The North Island kokako is a large songbird with a blue-grey body, a striking black mask and small, rich blue wattles that arise from the base of the bill and sit under the throat. Typically, when seen backlit in forest, kokako seem dark-plumaged and neither mask nor wattles are seen. They have long, strong legs and a long down-curved tail.
Kokako characteristically bound and run among branches on their strong legs, interspersed with glides on short, rounded wings. They are poor fliers; but may glide some hundreds of metres down gullies from treetops.
The sexes are alike; juveniles have pink or lilac wattles. A few adults have orange wattles.
North Island kokako defend large territories year-round by complex singing, including the longest known duetting of any songbird in the world. The tall forests they inhabit and their alert and skulking behaviour mean that most kokako are detected by their song and other vocalisation, frequently delivered from the tops of tall trees at dawn.
Natural remnant North Island kokako populations are confined to a few scattered forests in the northern half of the North Island, particularly in the Waikato, Bay of Plenty and Te Urewera National Park.
Since 1981, Kokako has been successfully translocated to Little Barrier, Kapiti and Tiritiri Matangi Islands, Mount Bruce Scenic Reserve (Wairarapa), Boundary Stream Mainland Island (Hawkes Bay) , Ngapukeriki (East Cape), Ark in the Park (Waitakeres, west Auckland), Whirinaki and Otanewainuku (Bay of Plenty).
They characteristically reside in tall, diverse native forest, usually with a canopy of tawa or taraire with emergent podocarps or kauri.
North Island kokako mainly eat fruit and leaves and, less often, flowers, moss, buds, nectar and invertebrates.
North Island kokako typically raise one brood during November-February, after which they moult. In occasional years of good food supply, the breeding season may last 6 months and up to three broods can be raised. Two-three pinkish-grey eggs are laid in cup nests c.13 m (range 3-25 m) up trees. Incubation is by the female alone for c.18 days. Both adults feed the nestlings. Young fledge at 32-37 days old, and so nests are vulnerable to predation for about 7 weeks. Fledged young usually remain in parents’ territory for a few months, up to a year, and continue to be fed by both parents.
Predation at nests by ship rats and possums is the primary cause of current declines of North Island kokako. Food reduction mainly by possums and predation by stoats are unhelpful secondary factors. All current populations must be continually managed against introduced mammal pests, either by repeated pest control on the mainland, or by vigilance against pest invasion on islands.
Ship rats and possums are routinely targeted by trapping and poisoning so that their numbers are low for the duration of the breeding season (November to February).
Several key populations are being restored primarily by community groups. Maintenance of genetic health also influences management; e.g. new populations are established with individuals from two different source populations.
The conservation status of this species was moved from nationally vulnerable to ‘at risk – recovering’ in 2013.