Archived 2016 topics: Capped White-eye (Zosterops fuscicapilla) is being split: request for information for Z. crookshanki.

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.

Capped White-eye Zosterops fuscicapilla is being split into Z. fuscicapilla and Z. crookshanki, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, Z. fuscicapilla was listed as Least Concern, on the basis that it did not approach the threshold for Vulnerable under any criterion. Z. fuscicapilla (as now defined following the taxonomic change) is found in the mountains of west and central New Guinea in a range of habitats including primary forest, secondary growth, gardens and abandoned cultivation (van Balen 2016). It is common to scare throughout its range (van Balen 2016), and in the absence of any known declines or current significant threats to this species it is not thought to approach the threshold for Vulnerable under any criterion. Therefore, it is proposed that this species be listed as Least Concern.

Z. crookshanki was originally only thought to be found on Goodenough Island, south-west Papua New Guinea, but a population of this species has recently been found on neighbouring Fergusson Island too (Pratt and Beehler 2015). It is found in montane cloud forest, and has been described as ‘locally common’ (Pratt and Beehler 2015). However, it has been stated that prior to the discovery on Fergusson it was only known from 2 female specimens from Goodenough (Pratt and Beehler 2015), which would suggest that this species may not be that common. As of 2013, the resumption of logging in the East Fergusson Timber Rights Purchase was in its second of five years of logging (D. Mitchellin litt. 2013), but it is not known to what extent this and an expanding human population within the species’s range may be affecting Z. crookshanki. We request any further information regarding this species, particularly any information regarding potential population estimates and trends. In the absence of any potential further information it is thought that the species is unlikely to approach the threshold for Vulnerable, and so would warrant listing as Least Concern.

Comments are invited on these proposed categories and further information would be welcomed.


Pratt, T. K. and Beehler, B. M. 2015. Birds of New Guinea. 2nd Edition. Princeton University Press, Princeton, NJ, USA.

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.

van Balen, B. 2016. Capped White-eye (Zosterops fuscicapilla). 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 on 26 September 2016).

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1 Response to Archived 2016 topics: Capped White-eye (Zosterops fuscicapilla) is being split: request for information for Z. crookshanki.

  1. James Westrip (BirdLife) says:

    Based on available information, our preliminary proposal for the 2016 Red List would be to list:

    Z. fuscicapilla and Z. crookshanki as Least Concern.

    There is now a period for further comments until the final deadline of 28 October, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from the initial proposal.

    The final 2016 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

Comments are closed.