Scientific name: Aptenodytes forsteri
Physical description and related species
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.
They can live to more than 40 years. Their closest relatives are king penguins.
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.
Distribution and abundance
Emperor penguins breed in colonies scattered around the Antarctic continent. Colonies range in size from a few hundred to over 20,000 pairs. All but two colonies are situated on the fast-ice (frozen sea) that is locked between islands or grounded icebergs.
For more information see adapting to a changing environment.
Conservation status: least concern
Emperor penguins are the only animals that breed during the Antarctic winter (see breeding cycle).
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.
Diet and feeding
Emperor penguins are exquisite divers! While they mostly forage at depths from 150 to 250 metres, the deepest dive recorded was to 565 metres. On average dives last 3–6 minutes but the longest dive on record was 22 minutes. (See diving and travelling).
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. Most prey items are small; since they are very cold when ingested it makes it easier to bring the food up to body temperature and to digest.
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.
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.