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. (Alten, 1997; Richdale, 1951)
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. (Ainley, 2002; Alten, 1997; Berger, 2004)
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. (Ainley, 2002; Alten, 1997; Berger, 2004)