Adelie Penguin Pygoscelis adeliae

Sections

Behavior

Behavior

Adults
The Ecstatic Display given by males may be used as an honest signal of male quality for female mate choice (Sladen 1959; Marks et al. 2010). The male performs this display by stretching his head and neck up while pointing his bill vertically. He then flaps his outstretched wings while making a call that resembles the Loud Mutual Display (Jouventin 1982; Ainley 1975). The Loud Mutual Display consists of the mutual display where the Adélie raises and waves its head from side to side plus the several syllable Loud Mutual Call (Spurr, 1975a).

During non-breeding times the Adélie penguin can be found as far as 1000 km away from its breeding grounds. They leave their breeding grounds sometime during late December through early February and don’t return to their breeding grounds until 7 months later in September or October.

Chicks 
Adélie chicks begin life as semi-altricial and with little ability to move about or call. As they grow older they learn and display a diverse set of behaviors for feeding, comfort, locomotion, aggression, calls and displays (Spurr 1975a).

Feeding
Soon after hatching most chicks will begin begging for food, but even if they don’t, parents still initiate the first feeding. Later feedings are initiated by the chick’s begging. The begging behavior begins with a chick reaching up with wobbly head movements and touching bills with their parent. They also let out a single syllable “peep” and may hold out their flippers for balance (Spurr 1975a).

Once the chicks are in the crèche stage, the second stage of parental care when both parents are away from the nest foraging so chicks gather together for safety forming a large group called a crèche,  a parent returning from foraging will give the Loud Mutual Call letting the chick know it is home. This alerts all chicks in the crèche who will chase the incoming parent for food, their parent or not. Other chicks give up quickly, but the parents actual chick(s) will continue to pursue the parent sometimes right out of the colony until only one chick is left chasing. While chasing, chicks run with their flippers held up over their back and bill opening and closing while giving off “peeps” (Spurr 1975a; Boersma & Davis 1997).

Comfort Activities
Young chicks begin performing comfort activities by 10 days old. Behaviors include yawning, shaking, stretching, swallowing, scratching, and preening, all very similar to the same behaviors in adults. Unlike adults, chicks will allopreen parents or siblings. In the beginning chicks sleep lying flat on the ground, but will start standing with their bill tucked under the flipper while sleeping after 15 days old (Spurr 1975a).

Locomotion
Chicks being semi-altricial are unable to move out of the nest until 11 to 15 days old. By then they can move about the nesting territory but will rarely wander far away until they join a crèche around 20 days old. The ability to walk is a gradual development and is accompanied by many head-long falls (Spurr 1975a).

Aggression
Adélie penguin chicks will huddle with siblings and neighbor chicks with no aggression. Around 11 days old the first sign of aggression shows, however it is more playful aggression than true aggression. Chicks will gape and bill-grip each other and may also grip one another’s feathers or beat one another with their flippers. Serious aggression begins to show after about 21 days old, usually towards unknown adult penguins or other chicks coming too close to the nesting territory. Once they are large enough, chicks in a crèche will act aggressively towards an attacking Skua. Common aggressive behavior includes physical attack with bill and flippers, charging forward, side-to-side head waving, and rolling the eyes to show the white sclerae (Spurr 1975a).

Calls and Displays
Chicks also perform a couple displays after 10 days old. An immature version of the Adult Loud Mutual Display is often performed in succession with begging when a parent comes home after foraging. They utter a several syllable call while they raise their head and wave it from side to side with bill open wide. A Quiet Mutual Display can also be performed with parents after being disturbed. This display is similar to the Loud Mutual Call minus the calling (Spurr 1975a).

An “aark call” can be heard often among crèches when chicks are alarmed by Skuas or humans. They also seem to make this call in response to novel situations, like when first dispersing on their own and entering the water (Spurr 1975a).

The Ecstatic Display in adults is a form of advertising to mates, but chicks older than 35 days will perform their own immature version. They raise their head vertically, roll their eyes showing the white sclerae and beating flippers up and down. They will emit a shrill multiple syllable call along with the physical display (Spurr 1975a).

Sexual Behavior

Adélie penguins form monogamous pairs each breeding season, though not necessarily with the same partner every year (Ainley et al. 1983). They engage in courtship and copulation behavior during mid-October to the end of November before eggs are laid(Spurr 1975b).

Extra Pair Copulations Females are found to acquire nesting material by engaging in extra pair copulations with an unpaired male, never with a paired male. The female’s extra partner may be located on her breeding grounds or in an adjacent breeding group. After copulation, which may result in fertilization, is finished the female will immediately get up, grab a stone from his nest, and take it back to her own nest. Some females return to take more stones, but this time without copulation. Cases have been observed where a female will initiate mutual courtship behavior with an unpaired male and then simply take a stone and leave. One female took 62 stones from a single male over a period of an hour. And other females will have several males from which they take stones (Hunter & Davis 1998).

Social and interspecific behavior

Adélie penguins are known to identify others as mates, neighbors, or strangers by the other’s Loud Mutual Call. When a male hears its mate’s call they will often respond by calling back to the mate, looking at or for their mate, and by rearranging nest stones or eggs. Females also respond similarly to a mate’s call. When hearing a neighbor, males show comfort behavior which includes actions such as preening, stretching, shaking, yawning, or defecating. They will also fix up their nest, similar to their response with a mate’s call. Males show little behavioral response to a stranger’s call other than looking around or raising their head. Females respond to calls from neighbors and strangers like a male responds to calls of strangers. It is possible that females can discriminate between neighbors and strangers and just show the same behavioral response, or they may not be able to distinguish a neighbor from a stranger (Speirs & Davis 1991).

Predation

There are two major predators of Adélie penguins, Leopard Seals (Hydruga leptonyx) and South Polar Skuas (Catharacta maccomicki). And though they don’t kill Adélies, Giant Petrals will feed on the remains of dead penguins. Leopard Seals are the biggest threat to Adélies while swimming. Seals will cruise along near the beach waiting for a group of penguins to dive in. The Adélies know the dangers of Leopard Seals lurk in the waters. So before jumping in Adélies are hesitant, especially when a seal can be seen nearby. Most departures occur in large groups where there is an extensive amount of calling and motivation before diving in (Penney & Lowry 1967; Richard 1981).

South Polar Skuas, the other predator to Adélies, prefer to nest near rookeries so there will be plenty of food for their young. They are a greater threat to young chicks than to adults. They will eat eggs, chicks, and sometimes the remains of penguins killed by seals. They often will predate on the spoiled eggs outside of nest, but there has been documentation of a Skua pulling the tail of an Adélie to get the egg it was incubating. Skuas will later predate on chicks that linger on the edge of crèches, but not the chicks in the middle (Muller-Schwarze & Muller-Schwarze 1973; Richard, 1981).

Recommended Citation

Adelie Penguin (Pygoscelis adeliae), In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. retrieved from Neotropical Birds Online: https://neotropical.birds.cornell.edu/Species-Account/nb/species/adepen1