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Penguins have extramarital affairs before returning to their regular partners

Ice cold.

By Cassidy Ward
Gentoo penguins (Pygoscelis papua)

The 2014 animated movie Penguins of Madagascar imagines a quartet of penguins with human level intelligence and behavior. Throughout the film’s 91-minute runtime, the animals get into all kinds of hijinks involving a mad scientist with a secret, a strange serum, and a submarine. As far as we know, penguin behavior doesn’t mirror humanity at quite that level, but they are more similar to us than we might have supposed, at least in terms of relationship fidelity.

We don’t often expect moral fidelity from non-human animals, but penguins have long been upheld as an example of romance in the animal kingdom. They commonly pair off to breed and those pair bonds can last a lifetime. In the frigid and unforgiving Antarctic environment, survival and successful reproduction are only achieved through cooperation, so partnership in parenting makes good survival sense. Finding a new breeding partner every year would unnecessarily complicate the already difficult endeavor of hatching and raising a new chick, so they largely don’t do it. Instead, when a penguin reaches adulthood, they find a mate and those mates tend to stick together, returning to one another year after year.

These romantic rendezvous are punctuated by long stretches, months at a time, when the avian lovers are separated while they forage for food at sea. Once it’s time to breed again, penguins return to the colony and wade through a figurative ocean of other penguins in search of their partner. Incredibly, they find one another, settle down at the nest, end embark upon the hard cooperative work of raising a baby. Everything is as it should be… at least on the surface.

While it’s true that penguins mostly return to the same mates to breed and raise chicks, it’s not uncommon for them to get a little side action before they meet up. It turns out that penguins might only be socially monogamous, but the sexual lines aren’t as strictly drawn.

Part of the problem stems from the fact that male and female penguins return to the breeding site at different times. Males return first and prepare the nest in anticipation of their partner. Sometimes, a female will arrive to find that their usual mate hasn’t returned. That’s happening more and more frequently as a consequence of predation and a decline in food supply resulting from climate change. Without a mate, an enterprising female might look to another male who is already on the scene. Then, when that male’s usual mate returns, drama ensues. According to Live Science, the original female usually wins that contest, but it can complicate things down the line.

If the interloper then finds a new mate to nest up with, it is unclear if that male is raising his own chick or the offspring of his new partner’s previous dalliance. Determining the paternity of penguin chicks in the wild is a challenging affair, but observations in captivity support the idea that penguins raise chicks which aren’t genetically theirs at least some of the time.

We know that because of genetic testing carried out at the Loveland Living Planet Aquarium in Utah. The aquarium is part of a penguin breeding program, so they keep an eye on their penguins’ activities in order to ensure a healthy and robust breeding population.

In the aquarium, there are two penguins named Roto and Copper who are pair bonded. Nearby, another pair named Coco and Gossamer are also pair bonded. While the penguin couples have solid relationships and continue to help one another raise chicks, aquarium workers have noticed they don’t always bed down with their partners. In fact, genetic testing revealed that Roto and Copper recently raised two chicks who were actually fathered by Gossamer, according to the New York Times.

Those two young penguins accounted for 25% of the animals tested. Of course, it’s possible that penguin behavior in captivity doesn’t wholly align with what happens in the wild, but based on what we know it probably does.

In the end, it might not be all that surprising. While humans are ostensibly monogamous, we know that infidelity occurs more often than we like to admit. It shouldn’t be too shocking that penguins exhibit similar behaviors. Still, there’s something a little disappointing in the realization. Penguins were supposed to be the best of us.