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-and-red Broadbill Cymbirhynchus macrorhynchos is being split into Cymbirhynchus macrorhynchos and Cymbirhynchus affinis, following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, Cymbirhynchus macrorhynchos (BirdLife species factsheet) was listed as Least Concern on the basis that the species had an extremely large range and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The pre-split species was characterised as a species of lowland forest near rivers and streams, including disturbed habitats such as logged forest and remnant patches in pastureland and does occur in plantations near water (Bruce 2016).
Cymbirhynchus affinis is restricted to SW Myanmar (del Hoyo and Collar in prep.). There remains a large extent of forest within the species apparent range in the Arakan Mountains, Myanmar, and the species range is considered to exceed the thresholds for listing under geographic range criteria, with the newly calculated EOO for the species being 135,000 km2. In addition, although Myanmar has the third highest global rate of deforestation overall, the rate of forest loss detectable from Landsat data for 2000-2014 within the presumed range of the species has been 2% (data from Hansen et al. 2013).
However, there appears to be very little recent information on this taxon, and there remains the possibility that the species does not have the same tolerance or occur in the same abundance as the more widely distributed C. macrorhynchos.
Is there any recent information suggesting the extent of the distribution of the species in the Arakan Mountains? And any indication of the likely abundance within that range? Have there been any recent surveys in Rakhine?
It is proposed that the species is listed as Least Concern, on the basis that it is not believed to approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation), nor under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure).
Comments are invited on these proposed categories and further information would be welcomed.
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 (15 November): 850–53. Data available from: earthenginepartners.appspot.com/science-2013-global-forest.
IUCN (2001) IUCN Red List Categories and Criteria: Version 3.1. Gland, Switzerland and Cambridge, UK: IUCN Species Survival Commission.
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.