Penguins

24.9.2012
Hannah

New Zealand is the penguin capital of the world. Of the 16 species of living penguins, nine breed in New Zealand or its territories, including the Ross Sea sector of Antarctica, and at least another four are visitors. New Zealand is home to the greatest diversity of penguins, and has more fossil species than any other region. The first and the oldest fossil penguins were found in New Zealand.

New Zealand has six species of penguin, and three more in the part of Antarctica New Zealand administers. Scientists have found bones of penguin ancestors dating back 55 million years. All penguins are protected by law, and five species are endangered.

Flightlessness

Penguins evolved from birds that could fly. Many other seabirds can fly as well as dive, but it is difficult to be good at both. The ancestors of today's penguins became better at diving and lost the ability to fly. This means that they can reach a bigger range of food from deep in the sea.

As the ancestors of penguins evolved into swimmers and divers, they developed special features:

• shorter, powerful wings for flippers
• large, heavy body for deep diving
• insulating feathers to keep them warm
• streamlined shape for fast swimming.

Smaller penguins dive 10–20 metres underwater, and the amazing emperor penguin can dive 100–200 metres looking for fish, krill or squid. But penguins can’t travel as far or as fast as many seabirds that can fly.

Life on land

Penguins can live for many weeks at sea, but some species come ashore every day or so. They also moult and breed on land. When they are nesting in the soil or among rocks, they can go without food for days or weeks.

Little blue penguin

Only 40 centimetres in length, these cute penguins come ashore at night. They nest all around the coast in burrows or caves, and lay two eggs each year.

Yellow-eyed penguin

This species has yellow eyes and a headband of yellow feathers, and breeds on subantarctic islands and in the South Island. Nesting in forests, these rare penguins are endangered by human activities such as farming and fishing.

The crested penguins

There are several species, which all have straggly yellow ‘eyebrows’. They lay two eggs, but only one hatches – no one is certain why. In Fiordland they nest in rainforest.

New Zealand’s antarctic penguins

Penguins breeding in Antarctica include the Adélie penguin and the largest of all, the emperor penguin. Emperors breed on sea ice in the middle of winter, and the males stay to incubate their egg on their feet, going without food for three months.

Northern hemisphere: a penguin-free zone

Penguins are found only in the southern hemisphere.  Firstly, flightlessness is only likely to evolve in places free of predators – especially mammalian ones – such as the isolated islands of New Zealand and the subantarctic. In contrast, being vulnerable to the bears, wolves and other predators of the northern hemisphere makes flight too valuable to give up. Secondly, tropical seas are generally too unproductive and the prey too dispersed, creating a barrier to penguins moving further north.

Modern-day threats

New Zealand and other southern islands and land masses with populations of penguins were not visited or settled by humans until the last few centuries. Once discovered, penguins were hunted for their meat, eggs, skin and oil. Although penguins are not directly preyed on by people any longer, things we introduced continue to threaten their survival: predators such as cats, dogs and mustelids; diseases; and habitat destruction.

Clearing the land for farming removes the vegetation yellow-eyed penguins need to shelter their nests. Indirect threats include pollution, overfishing and – perhaps most insidious – global warming. Periods of elevated sea-surface temperatures during the last 20 years have been associated with reductions in the yellow-eyed penguin’s principal prey species, and with toxic algal blooms that have decreased the survival and success of penguins breeding on the Otago Peninsula.

No Visitors Allowed

Codfish Island, to the west of Stewart Island, is the only place where you can find all three species of New Zealand’s mainland penguins – the yellow-eyed, little blue, and Fiordland crested penguins. But don’t think that it is the perfect place to observe penguins: the island is out of bounds to people for the recovery of the flightless native parrot, the kākāpō.