Archived 2014 discussion: Gough Moorhen (Gallinula nesiotis) is being split: list G. nesiotis as Extinct and G. comeri as Vulnerable?

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.

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.

Gough Moorhen Gallinula nesiotis is being split into G. nesiotis (Tristan Moorhen) and G. comeri (Gough Moorhen), following the application of criteria set out by Tobias et al. (2010).

Prior to the taxonomic change, G. nesiotis (BirdLife species factsheet) was listed as Vulnerable as it is restricted to a very small range on just two small islands and, although it coexists with introduced rats on the island of Tristan da Cunha, the accidental introduction of rats, or another predator, to its stronghold on Gough Island remains a risk.

The newly-defined Gallinula nesiotis was endemic to Tristan da Cunha (St Helena to UK) but became extinct in the late 19th century (Nicoll 1906). It is likely that it became extinct as a result of predation by black rat Rattus rattus, though this may have been in combination with feral cat and pig predation, habitat destruction and hunting by islanders (P. G. Ryan in litt. 1999, 2000). It is therefore proposed to list G. nesiotis as Extinct.

G. comeri was endemic to Gough Island (St Helena to UK) but in 1956 a small number of birds from Gough were introduced to Tristan (different reports state that the number of birds released was either seven birds or six pairs; Beintema 1997). There have been other possible releases onto Tristan but none have been documented. It is unclear whether the population on Tristan should be countable for the purposes of IUCN Red Listing since this is technically an introduction of G. comeri to Tristan rather than a reintroduction and it should only be countable if the intent of the introduction was for conservation.

The total population for G. comeri is estimated at 9,000 mature individuals based on past survey data, including 4,250 pairs on Gough based on 1983 data, and 250 pairs on Tristan in 1984 (P. G. Ryan in litt. 2000). This is roughly equivalent to 13,000-14,000 individuals in total.

It is proposed to list the newly-defined G. comeri as Vulnerable under criterion D2 as it is restricted to one small location (two if including the birds on Tristan), and the accidental introduction of rats or another invasive predator onto Gough could cause it to undergo very rapid declines within a short space of time.

References

Beintema, A. J. 1997 The Island Cock of Tristan da Cunha. http://www.beintema.com/moorhen.html

Nicoll, M. J. 1906. Mr M J Nicoll on the birds collected and observed during the voyage of the Valhalla, RYS, from November 1905 to May 1906. Ibis: 666-712.

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: Gough Moorhen (Gallinula nesiotis) is being split: list G. nesiotis as Extinct and G. comeri as Vulnerable?

  1. Andy Symes says:

    Preliminary proposals

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

    G. nesiotis as Extinct

    G. comeri as Vulnerable under criterion D2

    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 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.

  2. 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 in mid-2014, following further checking of information relevant to the assessments by BirdLife and IUCN.

Comments are closed.