Island Collared-dove (Streptopelia bitorquata) is being split: list S. dusumieri as Near Threatened?

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.

Island Collared-dove Streptopelia bitorquata is being split into S. bitorquata and S. dusumieri, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, S. bitorquata (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. This species was estimated to have a very large range, and hence did not 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 appears 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).

S. dusumieri is native to the Philippines, where it is widespread but apparently in decline, and has been introduced to Guam (where it is common but suffers predation by the brown tree-snake Boiga irregularis) and the Northern Mariana Islands (Gibbs et al. 2001). It may qualify as Near Threatened under criteria A2e+3e+4e, as it is potentially undergoing a moderately rapid population decline (approaching 30% over three generations [c.16 years]) owing to apparent competition with increasing feral populations of Spotted Dove Stigmatopelia chinensis.

S. bitorquata (as defined following the taxonomic change) is found on Java, Bali and the Lesser Sundas (Gibbs et al. 2001), and is likely to qualify as Least Concern, as it is not thought to approach the thresholds for Vulnerable under any of the IUCN criteria.

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

References:

Gibbs, D., Barnes, E. and Cox, J. (2001) Pigeons and doves: a guide to the pigeons and doves of the world. Robertsbridge, U.K.: Pica 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.

Related posts:

  1. Silvery Kingfisher (Alcedo argentata) is being split and Indigo-banded Kingfisher (A. cyanopectus) is being split: list A. argentata and A. flumenicola as Vulnerable and A. nigrirostris as Near Threatened?
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4 Responses to Island Collared-dove (Streptopelia bitorquata) is being split: list S. dusumieri as Near Threatened?

  1. S. dusumieri would appear to have undergone a rapid recline on Luzon. The late Tim Fisher (pers. comm.) suggested that the species was common throughout Luzon including areas around Metro Manila in the early 1990′s. Today the species has disappeared from most of these areas and the species has virtually disappeared from areas at Candaba Marsh where it was easily seen until just a few years ago. The decline appears to be due to competition from Spotted Dove and Red Collared Dove which are both abundant in the Luzon countryside where S. dusumieri would formerly have been present. The only area where the species is now regularly encountered are in the denuded foothills of the Northern Sierra Madre but in these areas competition from other species is likely to be a problem.
    I would suggest that the rapid population decline and isolated pockets of remaining birds might qualify it as Vulnerable.

  2. Ivan Sarenas says:

    I think there is only one record from Candaba, Luzon for this year. Not as easy to see elsewhere in the Philippines also. I have only seen it on small islands like Sumilon near Cebu where there were quite a few and Caramoan near Luzon where it mixed with Red Turtle Dove. According to bird guide Nicky Icarangal it can easily be found on Dos Palmas, Palawan but the number is never large.

  3. Joe Taylor says:

    Preliminary proposals

    Based on available information and comments posted above, our preliminary proposals for the 2014 Red List would be to treat:

    S. bitorquata as Least Concern

    S. dusumieri as Vulnerable under criteria A2e+3e+4e

    There is now a period for further comments until the final deadline of 31 March, after which recommended categorisations will be put forward to IUCN.

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

  4. Andy Symes says:

    Recommended categorisations to be put forward to IUCN

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

    The final categorisations will be published later in 2014, following further checking of information relevant to the assessments by BirdLife and IUCN.

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