Archived 2016 topics: Chat Tanager (Calyptophilus frugivorus) is being split: list C. frugivorus as Near Threatened and C. tertius 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.

Chat Tanager Calyptophilus frugivorus is being split into C. frugivorus and C. tertius, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, C. frugivorus was listed as Vulnerable under criteria A2c;B1ab(i,ii,iii,v);C2a(i), on the basis that it had a small range and population, which were fragmented and declining rapidly.

C. frugivorus (as now defined following the taxonomic change) is found in the central mountains of the Dominican Republic. The races abbotti, from Gonâve Island, Haiti, and frugivorus, from the Samaná Peninsula in the north-eastern Dominican Republic, are both likely to be extinct, with no confirmed records of either since the early 1980s; Gonâve though has not been extensively surveyed and so subspecies abbotti could possibly survive (N. Khwaja in litt. 2012). C. tertius is found in southwest Haiti (Massif de la Hotte and Massif de la Selle) and adjacent southwest Dominican Republic.

Both newly split species are largely terrestrial in broadleaf forest and dense thickets, especially in ravines and near water, but the C. frugivorus race abbotti was known to inhabit semi-arid scrub on Gonâve Island. The species are primarily montane, occurring above 1,000 m, but locally to 800 m, e.g. at Las Mercedes (G. M. Kirwan in litt. 1998). However, the C. frugivorus races abbotti and frugivorus occurred in areas below 600 m.

C. frugivorus (as newly defined) is threatened by habitat loss through agricultural conversion and logging. The species is thought to be declining and whilst there is no data on population change, tree cover across its range has declined by approximately 5% across three generations from 2003-2014 (Global Forest Watch 2016), which does not meet the threshold to list the species as Vulnerable under Criterion A. The species has an Extent of Occurrence of approximately 12,400km2 (calculated using a minimum convex polygon approach), is not severely fragmented and is likely to have more than 10 locations*, so does not qualify for Vulnerable under Criterion B1. There is no data on population size, but the population is estimated to number 15,000-25,000 individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 10,000-16,667 mature individuals, rounded here to 10,000-16,700 mature individuals.

It is therefore proposed that C. frugivorus is listed as Near Threatened under Criterion C2a(ii). However, if further evidence suggests that the population falls beneath 10,000 mature individuals and that there is only a single subpopulation, C. frugivorus could be listed as Vulnerable under Criterion C2a(ii).

C. tertius (as newly defined) is also threatened by habitat loss through agricultural conversion and logging. The species is thought to be declining and whilst there is no data on population change, tree cover across its range has declined by approximately 5% across three generations from 2003-2014 (Global Forest Watch 2016), which does not meet the threshold to list the species as Vulnerable under Criterion A. The species has an Extent of Occurrence of approximately 15,100km2 (calculated using a minimum convex polygon approach), is not severely fragmented and is likely to have more than 10 locations*, so does not qualify for Vulnerable under Criterion B1. There is no data on population size, but the population is estimated to number 10,000-20,000 individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 6,667-13,333 mature individuals, rounded here to 6,700-13,300 mature individuals.

It is therefore proposed that C. tertius is listed as Vulnerable under Criterion C2a(ii).

Comments are invited on these proposed categories and further information is requested on the population size and subpopulation structure of both C. frugivorus and C. tertius.

*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:

Global Forest Watch, 2016. Global forest watch. World Resources Institute, Washington, DC Available from http://www.globalforestwatch.org (accessed 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.

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: Chat Tanager (Calyptophilus frugivorus) is being split: list C. frugivorus as Near Threatened and C. tertius as Vulnerable?

  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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