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.
Cinnamon-bellied Imperial-pigeon Ducula basilica is being split into D. basilica and D. obiensis, following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, D. basilica (BirdLife species factsheet) was listed as Least Concern on the basis that it was not thought to approach the thresholds for Vulnerable under any of the IUCN criteria. Although this species was estimated to have a restricted range, it was not believed to approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence [EOO] of less than 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 population trend appeared to be stable, and hence the species did not approach the thresholds for Vulnerable under the population trend criterion (at least a 30% decline over ten years or three generations). The population size has not been quantified, but it was not believed to approach the thresholds for Vulnerable under the population size criterion (fewer than 10,000 mature individuals with a continuing decline estimated to be at least 10% over ten years or three generations, or with a specified population structure).
D. obiensis is endemic to Obi Island, where it inhabits primary, secondary and degraded forest, and may occur in cultivated areas (Gibbs et al. 2001). It could qualify as Near Threatened under criterion B1ab(ii,iii,v), if its habitats are considered to be very fragmented (approaching 50% in patches too small to support viable populations), as it occupies a very small range (with an EOO estimated at c.2,500 km2), in which habitat quality is in decline, and a decline in the population is inferred on the basis of this and potential levels of hunting pressure.
D. basilica (as defined following the taxonomic change) is found on the North Moluccan islands of Morotaio, Halmahera, Kasiruta, Ternate and Bacan, where it inhabits dense forest, including selectively logged, degraded and secondary forest, forest edge, and only rarely occurs in agricultural areas (Gibbs et al. 2001). It is likely to warrant listing as Least Concern, on the basis that it is not thought to approach the thresholds for Vulnerable under any of the IUCN criteria.
Comments are invited on these suggested categories and further information would be welcomed.
Gibbs, D., Barnes, E. and Cox, J. (2001) Pigeons and doves: a guide to the pigeons and doves of the world. Robertsbridge, U.K.: Pica Press.
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.