Males and females take it in turns to incubate the two eggs, and to guard them from marauding skuas. The eggs are laid with an interval of two days, so that when they hatch, one chick is larger and stronger than the other.

If food is in short supply, the smaller chick will rarely survive. The parents look after their own chicks for just over two weeks and then they form crèches. The chicks take to the water after about nine weeks.