New Zealand has at least eight species of birds that regularly have more than a breeding pair involved in nesting and rearing of young. One is a sea bird (the Southern Skua, Stercorarius lonbergi), others are small forest insectivores (the Whitehead, Mohoua albicilla; the Yellowhead, Mohoua ochrocephala; the Brown Creeper, Finschia novaeseelandiae; and the Rifleman, Acanthisitta chloris), while the remainder are rails (Takahe, Notornis mantelli; Weka, Gallirallus australis; and the Pukeko, Porphyrio porphyrio). The range of environments occupied (from sub-Antarctic to subtropical, from oceanic islands to dense evergreen forests and from alpine grasslands to lowland swamps), the range in size (from our smallest to some of our largest species), and the range in demography (from short-lived to long-lived birds that rarely breed before the age of nine years) make the quest for a universal explanation of cooperative breeding a difficult task indeed.

Pukeko have the most complex social system of all these species. (Pukeko is the Maori name for this gallinule, which is known as the Swamphen in other places.) Most Pukeko are found in communal groups of up to a dozen birds. All participate to a greater or lesser extent in the rearing of chicks and the defense of the territory. Birds are capable of breeding from one year of age but most do not until at least three years of age.