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.
Hill Myna (Gracula religiosa) is being split into G. religiosa (including enganensis), G. indica, G. robusta and G. venerata, following the application of criteria set out by Tobias et al. (2010).
Gracula robusta is highly desired as a songbird, more so than the other Hill Mynas due to its large size and loud voice (Shepherd et al. 2006, Harris et al. 2015). The species is known from the Banyak Islands and Nias Island (Craig and Feare 2016a) , but the only recent records are of two individuals seen on Nias in 2015 and a small, unquantified populations on one further island . Despite ongoing efforts to intercept poachers, this is still an ongoing threat. The disappearance of the species from the island of Babi followed the island being targeted by ‘hundreds of Javanese trappers’ primarily seeking White-rumped Shama around 2010, according to islands’ sole permanent resident, the radio antenna warden (per F. Rheindt in Eaton et al. 2015).
The proposal is to list Gracula robusta as Critically Endangered under criterion A2d + A3d + A4d, on the basis that the population has declined very rapidly with the past 12.3 years (three generations), and this decline is likely to continue despite the very small remaining population size in the wild. Additionally the species is considered to also qualify as Critically Endangered under criterion C2a(i,ii).
G. venerata, Tengarra Hill Myna, is known to have formerly occurred throughout the Lesser Sundas from Lombok to Alor and Pantar (Craig and Feare 2016c). The species has suffered high levels of trapping pressure for some time, with statements reporting trade-driven declines range wide, on Flores and on Lomblen, and an apparent absence of the species at Gunung Tambora on Sumbawa and on Adonara (Eaton et al. 2015). Recently, visits to Alor reflect a similar situation there; apparently locally common in 2005, only a tiny handful have been seen despite regular visits by birdwatchers (Eaton et al. 2015).
It is clear that the species had considerably declined prior to the most recent three generation period, but also that a considerable decline has continued subsequently. The suggestion from the information from Alor is that on this island the decline is likely to fall within the range of 50-79%, and could be in excess of 80%. Across the rest of the range the recent decline is likely to have been lower, if only because any remaining birds are in less accessible areas. On the basis that there has been a total suspected population reduction over the past, current and future three generation period (12.3 years) in the range of 50-79%, the newly split G. venerata is proposed to be listed as Endangered under criterion A2d+3d+4d.
There is still considerable suitable habitat remaining on Sumbawa, and also significant areas of habitat within protected areas through the rest of the species’ range. However, there is clear evidence that capture for trade has occurred throughout the entire range, thus making any estimate of population size very difficult. The very small numbers reported may imply that any one subpopulation comprises fewer than 1,000 mature individuals, with a total population of fewer than 10,000 mature individuals, additionally meeting the thresholds for classification as Vulnerable under criterion C2a(i).
More information on the estimated population size, recent trends anywhere from this species’ range and ongoing levels of trade in this form are required.
*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).
Craig, A. and Feare, C. 2016c. Common Hill Myna (Gracula religiosa). 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/60823 on 12 September 2016).
Craig, A. and Feare, C. 2016b. Enggano Myna (Gracula enganensis). 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/60825 on 30 August 2016).
Craig, A. and Feare, C. 2016a. Nias Myna (Gracula robusta). 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/60826 on 26 August 2016).
Eaton, J.A., Shepherd, C.R., Rheindt, F.E., Harris, J.B.C., van Balen, S. (B.), Wilcove, D.S. and Collar, N.J. 2015. Trade-driven extinctions and near-extinctions of avian taxa in Sundaic Indonesia. Forktail 31: 1-12.
Harris, J. B. C., Green, J. M. H., Prawiradilaga, D. M., Giam, X., Giyanto, Hikmatullah, D., Putra, C. A. & Wilcove, D. S. 2015. Using market data and expert opinion to identify overexploited species in the wild bird trade. Biol. Conserv. 187: 51–60.
IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, UK.
IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN.
Morris, P. 2014. Sumatra: 6 – 21/26/30 June 2014. Tour Report. Birdquest, UK.
Olah, J. 2010. Sumatra: 11 June – 12 July 2010. Tour Report. Birdquest, UK.
Shepherd, C. R. 2006. The bird trade in Medan, North Sumatra: an overview. BirdingASIA 5: 16–24.