The Australasian swamphen (Porphyrio melanotus), commonly known as the pūkeko in New Zealand, is a striking and socially complex bird found in Oceania, including eastern Indonesia (the Moluccas, Aru and Kai Islands), Papua New Guinea, New Zealand and Australia. A member of the rail family, it is part of the diverse order Gruiformes, which includes species with similar characteristics such as cranes and other rail species. Within the Australasian swamphen species, five recognised subspecies exist, with P. m. melanotus being the most common and widely distributed in New Zealand. They display phenotypic characteristics typical of rails: relatively short wings and strong, elongated bills, adapted to its semi-aquatic lifestyle in wetlands.
The swamphen is renowned for its distinctive blue-purple plumage, striking red frontal shield, and strong red legs. It is often found in swamps, marshes, and other wet lowland areas, though its habitat has expanded to include pastures, roadside verges, and farmland, due to significant landscape changes in New Zealand over the last 150 years. Unlike many other wetland birds, it is highly opportunistic and adaptable, thriving in both natural and human-modified environments. Its diet reflects this adaptability, consisting primarily of plant material such as grass stems, shoots, and leaves, but also including animal matter like invertebrates and, occasionally, the young of other bird species.
Classified as a communal gallinule, the birds often breed in social groups rather than pairs. These groups typically consist of three to nine individuals, including both males and females, which all contribute to territory defence, nesting, and chick rearing. They exhibit a linear dominance hierarchy within these groups that is reinforced by physical traits, such as the size of the bird's frontal shield, which serves as a signal of social dominance.
Taxonomy and phylogeny The Australasian swamphen, Porphyrio melanotus, is a communal gallinule and a member of the rail family, Rallidae. The Rallidae family is a diverse group of non-passerine birds (birds that do not belong to the order Passeriformes, which includes perching birds and songbirds) with primarily terrestrial habits, characterised by relatively short wings and strong, often elongated bills. This family has a deep evolutionary history, with its origins dating back to the Eocene epoch, approximately 40 million years ago. The rails belong to the order Gruiformes, which is split into two main suborders: Gruoidea, containing cranes (family Gruidae), and Ralloidea, which is dominated by the rail family. Within the Rallidae family, there are about 40 genera organised into nine tribes.
Recent phylogenetic studies have revealed that Porphyrio porphyrio, the widespread species group to which the Australasian swamphen was once thought to belong, is not monophyletic. This means that the group does not consist of all descendants from a common ancestor, suggesting that several subspecies and subspecies groups, including P. melanotus, may actually represent distinct species-level lineages.
Studies suggest that the Porphyrio clade originated in Africa during the Middle Miocene, about 10 million years ago (mya), with a single colonisation of the Americas and several dispersals into Southeast Asia and the Indo-Pacific. The oldest split among the currently recognised P. porphyrio lineage likely occurred in the Late Miocene (~6 mya), giving rise to P. porphyrio on the Mediterranean coast of Europe. Porphyrio melanotus is believed to have arrived in Australasia within the past 600,000 years; however, bone deposits suggest a more recent presence on certain remote islands. In New Zealand, for instance, fossil evidence indicates colonisation occurred approximately 500 years ago, following Polynesian settlement.
Description Australasian swamphen are long-legged birds, standing about 51 cm tall, with dark plumage, black upper-parts, and a contrasting white undertail. They have a large, bright red bill and an expanded frontal shield that extends from their culmen, giving them a distinctive appearance. Their throat and breast are purple, contributing to their striking colour pattern. Variations exist across subspecies, with some having greener or bluer upper-parts or smaller body sizes depending on the region. The New Zealand population (along with green-yellow swamphens in Tasmania) are possibly slightly larger than mainland Australian birds, but are otherwise identical.
Distribution The Australasian swamphen occurs in mainland Australia, eastern Indonesia, the Moluccas, Aru and Kai Islands, and in Papua New Guinea. It is also found on New Zealand's main islands and in the Chatham and Kermadec Islands.
Dispersal Although it is thought that P. porphyrio subspecies rarely use flight, this lineage has effectively dispersed, colonised, and established populations numerous times across extensive bodies of water. In support of the belief that Australasian swamphens are good flyers, and may have self-introduced, a dead bird was found on L'Esperance Rock, a tiny, isolated rock in the Kermadec group of New Zealand, more than 200 km from the nearest established population.Tennyson & Taylor (1989). This demonstrates the ability of swamphens to fly great distances over the sea.
Subspecies The Australasian swamphen has five subspecies distributed as follows: P. m. melanopterus – northern and south-eastern Sulawesi, the Moluccas, Lesser Sundas and New Guinea region. P. m. pelewensis – Palau (western Caroline Islands, western Micronesia). P. m. melanotus – northern and eastern Australia, Tasmania, Lord Howe and Norfolk Islands, as well as the North, South, Stewart, Kermadec and Chatham Islands of New Zealand. P. m. bellus – far south-west Australia. P. m. samoensis – Admiralty Islands to New Caledonia, Solomon Islands, Fiji and Samoa.
In New Zealand The swamphen, now widespread across mainland and offshore New Zealand, is thought to have been self-introduced from Australia about 1,000 years ago. However, Māori from the east coast hold the belief that their ancestors brought the swamphen to New Zealand aboard the vessel Horouta, which arrived from Polynesia approximately twenty-four generations ago. In contrast, west coast tribes connected to the Aotea waka assert that their ancestors introduced the swamphen, along with the kiore and the karaka tree, to the land on the Aotea.
Habitat The Australasian swamphen primarily inhabits swamps and marshes across Southeast Asia, Australia, and New Zealand. In New Zealand, these birds thrive in wet lowlands and breed in swamps, but they also utilise a variety of habitats such as pastures, crops, farm ponds, road verges, and forest margins. This adaptability has enabled them to exploit feeding opportunities that arose following large-scale lowland clearance and swamp drainage over the past 150 years. Typically found in low-lying wetlands with vegetation like flax, raupo, and rushes, the swamphen is also common in estuaries, salt marshes, and along riverbanks. Their large feet allow them to traverse swampy terrain without sinking, and while not webbed, they provide enough propulsion for swimming. Additionally, they are known for their speed, making them swift runners across their diverse habitats.
Behaviour Feeding and foraging Swamphens exhibit diverse feeding and foraging habits, making use of both plant and animal resources in their diet. Primarily, they consume plant material, including stems, shoots, leaves, and seeds of various grasses, sedges, rushes, and clover. However, they are also opportunistic feeders, supplementing their diet with animal matter, primarily invertebrates. Notably, they have been observed preying on larger vertebrate species, such as pied stilt eggs, Eurasian blackbird chicks, and pāteke and mallard ducklings in New Zealand, as well as common starlings, myna chicks, black swan eggs and cygnets in Australia. This positions them as both a predator and prey species within their ecosystems.
Their foraging habits extend beyond natural environments, often leading them to forage on roadsides, where they seek out invertebrates struck by vehicles and graze on grass shoots from mown verges. In these areas, they also ingest grit, which aids in processing food in their gizzards. Swamphens are bold foragers and have a history of raiding gardens for crops such as kumara and taro, a behaviour that has continued as they adapted to European farmland by feeding on grain and vegetable crops. Their foraging activities can sometimes result in the uprooting of vegetation, including tree seedlings and crops, which has led to the Australasian swamphen being culled under permit in certain areas.
Though considered native to New Zealand as a self-introduced species, swamphen are unique in their dual role as both predators of young birds and crop foragers, a behaviour that occasionally places them in conflict with agricultural interests.
Breeding
Swamphens exhibit a complex polygynandrous mating system, where both sexes mate with multiple partners, and groups typically consist of three to seven breeding males and one or two breeding females. These females lay their eggs in a single nest, resulting in joint laying—a rare avian breeding system where multiple females contribute eggs to the same clutch and provide collective parental care. Each female's eggs differ in colour and size, allowing for individual recognition within the shared nest.
However, joint laying does come with reproductive costs. Studies have shown that when total clutch sizes are large due to multiple females contributing to the same clutch, a lower percentage of eggs hatch.
The communal nature of breeding also extends to non-breeding females within the group. Although these females are of reproductive age, they do not breed, nor do they face aggression from dominant breeding females or engage in sexual behaviour with males. This hierarchy within the group also influences male behaviour, with males generally not guarding their mates or interrupting copulations with rival males.
Group participation in copulation and same-sex sexual behaviour is also common and is thought to help synchronise sexual cycles, enabling multiple females to lay in the same nest simultaneously. This behaviour, seen between late July and early December, fosters cooperation in the group and enhances breeding success.
The swamphens build multiple nests, with males being responsible for constructing 'trial' nests about a month before laying. Ultimately, one nest is chosen for laying, although occasionally two nests are used. In New Zealand they nest, typically well hidden in the middle of a clump of raupō, between August (end of winter) and March (start of autumn). Most eggs are laid between August and February with breeding reaching a peak in spring between September and December. The recent development of a useful PCR-based genetic marker to determine the sex of Australasian swamphen has revealed that there is no evidence of sex ratio bias in hatching-order. Patterns of growth, survivorship and adult dominance in this species is therefore thought to be attributed to hatching order rather than offspring sex.
Courtship behaviour Courtship behaviour includes allopreening, courtship feeding, mounting, and copulation, which can occur between all adult members of the territory, though male-female interactions are the most frequent. Courting behaviour, such as preening and feeding, often appear symbolic, with the passing of food, such as small pieces of duckweed, occurring in a head-bow posture, typically from male to female but sometimes reversed. Courtship usually involves a humming call given by males before mounting.
Parental care