The Yellow-eyed penguin (scientific name: Megadyptes antipodes) is one of seventeen species of flightless birds in the family of penguins. This bird is endemic to specific New Zealand coasts and islands, and the species viability is limited by the quality and quantity of its terrestrial breeding habitat. The species population has been successively reduced over the last millennium by arrival of Maori peoples who destroyed considerable breeding habitat by deforestation, followed by European introduction of massive livestock grazing enterprises. This species is the sole member of genus Megadyptes.
Like all penguins, the Yellow-eyed penguin is characterized by its erect posture, stiff wings (flippers), excellent swimming ability, awkward movement out of water, and colouring. The characteristic yellow eye-ring leads to the species appellation. The black back and white front, make penguins difficult to see when swimming, blending against the sea from above and the sky from below.
Yellow-eyed penguin. Source: Christian Mehlführer
The yellow-eyed penguin is one of the most endangered of all penguin species. These birds are slate gray with a white breast. As their common name suggests they have yellow eyes, accentuated by the yellow band that runs from the eyes around the back of the head. Males and females are identical, but juveniles lack the yellow eyes and bands of mature birds. The Maori name for these birds is Hoiho, which means 'the noise shouter' in reference to their shrill call.
The Yellow-eyed penguin is a tall and slender penguin. It stands just over 60 centimetres and has body mass of five to eight kilograms.
Males and females appear similar, but males often have a larger head and feet. The Yellow-eyed penguin only varies in appearance during the molting season, when feathers are being replaced. Juveniles have gray and not yellow eyes; the yellow feathers are usually absent or muted also. The rest of the body is a downy gray or dark brown. The Yellow-eyed penguin is the fourth largest penguin in the world
Yellow-eyed penguins are not particularly sociable, breeding in spaced-out territories in the forest rather than the close-knit colonies of other species of penguins.The Yellow-eyed penguin begins its breeding season in August with the selection of mates and nest sites. Prior to August, beginning in approximately May, the Yellow-eyed penguin begins the courting season. Pairs of Yellow-eyed penguins usually remain allied for years, only parting when one dies or there is a failure to raise a family.
When the penguins mate, the male mounts the female and rests his neck on the back of hers and vibrates his flippers along her sides. The male fertilizes two eggs that have already developed inside the female. Twelve days later the female lays the eggs in mid-September to mid-October on a nest constructed from sticks, typically in a burrow or other enclosed space.
The Yellow-eyed penguin has an incubation period that ranges between 39 and 51 days. Both parents participate in incubation of the eggs. For six weeks after hatching, the chicks are guarded. One parent will stay at the nest while the other dives for food in the ocean. After the chicks are six weeks old, both parents will hunt for food in the ocean, leaving the chicks on their own. Chicks usually leave the nest in mid-February. The Yellow-eyed penguin reaches sexual maturity at age two or three for females and three to five years for males.
An average life span of the Yellow-eyed penguin is 23 years.
The Yellow-eyed penguin molts once a year, but during this time they need to remain on land while the feathers are replaced. The three-week molt takes place in February and March, following the fledging of the chicks. This penguin species needs to accumulate considerable resources before this process takes place, since they can loose up to four kilograms of body weight during the molt. Yellow-eyed penguins feed on a variety of fish including red cod, opal fish, sprat and silversides. They tend to forage within 15 kilometers of the shore and can achieve diving depths of up to 160 metres.
Unlike other penguin species, the Yellow-eyed penguin is not a colonially nesting species. Pairs usually seek privacy for their nests. This bird does not socialize very much with penguins other than its mate. The only social times are during mating rituals and after molting.
During mating periods, the Yellow-eyed penguin congregates with other individuals in order to select a mate. Certain calls and body language evince whether mates are interested in a given overture. In the weeks after molting, the Yellow-eyed penguin returns to the sea in one of the most social times of the year. During molting individuals can lose up to four kilograms of body mass. All individuals then return to the sea to regain this lost weight. While there, it feeds, and also preens the new feathers. It avoids confrontations by turning its back and preening. Individuals usually hunt alone or in groups of two or three. They are strong swimmers and can outswim most predators in the sea.
The yellow-eyed penguin is found in the New Zealand sub-Antarctic regions. It is found on the southeast coast of South Island (south of and including the southern coast of the Otago Peninsula) and in the coastal forests of Stewart Island. It can also be found on Auckland and Campbell Islands.
The yellow-eyed penguin nests by constructing burrows in the coastal forest soils of New Zealand. It prefers secluded spots that are often backed by a tree or log. Couples will not generally nest within sight of other members of their species. Often the uneven coastal topography of their habitat assists in providing screening from other pairs; preferred habitat also has shrub and tree components, which further assist in this privacy function.
The Yellow-eyed penguin is a carnivore, chiefly feeding on fish and squid caught whilst diving. It is especially fond of red cod, opal fish, sprat, silversides, ahuru and blue cod. While the bulk of consumption is fish, cephalopods comprise approximately ten percent of the Yellow-eyed penguin diet.
The Yellow-eyed penguin is classified as an endangered species. A 1992 estimate concluded that the entire population of 5,930 to 6,970 individuals lived in New Zealand; however, more recent estimates place the total population of the species at approximately 1600 members, making it one of the rarest of the penguins. Moreover, not all of these birds are breeders. Declines in numbers of Megadyptes antipodes are attributed to destruction of habitat, fires, overgrazing, predation and marine food shortages. Humans and livestock also disturb this penguin. Predators of Megadyptes antipodes include feral cats, ferrets, stoats and domestic dogs.
Considerable effort is being made to conserve the Yellow-eyed penguin. The Yellow-Eyed Penguin Trust has set out to protect the animals' habitat, create reserves, fence in breeding areas and control predators. The New Zealand Department of Conservation in conjunction with the Royal Forest and Bird Protection Society has also committed to assist the Yellow Eyed Penguin Trust. This species is protected under law by the Wildlife Act of 1953.
Specific activities that are being conducted include protection of key coastal nesting areas, reforestation of these prime areas used for burrows, supplementing nest opportunities by providing nesting boxes and trapping predators such as stoats and ferrets; moreover, trapping of such invasive carnivores is conducted in many areas of New Zealand for the protection of a number of indigenous bird species. There are also limited facilities that have been developed for rehabilitating injured Yellow-eyed penguins and veterinary care on the Otago Peninsula of South Island, New Zealand .
The Yellow-eyed penguin may be considered the rarest penguin in the world. In the years 1986 and 1990 there were two major population crashes, the causes of which remain incompletely understood.
Large tracts of the coastal forests of their habitat, particularly of mainland South Island New Zealand, have been destroyed to make way for development and agriculture. Introduced sheep and cattle pose a threat as they can trample on penguin nests and overgraze the area, destroying and further fragmenting habitat. Currently, there is pressure for residential and commercial development on some of the coastal habitat areas, although historically agriculture, particularly livestock grazing, has been the greatest threat to habitat.
The other major threat to the yellow-eyed penguin comes from introduced mammalian predators such as ferrets, cats, rats and dogs; juvenile penguins or adults during their molt phase are extremely vulnerable to predation, since none of these terrestrial mammalian predators were present during the species evolution in New Zealand. Consequently, the species population has been decimated over the last two centuries since alien predator species have been introduced by humans.
Economic importance for humans
The yellow-eyed penguin attracts many tourists to New Zealand. The species is also of importance to scientists, since the bird is thought to be the most ancient species of penguin.
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