Katie Holt, UW Biology graduate student, and Dee Boersma, UW Biology Professor, were featured in an article in UW News for their research on the 2019 heat wave that killed at least 354 Magellanic penguins.
In June 2021, an unprecedented heat wave hit the Pacific Northwest and Canada, killing an estimated 1,400 people. 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.
Climate 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 2019, University of Washington researchers witnessed this in Argentina at one of the world’s largest breeding colonies for Magellanic penguins. On Jan. 19, temperatures at the site in Punta Tombo, on Argentina’s southern coast, spiked to 44 C, or 111.2 F, and that 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 search for bodies by UW researchers in the days following the record high temperature.
“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,” said lead author Katie Holt, a UW doctoral student in biology. “It’s the first time we’ve recorded a mass mortality event at Punta Tombo connected to extreme temperatures.”
The Jan. 19 heat wave was the highest temperature the researchers have ever recorded at Punta Tombo, where UW teams have been studying Magellanic penguins since 1982 under co-author P. Dee Boersma, a UW professor of biology. Temperatures at the site during the breeding season typically rise from the 50s F to the low 100s F. 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, according to Holt.
The extreme heat on Jan. 19 affected adults and chicks differently. Nearly three-quarters of the penguins that died — 264 — were adults, many of which likely died of dehydration, based on postmortem analyses conducted by the UW researchers. They 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. A 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. Dead adults were often found on their stomachs with their feet and flippers extended and mouth open, a common panting and cooling pose for Magellanic penguins.
Read the full article in UW News.