Mating calls, which are species specific, are called "ecstatic vocalization." This draws attention to the bird and announces its intentions. Penguins mate with the same partners from previous years.
Mating System: monogamous
Rockhopper penguins typically mate in the early spring or late summer, enabling the young to go to the sea in the mid-summer. They mate in vast colonies and lay up to two eggs, although sometimes pairs "adopt" a third egg. The first egg is usually 20-50% smaller than second one. The small egg is usually lost, although it is capable of maturing into a normal bird. Adopted eggs are also typically lost. After each egg is laid, it is turned over to the male who sits on it and keeps it in his brood pouch for the next four months until it hatches.
Breeding interval: Rockhopper penguins breed once yearly.
Range eggs per season: 1 to 2.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
While the male penguin sits on the incubating egg, he is nourished by the female, or else he fasts for the entire period. If the female does not return with food for the chick once it has hatched, the male produces "penguin's milk" from his digestive system and regurgitates it for the baby.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male)