Archived 2014 discussion: Black-mandibled Toucan (Ramphastos ambiguus) and Chestnut-mandibled Toucan (R. swainsonii) are being lumped as R. ambiguus: list the newly-defined species as Near Threatened?

The initial deadline for comments on this topic is 28 April 2014, and therefore later than for most other topics currently under discussion.

This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for non-passerines

Lynx Edicions and BirdLife International will soon publish 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 1 of the checklist (for non-passerines) will begin to be incorporated into the 2014 Red List update, with the remainder, and those for passerines (which will appear in volume 2 of the checklist), 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-mandibled Toucan Ramphastos ambiguus and Chestnut-mandibled Toucan R. swainsonii are being lumped as R. ambiguus, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, R. ambiguus (BirdLife species factsheet) was listed as Vulnerable under criterion A3c, on the basis that it was suspected to undergo a rapid population decline, in the range of 30-49% over 35 years (estimate of three generations), following analysis using a model of future deforestation in Amazonia. This species was predicted to lose 40.6-40.7% of suitable habitat within its distribution over 35 years, based on projected deforestation in the Amazon basin (as defined by the model) (Soares-Filho et al. 2006, Bird et al. 2011).

R. swainsonii (BirdLife species factsheet) was listed as being of Least Concern, on the basis that it was not thought to approach the thresholds for Vulnerable under any of the IUCN Red List criteria, although it was acknowledged to be decreasing.

R. ambiguus (as defined following the taxonomic change) is widespread from south-eastern Honduras, ranging south and east through Central America to Colombia, northern and western Venezuela, through Ecuador and Peru, to southern Peru. It occurs in the lowlands, foothills and mountains, although its elevation range varies within its geographic distribution, and it inhabits various forest types, as well as secondary growth, clearings, plantations, parks and gardens (Short and Horne 2001). This species can be common in some areas; however, hunting and forest destruction are said to be rapidly reducing its range (Short and Horne 2001).

This species has not been assessed using the Amazonia deforestation model, as less than 50% of its range occurs within the coverage of the model; however, given the previous assessment for the nominate form, and decreasing trend in swainsonii, the newly-defined species may qualify as Near Threatened under criteria A3cd+4cd, on the basis that it may be suspected to undergo a moderately rapid population decline, approaching 30% over 35 years, owing to habitat loss and hunting pressure.

Comments are invited on this proposed category and further information would be welcomed.


Bird, J. P., Buchanan, G. M., Lees, A. C., Clay, R. P., Develey. P. F., Yépez, I. and Butchart, S. H. M. (2011) Integrating spatially explicit habitat projections into extinction risk assessments: a reassessment of Amazonian avifauna incorporating projected deforestation. Diversity and Distributions DOI: 10.1111/j.1472 4642.2011.00843.x.

Short, L. and Horne, J. (2001) Toucans, Barbets and Honeyguides: Ramphastidae, Capitonidae and Indicatoridae. Oxford, UK: Oxford University Press.

Soares-Filho, B. S., Nepstad, D. C., Curran, L. M., Cerqueira, G. C., Garcia, R. A., Ramos, C. A., Voll, E., McDonald, A., Lefebvre, P. and Schlesinger, P. (2006) Modelling conservation in the Amazon basin. Nature 440: 520–523.

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 2014 discussion: Black-mandibled Toucan (Ramphastos ambiguus) and Chestnut-mandibled Toucan (R. swainsonii) are being lumped as R. ambiguus: list the newly-defined species as Near Threatened?

  1. Andy Symes says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2014 Red List would be to treat:

    R. ambiguus as Near Threatened, approaching the thresholds for classification as Vulnerable under criterion A2cd+3cd+4cd

    There is now a period for further comments until the final deadline of 14 May, after which recommended categorisations will be put forward to IUCN.

    The final Red List category will be published on the BirdLife and IUCN websites in mid-2014, following further checking of information relevant to the assessment by both BirdLife and IUCN.

  2. Andy Symes says:

    Recommended categorisation to be put forward to IUCN

    Following further review, there have been no changes to our preliminary proposal for the 2014 Red List status of this species.

    The final categorisation will be published in mid-2014, following further checking of information relevant to the assessment by BirdLife and IUCN.

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