Kokako  (Callaeas cinereus)

This medium-sized wattlebird has blue-grey feathers with black legs and bill, and a black highway-man mask which is in striking contrast to the wattles under the throat. There were two subspecies of kokako; the North Island kokako (Callaeas cinerea wilsoni) has blue wattles on the throat, whereas the now-extinct South Island kokako (Callaeas cinerea cinerea) had orange wattles. The wings are short and rounded (4).

As the last remaining subspecies of the wattlebird family to be found on the New Zealand mainland, the North Island kokako used to inhabit the whole of the North Island, but populations now occur in small and fragmented areas of the North Island and on four offshore islands. Translocations have taken place to create populations on Little Barrier, Kapiti, Tiritiri Matangi and Lady Alice Islands (4). The South Island kokako used to inhabit South and Stewart Islands, but is now deemed to be extinct (5).

These beautiful birds are found in middle to low layers of temperate forest with a high diversity of plant species and generally, very little human disturbance (1) (2) (3), although kokako can persist in some very modified habitat, such as on Tiritiri Matangi Island, if mammalian predators are completely absent (6).

The most distinctive feature of the kokako is its haunting song. The dawn chorus begins with each bird opening and closing its wings and fanning its tail, then arching the neck and uttering gentle mewing and buzzing sounds before launching into full song. The song resembles the sound of an organ with loud, clear and melodious notes (4). Males and females pair throughout the year and sometimes for several years (7). The male and female will answer each other's song for up to half an hour with impressive harmony. Birds in the surrounding area sing together from the top of tall trees on ridges producing an extraordinary chorus, which serves to defend their five to twenty hectare territories (4).

The birds also communicate through calls, clicks, buzzes and screeches which are all socially specific. Kokako are poor fliers, but their powerful legs allow them to leap, run and jump through trees in search of fruits, leaves and insects (4).

Breeding usually takes place between November and February but in years of abundant food supply it can last from October through to May (8), and pairs might raise up to three broods in one season (7). The female builds a large and untidy nest between branches fairly high in the trees (2 to 35 metres), beginning with a twig base, and weaving together moss, lichen, rotten wood and ferns, before lining the nest bowl with tree fern scales. The nest is built in dense foliage, with small contributions of material from the male, and is well concealed from aerial predators. In each clutch, the female lays two or three pinkish grey eggs with brown and purple spots, and these hatch after 18 days of incubation by the female alone. The male works to feed himself, his partner and the new hatchlings. The nestling begins life with pink wattles and fledges after 30 to 45 days (7). During the first year they must find an unoccupied area for their territory and their wattles will change from pink to blue or orange, depending on the subspecies (8).

The combination of deforestation and the introduction of invasive mammalian predators in two waves of human colonisation since 1270 AD nearly extirpated this species. Just one quarter of the forest present 1,000 years ago is still standing. European settlers brought with them ship rats, brush-tail possums, stoats and wild cats (1) (2) (4), which prey heavily on young and female kokakos at the nest, leaving an excess of males who are not able to breed. These males sometimes pair up and nest with each other in the absence of female partners (10). Whilst in 1999 the North Island kokako population stood at 1,160 birds, only 396 of these were female, thus limiting the number of reproducing pairs (9).

Intensive recovery planning and management since the mid 1980s has substantially recovered North Island kokako populations. In 2007, there were 18 increasing populations totalling 850 pairs. Such intensive management is vital, as nearly all unmanaged populations are now extinct. Translocations have established populations on four offshore islands and restored kokako to three sites in their original range (Wairarapa, Hawkes Bay and East Cape), and further translocations are planned as part of widespread active restoration of mainland New Zealand forest ecosystems. The recovery of the kokako requires intensive control of introduced mammal pests, particularly ship rats and brushtail possums (10). Some populations are now managed by pulsed control effort, a method in which pest control has ‘on' and ‘off' years. This effectively controls pest populations whilst minimising the input of pest control poisons at any site, and means that conservation resources can be spent on other sites or problems during the ‘off' years (11).

For further information on the recovery of the kokako see:

• Kokako Recovery:
  www.kokakorecovery.org.nz
• Basse, B., Flux, I. and Innes, J. (2003) Recovery and maintenance of North Island kokako (Callaeas cinerea wilsoni) populations through pulsed pest control. Biological Conservation, 109(2): 259-270.
• Higgins, P.J., Peter, J.M. and Cowling, S.J. (2006) Handbook of Australian, New Zealand and Antarctic Birds. Vol. 7: Boatbill to Starlings. Oxford University Press, Melbourne.
• Innes, J., Hay, R., Flux, I., Bradfield, H. and Jansen, P. (1999) Successful recovery of North Island kokako Callaeas cinerea wilsoni populations, by adaptive management. Biological Conservation,87: 201-21.

Authenticated (28/01/08) by John Innes, Landcare Research, Hamilton, New Zealand.