Over the past few decades, heat waves have become more common in several parts of the world as our planet warms. That's a huge problem for many animals, as it can lead to habitat loss and push their bodies to lethal thresholds. However, one penguin species appears to be adapting to these extreme conditions by shifting its breeding calendar.
Heat stress
Researchers at the Laboratory of Ecology and Wildlife Conservation in Argentina and the School of Biological and Medical Sciences at Oxford Brookes University spent a decade (from 2013 to 2024) monitoring a Gentoo penguin colony on Martillo Island, off the southern coast of Argentina. They wanted to understand how the seabirds, which are adapted to the cold, respond to extreme heat events.
It was already known that penguin chicks are vulnerable to overheating. Their thick coats of down that are designed to keep them warm when it's freezing are a problem when the temperatures are dialed up because they trap excess heat. That puts them at risk of heat stroke and sudden death.
To see how the colony was faring, the team placed a time-lapse camera in a wooden housing inside a hollow tree trunk and analyzed the images for signs of heat stress. They then cross-referenced these with local weather station data.
Their findings are published in a paper in the journal PLOS One.
Beating the heat
The researchers discovered that the penguins are successfully beating the heat by breeding about two days earlier each year. This has meant that the chicks have been able to develop their juvenile feathers and leave for the safety of the cool ocean before the worst of the heat arrives.
"This is a rare example in which a warming-induced phenological change withdraws chicks from potentially deadly hot summer days by fledging sooner," wrote the scientists in their paper. "Gentoo penguin plasticity to adjust the timing of breeding is helping chicks avoid the increasing amount of hot summer days on land."
The team's data demonstrates how important this head start is. When the thermometer hits 18°C, the chicks begin panting to cool down, and once temperatures surpass 20°C, they switch to other avoidance behaviors, such as finding shade under bushes. However, during a severe heat wave in January 2015, when the temperature reached 24°C, five chicks died within 45 minutes.
The paper notes that shifting the breeding calendar buys the colony time, but it is not a long-term solution. If temperatures continue to climb, the penguins may struggle to survive at this location.
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Publication details
Sabrina Harris et al, Rare upside of climate-induced phenological changes: Gentoo penguins (Pygoscelis papua) avoid heat events at Martillo Isl., Tierra del Fuego, Argentina, PLOS One (2026). DOI: 10.1371/journal.pone.0347877
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