Emperor penguins (Aptenodytes forsteri) are found throughout the Antarctic continent and sub-Antarctic islands. In breeding months (April to November), emperor penguin colonies are found between 66° and 78° south latitude, along the Antarctic coastline. One colony is located on the Antarctic peninsula, which is on the western base. Emperor penguins have been recorded on the Islas Malvinas, and are occasional visitors to Tierra de Fuego (South America’s southernmost tip) and Isla de Los Estados (18km east of Argentina). (Coria and Montalti, 2000; Raymond, et al., 2015)
Emperor penguins are marine birds that lives exclusively in the Antarctic. Winter temperatures there range from -40 to 0°C, with wind chills reaching -60°C. During their breeding season, emperor penguins congregate on dense stable ice attached to the coastline of Antarctica. About 7 to 8 weeks after juveniles hatch, they leave their colonies and migrate toward open ocean areas. Outside of breeding season, they spend most of their time in seasonally-packed ice zones, where open sea is easily available for foraging. Colonies migrate to ice shelves during breeding season, where ice cliffs and icebergs serve as protection against cross winds. (Kooymana, et al., 1990; Raymond, et al., 2015; Thiebot and Lescroel, 2013)
Emperor penguins are the largest sea birds in the Antarctic, standing 101 to 132 cm tall. They have wingspans ranging from 76 to 89 cm. These penguins have black and white bodies with stiff black wings. Their back, head, chin, throat, and the dorsal parts of their wings are black. Their undersides, or ventral sides, are completely white up to their necks. They have auricular (ear-region) patches of orange and yellow that fade towards their shoulders. This yellow fades to white around the top portion of their chest. They also have patches of orange and yellow on their heads and breasts. Emperor penguins have beaks that are long and black, with pinkish-orange stripes along their lower mandibles. Emperor penguins weigh 25 to 45 kg as adults. They gain and lose weight rapidly during breeding and feeding seasons. On average, females tend to weigh 18 kg less than males.
When they are born, emperor penguins have gray skin with no feathers and weigh around 315 g. Gray feathers fill in after the first couple of weeks of birth, after which a black crown of feathers going from their bill to the back and sides of their head develops. Around the same time, white cheeks and a white chin appear. As juveniles, emperor penguins are grayish-blue, aging as developing their distinct black-and-white patterns as they mature. (Bowles, 1991; Chere, 2008; Kooymana, et al., 1990)
Emperor penguins have a monogamous mating system. A long courtship period begins, lasting up to 6 weeks, and encompasses about 16% of the total breeding cycle. Mate pairing usually occurs in 82% of males and 56% of females within 24 hours of arrival to breeding grounds. Males and females use vocal calls to find mates. After they bond with a partner, emperor penguins no longer vocalize. This prevents disturbances by other individuals seeking mates. Vocal communication returns once females lay their eggs. Individual females lay one egg per mating season. (Ancel, et al., 2013; Maho, 1977)
Emperor penguins have annual breeding cycles that are in sync with Antarctic sea-ice cycles. From January to March, adults store energy in fat for the upcoming breeding season, where they fast for a period of months. Penguins arrive at breeding grounds on sea-ice in early-mid April at the onset of the Antarctic winter. Penguins reach reproductive maturity between 4 to 6 years old. Females lay a single egg in late April or May and pass the egg off to their mate almost immediately. Females then travel approximately 50 to 120km back to the ocean to find food. Eggs weigh around 450 g – just 2% of the body mass of an adult female. Because they incubate eggs for a long period with no food, males lose roughly 40% of their total body mass. Chicks hatch in mid-July, weighing about 315 grams. Because of the harsh conditions, males keep eggs in special brood pouches. Males feed hatchlings by producing a nutrient-rich, milky substance in their esophagus until females return. Depending on how far mothers have to travel for food, their return may be before the chicks hatch or up to a month thereafter. Females locate their mates upon return via vocal searches. Once females return, they take over caring for young. After roughly 4 months of fasting, males return to the ocean to eat. Females feed their young by regurgitating food from their stomachs. Chicks stay inside adult brood pouches until they are about a month old. At this age, they start to become independent and increasingly spend more time outside of brood pouches. Maho (1977) reported chick mortality rates of over 90%, with causes including starvation, predators, and harsh weather conditions. By the time chicks are 5 months old they are completely independent from their parents. Chicks molt at this age and are approximately 50% the size of a full grown adult. Molting is vital for any chance of survival. Chicks leave their parents and go off on their own with other chicks. Parents also molt and return to sea to start storing up energy for the next breeding season. Emperor penguins have a low mate fidelity rate. Bried et al. (1999) reported that only 15% of mates stayed together for multiple years, with a maximum time of 4 years. (Ancel, et al., 2009; Ancel, et al., 2013; Bried, et al., 1999; Maho, 1977)
Emperor penguins rely on their parents until independence – around 5 months of age. Males incubate and protect eggs in their brood pouches, a specialized skin fold on their lower abdomens. They do this for roughly 65 days, or until females have returned. When chicks are born, they live solely underneath the brood pouches of the males. They are fed a nutrient-rich, milky substance that is secreted in the esophagus. When the females return, they take over caring and feeding their offspring by regurgitating food from their stomachs. Both males and females take turns going to and from the ocean to forage, bringing their offspring food until they are 5 months old. At this point, chicks leave their parents and molt their juvenile feathers in preparation to start diving for their own food. (Ancel, et al., 2009; Bried, et al., 1999; Maho, 1977)
Emperor penguins have a lifespan expectancy in the wild of 15 to 20 years, but some researchers suggest that individuals have lived to up to 50 years. However, research suggests that only 1% of penguins reach such an age. Penguins in captivity have a lifespan of 20 to 34 years.
Depending on environmental and climate factors, survival rates of chicks in their first year varies, with 20% of chicks making it past the first year on average. Maho (1977) reported chick mortality to be over 90% in their first year, with causes including starvation, predation, and harsh weather conditions. Annual survival rates for adult emperor penguins are around 95.1%. Annual average sea surface temperature is a factor that has been shown to influence adult survival. Emperor penguins survived less when surface temperatures were higher, roughly between -24°C and 10°C. (Ainley, et al., 2012; Barbraud and Weimerskirch, 2001; Maho, 1977)
Emperor penguins display common behaviors characteristic of many seabird species, however there are behaviors unique to this species. During breeding and incubation periods in harsh Antarctic weather conditions, groups of penguins huddle as a way to conserve energy. Huddles may be small – less than 200 birds – or as large as 5,000 or 6,000 birds. The average duration of huddles averages 1.6 hours. Penguins in huddles make small, continuous movements, alternately getting closer to each other and breaking apart. This preserves energy and allows these penguins to fast for long periods of time. Ancel et al. (2009) report that 84% of mate pairs stay together during huddling events. Exactly how partners stayed together is not known. Chicks in groups, known as a crèche, also huddle to stay warm and conserve energy.
Emperor penguins also lie down, which helps lower metabolic rate and conserve energy in harsh Antarctic conditions. This individual behavior decreases the amount of body surface area exposed to cold air, minimizing heat loss due to high-speed winds. Ground-level snow also acts like a wind barrier. During incubation periods, males remain nearly motionless for days at a time to decrease their metabolic rates. Their stance has adapted in such way to minimize heat loss. They stand on 3 resting points: their 2 heels, and tail. The plantar surfaces of their feet do not touch the ground, minimizing heat loss to the ground. The rest of their body is situated in such way to prevent freezing. They tuck their heads to their chests and press their flippers tightly against their bodies. In breeding season, mating pairs use vocal songs as a demonstration of their partnership. Penguins use these vocal songs to locate their mates when they return from the ocean during breeding season. Chicks also use calls to locate their parents. (Ancel, et al., 2009; Bried, et al., 1999; Maho, 1977)
Emperor penguins are a relatively vocal bird that use different frequencies for mate pairing, mate recognition, and offspring/parent recognition. Most vocal communication is transmitted through a pair of different frequencies. Display calls are directed towards specific individuals, for example in-between mates. Mates rely on these specialized vocal calls during the breeding seasons to locate each other, because they spend the majority of their time apart. Parents and offspring also use calls to identify each other. Chicks also use high frequency whistles to tell their parents when they are hungry. In order for chicks to be fed, they must recognize and respond to their parents calls. Non-verbal movements are also used for communication. Parents teach their offspring how to swim and feed. Emperor penguins also a non-verbal posture to communicate between other individuals. They frequently stand in an obvious posture with their bills turned up and wings slightly out in order to avoid aggression. (Bried, et al., 1999; Burns and Kooyman, 2001; Maho, 1977; Young, 1994)
Emperor penguins are carnivorous and primarily feed on fish, crustaceans, and molluscs. They feed on fish and krill the most, as they are most abundant in the ocean surrounding Antarctica. Emperor penguins have a rough and spiky-textured tongue, which helps them catch and eat slippery fish and squids more easily. Prey abundance varies from location to location, but some research has found that the Antarctic silverfish (Pleuragramma antarcticum) is one of the most frequently consumed species. Fish from the family Nototheniidae are also consumed as a staple of their diet. Molluscs such as the glacial squid (Psychroteuthis glacialis), hooked squid (Kondakovia longimana), and the Antarctic krill (Euphausia superba) are also eaten regularly. They feed in the open waters of the ocean surrounding Antarctica, or underneath sea ice. They can dive to depths of up to 500 m. They can stay under for over 15 minutes and may travel up to 1000 km in one dive. Staying in the sea for unnecessary lengths of time increases their chance to be attacked by prey, so they tend to stay closer to the surface as long as food is plentiful. They can travel up to 20 km/hr in the water, however they generally travel around 10 km/hr. Some observations suggest that groups of penguins coordinate their dives and hunt cooperatively. An adult penguin eats 2 to 3 kg per day. However, before the long fasting breeding season, they tend to eat up to 6 kg per day. Chicks rely solely on their parents for food for the first 5 months of their lives, and typically require an average of 84 kg of food during those months. (Ainley, et al., 2012; Ancel, et al., 2009; LaRue, et al., 2015; Lengagne, et al., 2001)
Emperor penguins are one of the top predators in the Antarctic marine environment. Killer whales (Orcinus orca) have been observed to prey on emperor penguins, sometimes harassing them for fun. Leopard seals (Hydrurga leptonyx) are also marine predators of penguins, and have been observed to kill emperor penguins. However, research shows that emperor penguins are not a part of their staple diet. Because of their large size, emperor penguins may be unfavorable to killer whales and leopard seals, provided smaller penguins are abundant. However, observations by Kooymana et al. (1990) did observe adults and chicks being heavily preyed upon by leopard seals. This may have been because few other food sources were available. Seabirds called skuas (Stercorarium parasiticus) are also known to steal and eat emperor penguin eggs and chicks. Little is known about how penguins protect themselves from predators. Most emperor dives are shallow and fairly quick, which makes it harder for predators to reach them before they are out of the water again. In addition to a large pointed beak, their feathers and shape of their body also likely function as protection from predators. With black backs and white bellies, emperor penguins are countershaded. This makes it harder to distinguish their form while they are swimming. (Andrews, et al., 2008; Chere, 2008; Kooymana, et al., 1990; Maho, 1977)
Barbosa and Palacios (2009) found that wild emperor penguins are a common host for several gastro-intestinal parasites, including the tapeworms Tetrabothrius wright and Parorchites zederi.
Kleninertz et al. (2014) found that 26% of a small population of emperor penguins at the Atka Bay in Antarctica were parasitized by a parasitic nematode or roundworm of the family Capillariidae, along with tapeworms in the genera Tetrabothrius and Diphyllobothrium. Parorchites zederi was found in their feces. The parasitic louse species Austrogoniodes mawsoni has also been found to use emperor penguins as a host. (Andrews, et al., 2008; Barbosa and Palacios, 2009; Chere, 2008; Kleinertz, et al., 2014; Kooymana, et al., 1990; Maho, 1977)
Researchers study emperor penguins in order to understand the physical and behavioral adaptations that allow them to withstand extremely cold temperatures. Emperor penguins also attract tourists to the Antarctic. Many organizations and companies offer day trips to various areas for emperor sightseeing including overnight trips. (Raymond, et al., 2015; Thiebot and Lescroel, 2013)
There are no known negative impacts of emperor penguins on humans.
Emperor penguins are considered a near threatened species on the IUCN red list. Their populations are projected to rapidly decline about 27% over the next three generations (approx. 61 years) due to climate change. Currently, the population is considered stable, with ca. 476,000 individuals. The listing status of emperor penguins is under review to be re-listed as threatened or endangered by the U.S. Fish and Wildlife Service. There is ongoing international research of emperor penguins to predict what will happen to these birds if the climate continues to change. Researchers predict that, between the years of 2025 and 2052, all emperor penguin colonies north of 67°S will have disappeared due to lack of sea ice, caused by a warming climate.
Human proximity also poses a threat to emperor penguins. During the summer months, when emperor penguins are foraging at sea, the greatest amount of tourism takes place. Ongoing research is examining origins of diseases including infectious bursal disease virus, Newcastle disease, and avian influenza. Many researches suspect that these diseases were brought to Antarctica by humans that are now harming penguins and other Antarctic animals. (Ainley, et al., 2012; Barbraud and Weimerskirch, 2001; Boersma, 2008)
Sarah Wilber (author), Radford University - Fall 2015, Karen Powers (editor), Radford University, April Tingle (editor), Radford University, Cari Mcgregor (editor), Radford University, Zeb Pike (editor), Radford University, Jacob Vaught (editor), Radford University, Galen Burrell (editor), Special Projects.
lives on Antarctica, the southernmost continent which sits astride the southern pole.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
parental care is carried out by males
imitates a communication signal or appearance of another kind of organism
eats mollusks, members of Phylum Mollusca
Having one mate at a time.
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
generally wanders from place to place, usually within a well-defined range.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an animal that mainly eats fish
the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
uses sound above the range of human hearing for either navigation or communication or both
uses sight to communicate
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