The emperor penguin (Aptenodytes forsteri) is the tallest and heaviest of all living penguin species. It lives only in Antarctica. Male and female emperor penguins look similar, with black feathers on the head and back and white feathers on the belly, pale-yellow chest, and bright-yellow patches near the ears. They grow up to 100 cm (39 in) long and weigh between 22 and 45 kg (49 to 99 lb).
Like all penguins, emperor penguins cannot fly. They have a streamlined body shape and wings that are stiff and flat, acting as flippers for swimming in the ocean. They eat mainly fish, but also crustaceans like krill and cephalopods like squid. During hunting, they can stay underwater for about 20 minutes and dive as deep as 535 m (1,755 ft). This ability is helped by special adaptations, such as a unique type of blood protein that works well with low oxygen levels, strong bones that prevent pressure-related injuries, and the ability to slow their body functions to conserve energy.
Emperor penguins are the only penguin species that breed during the Antarctic winter. They travel 50 to 120 km (31 to 75 mi) across the ice to reach breeding colonies that may have thousands of individuals. The female lays one egg, which the male keeps warm for more than two months while the female goes to the sea to find food. After that, the parents take turns going to the sea to find food and caring for their chick in the colony. In the wild, emperor penguins usually live about 20 years, though some may live up to 50 years.
Taxonomy
Emperor penguins were first described in 1844 by English zoologist George Robert Gray. He created the group name Aptenodytes using parts of Ancient Greek words meaning "without wings diver." The special name forsteri honors Johann Reinhold Forster, a German naturalist who traveled with Captain James Cook on his second voyage. Forster officially named five other penguin species. He may have been the first person to see emperor penguins in 1773–74. He recorded seeing what he thought was a king penguin (A. patagonicus), but because of where he was, it might have actually been an emperor penguin (A. forsteri).
The emperor penguin and the king penguin are the only two living species in the genus Aptenodytes. Fossils of a third species, Ridgen's penguin (A. ridgeni), were found in New Zealand from the late Pliocene period, about three million years ago. Studies of penguin behavior and genetics suggest that Aptenodytes is a very old and separate group. This means it split off from the branch that led to all other living penguin species. Genetic evidence from mitochondria and nuclear DNA shows this split happened around 40 million years ago.
Description
Adult emperor penguins are about 110 to 120 centimeters (43 to 47 inches) long, with an average length of 115 centimeters (45 inches). Scientists measure the length from the beak to the tail, which can sometimes cause confusion between body length and standing height. Some sources report standing heights as high as 1.5 meters (4 feet 11 inches), but most studies focus on body length. Some older papers mention a standing height of 1.2 meters (3 feet 11 inches), though this is less commonly reported. Prévost (1961) measured the standing height of 86 wild emperor penguins and found the tallest to be 1.08 meters (3 feet 7 inches). Friedman (1945) recorded standing heights of 83 to 97 centimeters (33 to 38 inches) for 22 wild individuals. Ksepka et al. (2012) measured the standing height of 11 preserved emperor penguins and found it ranged from 81 to 94 centimeters (32 to 37 inches). Adult emperor penguins weigh between 22.7 and 45.4 kilograms (50 to 100 pounds), with males typically heavier than females. They are the fifth heaviest living bird species, after larger types of ratites. Their weight changes with the seasons, as both males and females lose weight while raising chicks and incubating eggs. During the Antarctic winter, males do not eat for over two months while protecting their eggs and can lose about 12 kilograms (26 pounds). Adult emperor penguins weigh between 25 and 45 kilograms (55 to 99 pounds), with weights decreasing during the breeding season. Females usually weigh about 18 kilograms (40 pounds) less than males.
Emperor penguins have streamlined bodies and stiff, flat flippers that help them swim quickly. Their tongues have small, backward-facing barbs to help them hold onto prey. Males and females look similar in size and color. Adult emperor penguins have dark black feathers on their heads, chins, throats, backs, flippers, and tails. Their black feathers sharply separate from the white feathers on their wings, bellies, and upper chests. The area around their ears is bright yellow. Their bills are 8 centimeters (3.1 inches) long, with the top part black and the bottom part pink, orange, or lilac. Juvenile emperor penguins have white feathers around their ears, chins, and throats, with black bills. Chicks are covered in silver-gray down, with black heads and white masks. One chick with all-white feathers was seen in 2001, but it was not considered an albino because it did not have pink eyes. Chicks weigh about 315 grams (11.1 ounces) after hatching and fledge when they reach about half the weight of an adult.
Emperor penguins' dark feathers become brown from November to February (the Antarctic summer) before they molt in January and February. Molting happens quickly, taking about 34 days. New feathers grow from the skin before old feathers fall out, helping reduce heat loss. New feathers then push out the old ones as they finish growing.
The average yearly survival rate of adult emperor penguins is 95.1%, with an average life expectancy of 19.9 years. Researchers estimate that 1% of hatched emperor penguins might live to be 50 years old. However, only 19% of chicks survive their first year, meaning 80% of the population consists of adults five years or older.
Emperor penguins do not have fixed nesting areas to find their partners or chicks, so they rely on vocal sounds for identification. They use a wide variety of calls to recognize mates, parents, and offspring. These calls use two frequency bands at the same time. Chicks use a special whistle to beg for food and contact parents.
Emperor penguins breed in the coldest environment of any bird species. Air temperatures can reach -40°C (-40°F), and wind speeds can reach 144 kilometers per hour (89 miles per hour). Water temperatures are as cold as -1.8°C (28.8°F), much lower than the penguins' average body temperature of 39°C (102°F). Emperor penguins have several adaptations to stay warm. Their dense feathers provide 80–90% of their insulation, and they have a thick layer of fat under their skin (up to 3 centimeters or 1.2 inches) before breeding. Their feathers are very dense, with about 9 per square centimeter (58 per square inch), and their afterfeathers and down feathers help keep them warm. On land, muscles help hold feathers upright to trap air and reduce heat loss. In water, feathers flatten to keep their skin and down layer waterproof. Preening (grooming) helps keep feathers oily and water-repellent.
Emperor penguins can maintain their body temperature without changing their metabolism in a range of temperatures called the thermoneutral range, which is from -10 to 20°C (14 to 68°F). Below this range, their metabolism increases significantly, but they can still keep their body temperature as low as -47°C (-53°F). They increase metabolism through swimming, walking, shivering, and breaking down fats with the help of the hormone glucagon. At temperatures above 20°C (68°F), emperor penguins may become stressed as their body temperature and metabolism rise. To cool down, they may increase breathing or raise their wings to expose more skin to the air.
In addition to cold, emperor penguins face high pressure during deep dives, up to 40 times the surface pressure, which could cause injury in other animals. Their solid bones, not filled with air, prevent this. During dives, emperor penguins reduce oxygen use by slowing their heart rate to as low as 15–20 beats per minute and shutting down non-essential organs. This allows longer dives. Their hemoglobin and myoglobin can carry oxygen even at low blood levels, helping them stay conscious despite low oxygen.
Distribution and habitat
Emperor penguins live around the Antarctic region, mostly between 66° and 77° south latitude. They breed on stable pack ice near the coast and up to 18 kilometers (11 miles) offshore. Breeding colonies are often found in areas with ice cliffs and icebergs that protect them from strong winds. Three land-based colonies have been recorded: one (now gone) on a shingle spit at the Dion Islands on the Antarctic Peninsula, one on a headland at Taylor Glacier in Victoria Land, and one at Amundsen Bay. Since 2009, some colonies have been found on shelf ice instead of sea ice, especially when sea ice forms late. As of 2022, 66 breeding colonies were known.
The northernmost breeding group is on Snow Hill Island, near the northern tip of the Antarctic Peninsula. Individual penguins have been seen on Heard Island, South Georgia, and sometimes in New Zealand. The farthest north a penguin was recorded was in Denmark, Western Australia, in November 2024. This penguin, likely from eastern Antarctica, was found by surfers and taken to conservationists for evaluation.
In 2009, the total emperor penguin population was estimated at about 595,000 adult birds, spread across 46 colonies in Antarctica and sub-Antarctic regions. About 35% of the population lives north of the Antarctic Circle. Major breeding areas include Cape Washington, Coulman Island in Victoria Land, Halley Bay, Cape Colbeck, and Dibble Glacier. Colonies can change over time, sometimes splitting into smaller groups or disappearing entirely. For example, the Cape Crozier colony on the Ross Sea decreased greatly between 1902–03 and 1910–11, nearly becoming extinct due to ice shelf changes. By the 1960s, it recovered but declined again by 2009 to around 300 birds.
In April 2026, the International Union for Conservation of Nature (IUCN) classified emperor penguins and Antarctic fur seals as endangered. The main cause of their decline is the loss of sea ice due to climate change from greenhouse gas emissions. Between 2009 and 2018, satellite images showed a 10% population loss, about 20,000 adult penguins. Studies suggest a 45% chance the population could drop by more than 50% by 2073.
Previously, emperor penguins were listed as near threatened by the IUCN and least concern before 2012. They are now being considered for the US Endangered Species Act. Risks include reduced food supplies from climate change and fishing, disease, habitat loss, and human disturbances at breeding sites. Tourism is a concern, as helicopter approaches near 1,000 meters (3,300 feet) can make chicks more nervous.
Population drops of 50% were seen in Terre Adélie due to higher adult deaths during a warm period in the late 1970s. Egg hatching success also dropped when sea ice expanded, causing more chick deaths. Emperor penguins are highly sensitive to climate changes. In 2009, the Dion Islands colony, studied since 1948, vanished completely over a decade. This was the first confirmed loss of an entire colony.
From September 2015 to 2017, strong El Niño conditions, winds, and low sea ice caused "almost total breeding failure" at Halley Bay, killing thousands of chicks. Meanwhile, penguins moved to the Dawson-Lambton colony 55 kilometers (34 miles) south, where their numbers increased tenfold between 2016 and 2018. However, this increase was much smaller than the number of penguins lost from Halley Bay.
In 2009, a study by the Woods Hole Oceanographic Institution predicted that climate change could push emperor penguins toward extinction by 2100. Using a computer model, the study estimated an 87% drop in the Terre Adélie colony’s population, from 3,000 breeding pairs in 2009 to 400 pairs by 2100.
A 2014 study by the same institution again warned that emperor penguins face risks from global warming, which melts sea ice. This loss reduces krill, a key food source. A 2023 study found that climate change could cause over 90% of emperor penguin colonies to face near extinction due to breeding failures as temperatures rise and sea ice disappears.
Behaviour
Emperor penguins are social animals. They live together when nesting and hunting. Birds that hunt together may work together when diving and coming up to the surface. These penguins are active during the day and night. A grown adult moves between the breeding colony and ocean areas where they hunt for food most of the year. The species spreads into the oceans from January to March.
In 1971, American physiologist Gerry Kooyman changed how scientists study penguin hunting behavior. He attached automatic devices to emperor penguins to record their dives. He found that the species dives to 265 meters (869 feet), with dives lasting up to 18 minutes. Later research showed a small female dove to 535 meters (1,755 feet) near McMurdo Sound. It is possible that emperor penguins can dive even deeper and longer, as the devices may not work well at great depths. Further study showed one penguin regularly dove to 150 meters (490 feet) in water 900 meters (3,000 feet) deep. It also made shallow dives of less than 50 meters (160 feet) and deeper dives of more than 400 meters (1,300 feet) in water 450 to 500 meters (1,480 to 1,640 feet) deep. This suggests they may be hunting near the ocean floor. In 1994, a penguin from Auster rookery reached 564 meters (1,850 feet) during a dive that lasted 21.8 minutes.
Both male and female emperor penguins hunt for food up to 500 kilometers (310 miles) from colonies to feed their chicks. Each trip covers 82 to 1,454 kilometers (51 to 903 miles) per individual. After incubating eggs, a male penguin goes directly to areas of open water called polynyas, which are about 100 kilometers (62 miles) from the colony.
Emperor penguins swim efficiently by using both upward and downward strokes. The upward stroke helps them stay at a certain depth. Their average swimming speed is 6 to 9 kilometers per hour (3.7 to 5.6 miles per hour). On land, they walk with a wobbling gait or slide on their bellies, using their feet and wing-like flippers to move. Like all penguins, they cannot fly. Emperor penguins are very strong. In one case, six men trying to catch a male penguin were pushed around and knocked over before they had to work together to capture it. The penguin weighed about half as much as a man.
To stay warm, emperor penguins huddle together in a group called a "turtle formation." This group can have 10 to several hundred birds. Each penguin leans on the one next to it. The center of the group is the warmest, so young penguins usually stay there. Birds on the outside move slowly to the leeward side, creating a slow movement that allows each penguin to take turns being on the inside and outside.
Emperor penguins face dangers from birds and aquatic mammals. Southern giant petrels are the main predators of chicks, causing over one-third of chick deaths in some colonies. They also eat dead penguins. South polar skuas mainly scavenge dead chicks, as live chicks are too large for them to attack. Sometimes, a parent may try to protect its chick, but it may not act if the chick is weak or sick.
The only known predators that attack healthy adult emperor penguins in the ocean are leopard seals, which hunt adult birds and young birds when they enter the water. Orcas mostly attack adult birds at sea but may also attack penguins of any age in or near water.
Although emperor penguins can breed at about three years old, they usually start breeding one to three years later. The breeding cycle begins in March and April, during the Antarctic winter, when all adult penguins travel to nesting areas. They often walk 50 to 120 kilometers (31 to 75 miles) inland from the edge of the pack ice. The start of this journey seems to be triggered by shorter days. Scientists have used artificial lighting to mimic Antarctic daylight and encourage breeding in captivity. The British Antarctic Survey used satellite images to find new breeding sites, increasing the estimated population by 5 to 10 percent to around 278,000 breeding pairs. Because these areas are remote and have harsh weather, scientists find penguin populations by looking at aerial images for large areas of ice stained with guano. This discovery increased the number of known breeding sites from 50 to 61.
Penguins begin courtship in March or April, when temperatures can drop to −40 °C (−40 °F). A male penguin stands still, places its head on its chest, and makes a courtship call for 1 to 2 seconds. It then moves around the colony and repeats the call. A male and female face each other, with one raising its head and neck and the other copying it. They hold this posture for several minutes. Once paired, couples walk together, with the female usually following the male. Before mating, one bird bows deeply to its mate, and the mate does the same.
Emperor penguins are not lifelong mates. They have one mate each year but may change mates the next year. Fidelity between years is about 15 percent. The short time available for mating seems to influence this, as penguins prioritize finding a mate and breeding quickly.
A female penguin lays one egg in May or early June. The egg is pear-shaped, pale greenish-white, and about 12 cm × 8 cm (4.7 in × 3.1 in). It weighs about 460 to 470 grams (16 to 17 ounces), or 2.3 percent of the mother’s body weight. This makes it one of the smallest eggs relative to the mother’s size among all bird species. About 15.7 percent of the egg’s weight is shell, which is thick to help prevent breaking.
After laying the egg, the female’s food reserves are used up. She carefully gives the egg to the male and returns to the sea for two months to feed. Transferring the egg can be difficult, especially for first-time parents, and many couples drop or crack the egg. If this happens, the chick inside dies quickly because the egg cannot
Relationship with humans
Since the 1930s, people have tried many times to keep emperor penguins in captivity. Malcolm Davis from the National Zoological Park was among the first to attempt this. He captured several penguins from Antarctica and successfully moved them to the National Zoological Park on March 5, 1940. These penguins lived there for up to six years.
Until the 1960s, most efforts to keep penguins in captivity failed because knowledge about caring for them was limited and learned through trial and error. Aalborg Zoo was the first to achieve success by building a special cold building for emperor penguins. One penguin lived there for 20 years, and a chick was born, but it died shortly after.
Today, emperor penguins are considered a flagship species and are kept at only a few zoos and public aquariums in North America and Asia. The first successful breeding of emperor penguins in captivity happened at SeaWorld San Diego, where more than 20 penguins have been born since 1980. In 1999, 55 emperor penguins were counted in North American zoos and aquariums. In China, the first successful breeding occurred at Nanjing Underwater World in 2009, followed by Laohutan Ocean Park in Dalian in 2010. Since then, emperor penguins have been kept and bred at a few other places in China. The only confirmed twin emperor penguins (the species usually lays one egg) were born at Sun Asia Ocean World in Dalian in 2017. In Japan, emperor penguins are housed at the Port of Nagoya Public Aquarium and Wakayama Adventure World, with successful breeding at Adventure World.
In June 2011, a young emperor penguin was found on a beach near Wellington, New Zealand. It had eaten 3 kilograms of sand, which it likely mistook for snow, along with sticks and stones. The penguin had several surgeries to remove these items to save its life. After recovering, the penguin was named "Happy Feet" (after the 2006 film) and fitted with a tracking device before being released into the Southern Ocean near Campbell Island on September 4. Scientists lost contact with the penguin eight days later, likely because the tracking device fell off or the penguin was eaten by a predator.
The emperor penguin’s unique life cycle in a harsh environment has been shown in books and films. A French documentary titled La Marche de l'empereur (also called March of the Penguins in English) was widely shown in movie theaters in 2005 and described the penguins’ reproductive cycle. The animated movie Happy Feet (2006) and its sequel Happy Feet Two (2011) use emperor penguins as main characters and show their life cycle while highlighting environmental issues like global warming and overfishing. The animated movie Surf’s Up (2007) features a surfing emperor penguin named Zeke "Big-Z" Topanga. More than 30 countries have shown emperor penguins on their stamps, including Australia, Great Britain, Chile, and France. The penguin also appears on a 1962 10 franc stamp as part of an Antarctic expedition series.