Archived 2014 discussion: Tahiti Kingfisher (Todiramphus veneratus) is being split: list T. youngi as Endangered?

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.

Tahiti Kingfisher Todiramphus veneratus is being split into T. veneratus and T. youngi, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, T. veneratus (BirdLife species factsheet) was listed as Least Concern on the basis that it was not thought to approach the thresholds for Vulnerable under any of the IUCN criteria. Although this species was estimated to have a restricted range, it was not believed to approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence of less than 20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appeared to be decreasing, the decline was not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (at least a 30% decline over ten years or three generations). The population size has not been quantified, but it was not believed to approach the thresholds for Vulnerable under the population size criterion (fewer than 10,000 mature individuals with a continuing decline estimated to be at least 10% over ten years or three generations, or with a specified population structure).

T. youngi is endemic to Moorea (French Polynesia), where it occupies primary and secondary forest up to c.300 m (Fry and Fry 1999, del Hoyo et al. 2001). It may qualify as Endangered under criterion C2a(ii), on the basis that there are probably fewer than 2,500 mature individuals, forming a single subpopulation, which is thought to be in slow decline owing to on-going habitat loss and degradation.

T. veneratus (as defined following the taxonomic change) is endemic to Tahiti (French Polynesia), where it inhabits woodland, gardens, plantations and montane forest up to 1,700 m (Fry and Fry 1999, del Hoyo et al. 2001). It is likely to warrant listing as Least Concern on the basis that it is not thought to approach the thresholds for Vulnerable under any of the IUCN criteria. This species is estimated to have a restricted range, and probably has a small population; however, its ability to use substantially modified and montane habitats implies that it is not currently in decline.

Comments on these suggested categories are invited and further information would be welcomed.

References:

del Hoyo, J., Elliott, A. and Sargatal, J. (2001) Handbook of the birds of the world, Vol 6: Mousebirds to Hornbills. Barcelona, Spain: Lynx Edicions.

Fry, C. H. and Fry, K. (1999) Kingfishers, Bee-Eaters & Rollers. Princeton, NJ: Princeton University Press.

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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