Pairs can mate for life, although ‘divorces’ are not uncommon (3). During the breeding season, that runs from June to March, they are extremely territorial; males usually defend their territory through calling displays but may occasionally fight intruding birds (5). Females produce one of the proportionally largest eggs of any bird, comprising about 15 percent of her body weight (3) (5). The enormous egg is laid within the burrow. Two eggs may be laid in a clutch, but they are laid three to four weeks apart (3). Up to three different clutches can be laid in a year (5). The male North Island brown kiwi has the role of incubating the egg, and he develops a bare patch of skin on his belly (known as a 'brood patch') that facilitates the transfer of heat to the developing egg (5). Incubation takes 75 to 90 days (3) and the male will leave the egg to forage during the night, concealing the burrow entrance whilst he is gone (5). Chicks hatch fully-feathered and will venture out of the nest when about a week old, but they keep returning to the nest each day until they leave their natal territory at four to six weeks of age (3) (5).
Kiwis are nocturnal, terrestrial birds, spending the day in burrows dug into the ground with powerful claws (4) (5). Invertebrates constitute the majority of the diet, and insects are found by probing beneath leaf litter with the long beak (3) (6).