Archived 2016 topics: Saddleback (Philesturnus carunculatus) is being split: list both Philesturnus carunculatus (South Island Saddleback) and Philesturnus rufusator (North Island Saddleback) as Near Threatened

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.

Saddleback (Philesturnus carunculatus) is being split into Philesturnus carunculatus (South Island Saddleback) and Philesturnus rufusator (North Island Saddleback) following the application of criteria set out by Tobias et al. (2010). Both species are endemic to New Zealand.

South Island saddlebacks P. carunculatus originally occurred throughout the South and Stewart Islands. Predation by introduced mammals (mainly ship rats) led to their extinction on the South Island and Stewart Island by about 1900, and they became confined to the South Cape Islands (Big South Cape, Solomon and Pukeweka Islands), islands off the south-west coast of Stewart Island. When ship rats invaded all three islands in the early 1960s, the Wildlife Service (which subsequently became part of the Department of Conservation) successfully moved birds from Big South Cape Island to nearby Big and Kaimohu Islands in 1964, thereby averting the extinction of this species. They have now been translocated to c20 offshore islands and one mainland sanctuary (Masuda and Jamieson 2013). In 2003 the population was estimated at 1265 individuals but in 2013 it was considered to be more than 2000 birds (Masuda and Jamieson 2013).

North Island saddlebacks P. rufusator were widespread at the time of first European contact, but rapidly declined on the mainland following the introduction of predatory mammals, especially ship rats and stoats. By the early 1900s, North Island saddlebacks were confined to a single population on Hen Island (Taranga) off the northeast coast of the North Island. A series of successful translocations was initiated by the New Zealand Wildlife Service in the 1960s, and there are now c15 island populations and five at predator-fenced mainland sites. North Island saddlebacks can be very abundant in suitable habitat free of introduced mammals. Recent population estimates (2013) suggested there were more than 7,000 birds across all populations (Parker 2013).

Both saddleback species are vulnerable to predation by introduced mammals such as ship rats and stoats due to their tendency to nest, forage and roost on or low to the ground, with P. curunculatus appearing extremely sensitive As a result, they are confined to sites where introduced predators are absent, primarily on offshore islands or fenced mainland sites (Masuda and Jamieson 2013, Parker 2013). Both taxa meet the area requirements under criterion B for threatened (Area of Occupancy <2,000 km2) and their populations are severely fragmented, but the populations are not declining, and they occur at more than 10 locations with no extreme population fluctuations. However, there is a realistic threat that these predator-free sites could be invaded by mammalian predators leading to a rapid decline in populations and uplisting to Vulnerable, and it is suggested that P. carunculatus and P. rufusator are both classified as Near Threatened on this basis.

Additional information and comments on these proposals are welcomed.

 

References

Hooson, S.; Jamieson, I. G. 2003. The distribution and current status of New Zealand Saddleback Philesturnus carunculatusBird Conservation International 13: 79-95.

Masuda, B.M.; Jamieson, I.G. 2013. South Island saddleback. In Miskelly, C.M. (ed.) New Zealand Birds Online.www.nzbirdsonline.org.nz

Parker, K.A. 2013. North Island saddleback. In Miskelly, C.M. (ed.) New Zealand Birds Onlinewww.nzbirdsonline.org.nz

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One Response to Archived 2016 topics: Saddleback (Philesturnus carunculatus) is being split: list both Philesturnus carunculatus (South Island Saddleback) and Philesturnus rufusator (North Island Saddleback) as Near Threatened

  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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