The Changing Climate Is Killing Baby Penguins

As the climate changes, penguin chicks are dying more frequently—and not just in the wishy-washy, semi-related ways you might expect. Abnormal weather patterns are drowning them, baking them, giving them heat stroke, and freezing them to death.

There are always going to be penguin chick casualties; every year, penguin chicks die from starvation and other “natural”-ish causes. But in recent years, Dee Boersma, a University of Washington professor and author of a new report published in PLOS One, has noticed they’ve been dying of more weather-related causes than ever before. For 28 years, Boersma has been studying Magellanic penguins at Argentina’s Punta Tombo, a spot roughly 200,000 penguins call home during the breeding season of September through February.

“The major reason chicks normally die is from starvation and predation, but in some years they die from rain and heat events,” she said. “But some years we get rainfall events, and those cause mass casualties.”

There are several reasons why rainstorms are bad. Penguins aren’t born waterproof, and if they get wet soon after they’re born, they can freeze to death. If they fall in the water, as many Emperor penguins do when the ice they’re living on has melted, they drown. Essentially, penguin chicks aren’t prepared for abnormal weather, and yet they're seeing more of it lately.

“It’s kind of like humans. There’s not a Katrina every day, but if there is one, it’s a mass casualty event,” she said. She’s observed 16 rainstorms that have killed penguins, and in some years, it can kill as many as 50 percent of all baby penguins at the colony, which is the largest breeding spot for Magellanic penguins in the world.

“None of these things are linear,” she said. “But these storms of more than 20 millimeters of rainfall have increased in frequency over the past few years.”

She says that some years could be so bad that “almost no chicks will survive.”

This year, for instance, no rainstorms killed penguins, but extreme heat did. This year, temperatures reached over 30 degrees C, high enough to kill adult penguins.

“We had a day that was a little over 30 and a big male came in—he tried to get underneath a bush for shade but couldn’t,” she said. “He had a massive heat stroke and died.”

Magellanic penguins are not considered endangered, but are classified as “near threatened.” And there’s evidence that all of these events are beginning to add up. Boersma notes that there are 24 percent fewer active penguin nests at the colony than there were in 1987, the first year she began taking annual penguin censuses.

“The real problem is whether these years stack up. If you have a lot of years where half the chicks are killed in storms, then clearly you’re not going to have great recruitment,” she said.

The colony isn’t necessarily doomed, however. Boersma said that the colony might be able to survive many years of high weather-related deaths if the area was better protected from things such as fishing and pollution and disruption from oil tankers.

“Climate change has already occurred and is already having these effects. The fact that they’re dying shows us that they’re ocean sentinels—they’re telling us what’s happening to the oceans,” she said. “But we could help them if their food was protected, if there weren’t tankers passing by all the time, if there was less fishing.”