Emperor Penguin

Emperor Penguin

Overview
The Emperor Penguin is the tallest and heaviest of all living penguin
Penguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...

 species and is endemic
Endemism in birds
An endemic bird area is a region of the world that contains two or more restricted-range species, while a "secondary area" contains one or more restricted-range species. Both terms were devised by Birdlife International....

 to Antarctica. The male and female are similar in plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

 and size, reaching 122 cm (48 in) in height and weighing anywhere from 22 to 45 kg (48.5 to 99.2 lb). The dorsal side and head are black and sharply delineated from the white belly, pale-yellow breast and bright-yellow ear patches.
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Encyclopedia
The Emperor Penguin is the tallest and heaviest of all living penguin
Penguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...

 species and is endemic
Endemism in birds
An endemic bird area is a region of the world that contains two or more restricted-range species, while a "secondary area" contains one or more restricted-range species. Both terms were devised by Birdlife International....

 to Antarctica. The male and female are similar in plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

 and size, reaching 122 cm (48 in) in height and weighing anywhere from 22 to 45 kg (48.5 to 99.2 lb). The dorsal side and head 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 habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

.

Its diet consists primarily of fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, but can also include crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, such as krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...

, and cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...

s, such as squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...

. 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 hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...

 to allow it to function at low oxygen levels, solid bones to reduce barotrauma
Barotrauma
Barotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding fluid...

, and the ability to reduce its metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

 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 – 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 feed; 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.

Taxonomy


The Emperor Penguin was described in 1844 by English zoologist George Robert Gray
George Robert Gray
George Robert Gray FRS was an English zoologist and author, and head of the ornithological section of the British Museum, now the Natural History Museum, in London for forty-one years...

, who created its generic name
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 from Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

 word elements, ἀ-πτηνο-δύτης [a-ptēno-dytēs], "without-wings-diver". Its specific name is in honour of the German naturalist Johann Reinhold Forster
Johann Reinhold Forster
Johann Reinhold Forster was a German Lutheran pastor and naturalist of partial Scottish descent who made contributions to the early ornithology of Europe and North America...

, who accompanied Captain James Cook
James Cook
Captain James Cook, FRS, RN was a British explorer, navigator and cartographer who ultimately rose to the rank of captain in the Royal Navy...

 on his second Pacific Voyage and officially named five other penguin species.

Together with the similarly coloured but smaller King Penguin
King Penguin
The King Penguin is the second largest species of penguin at about , second only to the Emperor Penguin. There are two subspecies—A. p. patagonicus and A. p...

 (A. patagonicus), the Emperor Penguin is one of two extant species in the genus Aptenodytes
Aptenodytes
The genus Aptenodytes contains two extant species of penguins collectively known as "the great penguins".-Taxonomy:...

. Fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 evidence of a third species—Ridgen's Penguin
Ridgen's Penguin
Aptenodytes ridgeni, occasionally called Ridgen's Penguin, is an extinct species of penguin from the Early Pliocene of New Zealand. It was intermediate in size between its living congeners, standing an estimated 90–100 cm tall....

 (A. ridgeni)—has been found in fossil records from the late Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

, about three million years ago, in New Zealand. Studies of penguin behaviour and genetics have proposed that the genus Aptenodytes is basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...

; in other words, that it split off from a branch which led to all other living penguin species. Mitochondrial and nuclear
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...

 DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 evidence suggests this split occurred around 40 million years ago.

Description


The adult Emperor Penguin stands up to 122 cm (48 in) tall. The weight ranges from 22.7 to 45.4 kg (50 to 100.1 lb) and varies by sex, with males weighing more than
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

 females. The weight also varies by season, as both male and female penguins lose substantial mass while raising hatchlings and incubating
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...

 eggs. A male Emperor penguin must withstand the Antarctic cold for more than two months to protect his eggs from extreme cold. During this entire time he doesn't eat a thing. Most male penguins will lose about 12 kg (26.5 lb) while they wait for their babies to hatch. The mean weight of males at the start of the breeding season is 38 kg (83.8 lb) and that of females is 29.5 kg (65 lb). After the breeding season this drops to 23 kg (50.7 lb) for both sexes.

Like all penguin species, the Emperor 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
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...

 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 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
Down feather
The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator and padding, used in goods such as jackets, bedding,...

 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
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...

 when they reach about 50% of adult weight.

The Emperor Penguin's dark plumage fades to brown from November until February, before the yearly moult
Moult
In biology, moulting or molting , also known as sloughing, shedding, or for some species, ecdysis, is the manner in which an animal routinely casts off a part of its body , either at specific times of year, or at specific points in its life cycle.Moulting can involve the epidermis , pelage...

 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 hatched 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



The Emperor Penguin breeds in the coldest environment of any bird species; air temperatures may reach -40 °C, and wind speeds may reach 144 km/h (89 mph). Water temperature is a frigid -1.8 °C, 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. This resultant blubber layer impedes the mobility of the Emperor on land compared to its less well fat-insulated cousin, the Magellanic Penguin
Magellanic Penguin
The Magellanic Penguin, Spheniscus magellanicus, is a South American penguin, breeding in coastal Argentina, Chile and the Falkland Islands, with some migrating to Brazil where they are occasionally seen as far north as Rio de Janeiro. It is the most numerous of the Spheniscus penguins. Its nearest...

. Its stiff feathers are short, lanceolate (spear-shaped), and densely packed over the entire skin surface. With around 100 feathers covering one square inch (15 feathers per cm2), 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
Thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different...

 (maintain its core body temperature) without altering its metabolism, over a wide range of temperatures. Known as the thermoneutral range, this extends from -10 C. Below this temperature range, its metabolic rate increases significantly, although an individual can maintain its core temperature from 38 °C (100.4 °F) down to -47 °C. 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
Glucagon
Glucagon, a hormone secreted by the pancreas, raises blood glucose levels. Its effect is opposite that of insulin, which lowers blood glucose levels. The pancreas releases glucagon when blood sugar levels fall too low. Glucagon causes the liver to convert stored glycogen into glucose, which is...

. 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.

Adaptations to pressure and low oxygen



In addition to the cold, the Emperor Penguin encounters another stressful condition on deep dives —markedly increased pressure of up to 40 times that of the surface, which in most other terrestrial organisms would cause barotrauma
Barotrauma
Barotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding fluid...

. The bones of the penguin are solid rather than air-filled, which eliminates the risk of mechanical barotrauma. However, it is unknown how the species avoids the effects of nitrogen-induced decompression sickness
Decompression sickness
Decompression sickness describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurization...

.

While diving, the Emperor Penguin's oxygen use is markedly reduced, as its heart rate is reduced to as low as 15-20 beats per minute and non-essential organs are shut down, thus facilitating longer dives. Its hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...

 and myoglobin
Myoglobin
Myoglobin is an iron- and oxygen-binding protein found in the muscle tissue of vertebrates in general and in almost all mammals. It is related to hemoglobin, which is the iron- and oxygen-binding protein in blood, specifically in the red blood cells. The only time myoglobin is found in the...

 are able to bind and transport oxygen at low blood concentrations; this allows the bird to function with very low oxygen levels that would otherwise result in loss of consciousness.

Distribution and habitat


The Emperor Penguin has a circumpolar distribution in the Antarctic almost exclusively between the 66° and 77° south latitudes. It almost always breeds on stable pack ice near the coast and up to 18 km (11 mi) offshore. Breeding colonies are usually located in areas where ice cliffs and icebergs shelter them from the wind. The total population is estimated at around 400,000–450,000 individuals, which are distributed among as many as 40 independent colonies.
Around 80,000 pairs breed in the Ross Sea
Ross Sea
The Ross Sea is a deep bay of the Southern Ocean in Antarctica between Victoria Land and Marie Byrd Land.-Description:The Ross Sea was discovered by James Ross in 1841. In the west of the Ross Sea is Ross Island with the Mt. Erebus volcano, in the east Roosevelt Island. The southern part is covered...

 sector. Major breeding colonies are located at Cape Washington (20,000–25,000 pairs), Coulman Island
Coulman Island
Coulman Island is an ice-covered island, composed of several connected shield volcanos in the Ross Sea off Antarctica. The Coulman caldera, wide and deep, can be found on the south end of the island. Emperor penguins inhabit this island. Coulman Island lies within the boundaries of Ross...

 in Victoria Land
Victoria Land
Victoria Land is a region of Antarctica bounded on the east by the Ross Ice Shelf and the Ross Sea and on the west by Oates Land and Wilkes Land. It was discovered by Captain James Clark Ross in January 1841 and named after the UK's Queen Victoria...

 (around 22,000 pairs), Halley Bay, Coats Land
Coats Land
Coats Land is a region in Antarctica which lies westward of Queen Maud Land and forms the eastern shore of the Weddell Sea, extending in a general northeast-southwest direction between 20º00´W and 36º00´W. The northeast part was discovered from the Scotia by William S. Bruce, leader of the Scottish...

 (14,300–31,400 pairs), and Atka Bay in Queen Maud Land
Queen Maud Land
Queen Maud Land is a c. 2.7 million-square-kilometre region of Antarctica claimed as a dependent territory by Norway. The territory lies between 20° west and 45° east, between the British Antarctic Territory to the west and the Australian Antarctic Territory to the east. The latitudinal...

 (16,000 pairs). Two land colonies have been reported: one on a shingle spit at Dion Island on the Antarctic Peninsula
Antarctic Peninsula
The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands....

, and one on a headland at Taylor Glacier
Taylor Glacier
The Taylor Glacier is an Antarctic glacier about long, flowing from the plateau of Victoria Land into the western end of Taylor Valley, north of the Kukri Hills, south of the Asgard Range...

 in the Australian Antarctic Territory
Australian Antarctic Territory
The Australian Antarctic Territory is a part of Antarctica. It was claimed by the United Kingdom and placed under the authority of the Commonwealth of Australia in 1933. It is the largest territory of Antarctica claimed by any nation...

. Vagrants have been recorded on Heard Island
Heard Island and McDonald Islands
The Heard Island and McDonald Islands are an Australian external territory and volcanic group of barren Antarctic islands, about two-thirds of the way from Madagascar to Antarctica. The group's overall size is in area and it has of coastline...

, South Georgia
South Georgia and the South Sandwich Islands
South Georgia and the South Sandwich Islands is a British overseas territory and overseas territory of the European Union in the southern Atlantic Ocean. It is a remote and inhospitable collection of islands, consisting of South Georgia and a chain of smaller islands, known as the South Sandwich...

, and in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

.

Conservation status



The Emperor Penguin is listed as a species of "least concern" by the IUCN
World Conservation Union
The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...

. Along with nine other species of penguin, it is currently under consideration for inclusion under the US Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...

. The primary reasons for this are declining food availability due to the effects of climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

 and industrial fisheries on the crustacean and fish populations. Other reasons for their potential placement on this list include disease, habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...

, and disturbance at breeding colonies by humans. Of particular concern is the impact of tourism. One study has shown Emperor Penguin chicks in a créche to become more apprehensive following helicopter approach to 1000 m (3,281 ft).

Population declines of 50% in the Terre Adélie
Adélie Land
Adélie Land is the portion of the Antarctic coast between 136° E and 142° E , with a shore length of 350 km and with its hinterland extending as a sector about 2,600 km toward the South Pole. It is claimed by France as one of five districts of the French Southern and Antarctic Lands, although not...

 region have been observed due to increased adult mortality, especially of males, during an abnormally prolonged warm period in the late 1970s, which resulted in reduced sea-ice coverage. On the other hand, egg hatching success rates declined when the sea-ice extent increased. The species is therefore considered to be highly sensitive to climatic changes.

A Woods Hole Oceanographic Institution
Woods Hole Oceanographic Institution
The Woods Hole Oceanographic Institution is a private, nonprofit research and higher education facility dedicated to the study of all aspects of marine science and engineering and to the education of marine researchers. Established in 1930, it is the largest independent oceanographic research...

 study in January 2009 found Emperor Penguins could be pushed to the brink of extinction by the year 2100 due to global climate change. By applying mathematical models to predict how the loss of sea ice from climate warming would affect a big colony of Emperor Penguins at Terre Adélie, Antarctica, they forecast a decline of 87% in the colony's population by the end of the century, from the current 3,000 breeding pairs in the colony to 400 breeding pairs. The decline may be mirrored in the whole Emperor Penguin population, estimated at about 200,000 breeding pairs.

In 2009, satellite images of areas of excrement-stained ice that are large enough to be visible from space helped scientists to discover ten previously unknown emperor penguin colonies in Antarctica.

Behaviour



The Emperor Penguin is a social animal
Social animal
A social animal is a loosely defined term for an organism that is highly interactive with other members of its species to the point of having a recognizable and distinct society.All mammals are social to the extent that mothers and offspring bond...

 in its nesting and its foraging behaviour; birds hunting together may coordinate their diving and surfacing. Individuals may be active day or night. A mature adult travels throughout most of the year between the nesting area and ocean foraging areas; the species disperses into the oceans from January to March.

The American physiologist
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...

 Gerry Kooyman revolutionized the study of penguin foraging behaviour in 1971 when he published his results from attaching automatic dive-recording devices to Emperor Penguins. He found that the species reaches depths of 265 m (869 ft), with dive periods of up to 18 minutes. Later research revealed a small female had dived to a depth of 535 m (1,755 ft) near McMurdo Sound
McMurdo Sound
The ice-clogged waters of Antarctica's McMurdo Sound extend about 55 km long and wide. The sound opens into the Ross Sea to the north. The Royal Society Range rises from sea level to 13,205 feet on the western shoreline. The nearby McMurdo Ice Shelf scribes McMurdo Sound's southern boundary...

. It is possible that the Emperor Penguin can dive even deeper, as the accuracy of the recording devices is diminished at greater depths. Further study of one bird's diving behaviour revealed regular dives to 150 m (492.1 ft) in water around 900 m (2,952.8 ft) deep, and shallow dives of less than 50 m (164 ft), interspersed with deep dives of more than 400 m (1,312.3 ft) in depths of 450 to 500 m (1,476.4 to 1,640.4 ft). This was suggestive of feeding near or at the sea bottom.

Both male and female Emperor Penguins forage for food up to 500 km (311 mi) from colonies while collecting food to feed chicks, covering 82–1454 km (51–903.5 mi) per individual per trip. A male returning to the sea after incubation heads directly out to areas of permanent open water, known as polynya
Polynya
A polynya or polynia is an area of open water surrounded by sea ice. It is now used as geographical term for an area of unfrozen sea within the ice pack. It is a loanword from , , which means a natural ice hole, and was adopted in the 19th century by polar explorers to describe navigable...

s, around 100 km (62 mi) from the colony.

An efficient swimmer, the Emperor Penguin exerts pressure with both its upward and downward strokes while swimming. The upward stroke works against buoyancy and helps maintain depth. Its average swimming speed is 6–9 km/h (4–6 mph). On land, the Emperor Penguin alternates between walking with a wobbling gait and tobogganing—sliding over the ice on its belly, propelled by its feet and wing-like flippers. Like all penguins, it is flightless.

As a defence against the cold, a colony of Emperor Penguins forms a compact huddle (also known as the turtle formation) ranging in size from ten to several hundred birds, with each bird leaning forward on a neighbour. Those on the outside upwind tend to shuffle slowly around the edge of the formation and add themselves to its leeward edge, producing a slow churning action, and giving each bird a turn on the inside and on the outside.

Diet


The Emperor Penguin's diet consists mainly of fish, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s and cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...

s, although its composition varies from population to population. Fish are usually the most important food source, and the Antarctic silverfish
Antarctic silverfish
The Antarctic Silverfish, Pleuragramma antarcticum is a member of the suborder Notothenioidei of the Perciform fishes.Pleuragramma antarcticum is a keystone species in the ecosystem of the Southern Ocean....

 (Pleuragramma antarcticum) makes up the bulk of the bird's diet. Other prey commonly recorded include other fish of the family Nototheniidae
Nototheniidae
The cod icefishes or nothothens are the family Nototheniidae of acanthopterygian fishes, containing about 50 species in 13 genera. They are traditionally placed in the perciform assemblage together with their relatives, but like every lineage in the "Perciformes" their actual relationships are not...

, the Glacial Squid
Glacial Squid
The Glacial Squid is the only known species in the monotypic genus Psychroteuthis, in the family Psychroteuthidae. While only one species has been confirmed, it is possible that two undescribed species also exist. The species occurs in coastal waters near Antarctica and South America. It grows to...

 (Psychroteuthis glacialis), and the hooked squid
Hooked squid
The family Onychoteuthidae currently comprises approximately 20–25 species , in 6 or 7 genera. They range in mature mantle length from 7 cm to a suggested length of 2 m for the largest member, the Robust Clubhook Squid...

 species Kondakovia longimana
Kondakovia longimana
Kondakovia longimana, also known as the Giant Warty Squid or Longarm Octopus Squid, is a large species of hooked squid. It attains a mantle length of at least 85 cm and probably over 1.15 m. The largest complete specimen of this species, measuring 2.3 m in total length, was found in Antarctica in...

, as well as Antarctic krill
Antarctic krill
Antarctic krill, Euphausia superba, is a species of krill found in the Antarctic waters of the Southern Ocean. It is a shrimp-like crustacean that lives in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic metre...

 (Euphausia superba). The Emperor Penguin searches for prey in the open water of the Southern Ocean
Southern Ocean
The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...

, in either ice-free areas of open water or tidal cracks in pack ice. One of its feeding strategies is to dive to around 50 m (164 ft), where it can easily spot sympagic
Sympagic
A sympagic environment is one where water exists mostly as a solid, ice, such as a polar ice cap or glacier. Solid sea ice is permeated with channels filled with salty brine. These briny channels and the sea ice itself have its ecology, referred to as "sympagic ecology".Residents of temperate or...

 fish like the Bald notothen
Bald notothen
The bald notothen is a cryopelagic fish of the Southern Ocean. Antifreeze proteins in its blood prevent it freezing in the sub-zero water temperatures of Antarctica...

 (Pagothenia borchgrevinki) swimming against the bottom surface of the sea-ice; it swims up to the bottom of the ice and catches the fish. It then dives again and repeats the sequence about half a dozen times before surfacing to breathe.

Predators



The Emperor Penguin's predators include birds and aquatic mammals. The Southern Giant Petrel
Southern Giant Petrel
The Southern Giant Petrel , also known as the Antarctic Giant Petrel, Giant Fulmar, Stinker, and Stinkpot, is a large seabird of the southern oceans. Its distribution overlaps broadly with the similar Northern Giant Petrel, though it overall is centered slightly further south...

 (Macronectes giganteus) is the predominant land predator of chicks, responsible for up to 34% of chick deaths in some colonies though they often scavenge dead penguins as well. The South Polar Skua
South Polar Skua
The South Polar Skua, Stercorarius maccormicki, is a large seabird in the skua family Stercorariidae. An older name for the bird is MacCormick’s Skua, after explorer and naval surgeon Robert McCormick, who first collected the type specimen...

 (Stercorarius maccormicki) mainly scavenges for dead chicks, as the live chicks are too large to be attacked by the time of its annual arrival in the colony.

The known aquatic predators are both mammals: the Leopard Seal
Leopard Seal
The leopard seal , also referred to as the sea leopard, is the second largest species of seal in the Antarctic...

 (Hydrurga leptonyx), which takes some adult birds, as well as fledglings soon after they enter the water, and the Orca
Orca
The killer whale , commonly referred to as the orca, and less commonly as the blackfish, is a toothed whale belonging to the oceanic dolphin family. Killer whales are found in all oceans, from the frigid Arctic and Antarctic regions to tropical seas...

 (Orcinus orca), which takes adult birds.

If one of a breeding pair dies or is killed during the breeding season, the surviving parent must abandon its egg or young and go back to the sea to feed.

Courtship and breeding


The Emperor Penguin is able to breed at around three years of age, and usually commences breeding around one to three years later. The yearly reproductive cycle begins at the start of the Antarctic winter, in March and April, when all mature Emperor Penguins travel to colonial nesting areas, often walking 50 to 120 km (31.1 to 74.6 mi) inland from the edge of the pack ice. The start of travel appears to be triggered by decreasing day lengths; Emperor Penguins in captivity have been induced successfully into breeding by using lighting systems mimicking seasonal Antarctic day lengths.

The penguins start courtship
Courtship
Courtship is the period in a couple's relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. In courtship, a couple get to know each other and decide if there will be an engagement or other such agreement...

 in March or April, when the temperature can be as low as -40 °C. A lone male gives an ecstatic display, where it stands still and places its head on its chest before inhaling and giving a courtship call for 1–2 seconds; it then moves around the colony and repeats the call. A male and female then stand face to face, with one extending its head and neck up and the other mirroring it; they both hold this posture for several minutes. Once in pairs, couples waddle around the colony together, with the female usually following the male. Before copulation, one bird bows deeply to its mate, its bill pointed close to the ground, and its mate then does the same.

Emperor Penguins are serially monogamous. They have only one mate each year, and stay faithful to that mate. However, fidelity between years is only about 15%. The narrow window of opportunity available for mating appears to be an influence, as there is a priority to mate and breed which often precludes waiting for the appearance of the previous year's partner.


The female penguin lays one 460–470 g (1 lb) egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 in May or early June; it is vaguely pear-shaped, pale greenish-white, and measures around . It represents just 2.3% of its mother's body weight, making it one of the smallest eggs relative to the maternal weight in any bird species. 15.7% of the weight of an Emperor Penguin egg is shell; like those of other penguin species, the shell is relatively thick, which minimises risk of breakage.

After laying, the mother's nutritional reserves are exhausted and she very carefully transfers the egg to the male, before immediately returning to the sea for two months to feed. The transfer of the egg can be awkward and difficult, and many couples drop the egg in the process. When this happens, the chick inside is quickly lost, as the egg cannot withstand the freezing temperatures on the icy ground. The male spends the winter incubating
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...

 the egg in his brood pouch, balancing it on the tops of his feet, for 64 consecutive days until hatching. The Emperor Penguin is the only species where this behaviour is observed; in all other penguin species both parents take shifts incubating. By the time the egg hatches, the male will have fasted for around 115 days since arriving at the colony. To survive the cold and winds of up to 200 km/h (120 mph), the males huddle together, taking turns in the middle of the huddle. They have also been observed with their backs to the wind to conserve body heat. In the four months of travel, courtship, and incubation, the male may lose as much as 20 kg (44 lb), from around 38 kg to just 18 kg (84 lb to 40 lb).

Hatching may take as long as two or three days to complete, as the shell of the egg is thick. Newly hatched chicks are semi-altricial
Altricial
Altricial, meaning "requiring nourishment", refers to a pattern of growth and development in organisms which are incapable of moving around on their own soon after hatching or being born...

, covered with only a thin layer of down and entirely dependent on their parents for food and warmth. If the chick hatches before the mother's return, the father feeds it a curd-like substance composed of 59% protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 and 28% lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...

, which is produced by a gland in his esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...

. The young chick is brooded
Offspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...

 in what is called the guard phase, spending time balanced on its parent's feet and sheltered in the brood pouch.


The female penguin returns at any time from hatching to ten days afterwards, from mid-July to early August. She finds her mate among the hundreds of fathers by his vocal call and takes over caring for the chick, feeding it by regurgitating the food that she has stored in her stomach. The male then leaves to take his turn at sea, spending around 24 days there before returning. His trip is slightly shorter than it was originally, because the melting of ice in the summer gradually decreases the distance between the breeding site and the open sea. The parents then take turns, one brooding
Offspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...

 while the other forages at sea.

About 45–50 days after hatching, the chicks form a crèche
Crèche (zoology)
The Crèche in zoology refers to care of another's offspring, for instance in a colony. This term is used in the study of bird colonies...

, huddling together for warmth and protection. During this time, both parents forage at sea and return periodically to feed their chicks. A crèche may comprise up to several thousand birds densely packed together and is essential for surviving the low Antarctic temperatures.

From early November, chicks begin moulting into juvenile plumage, which takes up to two months and is often not completed by the time they leave the colony; adults cease feeding them during this time. All birds make the considerably shorter trek to the sea in December or January and spend the rest of the summer feeding there.

Relationship with humans



The species has been bred outside Antarctica at SeaWorld San Diego
SeaWorld San Diego
SeaWorld San Diego is an animal theme park, oceanarium, and marine mammal park, located in San Diego, California, United States. The park is owned by SeaWorld Parks & Entertainment, a division of The Blackstone Group....

; more than 20 individuals have hatched there since 1980. Considered a flagship species, 55 individuals were counted in captivity in North American zoos and aquaria in 1999. The species is kept in captivity in only two places in the world.

Penguin rescue, rehabilitation and release


In June 2011, a juvenile Emperor Penguin was found on a beach north of Wellington in New Zealand. He had been consuming 3 kg of sand, which he had mistaken for snow, as well as sticks and stones, and had to undergo a number of operations to remove these and save his life. Following recovery, on 4 September, the juvenile, named "Happy Feet" (after the name of the 2006 film), was fitted with a tracking device and released into the Southern Ocean 80 km north of Campbell Island
Campbell Island
Campbell Island may refer to:* Campbell Island, Torres Strait, Queensland, Australia* Campbell Island , Canada* Campbell Island, New Zealand* Campbell Island, North Carolina, USA...

. However, 8 days later scientists lost contact with the bird, suggesting that the transmitter had fallen off (considered likely) or that he had been eaten by a predator (considered less likely).

Cultural references


The species' unique life cycle in such a harsh environment has been described in print and visual media. Apsley Cherry-Garrard
Apsley Cherry-Garrard
Apsley George Benet Cherry-Garrard was an English explorer of Antarctica. He was a survivor of the Terra Nova Expedition and is acclaimed for his historical account of this expedition, The Worst Journey in the World....

, the Antarctic explorer, said: "Take it all in all, I do not believe anybody on Earth has a worse time than an Emperor Penguin". Widely distributed in cinemas in 2005, the French documentary La Marche de l'empereur, which was also released with the English title March of the Penguins
March of the Penguins
March of the Penguins is a 2005 French nature documentary film. It was directed and co-written by Luc Jacquet, and co-produced by Bonne Pioche and the National Geographic Society. The film depicts the yearly journey of the emperor penguins of Antarctica...

, told the story of the penguins' reproductive cycle. The subject has been covered for the small screen three times by the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...

 and presenter David Attenborough
David Attenborough
Sir David Frederick Attenborough OM, CH, CVO, CBE, FRS, FZS, FSA is a British broadcaster and naturalist. His career as the face and voice of natural history programmes has endured for more than 50 years...

, first in episode five of the 1993 series on the Antarctic Life in the Freezer
Life in the Freezer
Life in the Freezer is a BBC nature documentary series written and presented by David Attenborough, first transmitted in the UK from 18 November 1993....

, again in the 2006 series Planet Earth
Planet Earth (TV series)
Planet Earth is a 2006 television series produced by the BBC Natural History Unit. Five years in the making, it was the most expensive nature documentary series ever commissioned by the BBC, and also the first to be filmed in high definition...

, and finally Frozen Planet in 2011.

The computer-animated movie Happy Feet
Happy Feet
Happy Feet is a 2006 American-Australian computer-animated family film with music, directed and co-written by George Miller. It was produced at Sydney-based visual effects and animation studio Animal Logic for Warner Bros., Village Roadshow Pictures and Kingdom Feature Productions and was released...

(2006) features Emperor Penguins as its primary characters, with one in particular that loves to dance; although a comedy, it too depicts their life cycle and promotes an underlying serious environmental message of threats from global warming and depletion of food sources by overfishing. The computer-animated movie Surf's Up
Surf's Up (film)
Surf's Up is a 2007 American computer-animated mockumentary family comedy film directed by Ash Brannon and Chris Buck. It stars the voices of Shia LaBeouf, Jeff Bridges, Zooey Deschanel and Jon Heder among others....

(2007) features a surfing Emperor Penguin named Zeke "Big-Z" Topanga. More than 30 countries have depicted the bird on their stamps – Australia, Great Britain, Chile and France have each issued several. It has also been depicted on a 1962 10 franc
Belgian franc
The franc was the currency of Belgium until 2002 when the euro was introduced into circulation. It was subdivided into centimes , 100 centiem or Centime .-History:...

 stamp as part of an Antarctic expedition series. Canadian band The Tragically Hip
The Tragically Hip
The Tragically Hip, often referred to simply as The Hip, is a Canadian rock band from Kingston, Ontario, consisting of Gordon Downie , Paul Langlois , Rob Baker , Gord Sinclair and Johnny Fay . Since their formation in 1983 they have released 12 studio albums, two live albums, and 46 singles...

included a song 'Emperor Penguin' on their 1998 album Phantom Power
Phantom Power (The Tragically Hip album)
Phantom Power is the sixth full-length album by Canadian rock band The Tragically Hip. The album was released in 1998. It won the 1999 Juno Awards for Best Rock Album and Best Album Design. The song "Bobcaygeon" won the Juno Award for Single of the Year in 2000...

.

External links