The Adélie penguin delays breeding until it is approximately 3-4 years old. They mate and raise chicks during October to February (Spurr 1975b).
The Adélie penguin nests in large groups called rookeries (Muller-Schwarze & Muller-Schwarze 1973). Their nests are made out of rocks that both the male and female in a pair will collect. The normal clutch size is two eggs but inexperienced breeders may lay just one (Sladen 1959; Boersma 1997). They only produce one clutch each breeding season and incubate for about 35 days (Sladen 1959). While incubating the orientation of an Adélie on its nest depend on several factors. The incubating penguin will face into strong winds. They also move depending on their neighbors. They will lay so they are not face to face with a neighbor, this usually means they will face towards inter-nest spaces. But if a neighbor starts to rearrange its nest then the penguin will situate itself to face its neighbor (Spurr 1975c).
There are two stages in the parental care given by Adélie penguins. Stage one is the guard stage. This stage lasts from the moment a chick is born until about 20-30 days after hatching. During this stage chicks are covered in down feathers and are unable to regulate their own temperature for the first 5 days so they will spend most of their time staying warm under their parent’s brood patch. Parents will take turns guarding chicks and foraging for food, usually switching off every other day or two. Towards the end of the guard stage, about day 15, the chicks are fully homeothermic so they are able to stand or lay in the nest while a parent stands off to the side. One interesting fact about the guard stage, chicks that are born earlier in the season tend to be guarded for a longer period of time. Also parents with nests on the periphery of the colony will also guard their chicks longer than parents in the center (Taylor 1962; Spurr 1975a).
Stage two is the crèche stage or the post-guard stage which begins around day 20-30 after hatching. During this stage parents are still feeding their chicks, but now both parents can leave the nest to gather food. While their parents are gone chicks may either remain at their nest or join the other chicks and form a group called a crèche. These large groups allow for protection from the aerial predator Catharacta maccomicki, South Polar Skua (Spurr 1975a).