They may have died because, with full bellies and small bodies, they could not regulate their body temperatures properly in the extreme heat, Holt says.Ĭlimate change is expected to produce more extreme weather events of all types globally, though effects will vary by locality. Based on postmortem analyses, the chicks that perished tended to be well fed and did not show signs of dehydration. This has likely contributed to an overall decrease in the size of the colony since the late 1980s.Ĭhicks accounted for the remaining 90 fatalities from the January 2019 heat wave. Research from Boersma’s group shows that adult females are less likely to return to Punta Tombo to breed, likely because they have more trouble finding enough food in the open ocean outside the breeding season. The colony’s skewed sex ratio has grown over time. That likely reflects the high prevalence of male Magellanic penguins at Punta Tombo-roughly three males to every female-rather than a differential survivability in extreme heat. If we’re losing large numbers of adults from a single event like this, that’s a major concern.”īased on examination of a subset of corpses, at least 8 out of 10 of the adults that died were males. “Adult Magellanic penguins can live more than 30 years, so they typically have many opportunities to successfully raise chicks. The population viability of long-lived seabirds-like Magellanic penguins-relies on long lifespans. But what is most concerning about heat-death mortality is that it has the potential to kill a lot of adults. “Any mass die-off like this is a concern. The 2019 heat wave is a particular concern because it led to the loss of a large number of adults in a single event, Holt says. Researchers have documented past mass mortality events at Punta Tombo linked to severe rainstorms that killed primarily chicks, including one year where deluges killed 50% of the colony’s recently-hatched offspring. But other sections saw few or no fatalities, indicating that microclimates and access to the ocean, as well as individual health and nutrition, may have influenced survival rates. In the central section of the colony, about 5% of adults perished.
Some sections of Punta Tombo, where thousands of Magellanic penguins gather to breed each austral spring and summer, fared worse than others. Researchers often found dead adults on their stomachs with their feet and flippers extended and mouth open, a common panting and cooling pose for Magellanic penguins. The researchers found 27% of adult penguin corpses along paths heading out of the breeding colony to the ocean, where they could get a drink-penguins have glands that can filter salt out of the water.Ī journey from the colony to the ocean can stretch up to one kilometer and, at its longest, might take an adult Magellanic 40 minutes to complete. Nearly three-quarters of the penguins that died-264-were adults, many of which likely died of dehydration, based on postmortem analyses. The extreme heat on January 19 affected adults and chicks differently. In a past season, researchers had previously recorded a shade high of 43 C, or 109.4 F, but that older record was not associated with a mass die-off of penguins, Holt says. Temperatures at the site during the breeding season typically rise from the 50s F to the low 100s F. The January 19 heat wave was the highest temperature the researchers have ever recorded at Punta Tombo, where teams have studied Magellanic penguins since 1982 under coauthor P. “It’s the first time we’ve recorded a mass mortality event at Punta Tombo connected to extreme temperatures.” “This extreme event fell near the tail end of the breeding season for Magellanic penguins, so it killed a large number of adults, as well as chicks,” says Katie Holt, a doctoral student in biology at the University of Washington and lead author of the study in the journal Ornithological Applications. On June 28, Seattle reached 108 F-an all-time high-while the village of Lytton in British Columbia recorded Canada’s highest-ever temperature of 121.3 F on June 29, the day before it was destroyed by a heat-triggered wildfire.Ĭlimate change is expected to bring more such extreme heat events globally, with far-reaching consequences not just for humans, but for wildlife and ecosystems. In June 2021, an unprecedented heat wave hit the Pacific Northwest and Canada, killing an estimated 1,400 people. An extreme heat wave in 2019 killed at least 354 Magellanic penguins at one of the world’s largest breeding colonies, researchers report.
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