Female macaroni penguins can begin breeding at around five years of age, while the males do not normally breed until at least six years old.
Females breed at a younger age because the male population is larger.
The surplus of male penguins allows the female penguins to select more experienced male partners as soon as the females are physically able to breed.
Commencing a few days after females arrive at the colony, sexual displays are used by males to attract partners and advertise their territory, and by pairs once together at the nest site and at changeover of incubation shifts.
In the 'ecstatic display', a penguin bows forward, making loud throbbing sounds, and then extends its head and neck up until its neck and beak are vertical.
The bird then waves its head from side to side, braying loudly.
Birds also engage in mutual bowing, trumpeting, and preening.
Monitoring of pair fidelity at South Georgia has shown around three-quarters of pairs will breed together again the following year.

Adult macaroni penguins typically begin to breed late in October, and lay their eggs in early November.
The nest itself is a shallow scrape in the ground which may be lined with some pebbles, stones, or grass, or nestled in a clump of tussock grass (on South Georgia Island).
Nests are densely packed, ranging from around 66 cm apart in the middle of a colony to 86 cm at the edges.
A fertile macaroni penguin will lay two eggs each breeding season.
The first egg to be laid weighs 90–94 g (3.2–3.3 oz), 61–64% the size of the 145–155 g (5.1–5.5 oz) second, and is extremely unlikely to survive.
The two eggs together weigh 4.8% of the mother's body weight; the composition of an egg is 20% yolk, 66% albumen, and 14% shell.
Like those of other penguin species, the shell is relatively thick to minimise risk of breakage, and the yolk is large, which is associated with chicks born in an advanced stage of development.
Some of the yolk remains at hatching and is consumed by the chick in its first few days.

The fate of the first egg is mostly unknown, but studies on the related royal penguin and erect-crested penguin show the female tips the egg out when the larger second egg is laid.
The task of incubating the egg is divided into three roughly equal sessions of around 12 days each over a five-week period.
The first session is shared by both parents, followed by the male returning to sea, leaving the female alone to tend the egg.
Upon the male's return, the female goes off to sea and does not return until the chick has hatched.
Both sexes fast for a considerable period during breeding; the male fasts for 37 days after arrival until he returns to sea for around 10 days before fasting while incubating eggs and young for another 36 days, and the female fasts for 42 days from her arrival after the male until late in the incubation period.
Both adults lose 36–40% of their body weight during this period.
The second egg hatches around 34 days after it is laid.
Macaroni penguins typically leave their breeding colony by April or May to disperse into the ocean.

From the moment the egg is hatched, the male macaroni penguin cares for the newly hatched chick.
For about 23 to 25 days, the male protects its offspring and helps to keep it warm, since only a few of its feathers have grown in by this time.
The female brings food to the chick every one to two days.
When they are not being protected by the adult male penguins, the chicks form crèches to keep warm and stay protected.
Once their adult feathers have grown in at about 60 to 70 days, they are ready to go out to sea on their own.
Female macaroni penguins can begin breeding at around five years of age, while the males do not normally breed until at least six years old. Females breed at a younger age because the male population is larger. The surplus of male penguins allows the female penguins to select more experienced male partners as soon as the females are physically able to breed. Commencing a few days after females arrive at the colony, sexual displays are used by males to attract partners and advertise their territory, and by pairs once together at the nest site and at changeover of incubation shifts. In the 'ecstatic display', a penguin bows forward, making loud throbbing sounds, and then extends its head and neck up until its neck and beak are vertical. The bird then waves its head from side to side, braying loudly. Birds also engage in mutual bowing, trumpeting, and preening. Monitoring of pair fidelity at South Georgia has shown around three-quarters of pairs will breed together again the following year.
Adult macaroni penguins typically begin to breed late in October, and lay their eggs in early November. The nest itself is a shallow scrape in the ground which may be lined with some pebbles, stones, or grass, or nestled in a clump of tussock grass (on South Georgia Island). Nests are densely packed, ranging from around 66 cm apart in the middle of a colony to 86 cm at the edges. A fertile macaroni penguin will lay two eggs each breeding season. The first egg to be laid weighs 90–94 g (3.2–3.3 oz), 61–64% the size of the 145–155 g (5.1–5.5 oz) second, and is extremely unlikely to survive. The two eggs together weigh 4.8% of the mother's body weight; the composition of an egg is 20% yolk, 66% albumen, and 14% shell. Like those of other penguin species, the shell is relatively thick to minimise risk of breakage, and the yolk is large, which is associated with chicks born in an advanced stage of development. Some of the yolk remains at hatching and is consumed by the chick in its first few days.
The fate of the first egg is mostly unknown, but studies on the related royal penguin and erect-crested penguin show the female tips the egg out when the larger second egg is laid. The task of incubating the egg is divided into three roughly equal sessions of around 12 days each over a five-week period. The first session is shared by both parents, followed by the male returning to sea, leaving the female alone to tend the egg. Upon the male's return, the female goes off to sea and does not return until the chick has hatched. Both sexes fast for a considerable period during breeding; the male fasts for 37 days after arrival until he returns to sea for around 10 days before fasting while incubating eggs and young for another 36 days, and the female fasts for 42 days from her arrival after the male until late in the incubation period. Both adults lose 36–40% of their body weight during this period. The second egg hatches around 34 days after it is laid. Macaroni penguins typically leave their breeding colony by April or May to disperse into the ocean.
From the moment the egg is hatched, the male macaroni penguin cares for the newly hatched chick. For about 23 to 25 days, the male protects its offspring and helps to keep it warm, since only a few of its feathers have grown in by this time. The female brings food to the chick every one to two days. When they are not being protected by the adult male penguins, the chicks form crèches to keep warm and stay protected. Once their adult feathers have grown in at about 60 to 70 days, they are ready to go out to sea on their own.
Macaroni penguin