Paternity Tests at the Penguin House

Roto and Copper, two gentoo penguins at Loveland Living Planet Aquarium in Utah, cared for three children together, taking turns feeding them. They are a social pair, just like Coco and Gossamer, a neighboring penguin couple that raised their own chicks.

Or did they?

We tend to think of penguins as monogamous, with social bonds formed between two parents for life. But researchers have discovered that penguins in captivity, like some species in the wild, sometimes stray. After sampling the DNA of 19 gentoo penguins at the aquarium, researchers revealed last month in the journal ZooBiology that Roto is the father of two chicks believed to be Gossamer’s offspring.

“We’ll go back to the classic movies where the male gives the female a rock and they start to build their nest with it, and they are totally monogamous,” Steve Vogel, the aquarium’s zoological operations director said, “and that is not true 20 percent of the time.” At least not at this aquarium.

The story sounds like a daytime TV talk show, climaxing with a surprise paternity test result. But for zoo animals, it’s important. These penguins are set to be part of a program pairing the most genetically diverse animals from different facilities, like people in a matchmaking service, to ensure a strong, healthy penguin population in case this species ever goes extinct. Although gentoo penguins are doing relatively OK in the wild, other species face threats from climate change, overfishing, oil drilling and other factors.

For this penguin dating service to work, documenting familial lineages is critical to avoiding inbreeding. And while the sample size is small, the study suggests that using DNA evidence to confirm behavioral observations may be the best way to ensure healthy penguin populations of the future.

At the aquarium, staff monitor the penguins like producers on a reality TV show. When they spot two penguins engaging in mating behavior, they call in a “code Romeo.” The signal summons an animal keeper, who determines as best she can which two penguins are getting busy, and documents it in the Gentoo Penguin Studbook, a database shared among zoos and aquariums that will be used to make the most genetically diverse matches.

At Loveland, staff started noticing some penguins mating outside their social pairs.

This called for paternity testing.

Of eight offspring they tested, two had a biological father that wasn’t their social father. In other words, Roto and Coco had been sneaking around. Another rogue female had been mating with two different males too — even though the males were in stable social pairs.

Eric Domyan, a biology professor at Utah Valley University who led the testing, wasn’t surprised.

“Most species that we think of as monogamous, including our very own species, we know that there’s always an asterisk beside that,” he said. “It’s very rare to find monogamy in any species where there’s 100 percent fidelity to one’s mate. I expected that to be the case with penguins as well.”

For those concerned about the lives of unfaithful penguins, there’s a moral to the story: “We could say that penguins are human, too,” Domyan said. “It’s probably not realistic to expect animals to have a higher level of moral perfection than we do.”