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.
Sao Tome White-eye Zosterops ficedulinus is being split into Z. ficedulinus and Z. feae, following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, Z. ficedulinus was listed as Vulnerable under criterion D1, on the basis that it was thought to have a small population, given the small area of suitable habitat in its range (BirdLife International 2016). Z. ficedulinus (as now defined following the taxonomic change) is found only on the island of Príncipe, where it is a rare resident of hillly forest in the interior of the island (Borrow and Demey 2014). Z. feae is endemic to the island of São Tomé, occurring in a range of forest habitats, including primary, secondary and plantations, as well other more open habitats (Borrow and Demey 2014). While both species underwent large declines in the last century, this has apparently ceased and the pre-split species was regarded as having a stable population (BirdLife International 2016).
The pre-split species was estimated to fall in the range of 250-999 mature individuals. Therefore, both of the newly split species are going to have populations of <1,000 mature individuals, and so qualify as Vulnerable under criterion D1. Given that the pre-split species was more abundant on São Tomé, it is likely that Z. feae will have a larger population size than Z. ficedulinus. Therefore, it is suspected that the population size of Z. feae will be in the range of 250-999 mature individuals and so it would warrant listing as Vulnerable under criterion D1. We request further information regarding whether the population size of the newly re-defined Z. ficedulinus falls above or below 250 mature individuals to see whether it qualifies as either Vulnerable or Endangered under criterion D, but in the absence of any further information we would tentatively propose that the species be listed as Vulnerable.
BirdLife International 2016. Species factsheet: Zosterops ficedulinus. Downloaded from http://www.birdlife.org on 22/09/2016.
Borrow, N. and Demey, R. 2014. Birds of Western Africa. Second Edition. Christopher Helm, 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.