The popular image of emperor penguins as the ultimate in dedicated dads, going without food for up to 115 days, may have been based on study of a misleadingly small sample size, according to new research.
When it comes to heroic dads, it’s hard to outdo the emperor penguin. But a newly released study suggests the reality may fall short of the legend.
Male emperor penguins are famous for going without food for up to 115 days while they mate and then shelter a solitary egg from the brutal winter winds. Dramatic footage of the semiannual ritual, which begins with a 100-kilometer Antarctic trek to an inland breeding ground, helped make 2005’s “March of the Penguins” one of the highest-grossing documentaries of all time.
But researchers who visited a different colony say they witnessed the animals taking breaks from their breeding duties to go fishing in the winter darkness, challenging the popular notion that they are nature’s most dedicated dads.
The behavior was witnessed at Antarctica’s Cape Washington in late May 1998 — after breeding season had begun and the sun had permanently set for the winter — by a team led by Gerald L. Kooyman, a marine biologist at the Scripps Institution of Oceanography at UCLA, San Diego.
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Kooyman and his fellow researchers were surprised to see about 30 penguins swim past their ship as they arrived. They later found fresh tracks marking the ground between the breeding area and the water, suggesting the animals had been taking frequent dips. By the end of their visit to the cape, they had witnessed more than 100 emperor penguins either swimming or returning from the sea.
Before they left, the researchers tagged four birds with satellite tags and “water switches” that allowed them to track how far the animals traveled and how often they entered the sea. The data confirmed that the penguins continued to take moonlight swims throughout the breeding season. The researchers believe the males ceased their hunting activity once the females laid their eggs.
The findings, published in the Journal of Experimental Biology, suggest that previous research on emperor penguins was focused on too small a population to be taken as representative for the entire species, Kooyman said.
“Almost all the studies about winter breeding have been conducted from the research station Dumont D’Urville, which is about 100 meters away from a colony,” he said. That colony, which was prominently featured in “March of the Penguins,” is also 100 kilometers from the ice edge, making it impossible for penguins that breed there to take breaks for fishing.
The colony that Kooyman observed was farther south than Dumont D’Urville, and was located only about 10 kilometers from the ice edge. Thus the authors suggest that the length of a fast depends largely on the breeding colony’s proximity to water. The male emperor penguins in Cape Washington probably fast for about 65 days, they estimated.
Additionally, the discovery that penguins — who are believed to be visual hunters — can successfully hunt in the dark may be good news for a species that is contending with loss of habitat because of a warming planet. Researchers have expressed concern that the loss of stable ice in Antarctica could make it difficult for the animal to perform their breeding ritual.
“If there’s global warming, the bird has the resilience to go south, where they will continue to have stable sea ice for breeding that they would not have in the northern colonies,” said Kooyman.
As for why the researchers waited 20 years to publish their findings, Kooyman said he had hoped to return to Cape Washington to conduct a more detailed study.
“I think that emphasizes the difficulty of observing what we did,” he said. “But after 20 years I said, ‘Well, I think it’s time to write something about it.’”