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January 4, 2022
In June 2021, an unprecedented heat wave hit the Pacific Northwest and Canada, killing an estimated 1,400 people. On June 28, Seattle hit 108 F – an all-time high – while the village of Lytton in British Columbia recorded the highest temperature on record in Canada of 121.3 F on June 29, the day before it . was destroyed by a forest fire started by heat.
Climate change is expected to lead to more extreme heat events around the world, with far-reaching consequences not only for humans, but also for wildlife and ecosystems.
In 2019, researchers at the University of Washington witnessed it in Argentina in one of the world’s largest breeding colonies of Magellanic penguins. On January 19, temperatures at the Punta Tombo site on Argentina’s south coast reached 44 ° C, or 111.2 ° F, and it was in the shade. As the team reports in a paper published Jan. 4 in the journal Ornithological Applications, the extreme heat wave killed at least 354 penguins, based on a body search by UW researchers in the days following the record high temperature.
“This extreme event occurred towards the end of the Magellanic penguin breeding season, so it killed a large number of adults, as well as chicks,” said the lead author. Katie holt, doctoral student in biology at UW. “This is the first time that we have recorded a mass mortality event in Punta Tombo linked to extreme temperatures.”
The January 19 heat wave was the highest temperature researchers ever recorded in Punta Tombo, where UW teams have been studying Magellanic penguins since 1982 under the co-author’s direction. Fr Dee Boersma, professor of biology at UW. Temperatures at the site during the breeding season typically increase by 50 F to 100 F. In a previous season, researchers had already recorded a shade maximum of 43 C, or 109.4 F, but this former record was not associated with a dead mass of penguins, according to Holt.
The extreme heat on January 19 affected adults and chicks differently. Almost three-quarters of the penguins that died – 264 – were adults, many of whom likely died of dehydration, according to post-mortem analyzes conducted by UW researchers. They found 27% of the dead adult penguins along the paths leading from the breeding colony to the ocean, where they could have a drink – the penguins have glands that can filter salt from the water. A trip from the colony to the ocean can be up to a kilometer and, at most, can take 40 minutes for an adult Magellan. Dead adults have often been found on their bellies, extended feet and fins, and open mouths, a common panting and chilling pose for Magellanic penguins.
Some sections of Punta Tombo, where thousands of Magellanic penguins congregate to breed each spring and southern summer, have fared less well than others. In the central part of the colony, about 5% of the adults perished. But other sections recorded little to no deaths, indicating that microclimates and access to the ocean, as well as individual health and nutrition, may have influenced survival rates.
UW researchers documented past mass death events at Punta Tombo linked to heavy torrential rains that mostly killed chicks, including a year in which downpours killed 50% of the colony’s recently hatched offspring. . The 2019 heatwave is of particular concern as it resulted in the loss of large numbers of adults in a single event, according to Holt.
“Any mass deaths like this is a concern,” Holt said. “But what is of most concern about heat mortality is that it has the potential to kill a lot of adults. The viability of populations of long-lived seabirds – such as Magellanic penguins – depends on a long lifespan. Adult Magellanic penguins can live for over 30 years, so they usually have plenty of opportunities to raise successful chicks. If we lose a large number of adults because of a single event like this, that is a major concern. “
Based on an examination of a subset of corpses, at least 8 of the 10 adults who died were males. This likely reflects the high prevalence of male Magellanic penguins at Punta Tombo – around three males for each female – rather than a differential survivability in extreme heat. The colony’s asymmetric sex ratio increased over time. Research by Boersma’s group shows that adult females are less likely to return to Punta Tombo to breed, possibly because they have a harder time finding enough food on the high seas outside of the breeding season. This has likely contributed to an overall decrease in colony size since the late 1980s.
The remaining 90 deaths from the January 2019 heat wave were chicks. Based on post-mortem analyzes, the chicks that perished tended to be well fed and showed no signs of dehydration. They may have died because, with a full stomach and a small body, they couldn’t properly regulate their body temperature in the extreme heat, according to Holt.
Climate change is expected to produce more extreme weather events of all types globally, although the effects vary by location. The consequences of this heat wave, while grim, also show scientists the limits that some species can endure.
Boersma is the founder of UW-based Ecosystem Sentinel Center, which studies Magellanic penguins and other species considered to be key indicators of ecosystem health.
“Penguins might have the ability to cope, like moving breeding sites,” Holt said. “But it will take time to determine whether these adaptations are effective.”
The research was funded by the Wildlife Conservation Society, the Exxon-Mobil Foundation, the Pew Fellows Program in Marine Conservation, the Disney Worldwide Conservation Fund, the Chase Foundation, the Cunningham Foundation, the MKCG Foundation, the Offield Foundation, the Peach Foundation , the Thorne Foundation, the Tortuga Foundation, the Kellogg Foundation and the Wadsworth Endowed Chair in Conservation Science at UW.
For more information, contact Holt at [email protected]
Tag (s): Center for Ecosystem Sentinels • College of Arts and Sciences • conservation • Dee Boersma • Department of Biology