This discussion was first published as part of the 2016 Red List update. At the time a decision regarding its status was pended, but to enable potential reassessment of this species as part of the 2017 Red List update this post remained open and the date of posting was updated.
Apteryx rowi is locally common in native lowland forests in a small area of coastal forest inland from Okarito, on the west coast of the South Island of New Zealand (Robertson 2013). The native population was restricted to 10,000 ha of coastal podocarp-hardwood forest between the Okarito River and the Waiho River (Tennyson et al. 2003), but they have been re-introduced to North Okarito Forest and introduced to two islands in the Cook Strait region (H. Robertson in litt. 2016).
“Operation Nest Egg” (the removal of eggs or young chicks from the wild and rearing in captivity or safe islands until large enough to cope with the presence of stoats), allowed the population to increase from 160 birds in 1991 to about 200 birds by 2000. A landscape-scale (10,000 ha) stoat trapping programme in South Okarito Forest from 2001-2005 largely failed to protect chicks from stoat predation (Robertson & de Monchy 2012). Operation Nest Egg was then reinstated, leading to strong population growth. A landscape-scale aerial 1080 operation in 2011 is believed to have boosted natural recruitment sites (H. Robertson in litt. 2016). Subadult birds have been released in adjacent North Okarito, which was part of the species range until very recently, and they have started breeding there. New populations have been established on Mana and Blumine Islands, and breeding has been recorded at both sites (H. Robertson in litt. 2016).
Colbourne et al. (2005) reported that the population was at a minimum of c.160 individuals in 1995 and had increased to c.200 by 2000. It was estimated to have increased further to 300 individuals by 2008 (Holzapfel et al. 2008), and 375 in 2013 (Heather and Robertson 2015). The 2016 population is 400-450 adults, and given that some (presumably very old) birds do not breed, the number of mature individuals is estimated to lie in the range 350-400 birds. The population is still growing and there have been over 250 mature birds for over five years (H. Robertson in litt. 2016). This means that A. rowi no longer qualifies as Endangered under criterion D. However, the total population is still below 1,000 individuals, so it is proposed to downlist A. rowi to Vulnerable under criterion D1.
Additional information and comments on this proposal are welcomed.
Colbourne, R., Bassett, S., Billing, A., McCormack, H., McLennan, J., Nelson, A. and Robertson, H. 2005. The development of Operation Nest Egg as a tool in the conservation management of kiwi. Department of Conservation, Wellington.
Heather, B. D., Robertson, H. A. 2015. The field guide to the birds of New Zealand. Penguin Random House NZ, Auckland, N.Z.
Holzapfel, S.; Robertson, H.A.; McLennan, J.A.; Sporle, W.; Hackwell, K.; Impey, M. 2008 . Kiwi (Apteryx spp.) recovery plan: 2008–2018. Department of Conservation, Wellington.
Robertson, H. A. 2013. Okarito brown kiwi. In Miskelly, C.M. (ed.) New Zealand Birds Online. Available at: www.nzbirdsonline.org.nz.
Robertson, H.A.; de Monchy, P.J.M. 2012. Varied success from the landscape-scale management of kiwi (Apteryx spp.) in five sanctuaries in New Zealand. Bird Conservation International, 22: 429-444.
Tennyson, A. J. D., Palma, R. L.; Robertson, H. A.; Worthy, T. H.; Gill, B. J. 2003. A new species of kiwi (Aves, Apterygiformes) from Okarito, New Zealand. Records of the Auckland Museum 40: 55-64.