The Yellow-eyed Penguin (Megadyptes antipodes) or Hoiho is a penguin native to New Zealand. 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 other penguins, it is mainly piscivorous.
The species breeds around the South Island of New Zealand, as well as Stewart, Auckland, and Campbell Islands. Colonies on the Otago Peninsula are a popular tourist venue, where visitors may closely observe penguins from hides, trenches, or tunnels.
The Yellow-eyed Penguin is the sole extant species in the genus Megadyptes. (A smaller, recently extinct species M. waitaha was discovered in 2008.) Previously thought closely related to the Little Penguin (Eudyptula minor), new molecular research has shown it 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.
This is a mid-sized penguin, measuring 62–79 cm (24–31 in) long (third largest penguin). Weights vary through the year being greatest, 5.5 to 8 kg (12–18 lbs), just before moulting and least, 3 to 6 kg (6.6–13.2 lbs), after moulting. The males are larger than the females. It has a pale yellow head and paler yellow iris with black feather shafts. The chin and throat are brownish-black. There is a band of bright yellow running from its eyes around the back of the head. The juvenile has a greyer head with no band and their eyes have a grey iris.
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.
Distribution and habitat 
This penguin usually nests in forest or scrub, among Native Flax (Phormium tenax) and lupin (Lupinus arboreus), on slopes or gullies, or the shore itself, facing the sea. These areas are generally sited in small bays or on headland areas of larger bays. It is found in New Zealand, on the south-east coast of the South Island most notably on Otago Peninsula, Foveaux Strait, Stewart Island, and sub-Antarctic islands of Auckland and Campbell Islands. It expanded its range from the subantarctic islands to the main islands of New Zealand after the extinction of the Waitaha Penguin several hundred years ago.
This species of penguin is endangered, with an estimated population of 4000. It is considered one of the world's rarest penguin species. The main threats include habitat degradation and introduced predators. It may be the most ancient of all living penguins.
In spring 2004, a previously undescribed disease killed off 60% of Yellow-eyed Penguin chicks on the Otago peninsula and in North Otago. The disease has been linked to an infection of Corynebacterium, a genus of bacteria that also causes diphtheria in humans. It has recently been described as diphtheritic stomatitis. However, it seems as if this is just a secondary infection. The primary pathogen remains unknown. A similar problem has affected the Stewart Island population.
The Yellow-eyed Penguin generally forages 7–13 km (4–8 miles) offshore, and travelling on average around 17 km (11 mi) away from the nesting site. Birds leave the colony at dawn and return the same evening during chick rearing, although may spend 2–3 days at sea at other times. Average depth dived is 34 m (112 ft).
The Yellow-eyed Penguin pursues prey in 20–60 m (66–196 ft) deep dives. Around 90% of the Yellow-eyed Penguin's diet is made up of fish; with cephalopods such as the arrow squid (Nototodarus sloanii) making up the remainder. Fish species consumed include the blue cod (Parapercis colias), red cod (Pseudophycis bachus), opalfish (Hemerocoetes monopterygius), and New Zealand Blueback Sprat (Sprattus antipodum), all between 2 and 32 cm (1–13 in) long. Cephalopods make up almost half (49%) of the diet of immature birds.
Whether Yellow-eyed Penguins are colonial nesters has been an ongoing issue with zoologists in New Zealand. Most Antarctic penguin species nest in large high density aggregations of birds. For an example see the photo of nesting Emperor Penguin. In contrast yellow-eyed penguins do not nest within visual sight of each other. While they can be seen coming ashore in groups of 4–6 or more individuals then disperse along track to individual nests sites out of sight of each other. The consensus view of New Zealand penguin workers is that it is preferable to use habitat rather than colony to refer to areas where yellow-eyed penguins nest.Nest sites are selected in August and normally two eggs are laid in September. The incubation duties (lasting 39–51 days) 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.
First breeding occurs at 3–4 years of age and long term partnerships are formed.
Penguins and humans 
Several mainland habitats have hides and are relatively easily accessible for those wishing to watch the birds come ashore. These include beaches at Oamaru, Moeraki light-house, a number of beaches near Dunedin, and The Catlins. In addition, commercial tourist operations on Otago Peninsula also provide hides to view Yellow-eyed Penguins.
In culture 
- The Hoiho appears on the reverse side of the New Zealand $5 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.
- BirdLife International (2012). "Megadyptes antipodes". IUCN Red List of Threatened Species. Version 2012.1. International Union for Conservation of Nature. Retrieved 16 July 2012.
- Boessenkool, Sanne; et al. (2008). "Relict or colonizer? Extinction and range expansion of penguins in southern New Zealand". Proc. R. Soc. B. 276 (1658): 815–821. doi:10.1098/rspb.2008.1246. PMC 2664357. PMID 19019791.
- Baker AJ, Pereira SL, Haddrath OP, Edge KA (2006). "Multiple gene evidence for expansion of extant penguins out of Antarctica due to global cooling". Proc Biol Sci. 273 (1582): 11–17. doi:10.1098/rspb.2005.3260. PMC 1560011. PMID 16519228. Retrieved 2008-03-21.
- Marion, Remi, Penguins: A Worldwide Guide. Sterling Publishing Co. (1999), ISBN 0-8069-4232-0
- Richdale, L (1957). A population study of penguins. Oxford: Oxford University Press.
- Williams, Tony D. (1995). The Penguins. Oxford, England: Oxford University Press. ISBN 0-19-854667-X.
- Other Penguin Species. Yellow-eyed Penguin Trust. Accessed 28 November 2007.
- Gwyneth Hyndman, Land set aside for yellow-eyed penguin protection in Catlins. The Southland Times, Wednesday, 28 November 2007.
- 12km coastal reserve declared for yellow-eyed penguins, Radio New Zealand News, 27 November 2007.
- Five Penguins Win U.S. Endangered Species Act Protection Turtle Island Restoration Network
- Kerrie Waterworth, Mystery illness strikes penguins, Sunday Star Times, 25 November 2007.
- Moore, P. J.; Murray, E. D.; Mills, J. A.; McKinlay, B.; Nelson, D.; Murphy, B. 1991: Results of pilot study (1990-1991): marine based activities of yellow-eyed penguin. In: Science and Research Internal Report No. 110: yellow-eyed penguin research and monitoring studies. Wellington, Department of Conservation. 29 p.
- "Rubbish and Recycling - Services". Dunedin City Council. Retrieved 14 March 2011.