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.
Rufous-brown Solitaire Cichlopsis leucogenys is being split into C. leucogenys, C. chubbi, C. gularis and C. peruviana following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, C. leucogenys was listed as Least Concern, on the basis that it did not approach the threshold for Vulnerable under any criterion. C. leucogenys (as now defined following the taxonomic change) is found only on the east coast of Brazil in the states of Bahia and Espírito Santo. C. chubbi is found on the west slope of the Andes in south-west Colombia and north-west Ecuador, and C. peruviana is found on the eastern slope of the Andes in central Peru. C. gularis is found on the Tepuis of south-eastern Venezuela, Suriname and Guyana. These newly defined species occur in lower montane mossy forest and dense secondary growth (Collar 2016). Deforestation continues to occur within the ranges of these species, and so the populations are inferred to be declining.
The pre-split species was thought to be ‘uncommon and patchily distributed’ (Stotz et al. 1996), though C. leucogenys was recently evaluated as Endangered in Brazil as part of a regional red list assessment (MMA 2014) under criterion C2a(i) because it is thought to have a population size of <2,500 mature individuals with ≤ 250 mature individuals in each subpopulation. Further information regarding the species’s population size is requested to ascertain whether it does meet the threshold for listing globally as Endangered under C2a(i).
The occupied ranges of C. chubbi, C. peruviana and C. gularis appear to be less than that of C. leucogenys, and so population sizes may be even smaller in these three species. However, without further information it may not be possible to directly state whether these species meet the threshold for Endangered under criterion C2. The case of C. gularis is further complicated as there can be seasonal changes in abundance, suggesting the species undergoes local movements (Collar 2016).
Using population density estimates of closely related species and assuming only a proportion of the range of these species is occupied would still give sub-population size estimates of >1,000 mature individuals for all three species. As C. peruviana is likely only found in one sub-population however, it may approach or meet the threshold for Vulnerable under criterion C2a(ii), pending further information regarding population size estimates and so would likely warrant listing as either Vulnerable or Near Threatened under criterion C2a(ii).
We request further information regarding population and sub-population size estimates to ascertain whether C. chubbi and C. gularis may meet the threshold for Vulnerable under criterion C2a(i) (a declining global population of <10,000 mature individuals with ≤1,000 mature individuals per sub-population). In the absence of this information, however, these species may be considered not to meet the threshold for Vulnerable under any criterion, but may conservatively be assessed to approach the threshold for Vulnerable under criterion C2a(i) hence would be listed as Near Threatened under that criterion.
Comments are invited on these proposed categories and further information would be welcomed.
Collar, N. 2016. Rufous-brown Solitaire (Cichlopsis leucogenys). 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/58361 on 10 October 2016).
MMA 2014. Lista Nacional Oficial de Espécies da Fauna Ameaçadas de Extinção. Portaria No 444, de 17 de dezembro de 2014. Diário Oficial da União – Seção 1. Nº 245, quinta-feira, 18 de dezembro de 2014.
Stotz, D. F., Fitzpatrick, J. W., Parker, T. A. and Moskovits, D. K. 1996. Neotropical birds: ecology and conservation. University of Chicago Press, Chicago.
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.