Data Zone
Justification of Red List category
This species is classified as Vulnerable because its small population has declined rapidly within the past three generations, primarily owing to the effects of introduced predators.
Population justification
The population is suspected to be in the band 2,500-9,999 mature individuals in total, equating to 3,750-14,999 individuals. However, this estimate should be treated cautiously, as good data are only available from one population in the central North Island (T. Greene in litt. 2016). Less than 50% of the population is now found on the mainland (R. Moorhouse per R. Hitchmough in litt. 2005), with numbers high only in a few intensely managed sites and islands that remain free of possums and stoats.
Trend justification
N. m. meridionalis is listed as Nationally Vulnerable under the New Zealand Threat Classification System, thought to be declining at a rate of 10-50% within three generations, while subspecies septentrionalis is listed as Recovering due to ongoing pest control (Robertson et al. 2021). While there have been increases of both subspecies at some mainland sites, these are limited to the few sites where predator control has been successful. The species is overall thought to be declining across much of the range where predator control is absent and populations are highly skewed towards males (T. Greene in litt. 2022). Although the ongoing rate of decline is uncertain, the past rate of decline is suspected to exceed 30% (T. Greene in litt. 2022), placed here in the range 30-40%.
Nestor meridionalis is endemic to New Zealand. The North Island subspecies septentrionalis survives in large forest tracts from Coromandel to Wairarapa, and is moderately common only in the forests of Pureora and Whirinaki and some offshore islands such as the Hen and Chickens, Little Barrier, Great Barrier, Mayor and Kapiti islands (Heather and Robertson 1997, Greene and Fraser 1998, T. Greene in litt. 1999). The South Island subspecies meridionalis is mostly found west of the Southern Alps, Fiordland and south-western Southland, Stewart Island and several offshore islands such as Ulva and Codfish islands, and is in low numbers in all areas other than pest-free islands where it can be common (T. Greene in litt. 2020).
This species inhabits large areas of low to mid-altitude forest. Its diet is diverse, consisting of fruit, seeds, nectar, sap, invertebrates (Beggs and Wilson 1991, Moorhouse 1997), and also "honeydew" in South Island Nothofagus beech forests (Beggs and Wilson 1991). It appears to depend on infrequently available, superabundant food crops in order to breed (Moorhouse 1997, Wilson et al. 1998, Greene et al. 2004, Powlesland et al. 2009). It nests in natural cavities in old or dying trees and usually lays four eggs (T. Greene in litt. 1999), with the chicks taking over seven months from hatching to become fully independent (Heather and Robertson 2015).
Historically, forest clearance and hunting decimated habitat and numbers (Heather and Robertson 1997, Moorhouse 1997, Greene and Fraser 1998, Wilson et al. 1998). Stoats Mustela erminea kill adults, in particular females incubating eggs, probably causing the highly skewed sex ratio on the mainland (Greene and Fraser 1998, Wilson et al. 1998, Ledgard 2010). Relatively large numbers of males can therefore remain highly visible for a long time after the population reaches a very poor condition functionally (Greene & Fraser 1998, R. Hitchmough in litt. 2005). Common Brushtail Possums Trichosurus vulpecula rob nests, being responsible for the failure of six out of 13 nests in Whirinaki during a single breeding season (Greene et al. 2004), and compete for high-energy foods (especially native mistletoe) required for successful breeding (Wilson et al. 1998, Ledgard 2010, Heather and Robertson 2015). Brown Rats Rattus norvegicus are also implicated (Moorhouse 1997). Sites with predator control have a nest failure incidence of 16%, compared to 84% in sites without predator control (Moorhouse et al. 2003). Introduced wasps Vespula spp. compete for honeydew, and may be contributing to declines in Nothofagus forests (Beggs and Wilson 1991, Moorhouse 1997).
Conservation Actions Underway
CITES Appendix II. Predator/pest control is carried out in several large areas and around known nest-sites (Greene et al. 2013). Kaka have been successfully released into several pest free sanctuaries (e.g. Maungatautiri, Pukaha/Mt Bruce, Zealandia/Karori, and Orakanui). Successful breeding has been recorded at both Pukaha/Mt Bruce and Zealandia/Karori with both populations increasing steadily in conjunction with effective pest control. Landscape scale pest control is now being conducted in a number of large areas (>30,000 ha) throughout New Zealand and the response by kaka has been marked (e.g. Greene et al. 2010, Greene et al. 2013). Results strongly suggest that predator control has a positive influence on the incidence of successful fledging (Ledgard 2010), population abundance and other demographic parameters such as population sex ratios following disproportionate predation on female birds in areas without integrated pest control (T. Greene in litt. 2020). Supplementary foods were trialed where wasps are a major problem, but did not increase productivity (Wilson et al. 1998). Radio-tracking is used to identify adult and juvenile movements and survival, habitat requirements and important food sources.
Conservation Actions Proposed
Continue large-scale pest control to benefit this and other forest species (i.e. Tiakina Nga Manu/Battle for our Birds) (T. Greene in litt. 2020).
45 cm. Vocal forest parrot. Crimson underwings, rump, collar. Golden cheeks. North Island subspecies, mainly olive-brown. Dark feather edges. Paler, greyer crown. South Island subspecies, brighter. Crown almost white. Longer bill, more arched in males. Juvenile has yellow base of mandible. Similar spp. Kea N. notabilis is much larger, olive-green all over with scarlet underwing, dark red rump. Voice Noisy, varied, from whistling to grating calls.
Text account compilers
Vine, J.
Contributors
Greene, T., Hitchmough, R. & Moorhouse, R.
Recommended citation
BirdLife International (2024) Species factsheet: New Zealand Kaka Nestor meridionalis. Downloaded from
https://datazone.birdlife.org/species/factsheet/new-zealand-kaka-nestor-meridionalis on 23/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/11/2024.