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.
Asian Fairy-bluebird Irena puella is being split into I. puella and I. tweeddalii, following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, I. puella (BirdLife species factsheet) was listed as Least Concern, on the basis that it did not approach the threshold for any criteria to be listed as Vulnerable. I. puella (as defined now following the taxonomic change) is widespread through large areas of south east Asia and the Indian subcontinent. No population estimate is available, but pre-split it was described as common throughout its range, and only locally uncommon or rare (del Hoyo et al. 2005). It is suspected to be declining due to hunting pressure, trapping for the cage bird trade and habitat destruction but the rate of decline across the very large range are not thought to be sufficient to warrant listing in a threatened category. Therefore it is proposed that this species be listed as Least Concern.
I. tweeddalii is found on Palawan, the Calamians and Balabac in western Philippines, in lowland broadleaf evergreen to semi-evergreen forest (Wells 2016). Hunting, and large habitat losses mean this species is suspected to have undergone a significant decline over the past three generations (Wells 2016) and this is likely to continue. The rate of decline has not, however, been quantified. If evidence exists to suggest declines are in the region of ≥30% over three generations this species would qualify as Vulnerable under criteria A2cd+A3cd+A4cd.
In the absence of further information, however, it is proposed that this species be listed as Near Threatened under criterion A2cd+A3cd+A4cd, because it is suspected to be experiencing at least a moderate to rapid decline in line with habitat loss.
Comments are invited on these proposed categories and further information would be welcomed.
del Hoyo, J., Elliott, A., and Christie, D. (2005) Handbook of the Birds of the World, vol. 10: Cuckoo-shrikes to Thrushes. Lynx Edicions, Barcelona, Spain.
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.
Wells, D. (2016). Asian Fairy-bluebird (Irena puella). 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/60466 on 26 August 2016).