Climate change is killing chicks in the world’s largest colony of Magellanic Penguins directly — as a result of drenching rainstorms and, at other times, heat — as well as by depriving them of food, reports a new study in the online journal Public Library of Science ONE.
Too big for parents to sit over protectively but still too young to have grown waterproof feathers, downy chicks exposed to drenching rain can struggle and die in spite of the best efforts of their parents. And during extreme heat, chicks without waterproofing can’t take a dip in cooling waters as adults can.
Various research groups have published findings on the reproductive repercussions from single storms or heat waves, events that are impossible to tie to climate change when considered individually. The new results span 27 years of data (1983-2010) collected in Argentina under the direction of biologist Dee Boersma, Wadsworth Endowed Chair in Conservation Science at the University of Washington. She is the lead author of the paper that describes the findings.
“It’s the first long-term study to show climate change having a major impact on chick survival and reproductive success,” says Boersma.
She has led field work at Punta Tombo, the world’s largest breeding area for Magellanic Penguins, since 1983. Punta Tombo is located about halfway up the Atlantic coast of Argentina. Some 200,000 penguin pairs lay eggs and raise their young there from September through February.
During the 27-year span, an average of 65 percent of chicks died per year; about 40 percent starved. Climate change, a relatively new cause of chick death, killed an average of 7 percent of chicks per year, but in some years it was the most common cause of death, killing 43 percent of all chicks one year and fully half in another.
Starvation and weather will likely interact increasingly as climate changes, Boersma says.
“Starving chicks are more likely to die in a storm,” she says. “There may not be much we can do to mitigate climate change, but steps could be taken to make sure the Earth’s largest colony of Magellanic Penguins have enough to eat by creating a marine protected reserve, with regulations on fishing, where penguins forage while raising small chicks.”
Just back from two months in the field, Boersma says heat this season took a greater toll on chicks than storms. Such variability between years is the reason why the number of chicks dying from climate change is not a tidy, ever-increasing figure each year. Over time, however, the researchers expect climate change will be an increasingly important cause of death.
Also contributing to increasing deaths from climate change is the fact that, over 27 years, penguin parents have arrived at the breeding site later and later in the year, probably because the fish they eat also are arriving later, Boersma notes. The later chicks hatch, the more likely they’ll still be in their down-covered stage when storms typically pick up in November and December. — Matt Mendenhall, Managing Editor