Yellow-eyed Penguin

The yellow-eyed penguin (Megadyptes antipodes), known also as hoiho, is a species of penguin endemic to New Zealand. It is the sole extant species in the genus Megadyptes, from Ancient Greek μέγας (mégas), meaning "large", and δύπτης (dúptes), meaning "diver". Previously thought closely related to the little penguin (Eudyptula minor), molecular research has shown it more closely related to penguins of the genus Eudyptes. Like most penguins, it is mainly piscivorous. The species breeds along the eastern and south-eastern coastlines of the South Island of New Zealand, as well as Stewart Island, Auckland Islands, and Campbell Islands. Colonies on the Otago Peninsula are a popular tourist ven...

Until recently, it was assumed that M. a. antipodes was widespread and abundant before the arrival of Polynesian settlers in New Zealand. However, genetic analysis has since revealed that its range only expanded to include mainland New Zealand in the past 200 years. Yellow-eyed penguins expanded out of the subantarctic to replace New Zealand's endemic Waitaha penguin (M. a. waitaha). The Waitaha penguin became extinct between about 1300 and 1500, soon after Polynesian settlers arrived in New Zealand. Jeremy Austin, a member of the team that discovered the Waitaha penguin, said, "Our findings demonstrate that yellow-eyed penguins on mainland New Zealand are not a declining remnant of a previous abundant population, but came from the subantarctic relatively recently and replaced the extinct Waitaha penguin". An island dwarf subspecies from the Chatham Islands, M. a. richdalei, is extinct. The modern population of yellow-eyed penguins does not breed on the Chatham Islands. Today, yellow-eyed penguins are found in two distinct populations. The northern population extends along the southeast coast of the South Island of New Zealand, down to Stewart Island / Rakiura and Codfish Island / Whenua Hou. It includes four main breeding areas in Banks Peninsula, North Otago, Otago Peninsula and the Catlins. It is also referred to as the mainland population. The southern population includes the subantarctic Auckland Islands and Campbell Island / Motu Ihupuku. There is little gene flow between the northern and southern populations as the large stretch of ocean between the South Island and subantarctic region and the subtropical convergence act as a natural barrier. Based on monitoring between 2012-2017, there are on average 577 breeding pairs per year on Enderby Island in the Auckland Islands, which comprise 37-49% of the total breeding population for the species.

New Zealand

Around 90% of the yellow-eyed penguin's diet is made up of fish, chiefly demersal species that live near the seafloor, including silversides (Argentina elongata), blue cod (Parapercis colias), red cod (Pseudophycis bachus), and opalfish (Hemerocoetes monopterygius). Other species taken are New Zealand blueback sprat (Sprattus antipodum) and cephalopods such as arrow squid (Nototodarus sloanii). They also eat some crustaceans, including krill (Nyctiphanes australis). Recently, jellyfish were found to be targeted by the penguins. While initially thought that the birds would prey on jellyfish itself, deployments of camera loggers revealed that the penguins were going after juvenile fish and fish larvae associated with jellyfish. Breeding penguins usually undertake two kinds of foraging trips: day trips where the birds leave at dawn and return in the evening ranging up to 25 km from their colonies, and shorter evening trips during which the birds are seldom away from their nest longer than four hours or range farther than 7 km. Yellow-eyed penguins are known to be an almost exclusive benthic forager that searches for prey along the seafloor. Accordingly, up to 90% of their dives are benthic dives. This also means that their average dive depths are determined by the water depths within their home ranges, but can swim up to 240 meters below the water surface.

The nesting behaviour of yellow-eyed penguins is thought to be the least colonial of all penguin species. While other penguin species nest in large aggregations, yellow-eyed penguins tend to nest in solitary pairs or loose aggregations. Yellow-eyed penguins begin forming pairs and breeding at around two years of age. An analysis of data collected from 1991 to 2002 showed that the species has a 63% rate of retaining mates each breeding season. The majority of changes were due to the death of their partner. While they can be seen coming ashore in groups of four to six or more individuals, they then disperse along tracks to individual nest sites up to one kilometre inland. Accordingly, the consensus among New Zealand penguin workers is to use habitat rather than colony to refer to areas where yellow-eyed penguins nest. The species prefers to nest in forest or scrub habitat with dense vegetation cover. Adults will incorporate vegetation such as twigs, grasses and leaves into their nests, and often return to the same nesting area each year. Breeding sites are frequented year-round, and adults may continue to defend their nest areas outside of the breeding season. Nests tend to be visually isolated from one another, though they are usually in audible distance from each other. Nest site selection takes place from June onwards, with breeding beginning in late August, followed by incubation from September to November. After hatching, chicks are guarded by an adult full-time for the first 40–50 days. Incubation duties are shared by both parents, who may spend several days on the nest at a time. For the first six weeks after hatching, the chicks are guarded during the day by one parent while the other is at sea feeding. The foraging adult returns at least daily to feed the chicks and relieve the partner. After the chicks are six weeks of age, both parents go to sea to supply food to their rapidly growing offspring. Chicks usually fledge in mid-February and are totally independent from then on. Chick fledge weights are generally between 5 and 6 kg.

The yellow-eyed penguin was first described by Jacques Bernard Hombron and Honoré Jacquinot in 1841. The yellow-eyed penguin is the sole species in the genus Megadyptes, though there have been multiple subspecies. It was previously thought closely related to the little penguin, but molecular research has shown it is more closely related to penguins of the genus Eudyptes. Mitochondrial and nuclear DNA evidence suggests it split from the ancestors of Eudyptes around 15 million years ago. In 2019 the 1.25Gb genome of the species was published as part of the Penguin Genome Consortium, aiming to understand the origins and aid conservation by helping to inform any future breeding programmes. The yellow-eyed penguin (M. a. antipodes) is most easily identified by the band of pale yellow feathers surrounding its eyes and encircling the back of its head. Its forehead, crown and the sides of its face are slate grey flecked with golden yellow. Its eye is yellow. The foreneck and sides of the head are light brown. The back and tail are slate blue-black. Its chest, stomach, thighs and the underside of its flippers are white in colour. Juvenile birds have a greyer head with no yellow band around their eyes. It is the largest living penguin to breed on the mainland of New Zealand and the fourth or fifth heaviest living penguin by body mass. It stands 62–79 centimetres (24–31 in) tall and weighs 3–8.5 kilograms (6.6–18.7 lb). Weight varies throughout the year, with penguins being heaviest just before moulting, during which they may lose 3–4 kilograms in weight. Males at around 5.53 kg (12.2 lb) on average are somewhat heavier than females at an average of 5.13 kg (11.3 lb). The yellow-eyed penguin may be long lived, with some individuals reaching 20 years of age. Males are generally longer lived than females, leading to a sex ratio of 2:1 around the age of 10–12 years. The yellow-eyed penguin is mostly silent. It makes a shrill bray-like call at nest and breeding sites.

Populations of yellow-eyed penguins are threatened by multiple factors. A risk assessment published in November 2025 indicated the biggest threats to the species are malnutrition, predation, disease, other trauma/unidentifiable sources, and fishing. Sea surface temperature has also been shown to influence the survival of both adults and fledglings. The northern population is declining as a result of recurring poor breeding seasons and ongoing high adult mortality. Threats at sea include poor foraging success, and becoming caught in fisheries equipment. Chicks are often lost at sea, with only 20% projected to make it back to land for nesting, and only 5% expected to breed. The use of gillnets has been identified as a particular threat to the species. Studies carried out during the 1980s showed that red cod is a key part of their diet, however red cod populations have since declined, and more recent investigation has found that the penguins are feeding on blue cod instead, which provide less suitable nutrition. Disease also poses a key threat to the species, which poor nutrition makes them more vulnerable to. A previously undescribed disease killed off 60% of yellow-eyed penguin chicks on the Otago Peninsula and in North Otago in 2004. The disease has been described as diphtheritic stomatitis, caused by infection of Corynebacterium, a genus of bacteria that also causes diphtheria in humans. A similar problem has affected the Stewart Island population. In 2023, a novel Gyrovirus was identified as the likely cause of the mysterious and fatal respiratory illness which had killed roughly a quarter of the yellow-eyed penguin chicks from the mainland during the 2021 November to December hatching season. The disease has a mortality rate of more than 90%. It was estimated in 2023 around 320 individuals died. Severe disease appears to be concentrated in the mainland population, and research suggests this may be due to their unique evolutionary history, identifying genes associated with susceptibility to disease.

The yellow-eyed penguin is considered one of the rarest penguin species in the world. It is listed on the IUCN Red List as being endangered. It was first included on the list in 1988 when it was listed as threatened, and was changed to endangered in the year 2000.

The hoiho appears on the reverse side of the New Zealand five-dollar note. The yellow-eyed penguin is the mascot to Dunedin City Council's recycling and solid waste management campaign. The yellow-eyed penguin is also featured in Farce of the Penguins, in which they complain about global warming. In 2019 the yellow-eyed penguin was crowned the Bird of the Year in New Zealand, the first win for a seabird in the competition's 14-year history. It was again victorious in the 2024 competition.