The Adélie Penguin (Pygoscelis adeliae), a close relative of the Chinstrap Penguin (P. antarctica), nests on ice-free rocky coasts around Antarctica. It tends to occupy higher ground than does the less colonial Gentoo Penguin (Pygoscelis papua). Adélie Penguin colonies are typicaly large and are thus often located in extensive open areas, sometimes far from the open sea. Adélie Penguins feed mainly on krill (Euphausia superba, E. crystallorophias), along with smaller quantities of fish, amphipod crustaceans, and cephalopods (squid and relatives). Although these penguins generally hunt at depths less than 20 m, they have been recorded as deep as 175 m. Adélies typically arrive at their breeding colony in September or October and most eggs are laid in November. Colonies may be enormous, with densely packed nests, and may include Gentoos and Chinstraps, but the Adélies tend to cluster together in the colony. Two eggs are deposited in the simple nest (a small depression lined with pebbles). Eggs are incubated by both sexes for 30 to 43 days, broken into stints of 7-23 days. The young gather together in creches starting around 16 to 19 days and fledge at 50 to 56 days. They are sexually mature by 8 years (rarely at 5 and exceptionally at 3). After breeding, birds move north toward rich feeding grounds. Adults do not molt at the colony, but rather on ice floes. (Martínez 1992) Dunn et al. (2011) used ARGOS satellite telemetry and Global Location Sensors (geolocators) to identify the molt locations and winter foraging dispersal of Adélie penguins after they left their breeding colonies on Signy Island in the South Orkney Islands. They found that the birds remained away from colonies (at distances up to 2235 km) for around 9 months (Ballard et al. [2010] report that Ross Island Adélies make the longest migration known for this species, traveling as far as 17,600 km round trip between autumn and spring). Dunn et al. found that molt took place within the pack ice during February and March within a narrow latitudinal range (65 to 71 degrees S), at a mean distance of 126 km from the ice edge; the mean duration of individual molt was around 18.6 days. After molting, the birds spent the subsequent winter months moving north or northeastward within the expanding winter pack ice, at a mean distance of 216 km from the ice edge, and in areas with ice cover > 80%. Dunn et al. note that the dependence of Adélie Penguins on sea ice habitat suggests that any further reductions in sea ice extent in the Weddell Sea region would potentially have important impacts on Adélie Penguin population dynamics. Ballard et al. (2010) studied changes in annual migration patterns of Adélie Penguins through time. They suggest that although these penguins have had to modify their life history characteristics and movements through the millenia as ice ages have come and gone (with coincident changes in breeding and sea ice habitat), the current rate of habitat change may be unprecedented for this species.

Pygoscelis adeliae is found only in the Antarctic region. Adelie penguins breed on the coasts of Antarctica and on surrounding islands. The area with the most abundant population of Adelie penguins is in the Ross Sea.

Biogeographic Regions: antarctica (Native )

Adelie penguins are one of the smaller species of penguins, just above 60.96 cm tall. Their back, tail, head, and face are black. They have a white belly and a white ring around their brown eyes. Their feathers cover half of their bill, which is black with an orange base. They have dull white to pink legs and feet with black soles.

Range mass: 3.62 to 4.99 kg.

Average length: 69.85 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

• Terrestrial
• Marine

Living in the Antarctic region, Adelie penguins must withstand very cold temperatures. During the winter months they inhabit large coastal ice platforms, so they will have better access to food. Krill, the primary staple in their diet, feed on plankton that live underneath sea ice, so there is an abundance of krill in those areas. During the breeding season, typically in the early spring and summer months, they travel to coastal beaches to build their nests on ice-free ground. With access to open water, this locale provides the penguins with almost immediate access to food for themselves and their young.

Average depth: 200 m.

Habitat Regions: polar ; terrestrial ; saltwater or marine

Terrestrial Biomes: icecap

Aquatic Biomes: coastal

The primary food source for Adelie penguins is krill (Euphausia superba). They also consume fish, such as lantern fish and other members of the family Myctophidae and Antarctic silverfish (Pleuragramma antarcticum). Squid, other cephalopods, and amphipods are part of their normal diet as well. Adelie penguins store food and regurgitate it later to feed their newly hatched young.

Animal Foods: fish; mollusks; aquatic crustaceans; other marine invertebrates

Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )

Adelie penguins impact krill (Euphausia superba), Antarctic silverfish (Pleuragramma antarcticum), and cephalopod populations, the main species in their diet. These penguins are impacted by leopard seals (Hydrurga leptonyx), killer whales (Orcinus orca), south polar skuas (Stercorarius maccormicki), and sheathbills (Chionis albus).

Typical predators of Pygoscelie adeliae are leopard seals (Hydrurga leptonyx), killer whales (Orcinus orca), and south polar skuas (Stercorarius maccormicki). Leopard seals are the most common predators of Adelie penguins, usually near the edge of the ice pack. Leopard seals are never an issue for penguins on shore, because leopard seals only come ashore to sleep or rest. Adelie penguins have learned to evade these predators by swimming in groups, avoiding thin ice, and spending little time in the water within 200 m of the beach. Killer whales generally prey on larger penguin species, but may occasionally take Adelies. South polar skuas prey on eggs and chicks left unguarded by adults or at the edges of creches. act more as scavengers than predators. Sheathbills (Chionis albus) also sometimes taken unguarded eggs.

Known Predators:

• leopard seals (Hydrurga leptonyx)
• killer whales (Orcinus orca)
• south polar skuas (Stercorarius maccormicki)
• sheathbills (Chionis albus)

Adelie penguins are very social and communication with neighbors and mates is important. The most common mode of communication with neighbors are displays and posturing. Mates also communicate using displays, but these are most often more ecstatic and one that only each mate would recognize. Mated Adelie penguins also use calls to identify each other and their offspring. Males and females actively defend their nest site and will often fight with their neighbors. Adelie penguins can signal apprehension by raising their head feathers and they can signal threat by a sideways stare with their crest raised and their eyes rolled downward.

Communication Channels: visual ; acoustic

Survivorship among Adelie penguins is lower in individuals who begin to breed at younger ages, between 3 and 5 years. However, individuals that do attempt to breed at an earlier age tend to breed more successfully in later years than penguins that first breed at 5 to 6 years old. Adelie penguins have been known to live as long as 16 years.

Range lifespan

Status: wild: 5 to 16 years.

Male Adelie penguins attempt to attract mates with a "salute" in which they they stand about 4 m away from the female of interest and put on a display of beak thrusting, neck arching, and reaching his full height. This salute also serves to announce that male's territory in the colony. In early spring, Adelie penguins journey back to their breeding grounds. Males arrive first. Each pair recognizes each other's mating call and their nesting site from the previous year. These pairs may reunite for consecutive years unless one of the mates does not return to the nesting site. Males also exhibit defensive measures of beak pecking and open yelling to defend territories and mates.

Mating System: monogamous

Generally, Adelie penguins return to their same nesting site around springtime for mating. The lengthening of days in the spring stimulates penguins to begin their period of hyperphagia, or persistent feeding. They feed constantly to store fat that they need during the breeding and incubation periods. They build stone nests in preparation for their two eggs.  Adelie penguins most commonly produce two offspring per breeding season, with one egg laid shortly after the first. The eggs incubate for about 36 days. The parents alternate caring for the young for about 4 weeks post-hatching, when the young enter a creche with other juvenile Adelie penguins for protection. At this time, both parents return to the sea to feed.

Breeding interval: Breeding occurs once a year from early spring to summer.

Breeding season: Breeding occurs in the austral spring and summer.

Range eggs per season: 1 to 3.

Range time to hatching: 24 to 39 days.

Average time to hatching: 32 days.

Average fledging age: 28 days.

Average time to independence: 60 days.

Range age at sexual or reproductive maturity (female): 3 to 6 years.

Average age at sexual or reproductive maturity (female): 4 years.

Range age at sexual or reproductive maturity (male): 4 to 6 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization

Both parents invest heavily in their young. During incubation males and females take turns with the egg while the other is feeding. Once the chick is hatched, both adults take turns in feeding and searching for food. Newly hatched chicks are born with down feathers but are unable to feed themselves; they are semi-precocial. Four weeks after a chick has hatched it will join a creche of other juvenile Adelie penguins for protection. During its time in the creche the parents still feed their young. After 56 days in the creche most Adelie penguins become independent.

Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Male, Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female)

According to the IUCN Red List, Pygoscelis adeliae is considered "low risk" and of "least concern."

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

There are no known adverse effects of Pygoscelie adeliae on humans.

Adelie penguins are often good indicators of climate change. Adelie penguins are beginning to inhabit beaches that were previously perenially covered in ice, suggesting warming of Antarctic environments. Adelie penguin colonies are highlights for ecotourism in the Antarctic. From the eighteenth to the early twentieth century these penguins were used for food, oil, and bait. Their guano was mined and used as fertilizer. Now they are a protected species in most countries.

Positive Impacts: food ; body parts are source of valuable material; ecotourism ; research and education; produces fertilizer