Archived 2016 topics: Solomons Cuckooshrike (Coracina holopolia) is being split and moving to genus Edolisoma: list Edolisoma holopolium as Near Threatened and E. pygmaeum as Vulnerable?

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.

Solomons Cuckooshrike Coracina holopolia is moving to genus Edolisoma and being split into Edolisoma holopolium and E. pygmaeum, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, Coracina holopolia was listed as Near Threatened under criterion C1, on the basis that it had a small population, and it was likely to suffer a moderately rapid population reduction as a result of an increase in logging within its range. Edolisoma holopolium (as defined following the taxonomic change) is found in Papua New Guinea and the Solomon Islands, on the islands of Bougainville, Buka, Choiseul, Guadalcanal, Malaita and Santa Isabel, in forested habitat as well as on the forest edge (Taylor 2016). The population size has not been quantified, but it has been described as rather scarce, apart from on Buka and Bougainville, where it is common (del Hoyo et al. 2005), and as fairly common but easily overlooked on Buka, Bougainville and Malaita, and uncommon on Choiseul and Isabel (Dutson 2011). Logging continues to occur on the Solomon Islands, and is increasing, but a large part of this species’s habitat is not suitable for logging and so declines are thought to be slow. Therefore, it is proposed that this species be listed as Near Threatened under criterion C1.

E. pygmaeum is found on Gatukai, Kolombangara, New Georgia and Vangunu in the Solomon Islands, in forest and forest edge habitats (Taylor 2016) (Extent of Occurrence: <7,000 km2). The population size has not been quantified, but the pre-split species was described as ‘rather scarce’ on these islands (del Hoyo et al. 2005). Logging continues to threaten its habitat (Taylor 2016), and the population is inferred to be declining in line with this. It is described as ‘less common in lowlands’ (Dutson 2011). If the population is considered to occur at ten or fewer locations (see definition below), or to be severely fragmented, it may warrant listing as Vulnerable under criterion B1ab(i,ii,iii,v). If these latter conditions are not me, it may instead be listed as Near Threatened, approaching the thresholds for listing as Vulnerable under criteria B1, C1 and C2.

Comments are invited on these proposed categories and any 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:

del Hoyo, J.; Elliott, A.; Christie, D. 2005. Handbook of the Birds of the World, vol. 10: Cuckoo-shrikes to Thrushes. Lynx Edicions, Barcelona, Spain.

Dutson, G. (2011). Birds of Melanesia. Helm, London.

Taylor, B. (2016). Solomon Cuckoo-shrike (Coracina holopolia). 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/57876 on 12 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.

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2 Responses to Archived 2016 topics: Solomons Cuckooshrike (Coracina holopolia) is being split and moving to genus Edolisoma: list Edolisoma holopolium as Near Threatened and E. pygmaeum as Vulnerable?

  1. Guy Dutson says:

    See maps of logging concessions in Katovai et al 2015 http://ecologicalsolutions-si.com/files/114248024.pdf and note that logging is very minor on Bougainville
    holopolia: NT C1 is precautionary and appropriate
    pygmaeum: occurs at >>10 locations and not severely fragmented; rates of logging are higher on these islands and this sp is scarce within its narrow altitudinal range: Buckingham et al 1995 recorded “Maximum of seven per day from 500 to 940 m. Common in hill forest and low-lying moss forest on a ridge at 490 m on Kolombagara” and estimated 27 contacts per km2 in hill and montane forest, which implies population densities of several times 27 per km2 of old-growth forest at these altitudes. On four visits to Kolombagara of 3-5 days each in 1998 – 2006, I have only seen one and heard one, but have walked rapidly through this altitudinal range. I have not been to this altitude on other islands in the species’ range. I would be interested to see the EOO if it is precautionarily assumed to be restricted to 500-1000 m in altitude; might qualify as VU C2ai

  2. James Westrip (BirdLife) says:

    Based on available information, our preliminary proposal for the 2016 Red List would be to list:

    E. holopolium as Near Threatened under criterion C1.

    E. pygmaeum as Near Threatened under criterion C2a(i).

    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 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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