Emperor Penguins
The Emperor Penguin is the largest species of penguin measuring up to 4 feet in height (122 cms) with a weight between 25 and 40 kg. They have white bellies and black backs, their flippers are black on one side and white on the other and they also have distinctive yellow markings on their beaks, neck and close to their ears. One of the effects of their black and white colouring is that when swimming they are hard to see from below (looking white) and hard to see from above (looking black). Because of their weight, emperor penguins look cumbersome when walking. They walk with a slow pace and a rolling - almost comical - gait unlike the scampering of the Adelie Penguins. Whenever possible they will flop to their stomachs and, propelling themselves with their flippers, will toboggan over the sea ice.
Their diet is mainly krill and squid and they are able to dive to considerable depths (up to 500 metres) and for a considerable length of time (up to 15 minutes) to find their food. Emperors are best known for their extraordinary and unique breeding behaviour much publicised by the film 'The March of the Penguins' and by Attenborough documentaries. Unlike all other penguin species, the incubation period is during the winter and the birds travel to the colder South to establish their breeding colonies (rookeries).
Most rookeries are on the sea ice itself and therefore have to be recreated each year. The birds must sometimes travel 50 miles or more across the frozen ocean to where courtship and mating takes place. The females lay a single egg, generally in late May, which is the beginning of the Austral winter. The egg is transferred to the male and is lodged in a brood pouch between the feet. The females now begin the long journey back to the open sea to feed whilst the males remain in the rookery to commence the most harsh incubation process of any animal or bird. For the next 2 months, the males remain in the colony, huddling together to preserve warmth whilst the weather conditions turn brutal in the extreme. The temperatures can fall to -70 C, winds can be up to 100 mph and most of the time is total darkness. During this time the emperors have no food and lose sometimes more than 50% of their body weight. The eggs generally hatch at the beginning of August and the chicks' first feed is given to them bythe males. This is a high protein liquid substance produced in the males' throats. The newly hatched chicks remain in the brood pouch as they are covered by only a thin layer of down feathers. Within a few days of hatching, the mother returns - well fed. They recognise their mates by their distinctive calls - a musical trumpeting sound. The chick is transferred from the father's pouch to the mother's and the males then begin theirlong journey to the sea to feed. Meanwhile, the mother can feed the growing chick with regurgitated fish from its very full stomach.
Whilst the chicks grow, the parents take turns in returning to the sea for food and caring for the infant. The chicks quickly grow a thick layer of down feathers and rapidly put on weight. Predators at this stage are birds like skuas and giant petrels. As the sea ice gradually melts with the coming of the summer, the journey to the sea becomes progressively shorter and we can see the explanation for the seemingly strange behaviour of having their rookeries so far from the sea. The chicks are not ready to go to sea until their mesoptile plumage has been shed and their adult plumage grown. This occurs by the beginning of December when the parents go back to sea leaving the chicks to fend for themselves. By now, the ice has melted as far as the colony itself (or very near) so the journey to the sea is very short. Any chicks who do not yet have their adult plumage will now perish. Even those that make it to the water have to overcome the significant danger of being caught by Leopard Seals. Only about 17% of hatched chicks survive to adulthood despite the fact that the breeding process occupies about 9 months of each year for the adult birds.
Those that survive will live happily at sea where they are far more mobile - they can be seen 'porpoising' across the water at spectacular speeds. They have a life expectancy of about 25 years and when about 4 years old will themselves start the annual ritual of returning to their breeding colonies to take their turn as parents of a new generation.
The pictures shown here were taken in October 2006 at the Snow Hill Island Rookery just off the Antarctic Peninsula. This is the most northerly known rookery of emperors and thus enabled us to visit so early in the season. Many of the chicks were less than 8 weeks old. To reach the rookery, our icebreaker (Kapitan Khlebnikov) garaged in the sea ice about 12 miles away from the rookery. We were then transferred to within 2 miles by helicopter (sheltered by large icebergs to ensure the birds were not disturbed). We then completed the trip on foot. Temperatures were as low as -20C and there was sometimes a brisk wind producing an effective temperature including wind chill of -40C.
