Adelie Penguin

Distribution:

Adelie penuins are spread around the coastlines of the Antarctic continent and nearby islands. Breeding colonies are found on ice-free coastal areas. Individual birds may be rarely sighted on subantarctic islands.

Feeding:

Adelie penguins feed on a variety of organisms such as small fish (e.g. anchovies), cephalopods (e.g. squids) and crustaceans (e.g. krill). The diet at any particular location and time reflects fluctuations in food availability. Krill (antarctic or crystal) seems to be the preferred foodsource when available. Fish are the most abundant prey during the breeding season, whereas squid predominates in the winter. Hunting is by sight so the dive depth is dependant on the amount of light. Usually dives dont last longer than 5 minutes are are not deeper than 50m, however dives of 170m have been recorded. Most of the feeding takes place in areas where there is broken up sea ice around land. Especially at the beginning of the breeding season, large areas of unbroken sea ice may seperate Adelies from the water, necessitating long foraging trips. If the sea ice does not retreat fast enough, the Adelies may be unable to feed their chicks sufficiently.

During the breeding period, birds only spend short periods at sea, whilst during feeding in the winter season birds may rarely be on land, although the birds do leave the water to moult on pack ice in Febr./March.

Reproduction:

After a period of feeding to gain bodyweight before breeding, Adelies migrate to their colonies around October. Courtship is instigated by the male and usually initially involves the "ecstatic display" where the penguin faces skywards with breast thrust outwards and flippers flapping horizontally and makes a series of short calls. This is repeated many times until a female penguin becomes interested. Following this, the male may perform the "Bill-to-Axilla display" where it essentially alternatively looks into each of its "armpits". Birds may also proceed to bow to eachother. Once a pair bond has been established, birds may stand breast to breast with heads raised and beaks open but flippers against the body, and may accompany this by calling and swaying of bodies from side to side ("mutual display").

Adelies are not particularly faithful to previous partners. Females will either choose a new mate or if they find their previous one they will mate with try and drive any competitors away and mate with it. This is possibly a result of the intense pressure to make use of the short summer breeding timeframe and also the result of the high mortality rate of adult Adelie penguins. The nest is made of little pebbles lined with e.g. feathers and the colonies are often extensive with each nest being located just out of pecking distance of the surrounding ones. Adelies often try to steal rocks from other nests.

Copulation is started when the male approaches the female from the side, often repeatedly bowing, and climbs onto the middle of her body. The bills then meet and gently beat against eachother as the male moves backwards and the female raises her tail to allow the cloacas to meet. The process is repeated numerous times.

One or two eggs weighing 100-125g are laid in Nov./Dec. and incubated alternatively by both parents, but first by the heavier male, for only about 35 days. Eggs may be lain on or may be held on the feet. This short incubation period is probably an adaptation to the short antarctic summer. After hatching, chicks initially remain on the nest but after 3 weeks they start to form small creches. At 7-8 weeks, the chicks leave the colony and head out to sea. Sexual maturity is reached in 3 years by females and 4 by males, yet breeding usually is started 1-2 years later.

Adelie penguins copulating	Adelie penguin bringing rock to nest

General Behaviour:

Adelie penguins are less timid than other Pygoscelis species and may not retreat when approached by humans. Further, Adelie penguins may attack the nests of Skuas, breaking eggs or even killing chicks. Three different threat postures are adopted by Adelie penguins; (i) penguin stands upright with flippers against body, eyes looking down, crest erected, and usually additionally points body towards the threat with its bill pointing directly at it ("direct stare posture"), (ii) the penguin stares with one eye at the threat with its neck arched to one side ("fixed one eye stare"), and (iii) the penguin alternates between one eyed stares with left and right eyes and slowly waves its flippers as it does this ("alternate stare"). Each of these postures may be accompanied by calls. Birds may also crouch forwards with their bellies close to the ground, whilst pecking or calling. In order to avoid fights, penguins may assume a defensive pose (for example when walking between nests) which involves holding feathers and flippers tightly against body and elongating the neck, all of which make the body seem smaller.

When Adelie penguins fight, they tend to come breast to breast and bump eachother whilst hitting with their flippers and grabbing and pecking eachother with their bills. Penguins may charge at eachother or at skuas with upright bodies and crests and flippers extended.

Similar to Emperor penguins, Adelies sometimes have to cross large areas of sea ice. It may be necessary to cross 100km of sea ice to reach their colonies at the start of the breeding season. Unlike the Emperor, Adelie penguins can not actually nest on ice. Adelies also make use of the sledging technique used by the Emperor.

Threats:

Natural predators of adult Adelie penguins are leopard seals and killer whales. Chicks and eggs may fall victim to Skuas and Giant Petrels.

Adelie penguins feeding is limited by the range of the sea ice around the antarctic continent. Consequently there is some concern that they may be adversely affected by global warming. Further, increased commercial fishing near their breeding grounds is a concern.

Human disturbance is also known to affect the breeding success in Adelie colonies.

Where To See:

Large numbers of Adelie penguins are found near Ross island and in McMurdo sound. However, only few ships visit the area with tourists and prices are prohibitive. Adelie penguins also inhabit the antarctic peninsula and some of the nearby islands (e.g. South Shetlands, Balleny and Peter Island). In the antarctic summer, these areas are frequented nearly daily by cruise ships of various sizes, most of which depart from Ushuaia in Argentina.