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).