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Emperor penguins are truly amazing birds. They not only survive the Antarctic winter, but they are capable of breeding during the worst weather conditions on earth.

Our research aims to learn more about the penguins themselves (how they live, where they go, what they do, and what they need to survive), and how human activities may impact on their lives and survival chances.

The emperor is the largest of the 17 penguin species growing up to 1.15 metres tall and weighing up to 40 kg.

There emperor penguin colonies are distributed right around the Antarctic continent. Most of the known colonies are located in East Antarctica. Emperors usually breed on the frozen sea and link their breeding cycle to the annual setting and breaking up of the ice.

Emperors are the deepest divers of any bird. They often dive to about 250 m and dives last on average 3–6 minutes. They seem clumsy on land but when they are in water, their shape gives them great agility. They are also very strong birds and their strength and agility make them very effective predators.

Special adaptations to the cold

Nature has provided the emperor with excellent insulation in the form of several layers of scale-like feathers and it takes very strong winds (over 60 knots) to get them ruffled. They have a very small bill and flippers which conserve heat. Their nasal chambers also recover much of the heat that is normally lost during exhalation. Emperor penguins have large reserves of energy-giving body fat and a low level of activity during winter. They are also very social creatures, and one of their survival mechanisms is an urge to huddle together to keep warm. This huddling instinct means that they do not defend any territory. The emperor penguin is the only species of penguin that is not territorial.

Another special adaptation of the emperor penguin is the ability to 'recycle' its own body heat. The emperor's arteries and veins lie close together so that blood is pre-cooled on the way to the bird's feet, wings and bill and warmed on the way back to the heart.

Emperor's feet are adapted to the icy conditions, since they have strong claws for gripping the ice.

Diet

Emperor penguins are near the top of the Southern Ocean's food chain. They have a varied menu with some prey items being more important than others. One of the most frequently eaten prey species is the Antarctic silverfish Pleuragramma antarcticum. They also eat other fish, Antarctic krill and some species of squid.

An adult penguin eats 2–3 kg per day. When they need to fatten up before a moult or at the start of the breeding season, they can eat as much as 6 kg per day.

Breeding adults really have to fill up their stomachs before they return to the colony. They need to feed their chicks and the colonies are often a long way from the fishing grounds.

Each chick needs about 42 kg of food from each parent.

Breeding

Proud parents. Photo: Kirsten Johnston

The emperor has not only evolved special physical characteristics to help it survive the extreme Antarctic conditions, it has also developed some unique social features. Like most penguins, emperor parents closely share parental duties. What is unique about emperors however, is the co-operation between males while carrying out their parenting duties.

The male emperor endures a 115-day ordeal, during which he courts, mates and incubates an egg without eating a single meal. Along with this, he has to cope with wind chill temperatures reaching down to minus 60ºC. The males conserve their energy by huddling together to keep warm.

The female lays her egg in mid-May, then leaves to spend the winter at sea. The male spends the next 65 days with the egg resting on his feet enveloped in a patch of naked skin on his lower abdomen. The egg's incubation chamber is completed by an abdominal fold that is lowered over the egg.

Breeding begins in March and ends in December. This allows the parents to fledge their chicks during summer when the weather is warmer and food is abundant. Read more about breeding...

Huddling

Feeding time. Photo: Cal Young

Emperor penguins have to face freezing winds called katabatic winds, which blow off the polar plateau and intensify the cold. Emperor colonies also face blizzards of up to 200 km/h. To keep warm, the males close ranks to share their warmth. Emperors are big birds, when carrying their incubation fat, they are about as large around the chest as a man. Yet on very cold days, as many as 10 of them pack into every square metre of a huddle. In the huddle, individuals seem to temporarily lose their identity, and the mass of emperors takes on the appearance and behaviour of a single living entity. On a functional level, huddling cuts the heat loss by as much as 50%, and enables males to survive the long incubation fast since the warmer they are, the longer their fat lasts. The temperature inside a huddle can be as high as +24°C.

On a social level, huddling behaviour is an extraordinary act of co-operation in the face of a common hardship, and emperors take this act of group co-operation to its extreme, they take turns to occupy the warmest and coldest positions in the huddle. On windy days, those on the windward edge feel the cold more than those in the centre and down-wind. One by one they peel off the mob and shuffle, egg on feet, down the flanks of the huddle to rejoin it on the lee. They follow one another in a continuous procession, passing through the warm centre of the huddle and eventually returning back to the windward edge. Because of this constant circulation the huddle gradually moves downwind. During a 48 hour blizzard, the huddle may shift as much as 200 m.

Hatching and growing

Emperor chick. Photo: Gary D.

In mid-July, when the female returns, she finds her mate by having memorised his call. The male carefully transfers the egg to the female in about ten seconds. The egg hatches soon after the egg is transferred to the female. An egg or chick accidentally tipped on the snow and abandoned can freeze to death in two minutes. The male then starts the long trip to open water and food. When he feeds again, it will be the first time he has eaten in nearly four months.

Emperor chicks grow quickly because they have only five months to reach the stage where they can fend for themselves. Male and female parents take turns to travel to the sea and return to feed the chick. It takes so long to get to the sea and back that both parents between them can only manage 16 meals in the entire five months of incubating the egg and raising the chick.

Barbara Wienecke, Graham Robertson, Australian Antarctic Division

This page was last modified on January 17, 2012.