Adelie Penguin

Adelie Penguin
Adelie Penguin

Penguins are found in Antarctica, but not the Arctic, and are not, as is often thought, restricted to the frozen land and sea. Various species of penguin live around the coasts of South America, Africa and Australasia, usually not going far north but staying where the sea is still quite cool. The exception to this is the Peruvian penguin which can be found right along the coasts of Chile and Peru, where a cold current of water sweeps up towards the Equator. The Galapagos penguin lives even on the Galapagos Islands, just on the Equator.

With the emperor penguin, the Adélie is confined to the Antarctic continent and its neighbouring islands. Other species, including the chinstrap, gentoo and macaroni penguins, live around the fringes of the continent and on the islands, but their main breeding grounds are farther to the north, in sub-Antarctic and temperate latitudes.

The penguin is a flightless gregarious bird; a superb swimmer, it is completely adapted to life in water; the wings having evolved into flippers, and the body become covered with a protective layer of blubber. Its progress on land seems comically clumsy when compared with the efficient grace with which it moves through the water.

Many penguins have distinctive colouring around the head, sometimes with plumes or crests of orange feathers. But the Adélie penguin, which stands about 18 in, tall, is simply coloured, with a white belly and black back and throat. The eye is distinguished by a surrounding circle of white that gives the bird the appearance of a golliwog.

Antarctic environment

On a September or October day on the edge of the Antarctic continent, with the sea frozen as far as the eye can see, quite suddenly, a line of dots might appear, moving in a straight line across the ice. Each dot seems to be gliding along as if pulled by a string, until it reaches a crack in the ice when some of the dots suddenly change shape. A closer inspection would show them to be Adélie penguins which have been tobogganing over the ice on their bellies, using their feet and flippers to propel themselves. When they reached the crack they stood up to get a better view across it. After a bit of jostling they walk to the edge of the crack, waddling on their ridiculously short legs, and holding out their flippers for balance. Eventually they jump across and resume their slow progress.

These penguins are on their way to the nesting grounds, or rookeries, where they nest in thousands. They have spent the long winter on the edges of the frozen seas where there is an abundance of food and they are now in prime condition, their bodies padded with half an inch of blubber and their feathers sleek and glossy. At first the groups consist of a dozen or so penguins, but they increase in numbers until streams of penguins are flowing in towards the rookeries.

From rookery to crèche

At the rookery, which is usually situated on a rocky headland, each penguin searches for its old nest, or if it is breeding for the first time, finds an empty space. The nests are still covered with snow, but the penguins know exactly where to look for them. The males usually arrive first and they stand on the nest, fighting off other males and waiting for their mates. They have a special display that at once intimidates other males and attracts females. It is called the ‘ecstatic display’: the penguin points his bill to the sky, waves his flippers to and fro and utters a loud braying call.

When all the penguins have arrived and the pairs have formed it can be seen that each penguin sitting on its future nest is exactly the same distance from each of its neighbours. This even spreading ensures that they do not interfere with each other too much and that the eggs and chicks will not be disturbed. Occasionally a penguin does get in the way of its neighbours and a fight breaks out. Penguins fight by pecking and by beating with their flippers.

When the snow melts, nest-building can begin. The male collects pebbles which he takes one at a time to the female, who remains standing on the nest site. He drops each pebble in turn at her feet and she uses them to build up a ring around her. Usually the pebbles are laboriously collected from the beach, but the penguins miss no chance to steal them from any unguarded nest.

Two white eggs, each 2 in. long, are laid in the nest of pebbles; the male broods them while the female goes back to the sea to feed for she will not have eaten for two or three weeks. A fortnight later she returns, while the male goes off to break his fast of some six weeks, during which he will have lost almost half his weight. The eggs hatch after 36 days and for the first few days the chicks stay under their parents.

While one parent is guarding the chicks the other collects food for them, returning with it stored in the crop where it is partly digested. Reaching the nest, the adult penguin opens its beak to the chick. The chick then pushes its head into the adult’s mouth to take the food that is disgorged.

The chicks grow rapidly, coming out from under the parents to stand by the nest. Then, when a month old, they leave the nest to gather in groups called crèches, from the French word for public nurseries. It was once thought that the adult penguins that stood, around the crèches were special guardians, looking after the chicks while the parents were away feeding; but it is now known that they are birds that have lost their eggs and are just standing around.

Once the chicks have joined the circles the adults do not simply walk up and feed them. Instead they lead the chicks away from the crèche, making them run over the rocks and then make their way back again after they have been fed. One function of this is to introduce the chicks to the outside world; for soon they will be leaving the crèche and taking to the sea.

Crustacean feeder

It is at first sight surprising to find colonies of thousands of penguins in the apparently desolate wastes of the Antarctic; but in contrast with the land, the Antarctic seas are teeming with life-especially with the small shrimp-like creatures such as amphipods and krill on which the penguins, as well as the seals and whales, feed. The reason for this abundance of food lies in the circulation of the oceans. Moving southwards toward Antarctica, there is a current that flows along the ocean beds. In it are the salts, such as phosphates and nitrates, that are brought down to the seas in rivers and are also released when dead animals from the surface layers sink and decompose. On reaching the cold Antarctic this warm current, rich in nutrient salts, wells up to the surface and the salts nourish myriads of minute planktonic plants. These in turn nourish the small animals on which the penguins feed.

Skua and leopard seal enemies

There are no land animals in the Antarctic to menace the rookeries, but a predatory sea bird, the great skua, breeds near the rookeries, and takes the eggs and chicks of the penguins whenever the opportunity arises. They wait for a penguin to neglect its eggs for a second and swoop down to carry one away in the bill. Sometimes a pair of skuas will work together, one attracting the penguin’s attention while the other sneaks up behind to steal an egg. Later, the skuas wait around the crèches for a chick to become separated from its fellows. The skuas are unable to kill a healthy chick but can harass a weakened one until it succumbs.

Both adults and the young are in danger from leopard seals as they enter the water. Again a healthy alert bird will probably be safe from them and the seals have to be content with chasing weakly penguins.

Selfish and callous?

There is a story of Adélie penguins which seems to credit them not only with a high level of intelligence but with a selfishness that is rivalled only by the most callous of humans. The story as usually told is that the penguins will go to the edge of the ice, line up along it and then push one of their number into the water. If that one comes to the surface again all go in, because they then know there are no leopard seals about. If the unfortunate one that has been ducked does not surface, they know a leopard seal has eaten it and all turn round and walk away, postponing their fishing until later.

On the face of it this seems too extraordinary a story to swallow, and yet it has been reported again and again even by serious zoologists. It seems the story was brought back by the early Antarctic explorers and particularly by Ponting, the photographer on Scott’s expedition to the Antarctic, who lectured widely on his return.

A simpler explanation is much more likely. When a crowd of penguins are walking across the ice and come to an obstacle, for example, a wide crack in the ice, all will stop and inspect it. There is a good deal of jostling, and any penguin that is pushed to the edge tries to get away and run round to the back of the crowd. They may even do the same if they come to a hump in the ice. After this exploration one of them will in due course jump across the crack and the others stream after it: penguins tend to behave like a flock of sheep and will stand around until one of them starts moving.

It is easy to see that if this sort of thing happened at the edge of the ice a penguin might go into the water of its own volition; but it might look as if it had been pushed. Anyone seeing this, who did not have the advantage of the increased knowledge of penguins and of animal behaviour that we have today could very readily misinterpret what he had seen.

Pictures of Adelie Penguin

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