Nesting and breeding
While abundant ripe fruit is important for stimulating and sustaining breeding, other foods may be important as well, such as nutritious varieties of leaves, flower buds and flowers. In years when food sources are in short supply, especially fruit, none or few pairs of a population nest.
The timing of the breeding season varies regionally through New Zealand. When food is readily available, nesting by kerer? in Northland often starts in winter, elsewhere nesting starts in spring, except that in Southland most pairs do not start nesting until summer. The breeding season often continues for over six months, and in central New Zealand this is from September to April. During the breeding season male kerer? perform spectacular display flights. The bird flies up steeply, stalls with wings and tail outspread to make itself as conspicuous as possible, and then glides back down to an exposed perch on the forest canopy (see Display Dive video clip on previous page).
Usually the male collects twigs from nearby trees and delivers them to the female at the nest site, who then incorporates them into the nest. The male sits on the single white egg from mid-morning to late afternoon, and the female incubates for the rest of the time. The egg hatches after nearly a month of incubation, the chick being naked except for some wispy golden hair-like feathers (see Nest Cam video clip on previous page).
At first both parents feed the chick with protein-rich "milk" secreted from their crops. Partially-digested fruit is soon combined with the crop milk, and by the time the chick is ready to leave the nest at 30-45 days of age, much of its diet is undigested fruit, flowers and leaves. Chicks continue to be fed by their parents for at least two weeks after leaving the nest, and may remain with their parents until the following breeding season. However, if food is plentiful, kerer? will build a new nest and be incubating an egg while raising their first chick. By the time the second egg hatches, the first chick, having left the nest by this stage, will have reached independence, being able to feed itself.
