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.
White-browed Crombec Sylvietta leucophrys is being split into S. leucophrys and S. chapini, following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, S. leucophrys was listed as Least Concern, on the basis that it did not approach the threshold for Vulnerable under any criterion. S. leucophrys (as now defined following the taxonomic change) is found in the highlands of eastern Democratic Republic of Congo, south-west and western Uganda, west and central Kenya and western Rwanda, Burundi and Tanzania (Pearson 2016). It inhabits open areas and edges of montane forest and bamboo and it has been described as locally common (Pearson 2016). Given its large range and potentially reasonably large population, it is not thought to approach the threshold for Vulnerable under any criterion and so it is proposed that it be listed as Least Concern.
S. chapini is known only from montane vegetation on the Lendu Plateau in Democratic Republic of Congo (Pearson 2016). It is very rare and has even been suggested to be possibly extinct (Hume and Walters 2012). However, while much of the forest on Lendu has been cleared (N. Burgess in litt. 2003), unexplored forest where the species could occur exists within its known range and so the species likely persists (L. Fishpool in litt. 2011). The species is likely to be very rare (possibly <50 mature individuals), given the lack of reports, and in deed the suggestion that it could be extinct, and so we request any further information regarding this species to better understand its status, but in the absence of any further information or comments it may qualify as Critically Endangered or Critically Endangered (Possibly Extinct).
Pearson, D. 2016. White-browed Crombec (Sylvietta leucophrys). 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/58946 on 30 September 2016).
Hume, J.P. and Walters, M. 2012. Extinct Birds. T and AD Poyser, London.
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.