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 Barbtail Premnoplex tatei is being split into P. tatei and P. pariae, following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, Premnoplex tatei was listed as Vulnerable under criterion B1ab(i,ii,iii,v), on the basis that it had a very small range, which was presumed to be declining in line with the conversion of its habitat to plantations, and changing agricultural techniques. It may have qualified as Endangered, but it was found at 7 locations* in the understorey of montane humid forest in the mountains of north-east Venezuela. P. tatei (as now defined following the taxonomic change) is known from four locations (Cerros Peonía, Turimiquire, Macanillal and Negro in north-east Venezuela). Its already very restricted habitat (EOO <2,500 km2) is declining due to habitat loss, and this is suspected to be driving a population decline. The population prior to the taxonomic change was in the range of 2,500-9,999 individuals (BirdLife International 2016). No direct estimate for this newly defined taxon is known, but as the population for the split taxon has been estimated at 3,600 individuals (Bond et al. 1989). Therefore, the population for the newly defined P. tatei may be conservatively kept in the 2,500-9,999 individuals range unless further information is available. Given this species’s highly restricted range, which is declining due to habitat loss it is proposed that it be listed as Endangered under criterion B1ab(i,ii,iii,v).
P. pariae is known from three locations* (Cerros Humo, Olvido and Azul in the Paria Peninsula of north-east Venezuela). It is found in the understorey of montane humid forest, and has suffered from habitat destruction in its restricted range (EOO <475 km2). Its range is within the Paria Peninsula National Park, but there has been a historical lack of legal enforcement in the park, and habitat destruction continues (Remsen and Sharpe 2016). The population has previously been estimated at 3,600 individuals (Bond et al. 1989), roughly equivalent to 2,400 mature individuals. However, given the age of this figure, and the fact that the population is suspected to be declining in line with the loss of its habitat, it may require revising. Given this species’s highly restricted range, which is declining due to habitat loss, it is proposed that is be listed as Endangered under criterion B1ab(i,ii,iii,v).
Comments are invited on these proposed categories and further information would be welcomed.
*Note that the term ‘location’ defines a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the taxon present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat (IUCN 2001, 2012).
BirdLife International (2016) Species factsheet: Premnoplex tatei. Downloaded from http://www.birdlife.org on 09/09/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 09/09/2016
Bond, R. E., Convey, P., Sharpe, C. J., Varey, A. (1989) Cambridge Columbus zoological expedition to Venezuela 1988. University of Cambridge , Cambridge, UK
IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. Gland, Switzerland and Cambridge, UK: IUCN Species Survival Commission.
IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN.
Remsen, J.V., Jr and Sharpe, C.J. (2016). White-throated Barbtail (Premnoplex tatei). 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/56527 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.