GENERAL PENGUIN INFO:
Yellow-eyed Penguins (Megadyptes antipodes) were called Hoiho ("noise-shouter") by the Maori. They are 65 - 70cm tall, the third tallest penguin and weigh between 5 and 6 kg. They can reach the age of 20 - 25 years (oldest known penguin was 32 years) but average life expectancy is closer to 12 - 15 years.
Yellow-eyed Penguins gain their names from their yellow iris and the characteristic yellow head band. They only live in New Zealand and they are one of the rarest penguins in the world with a total population of about 4000-5000 individuals. About one-quarter of these live on the east coast of the South Island and Stewart Island. Most of them live on Campbell and Auckland Islands, about 600 km to the south. The Yellow-eyed Penguin is different from other penguins in many aspects of its biology and it is the only penguin species that does not become tame. They originally nested in the coastal forest, but their distribution is now restricted to forest remnants and coastal shrubs after extensive logging during the last 150 years.
Reproduction
Females become sexually mature at two years and males at three years of age. Both sexes stay fertile until their death and as far as known they breed every year. The pairs are faithful to each other when breeding is successful, but the odd "divorce" does occur (about 7% per year). Each pair holds a large territory around the nest site that is defended very aggressively against intruders. Two eggs are normally laid in the second half of September and both parents share the six-week incubation period equally. The chicks start hatching at the beginning of November and the parents will feed them for three and a half months. On fledging in February, the chicks become independent and are then called juveniles.
Juveniles
They can easily be distinguished from adults by their lack of the yellow head band and their gray iris. After leaving their parents they spend 3 - 4 months at sea learning how to fish and little is known about their whereabouts. About one in three chicks survive the first few months and about half of these will end up breeding. In June, the first ones will be seen ashore again and juveniles will visit many colonies along the coastline in the following months. One year after fledging they moult for the first time and develop the characteristic yellow head band and the yellow iris . . . they are now considered adults.
Moult
All penguins have to moult once a year. Juvenile and non-breeding Yellow-eyed Penguins start their moult in February, the breeding adults will follow suit in March and April after their chicks have left for sea. Old feathers are replaced with new ones during this four-week period and the penguins have to stay out of the water during this time because their plumage is not water resistant. They are thus fasting for the four weeks living off the extra body fat they have accumulated in anticipation of the moult. They will start the moult weighing between 7 and 8kg, by the end of the moult they have lost half their body weight. Penguin feathers become water resistant when the bird stimulates the oil gland at the base of their tail and distributes the oil over the whole body.
Voice
The Maori named the Yellow-eyed Penguin the Hoiho meaning the "noise shouter". Their ‘ecstatic display’ call can be ear-piercing close-up and they use their voices for recognition, territorial claims, courting and threatening. Their monosyllabic inquiry call is also easily recognised.
Senses
The eyes are the best sense in penguins and a membrane enables sharp vision underwater and in air. Their hearing ability is good but their sense of smell is of little importance.
Food
Daily foraging trips usually alone or in pairs take the penguins between 5 and 25 km off the coast. They leave the colony at sun-rise and usually return every evening, but they can stay out over night. Maximum diving depth recorded was 123 m, but the average dive is to about 50 m. Dives are short (2-5 minutes) but continuous with only a few seconds on the surface for a breath of air. They eat mainly sprat, juvenile red cod and also squid, usually between 15 and 25cm long (the record stands at a 35cm blue cod). All prey is swallowed head first and regurgitated to feed the chicks.
