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.
Black-crested Bulbul (Pycnonotus melanicterus) is being split into P. melanicterus, P. gularis, P. flaviventris, P. dispar and P. montis, following the application of criteria set out by Tobias et al. (2010).
Prior to the taxonomic change Pycnonotus melanicterus (BirdLife species factsheet) was listed as Least Concern, on the basis that it was not believed to approach any of the thresholds for listing as Vulnerable under any of the criteria. The pre-split species had a very large range extending from Sri Lanka, the Western Ghats and east India, throughout the Himalaya, through Indochina, Peninsular Malaysia, Borneo and the Greater Sundas.
Following the taxonomic changes, Pycnonotus dispar is restricted to Sumatra, Java and Bali, and has been described as fairly common to common but rare in Bali (Fishpool and Tobias 2016). Considered to prefer disturbed habitats and previously considered common throughout much of Java and Sumatra, trapping pressure on the species continues to be high and the species was classified as ‘Severely Declining’ during an expert review process in 2014 (Harris et al. 2015). Additionally the trade price of the species is increasing while the trade volume has been decreasing, a pattern indicative of unsustainable exploitation (Harris et al. 2015).
While there is no quantification of the rate of decline, it is suspected that the species is likely to be declining at a moderately rapid rate (approaching 30% in nine years/three generations), sufficient to approach the thresholds of Vulnerable under criterion A2d+A3d+A4d. On this basis, it is proposed that the species should be listed as Near Threatened, and effort to quantify declines in the field are required throughout the range.
It is proposed that P. melanicterus, P. gularis, P. flaviventris and P. montis all be listed as Least Concern on the basis that they do not approach any thresholds for threatened status.
Fishpool, L. & Tobias, J. (2016). Ruby-throated Bulbul (Pycnonotus dispar). 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/57929 on 31 August 2016).
Harris, J. B. C., Green, J. M. H., Prawiradilaga, D. M., Giam, X., Giyanto, Hikmatullah, D., Putra, C. A. & Wilcove, D. S. 2015. Using market data and expert opinion to identify overexploited species in the wild bird trade. Biol. Conserv. 187: 51–60.