Rising temperatures are forcing some Antarctic penguins to breed earlier, study says

Rising temperatures are forcing Antarctic penguins to breed earlier, posing a big problem for two of the cute tuxedo species facing extinction by the end of the century, according to a study.

Three different species of penguins — the cartoon-eyed Adelie penguin, the black-striped chinstrap and the fast-swimming gentoo — are beginning their reproductive process about two weeks earlier than they did a decade ago, according to a study published Tuesday in the Journal of Animal Ecology. The change in habits is generating possible feeding problems for the chicks.

Researchers used remote-controlled cameras to photograph penguins breeding in dozens of colonies between 2011 and 2021. Between 2012 and 2022, temperatures on breeding grounds rose 5.4 degrees Fahrenheit.

“Penguins are changing the timing of their reproduction at record speed, faster than any other vertebrate,” said the study’s lead author, Ignacio Juárez Martínez, a biologist at the University of Oxford in the United Kingdom. “And this is important because the time when it reproduces must coincide with the time when there are more resources in the environment and this is mainly food for the chicks, so that they have enough to grow.”

The researchers said it was the most rapid change over time in the life cycles of any animal with a backbone they had ever seen. For some perspective, scientists have studied changes in the life cycle of the great tit, a European bird. They found a similar two-week shift, but that took 75 years, compared to just 10 years for these three penguin species, said study co-author Fiona Suttle, another Oxford biologist.

Winners and losers in a warming world

Suttle said climate change is creating winners and losers among these three penguin species, at a time in the penguin life cycle where food and competition for it are critical to survival.

Adélie and chinstrap penguins are specialists and feed mainly on krill. Papuans have a more varied diet. Birds used to breed at different times, so there was no overlap. But gentoo breeding has advanced faster than the other two species, creating competition. That’s a problem because gentoos, which don’t migrate as far as the other two species, are more aggressive in finding food and establishing nesting areas, Martinez and Suttle said.

Suttle said he returned in October and November to the same areas of the colony where he used to see Adelies in previous years only to find their nests replaced by gentoos. And the data backs up his observations, he said.

“Masks are decreasing worldwide,” Martínez said. “The models show that they could go extinct before the end of the century at this rate. The Adélies are doing very poorly on the Antarctic Peninsula and are very likely to go extinct on the Antarctic Peninsula before the end of the century.”

Other factors threaten penguin populations

Martínez theorized that warming West Antarctica (the second warmest place on Earth, behind only the North Atlantic Arctic) means less sea ice. Less sea ice means more spores come out earlier in the Antarctic spring and then “you have this incredible bloom of phytoplankton,” which is the base of the food chain that eventually leads to penguins, he said. And this happens earlier every year.

Chinstraps and Adélies not only have more competition for food from gentoos due to warming and changes in plankton and krill, but the changes have brought more commercial fishing that arrives earlier and further shortens the supply for penguins, Suttle said.

This change in breeding timing “is an interesting sign of change and it is now important to continue to observe these penguin populations to see if these changes have negative impacts on their populations,” said Michelle LaRue, professor of Antarctic marine sciences at the University of Canterbury in New Zealand. She was not part of the Oxford study.

Using millions of photographs, taken every hour by 77 cameras for 10 years, scientists recruited ordinary people to help tag reproductive activity using the Penguin Watch website.

“We’ve annotated more than 9 million of our images through Penguin Watch,” Suttle said. “A lot of that is due to the fact that people love penguins so much. They’re so cute. They’re on all the Christmas cards. People say, ‘Oh, they look like little waiters in tuxedos.'”

Other penguin species in Antarctica face problems. Researchers from the British Antarctic Survey and the University of Southampton said last June that the continent’s emperor penguin population may be declining faster than even the most pessimistic predictions. The images showed that the species, recognizable by its height and yellow spots, decreased in Antarctica by 22% between 2009 and 2024.