THE largest of all penguins, the emperor stands nearly four feet [stands more than a meter] tall and weighs up to 85 pounds [40 kg]. When other penguins head north to escape Antarctica’s brutal, dark winter, emperors head south—for Antarctica! Why? Amazingly, to have their young.
When the female emperor lays her egg, the male quickly scoops it up off the ice and onto his feet. He then tucks it under his brood pouch—a fold of skin on his lower abdomen. The female then heads for the open sea and food. For 65 days, during the harshest of weather, the male incubates the egg while living off his body fat. To preserve body heat while being raked with blizzards that may reach 120 miles [200 km] per hour, these canny birds huddle together in large groups, each one taking its turn on the outside, with its back to the wind.
With incredible timing, the egg hatches just when the female returns. But how does she find her mate among the thousands of look-alikes? By means of a song. During their initial courtship, the pair sang to each other and committed each other’s rendition to memory. When the females return, males and females sing with all their heart. Humans would be thoroughly confused by the cacophony, but the emperors soon find their mates. Then, after reluctantly handing over the newly hatched chick, the near-starving male waddles and belly-slides across some 45 miles of ice in his quest for open water and food.
The Emperor Penguin (Aptenodytes forsteri) is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching 122 cm (48 in) in height and weighing anywhere from 22–37 kg (48–82 lb). The dorsal parts are black and sharply delineated from the white belly, pale-yellow breast and bright-yellow ear patches. Like all penguins, it is flightless, with a streamlined body and wings stiffened and flattened into flippers for a marine lifestyle.
Fish form the bulk of its diet, which can include crustaceans, such as krill, and cephalopods, such as squid. In hunting, the species can remain submerged up to 18 minutes, diving to a depth of 535 m (1,755 ft). It has several adaptations to facilitate this, including an unusually structured haemoglobin to allow it to function at low oxygen levels, solid bones to reduce barotrauma, and the ability to reduce its metabolism and shut down non-essential organ functions.
The Emperor Penguin is perhaps best known for the sequence of journeys adults make each year in order to mate and to feed their offspring. The only penguin species that breeds during the Antarctic winter, it treks 50–120 km (31–75 mi) over the ice to breeding colonies which may include thousands of individuals. The female lays a single egg, which is incubated by the male while the female returns to the sea to forage; parents subsequently take turns foraging at sea and caring for their chick in the colony. The lifespan is typically 20 years in the wild, although observations suggest that some individuals may live to 50 years of age.
The adult Emperor Penguin stands up to 122 cm (48 in) tall and can weigh from 22 to 37 kg (48.5–82 lb), depending on where it is in the reproductive cycle; both male and female penguins lose substantial mass while raising hatchlings and incubating eggs. Like all penguin species, it has a streamlined body to minimise drag while swimming, and wings that have become stiff, flat flippers. The tongue is equipped with rear-facing barbs to prevent prey from escaping when caught. Males and females are similar in size and colouration. The adult has deep black dorsal feathers, covering the head, chin, throat, back, dorsal part of the flippers, and tail. The black plumage is sharply delineated from the light-coloured plumage elsewhere. The underparts of the wings and belly are white, becoming pale yellow in the upper breast, while the ear patches are bright yellow. The upper mandible of the 8 cm (3.1 in) long bill is black, and the lower mandible can be pink, orange or lilac. In juveniles, the auricular patches, chin and throat are white, while its bill is black. The Emperor Penguin chick is typically covered with silver-grey down and has a black head and white mask. A chick with all-white plumage was found in 2001, but was not considered to be an albino as it did not have pink eyes. Chicks weigh around 315 g (11 oz) after hatching, and fledge when they reach about 50% of adult weight.
The Emperor Penguin’s dark plumage fades to brown from November to February, before the yearly moult in January and February. Moulting is rapid in this species compared with other birds, taking only around 34 days. Emperor Penguin feathers emerge from the skin after they have grown to a third of their total length, and before old feathers are lost, to help reduce heat loss. New feathers then push out the old ones before finishing their growth.
The average yearly survival rate of the Emperor Penguin has been measured at 95.1%, with an average life expectancy of 19.9 years. The same researchers estimated that 1% of Emperor Penguins born could feasibly reach an age of 50 years. In contrast, only 19% of chicks survive their first year of life. Therefore, 80% of the Emperor Penguin population comprises adults five years and older.
Vocalization As the species has no fixed nest sites that individuals can use to locate their own partner or chick, the Emperor Penguin must rely on vocal calls alone for identification. It uses a complex set of calls that are critical to individual recognition between parents, offspring, and mates, displaying the widest variation in individual calls of all penguins. Vocalizing Emperor Penguins use two frequency bands simultaneously. Chicks use a frequency-modulated whistle to beg for food and to contact parents.
Adaptations to cold An Emperor Penguin can hold its breath anywhere up to 20 minutes, and dive over 550 meters (1,800 feet)[17]The Emperor Penguin breeds in the coldest environment of any bird species; air temperatures may reach −40 °C (−40 °F), and wind speeds may reach 144 km/h (89 mph). Water temperature is a frigid −1.8 °C (28.8 °F),which is much lower than the Emperor Penguin’s average body temperature of 39 °C (102 °F). The species has adapted in several ways to counteract heat loss. Feathers provide 80–90% of its insulation, and it has a layer of sub-dermal fat which may be up to 3 cm (1.2 in) thick before breeding. Its stiff feathers are short, lanceolate (spear-shaped), and densely packed over the entire skin surface. With around 100 feathers covering 6.5 cm2 (1 in2), it has the highest feather density of any bird species. An extra layer of insulation is formed by separate shafts of downy filaments between feathers and skin. Muscles allow the feathers to be held erect on land, reducing heat loss by trapping a layer of air next to the skin. Conversely, the plumage is flattened in water, thus waterproofing the skin and the downy underlayer. Preening is vital in facilitating insulation and in keeping the plumage oily and water-repellent.
The Emperor Penguin is able to thermoregulate (maintain its core body temperature) without altering its metabolism, over a wide range of temperatures. Known as the thermoneutral range, this extends from –10 to 20 °C (10–70 °F). Below this temperature range, its metabolic rate increases significantly, although an individual can maintain its core temperature between 37.6 and 38.0 °C (99.7–100.4 °F) down to −47 °C (−53 °F). Movement by swimming, walking, and shivering are three mechanisms for increasing metabolism; a fourth process involves an increase in the breakdown of fats by enzymes, which is induced by the hormone glucagon. At temperatures above 20 °C (68 °F), an Emperor Penguin may become agitated as its body temperature and metabolic rate rise to increase heat loss. Raising its wings and exposing the undersides increases the exposure of its body surface to the air by 16%, facilitating further heat loss.
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