Do Penguins Mate for Life? Pair Bonds, Pebbles and Divorce

Why do penguins form pairs at all?

Raising a penguin chick takes two parents. Eggs must be kept warm for weeks, and chicks need to be guarded and fed constantly, while food may be many kilometers away at sea. One parent stays on the nest while the other goes fishing, and they swap places, sometimes after days or even weeks.

Because of this, nearly all penguins are socially monogamous: one male and one female cooperate for the whole breeding season. The exception is the emperor penguin, where the male alone incubates the egg on his feet for about two months; see how emperor penguins keep their eggs warm. Even emperors, though, rely on both parents to feed the growing chick.

Penguins that often reunite

Species that nest in the same burrow or nest site each year tend to be the most faithful. When partners return to the colony, they head for their old nest, and the bird already there is often their mate from last year. This “meet at the nest” system makes reunions easy.

• African penguins are monogamous and many pairs return to the same nest site year after year, recognizing each other by their braying calls.
• Magellanic penguins in Argentina are known for high nest-site fidelity: males usually return first to dig out the old burrow, and the female rejoins them there.
• Gentoo penguins often reunite with the same partner, and pairs that bred successfully together are more likely to stay together.

Some pairs of these species stay together for many seasons, which is as close to “mating for life” as penguins come. Given that many penguins live 15–20 years or more, that can mean a long partnership; see how long penguins live.

Emperor and king penguins: new partners most years

The two largest penguins have no nest. They incubate their egg on their feet and move around the colony, so they cannot use a nest site to find a partner. Instead, they recognize each other by voice, and finding last year’s mate among thousands of calling birds is difficult.

The emperor penguin is faithful within a season, but studies suggest that only about 15% of pairs reunite the next year. Timing is critical: the breeding season is short, so a bird that waits too long for its old partner risks not breeding at all.

The king penguin has an even more complicated schedule. Raising one chick takes 14 to 16 months, longer than a year, so a pair that bred successfully is out of step with the colony the following season. Most king penguins therefore pair with a new partner each time they breed, and researchers have found that birds that wait for their former mate often end up breeding late and less successfully.

Pebbles, bows and courtship

Penguin courtship is full of displays that help pairs form and keep their bond. Partners bow to each other, point their bills to the sky while calling, and preen each other’s heads and necks. These rituals help a pair recognize each other and coordinate their nest duties.

Adelie and gentoo penguins build nests of small stones, which keep eggs above the meltwater and mud of the breeding season. Males collect stones and bring them to the nest, and offering stones is part of courtship and pair bonding. Good stones are scarce, so penguins regularly steal them from neighbors’ nests. Studies of Adelie penguins have also seen some females mate with males other than their partner, sometimes leaving with a stone afterward.

Do penguins get divorced?

Yes. Biologists call it divorce when both members of a pair survive but one or both breed with a new partner. It is common in many penguin species. The main reasons are:

• Late arrival: if one partner returns to the colony late, the other may pair with a new mate rather than miss the breeding season.
• Breeding failure: pairs that lost their eggs or chicks the year before are more likely to split up.
• Competition: an unpaired bird may push its way into an existing pair.

Divorce rates vary from year to year as well as between species. Long-term studies of little penguins in Australia and New Zealand, for example, found that divorce is more common after poor breeding seasons.

Same-sex pairs

Penguins sometimes form same-sex pairs, both in zoos and in the wild. The most famous were two male chinstrap penguins named Roy and Silo at New York’s Central Park Zoo, who were given an egg to incubate and raised a female chick named Tango. Their story became the 2005 children’s book And Tango Makes Three. Such pairs show how strongly penguins are driven to form bonds and care for chicks.