The Yellow-eyed penguin
Written by Andrea Court (Lincoln University)
Edited by Jon Sullivan, Lincoln University, May 2008
- Scientific name: Megadyptes antipodes (Hombron & Jacquinot, 1841)>
- Popular Common names: Yellow-eyed penguin, hoiho
- Other common names: yellow-crowned penguin
- Kingdom: Animalia
- Phylum: Chordata
- Class: Aves (the birds)
- Order: Sphenisciformes (the penguins)
- Family: Spheniscidae (the penguins)
- New Zealand Status: native (endemic)
- Taxonomy sources: Moncrieff (1957), Moon (1991).
Megadyptes antipodes (meaning “big diver from the southern lands”) is one of the most distinctive of the penguins, with its band of yellow feathers encircling the head from its reddish-brown bill (Reilly, 1994), and as their name suggests, their eyes are a straw-yellow colour, the only penguin in their family with this characteristic (Davis, 2001; Reilly 1994; Vernon, 1991). Their feet are bright pink, in contrast to their sparkling white front, and slate grey upper body, head and flippers (Reilly, 1994)(Fig. 1–3). The juvenile chicks in second down are uniformly light brown, while the fledglings do not yet have the yellow band of feathers around the hind crown, the chin is white and their eyes are a pale grey-yellow (Davis, 2001; Reilly, 1994). Both of the sexes are alike in this species, with the male having only slightly larger head and feet, both standing at 65 cm and weighing 5 to 6 kg as an adult (Moncrieff, 1957; Vernon, 1991).
Yellow-eyed penguins have a distinguished trill of “hoi-ho, hoi-ho”, which is why the native Maori named this penguin hoiho, the “noise shouter” for these vibrant musical calls (Vernon, 1991).
For those that are unfamiliar with penguins, you would have no trouble identifying the yellow-eyed penguin as they are the only one in their family to have their distinctive gold band of feathers encircling their head (Davis, 2001; Reilly, 1994; Vernon, 1991).
Full natural and naturalised range
The yellow-eyed penguin is presently only found naturally on the south eastern coasts of New Zealand, Stewart Island and New Zealand’s sub Antarctic Islands, Campbell and Auckland (Bull & Gaze & Robertson, 1985; Moon, 1991; Reilly, 1994; Vernon, 1991). It is not found naturalised anywhere in the world (Moncrieff, 1957; Reilly, 1994).
New Zealand range
The yellow-eyed penguin’s distribution is restricted to the coasts of Canterbury, Otago, and Southland of our South Island, Stewart Island, and two of our sub Antarctic Islands, Campbell and Auckland (Moon, 1991; Vernon, 1991).
As this shy penguin is endangered in this province, only a few breeding pairs may be seen along the coast, and not further inland than 1 km (Vernon, 1991).
Natural History in Canterbury
The yellow-eyed penguin’s natural habitat is within dense forest, which provides shelter from storms and the blazing sun, and safety from aerial predators, and the ocean which provides their food. However since Maori and European settlement of New Zealand, this penguin can be found in many coastal habitats, shrubbery, native forest and grazed pasture (Vernon, 1991).
The natural habitat of the yellow-eyed penguin on land ranges from near sea level to 250 m above sea level, and up to 1 km inland (Reilly, 1994). The lack of suitable habitat and the climate further north along the coast of Canterbury prevents this penguin from dispersing and having permanent breeding sites here (Reilly, 1994). The yellow-eyed penguin can be found on or near their breeding ground throughout the year, feeding at sea during the day and returning for the remainder, unlike all other penguins which only return during the breeding season (Moon, 1991).
The modern habitat of this penguin has altered as there are now only small patches of native forest remaining since human discovery of New Zealand (Reilly, 1994). Now the yellow-eyed penguin inhabits a range of habitats that provide cover, from rock outcroppings, to flax bushes, shrubs and felled tree roots (Reilly, 1994). A territory of 1.5Ha is defended by a pair in the breeding season, indicating how solitary they are (Moon, 1991).
On the Campbell and Auckland Islands, this robust penguin is subject to the harsh sub Antarctic weather, which is cool with persistent westerly winds, and cold fronts – the “Roaring Forties” and the Furious Fifties”, with sunshine hours 16% that of on the mainland of New Zealand (O’Connor, 1999).
The yellow-eyed penguin has one of the longest breeding seasons of all the penguins, with six and a half months devoted to family duties. Females enter the breeding population at 2 to 3 years, while males can take up to five years (Bull, et al 1985; McKinley, 2001). Like most other penguins, they are monogamous, staying together year after year, and begin the season with courtship and the building of nests in mid august (Moon, 1991; Wilson, 2004). Both mates will build at least 2 nests made from a range of plant materials to form a shallow bowl (Reilly, 1994), hidden from other mating pairs by dense vegetation (Vernon, 1991). These birds prefer these solitary nests, because if they attempt to breed insight of another pair, one or both pairs usually fail to have a family (Reilly, 1994).
Two eggs are generally laid in September to October, with both parents sharing the job of incubation for 39 to 51 days, until both chicks hatch on the same day, regardless of whether they were laid on the same day (Reilly, 1994). For up to 50 days, the parents alternate between guarding the chicks, and going out to sea daily for fish and squid, regurgitating it for the chicks which need to gain 2 to 3 kg (Moon, 1991; Reilly, 1994). Breeding success can be affected by the productivity of the marine environment, as the cooler waters increase food abundance, therefore plenty of food for growing chicks. Warmer waters are not so abundant, and have an effect on chick survival (Reilly, 1994; Vernon, 1991). The chicks then fledge at 14 weeks of age, around February/March, later than most species of penguin. The breeding birds are then tied to land for a further 3 to 4 weeks while they molt, as they are unable to go out to sea in this state (Reilly, 1994).
The yellow-eyed penguins are generally long-lived with a life span of 20 years (McKinley, 2001). The Department of Conservation in New Zealand has also noted a lower mortality rate for males of this species, which leads to a skewed sex ratio of 2:1, at around 12 years of age, making some males redundant in the breeding department (McKinley, 2001).
The yellow-eyed penguin doesn’t normally migrate and is present at its breeding site throughout the year (Reilly, 1994; Vernon, 1991). If they do disperse however, they use the currents in the ocean and their amazing skill at swimming to travel. On land they can move with surprising speed and agility over rugged terrain with a rocking gait, as their short legs with flat webbed feet, are placed far back on their bodies, with their head thrust forward and flippers held out for balance (Vernon, 1991).
Their navigational skills are impeccable, which was tested in an experiment when a penguin was released 87 km from its breeding site, returning within 2 days (Reilly, 1994). Another penguin was released 350 km away from its breeding site, and returned within 17 days (Reilly, 1994).
The yellow-eyed penguin gathers its food from its marine environment daily, foraging at least 160 m deep, and up to 50 km offshore, spending an average of 4 minutes under the water at a time (McKinley, 2001). Seven species of fish make up 95% of their yearly diet. These include: Sprat, Red Cod, Blue Cod, Silverside, Opal fish, Squid and Ahuru (McKinley, 2001). Of these species, it is mainly the juvenile that they are consuming. If the dominant seafood in their diet is Squid, generally that breeding season is poor (McKinley, 2001).
When an intruder threatens another of this species, they will react by hunching their shoulders, and glaring at each other while yelling harsh, (and probably obscene) remarks at each other. A defender may charge, and if the intruder is still not deterred, they will proceed to peck, and strike out with their flippers (Reilly, 1994).
Sexual behavior is displayed with throbbing and shaking of the head, whilst trumpeting calls out to either prospective or current mates. An ecstatic display by the penguin is when the bird’s head is thrown as far back as possible to trumpet (Reilly, 1994; Richdale, 1951).
The yellow-eyed penguin is extremely musical with their calls, which generally occur during the breeding season, with contact calls at other times, while nesting areas generally remain quiet (Reilly, 1994).
The yellow-eyed penguin will have some parasites however research on them is limited. As they are in and out of the ocean a lot, most would be cleansed off of them with the fast movement of their bodies through the water. When they step out of the water they generally groom themselves with their bill, evicting any parasites they come across (Vernon, 1991).
The research on the yellow-eyed penguin and other organisms is also limited, but it is unlikely that there would be many as they are a shy and private penguin, whom doesn’t share breeding areas with any other species of penguin, and seeks out sheltered and completely isolated nests from neighbors (Vernon, 1991).
The main competitors of the yellow-eyed penguin are in the ocean, such as other penguin species which feed on the same types of seafood. Fishing companies, who are using set and gill net to catch fish, are mainly collecting the adults of fish species, so are not in direct competition with the penguins which consume the juveniles, but are having an influence with the numbers of fish available for them by catching a large proportion of the adults (Reilly, 1994; Vernon, 1991).
There are predators of the yellow-eyed penguin in the ocean as well as on land, with introduced mammalian predators in New Zealand being the most significant in reducing their numbers. Predation of this solitary penguin is high where the nesting areas are close to human habitation, with wild cats, ferrets and stoats killing chicks and eating the eggs, while adults often fall victim to dog attacks (Reilly, 1994; Wilson, 2004). In two Otago studies, it was found that the bulk of ferret prey were yellow-eyed penguins, along with the Blue penguin and Sooty shearwaters (Wilson, 2004).
As they are scampering their way from the water’s edge to the protection of the scrub or native forest, they are also threatened by aerial predators such as albatrosses, and in the ocean by Leopard seals and the Hookers sea lion, which both regularly eat warm-blooded prey – Penguins (O’Connor, 1999; Wilson, 2004).
On the mainland of New Zealand it is estimated that populations have declined by 75% in the last 40 years, mostly due to these predators (Ford, 1989, Reilly, 1994).
How to find the Yellow-eyed penguin
The yellow-eyed penguin is extremely wary of humans and rarely comes ashore if they know people are about. To see them, going to tourist locations where platforms have been specially set up for the protection of these birds are essential (Vernon, 1991).
Abundance and Conservation Status
- New Zealand: endangered
- Canterbury: endangered
It was estimated in 1993 that there were only 1100 to 1350 breeding pairs left in New Zealand and its sub Antarctic Islands, with its population declining every year, with now only 15% living to breeding age (Reilly, 1994; Vernon, 1991). The Department of Conservation has ranked this penguin a category B species for conservation priority, and is considered threatened due to their restricted range, and their alarming periods of decline in these ranges (McKinley, 2001).
Loss of coastal forest has played a major part in their decline on the mainland, with deforestation and shrub clearance for pasture pressuring the penguins (Vernon, 1991). A recovery and management program has been introduced by the Department of Conservation, with establishing reserves to accommodate their solitary breeding and nesting habits that are securely fenced for stock as well as a deterrent to people and their dogs (Vernon, 1991). Trapping to control mammal predators is also being attempted as well as plantings of flax, shrubs and native trees to provide shelter and hide these precious penguins of ours (Vernon, 1991).
A threat in the sea is bio-toxins caused by Algal blooms which are eaten by fish, which in turn are eaten by the penguins, causing adult mortality (Moon, 1991). Set and gill nets, along with discarded fishing line associated with fishing companies, collect large numbers of penguins every year, as they have a feeding range of up to 50 km off shore (Vernon, 1991).
If this penguin had received management while they were still common in their ranges, conservation for them today would not be as much of a priority, and would be cheaper for this now endangered species (Wilson, 2004).
Significance for people
The Maori affectionately named this special penguin hoiho, the “noise shouter”, appropriate for their loud, trilling calls (Reilly, 1994; Vernon, 1991).
Wildlife tourism is a major attraction for tourists to New Zealand, with the yellow-eyed penguin being one of the animals people most want to see (Vernon, 1991). To let the public view these special birds in their natural environment, viewing platforms, far removed from their activity, have been set up by the Department of Conservation, to inform and protect the remaining populations from unwitting tourists frightening these timid birds (Vernon, 1991).
The native yellow-eyed penguins live a solitary life, spending the day out at sea feeding and returning to land at nightfall. Most New Zealanders in the South Island would be able to identify these penguins as they have a distinctive crown of yellow feathers encircling their head, along with straw-yellow eyes. They are only found naturally on the south-eastern coasts of New Zealand, Stewart Island and two of our sub Antarctic Islands, Campbell and Auckland, and have been declining in numbers since modification of these landscapes and the introduction of mammalian predators. They are considered endangered, with the possibility of extinction if New Zealanders do not act fast enough to save these beautiful birds for future generations.
Bull, P.C; Gaze, P.O; Robertson, C.J.R. (1985) The atlas of bird distribution in New Zealand. The Ornithological society of New Zealand. New Zealand.
Davis, C.S. (2001) The plight of the penguin. Longacre Press. Dunedin, New Zealand.
Ford, H.A. (1989) Ecology of birds, an Australian perspective. Surrey Beatty & Sons Limited. Australia.
McKinley, B. (2001) hoiho (Megadyptes antipodes) recovery plan 2000 – 2025
Threatened species recovery plan 35. Department of Conservation. Wellington, New Zealand.
Moncrieff, P. (1957) New Zealand birds and how to identify them. Whitcombe & Tombs Limited. Christchurch. New Zealand.
Moon, G. (1991) What New Zealand bird is that? Weldon Publishing. Sydney, Australia.
O’Connor, T. (1999) New Zealand Sub Antarctic Islands. Reed Books. Auckland, New Zealand.
Reilly, P. (1994) Penguins of the world. Oxford Books. Melbourne, Australia. 8: 99-105
Richdale, L.E. (1951) Sexual behavior in penguins. Kansas Press. Kansas, United States of America.
Vernon, A. (1991) The hoiho; New Zealand’s yellow-eyed penguin. G.P Putnam’s Sons. New York, United States of America.
Wilson, K. (2004) Flight of the Huia, Ecology and conservation of New Zealand’s frogs, reptiles, birds and mammals. Canterbury University Press. Christchurch, New Zealand.