Kiwis are monogamous and typically mate for life. Females lay a single large egg, which can weigh up to one-quarter of their body weight, and both parents take turns incubating the egg. Kiwis are unusual among birds in that their eggs have a large yolk and a small albumen (egg white), which is a reversal of the pattern seen in most other birds. After hatching, the chick remains in the nest for several days before venturing out with its parents in search of food. Kiwis only have one chick per breeding season, and they only breed once every 1-3 years depending on the species.