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.
Red-collared Myzomela Myzomela rosenbergii is being split into M. rosenbergii and M. longirostris, following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, M. rosenbergii was listed as Least Concern on the basis that it did not approach the threshold for Vulnerable under any criteria. M. rosenbergii (as now defined following the taxonomic change) is found in a variety of forest habitat, as well as shrubland and sometimes gardens on New Guinea from lower montane to high mountain elevations, usually from 1,200-3,700 m (Beehler and Pratt 2016, Higgins et al. 2016). It is common, and abundant in some areas (Higgins et al. 2016), and so in the absence of knowledge of any substantial threat or decline in this species it is proposed that it be listed as Least Concern.
M. longirostris is common and found in montane forest, but is restricted to Goodenough Island, off the south-east coast of New Guinea (Extent of Occurrence c.770 km2). While it is common, given its very small Extent of Occurrence, the population size is still unlikely to be very large. Assuming population densities are similar to that of congeners and that not all of the Extent of Occurrence is occupied, the population size may fall in the range of 10,000 to 19,999 mature individuals. The effective population size may actually less than observed because it was noted that the pre-split rosenbergii exhibited a highly biased sex ratio of up to 20 males to each female on the mainland (see Higgins et al. 2016). It is not certain whether this represents a genuine sex bias, or if this is relevant for the newly split M. longirostris and so it is not taken into account here. However, given that the species is only know from one subpopulation on Goodenough Island, it may then qualify as Near Threatened under criterion C2a(ii).
Comments are invited on these proposed categories and further information would be welcomed.
Beehler, B. M. & Pratt, T. K. 2016. Birds of New Guinea: Distribution, Taxonomy and Systematics. Princeton University Press, Princeton, NJ, USA.
Higgins, P., Christidis, L. & Ford, H. (2016). Red-collared Myzomela (Myzomela rosenbergii). 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 fromhttp://www.hbw.com/node/60376 on 9 September 2016).
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.