Emperor Penguins

Emperor Penguins

Aptenodytes forsteri

The Emperor is the largest of the penguins and also the only one to breed in Antarctica during the winter months. Male and female Emperor Penguins area very similar size, but the male is slightly heavier. They are around 115cm tall and weighing between 24 & 40kg. (48-99lbs). They are the least common Antarctic Penguin with a population estimated at around 400,000-450,000 with 200,000 breeding pairs. In 2009 scientists from the British Antarctic Survey discovered 10 previously unknown Emperor Penguin colonies from satellite pictures by identifying penguin poo on the spring sea ice as an indicator that there was a colony in that place.

Description

Emperor's Auricular Patch
Studies in New Zealand suggest that the Emperor and King penguins, both Aptenodytes, split from other line of penguins about 40 million years ago. Both have dapper grey backs and black heads and tails, but at a glance the best way to tell them apart is that the King penguin has a Yellow Auricular patch that is closed, forming an upside down teardrop shape while the Emperor Penguin has an open Auricular patch with the yellow bleeding into the yellowy cream breast feathers. The two penguins are not often found in the same habitat.

The Emperor Penguin chick is the world’s most beautiful baby bird with a black head and tail, soft grey down over the rest of the bird and white cheek patches around the dark eyes, they are still cute when nearly half adult size. In 2001 an all white chick was found in a colony in the Ross Sea, Survival rates for chicks are less than 20% in the first year and there have not been any more sightings in subsequent years.

Behavior

Emperor Penguins are sociable birds, they not only form groups for breeding but they also forage in groups. Studies into their diving patterns discovered that they regularly dive to 150m and can stay submerged for nearly 20 minutes. Another strategy that has been recorded is that they make a shallow dive to about 50m and then feed on the fish that they can see silhouetted against the ice as they look up. Well known for the extraordinary feat of the males who incubate their single egg on their feet during the Antarctic winter, these penguins will travel up to 500km (300 miles) from the colony while on trips to find food for their chick. On land the birds alternate between a slow shuffling walk and tobogganing on their bellies. At the Snow Hill Island colony I frequently saw birds slip and fall on the slick ice, which seemed hard when you considered all the other obstacles they overcome.

Emperor Penguin Chick
During the breeding season the birds move to the colony sites appears to be triggered by the shortening days. Birds are serially monogamous with only 15% staying with the same mate as the year before, time is short and waiting for last years partner will diminish chances of raising a chick. The female lays the egg and transfers it to her mate, then nutritionally drained, she heads out to sea to feed for two months. The males sit out the worst of the Antarctic winter, huddled together for warmth. During this time the male will lose almost half of his body weight. The egg hatches after 64 days and if the female hasn’t returned the male manages to feed the hungry chick with a white substance he regurgitates which is high in protein and lipids. When the female returns she has fresh food for the chick and he heads out to sea to feed, returning after about 24 days, from then on they take turns to brood the growing chick until it is large enough to be left unattended, around 40 to 50 days old. Chicks will crèche together at this time if the temperatures drop but mostly they wander in groups, waiting to hear the voice of a returning parent. One of our photographers was at an Emperor Penguin colony during a particularly nasty spell of weather, the chicks were half grown, but I was surprised to see that often it was the adults who were huddled in groups to keep warm while individual chicks wandered around in the wind.

Chicks start to moult into juvenile plumage in November and sometimes still have traces of down when they head out to sea. Leopard seals and Orcas will take adults and chicks at sea and the main predators on land are Giant Petrels and the South Polar Skua, who scavenge the remains of dead penguins.

Range

The range of Emperor Penguins is circumpolar in the Antarctic. They breed almost exclusively on stable sea ice close to the shelter of icebergs and cliffs of ice shelf where they can get shelter from the wind and the sea ice stays in well into the spring. There are only two colonies recorded on land

Status

At present the Emperor penguin is classified as a species of ‘least concern’ but it has been estimated that they could well become victims of Global Warming as the sea ice they rely on diminishes rapidly

Links

Rare White Emperor Chick found

Penguin poo identifies unknown colonies


Text © B & C Alexander