Archived 2016 topics: White-throated Greenbul (Phyllastrephus albigularis) is being split: list P. albigularis as Least Concern and P. viridiceps as Near Threatened?

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-throated Greenbul Phyllastrephus albigularis is being split into P. albigularis and P. viridiceps, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, P. albigularis was listed as Least Concern on the basis that it did not approach the threshold for Vulnerable under any criterion. P. albigularis (as now defined following the taxonomic change) is found across west and central Africa, from south-west Senegal and Sierra Leone east to north-west, west and central Uganda. It inhabits primary and secondary forest, and favours edge habitats (Fishpool and Tobias 2016). In the absence of any known declines or substantial threats to this species, it is unlikely to approach the threshold for Vulnerable under any criterion. Therefore, it is proposed that this species be listed as Least Concern.

P. viridiceps is found in north-west Angola from Cuanza Norte and Cuanza Sul. It is described as common and is associated with dense undergrowth in forest, and at the edge of clearings (Dean 2000). It is likely threatened by habitat loss due to subsistence agriculture. In some areas, 20-70% of canopy trees and all the undergrowth in valley bottoms is being cleared to plant bananas and sweet potatoes (Dean 2001). In other areas, up to 95% of the forest canopy is being removed to plant cassava and maize (Dean 2001). It is unclear to what extent such habitat loss is occurring throughout the entirety of this species’s range, and the species does utilise edge habitats (e.g. Dean 2000). Therefore, population declines may not be as severe as these habitat loss figures suggest. However, loss of habitat is still suspected to be causing a moderate decline in the population size of this species, and with the end of the civil war commercial farming may resume in some areas of Angola (Sinclair et al. 2004). This may then increase deforestation even further, and so it is proposed that this species be listed as Near Threatened under criteria A2c+3c+4c.

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

References:

Dean, W.R.J. 2000. The birds of Angola. British Ornithologists’ Union, Tring, UK.

Dean, W. R. J. 2001. Angola. In: Fishpool, L.D.C.; Evans, M.I. (ed.), Important Bird Areas in Africa and associated islands: Priority sites for conservation, pp. 71-91. Pisces Publications and BirdLife International (BirdLife International Conservation Series No.11), Newbury and Cambridge, UK.

Fishpool, L. & Tobias, J. 2016. White-throated Greenbul (Phyllastrephus albigularis). 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/57999 on 21 September 2016).

Sinclair, I., Spottiswoode, C., Cohen, C., Mills, M., Cassidy, R., vaz Pinto, P. and Ryan, P. 2004. Birding western Angola. Bulletin of the African Bird Club 11(2): 152-160.

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.

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2 Responses to Archived 2016 topics: White-throated Greenbul (Phyllastrephus albigularis) is being split: list P. albigularis as Least Concern and P. viridiceps as Near Threatened?

  1. Michael Mills says:

    I travelled through various parts of its range in Angola last month. Since my last visit to the northern escarpment (2014), broad-scale logging is diminishing most of the northern scarp. After logging, subsistence farmers are moving in and slashing and burning secondary growth. This is not yet quantified, but this taxon is neither common nor widespread. I have only found it at three locations, and seen it on three occasions. The slump in oil prices means that Angola is “diversifying” its economy into timber extraction in a big way. Based on a comparison to Braun’s Bushshrike, currently listed as Endangered, I would say it is rarer and less widespread. I suspect that Brauns’ Bushshrike should be down-listed to Vulnerable (finding it at more and more localities, in quite degraded habitat). But this means that viridiceps should be at least Vulnerable.

  2. James Westrip (BirdLife) says:

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

    P. albigularis as Least Concern.

    P. viridiceps as Vulnerable under criterion C2a(ii).

    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.

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