This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for passerines
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.
Callaeas cinereus is being split into Callaeas cinereus (South Island Kokako) and Callaeas wilsoni (North Island Kokako), following the application of criteria set out by Tobias et al. (2010). Both species are endemic to New Zealand.
The last accepted sighting of the South Island species Callaeas cinereus was in 2007 (Miskelly et al. 2013); prior to that it was last sighted in 1967 (Szabo 2013). South Island kokako were slightly smaller and darker than the North Island birds, with orange rather than blue facial wattles. In early 1800s, they occupied beech forests and low scrub above the tree line on both sides of Southern Alps from north-western Nelson south to Fiordland and mixed podocarp forest on Stewart Island and some forested areas of Otago and Southland. They declined markedly after introductions of cats, ship rats and stoats, and were was rare by the 1880s (Szabo 2013). South Island kokako were declared extinct by the New Zealand Department of Conservation in 2008, but the species’ conservation status was moved from extinct to data deficient under New Zealand’s local threat classification system in 2013 following the acceptance of the 2007 sighting (Miskelly et al., 2013, Szabo 2013).
Efforts are continuing to be made to locate individuals of this species (see, e.g. Evans 2016), and sightings continue to be claimed (e.g. Redmond 2016). If birds do remain, there are likely to be fewer than 50 individuals, and given the ongoing threat from introduced predators a continuing decline inferred, justifying listing as Critically Endangered under criteria C2a(i); D. Due to the lack of visual or audio documentation accompanying reported sightings since 1967 it may be most appropriate to list the species as Critically Endangered (Possibly Extinct).
The North Island species Callaeas wilsoni has increased its population from around 330 pairs in 1999 to 1,310 pairs in 2012 and 1400 pairs in 2014 (DOC 2016), following a programme of pest control and translocations into managed areas (Innes 2013, Innes et al. 2011). Following translocations of birds in the 1980s, predator-free Little Barrier Island/Hauturu held an estimated 422 pairs in 2013 (DOC 2016). The other largest populations, with more than 100 pairs each, are in Te Urewera National Park and Waipapa Ecological Area of Pureora Forest Park. Other large populations (> 50 prs) are at Kaharoa-Onaia near Rotorua, Mangatutu (Pureora) and Mapara (King Country), and there are 19 other smaller populations (Innes 2013). All populations are entirely conservation dependent, requiring regular pulsed pest management to persist.
Prior to 1999, Callaeas wilsoni underwent a rapid decline over three generations leading to it being classified as Endangered under criteria A2bd. This decline was due to large-scale habitat destruction, fragmentation and the introduction of predators and competitors. No unmanaged populations now exist on the mainland of the North Island, and as the managed populations are stable or increasing, there is not considered to be an ongoing decline in numbers or range. The species was reclassified in New Zealand from nationally vulnerable to ‘at risk – recovering’ in 2013 (Robertson et al.). With a four-fold increase in the population of breeding pairs since 1999, and a stable and secure population of 422 pairs on pest-free Little Barrier / Hauturu, it seems that this species no longer meets the IUCN criteria for classification as Endangered. Given its current population size and distribution, and the stable or increasing population trend that has been ongoing for more than a decade, Callaeas wilsoni does not currently meet the IUCN criteria for classification as Vulnerable.
We therefore suggest that this species should be classified as Near Threatened, as if conservation management were to cease, populations could rapidly decline resulting in future range reduction and a drop in population size leading it to qualify as Endangered or Vulnerable.
Additional information and comments on this proposal are welcomed.
DOC 2016 Kokako – http://www.doc.govt.nz/nature/native-animals/birds/birds-a-z/kokako/. Accessed on 25/08/2016.
Evans, K. 2016. In Search of the Grey Ghost. New Zealand Geographic. 140. Available at https://www.nzgeo.com/stories/in-search-of-the-grey-ghost/
Innes, J. 2013 [updated 2015]. North Island kokako. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz
Innes, J.; Molles, L.E.; Speed, H. 2012. Translocations of North Island kokako, 1981-2011. Notornis 60: 107-114.
Miskelly, C.; Crossland, A.C.; Sagar, P.M.; Saville, I.; Tennyson, A.J.D.; Bell, E.A. 2013 Vagrant and extra-limital bird records accepted by the OSNZ Records Appraisal Committee 2011-2012. Notornis 60: 296-306.
Redmond, A. 2016. Once-extinct Kokako sighting near Nelson ‘the best in many years’ Available at: http://www.stuff.co.nz/environment/78378330/once-extinct-kokako-sighting-near-nelson-the-best-in-many-years
Robertson, H. A.; Dowding, J. E.; Elliott, G. P.; Hitchmough, R. A.; Miskelly, C. M.; O’Donnell, C. F. J.; Powlesland, R. G.; Sagar, P. M.; Scofield, R. P.; Taylor, G. A. 2013. Conservation status of New Zealand birds, 2012. NZ Threat Classification Series 4. Department of Conservation. Wellington.
Szabo, M. J. 2013 [updated 2016]. South Island kokako. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz
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.