Archived 2016 topics: Black-throated Laughingthrush (Garrulax chinensis) is being split: list G. chinensis as Least Concern and G. monachus 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.

Black-throated Laughingthrush Garrulax chinensis is being split into G. chinensis and G. monachus, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, G. chinensis was listed as Least Concern, on the basis that it did not approach the threshold for Vulnerable under any criterion. G. chinensis (as now defined following the taxonomic change) retains a large distribution, and suspected large population size across South East Asia, occurring in southern China, Myanmar, Thailand, Laos, Cambodia and Vietnam (see Collar and Robson 2016). This species has been traded frequently, at least in the past (see Collar and Robson 2016), and is suspected to be in decline as a result of habitat loss. However, this is not suspected to be at sufficient a rate to approach the threshold for Vulnerable and so this species likely warrants listing as Least Concern.

G. monachus is found only on Hainan Island, China, with remnant forest mainly found in the southern half of the island. Surveys have suggested that this species’s abundance can be severely affected by habitat use alteration with sightings in secondary forest being c.10 times greater than in rubber plantations on Hainan (Li et al. 2013). There was extensive deforestation on Hainan during the Chinese Cultural Revolution, and forest continues to be lost on the island at a rate approaching 10% in 3 generations (c.14 years) within the species’s range (Madge 2016, see Global Forest Watch webpage: http://www.globalforestwatch.org/map). The continuing loss of forest means this species is likely in decline. This species may also be traded (see Liang et al. 2013), but it is not known to what extent trade may be impacting this species’s population.

While the population size of this species on Hainan has not been directly estimated, using population density estimates of congeners, and assuming that only a proportion of its range is occupied, this species is still likely to have a population size of greater than 10,000 mature individuals. However, given its restricted range it may approach the threshold for Vulnerable under criterion B1ab(i,ii,iii,v) as the rate of deforestation suggests that the number of locations* where the species is found may approach 10 locations. Therefore, it is proposed that this species be listed as Near Threatened 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).

References:

Collar, N. and Robson, C. 2016. Black-throated Laughingthrush (Dryonastes chinensis). 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/59582 on 8 October 2016).

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.

Li, S., Zou, F., Zhang, Q. and Sheldon, F.H. 2013. Species richness and guild composition in rubber plantations compared to secondary forest on Hainan Island, China. Agroforest. Syst. 87: 1117-1128.

Liang, W., Cai, Y. and Yang, C.-C. 2013. Extreme levels of hunting of birds in a remote village of Hainan Island, China. Bird Conservation International 23: 45-52.

Madge, S. 2016. White-winged Magpie (Urocissa whiteheadi). 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/60737 on 7 October 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.

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One Response to Archived 2016 topics: Black-throated Laughingthrush (Garrulax chinensis) is being split: list G. chinensis as Least Concern and G. monachus as Near Threatened?

  1. James Westrip (BirdLife) says:

    Based on available information, our preliminary proposal for the 2016 Red List would be to adopt the proposed classifications outlined in the initial forum discussion.

    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 those in 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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