsoni following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, C. striata (BirdLife species factsheet) was listed as Least Concern, on the basis that it did not approach any of the thresholds for listing as Vulnerable. The abundance of the pre-split species varied across the range, considered rare to locally common in S Thailand and Peninsular Malaysia, is extinct on Singapore and likely scarce on Sumatra (Taylor 2016). While this suggests that the species is declining, the levels of decline for this species and C. panayensis are not considered sufficient to approach listing under criterion A.
Coracina dobsoni is found in the southern Andaman Islands, at least being present on South Andaman (Rasmussen & Anderton 2012). It is described as being an uncommon forest bird which keeps largely to tall trees (Rasmussen and Anderton 2012). The extent of occurrence has been calculated as 10,140km2, however only a small percentage of this area is suitable for the species, and a population estimate based upon density estimates of congeners places the population in a band of 10,000-19,999 individuals, which equates to 6,667-13,333 mature individuals, rounded here to 6,000-15,000 individuals. Threats for the species are presumed to be the same as for other Andaman endemics, namely habitat degradation and hunting, which would suggest that the species could be suffering an ongoing decline.
The species is proposed as Near Threatened on the basis that it approaches the thresholds for listing as Vulnerable under criterion C2a(ii), assuming that there is only one subpopulation.
Should it be considered that there are multiple subpopulations within the species then it would no longer approach the threshold for listing under the small population criterion, unless there was evidence that there were fewer than 1,000 mature individuals in each subpopulation.
Further information is sought in order to inform the accuracy of the population estimate and trend, whether there are likely to be multiple subpopulations or whether the number of locations* is likely to be fewer than 11.
*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).
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.
Rasmussen, P. C. and Anderton, J. C. 2012. Birds of South Asia. The Ripley Guide. Vols. 1 2: Attributes and Status. Second Edition. National Museum of Natural History – Smithsonian Institution, Michigan State University and Lynx Edicions, Washington, D.C., Michigan and Barcelona.
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.