Is climate change killing Magellanic penguins?

‘Increasing storminess bodes ill not only for Magellanic penguins but for many other species …’

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New research suggests that some penguin colonies are likely to see direct impacts from climate change. bberwyn photo.

By Summit Voice

FRISCO — A 27-year study of Magellanic penguins at Punta Tombo, Argentina, offers convincing evidence that climate change is killing penguin chicks, as the starving young birds succumb to increasing rainfall during stormy weather and, at other times, heat.

The University of Washington biologists who led the study say their findings are proof that climate change is directly responsible for penguin mortality — not just indirectly by depriving them of food, as has repeatedly been documented by other research.

Other recent research has shown similar impacts to white pelicans at their breeding grounds in North Dakota, and climate change is also disrupting breeding of migratory songbirds.

The research is based on careful chick counts at breeding sites and analyses of regional weather weather data showing that storminess increased between 1983 and 2010. Along with showing climate change impacts, the researchers said their finding show the need to create a protected area to at least ensure an adequate food supply for the chicks that do survive.

“It’s the first long-term study to show climate change having a major impact on chick survival and reproductive success,” said UW biology professor Dee Boersma, who has led field work since 1983 at the world’s largest breeding area for Magellanic penguins, about halfway up the Atlantic coast of Argentina. About 200,000 pairs of Magellanic penguins live at the site during the September to February breeding season.

The storminess has increased at a critical time, when the chicks are too big for parents to sit over protectively, but still too young to have grown waterproof feathers. The downy penguin chicks exposed to drenching rain can struggle and die of hypothermia in spite of the best efforts of their concerned 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 individually are impossible to tie to climate change.

But the new results span 27 years of data collected in Argentina by Boersma’s team, with the support of the Wildlife Conservation Society, the Office of Turismo in Argentina’s Chubut Province, the Global Penguin Society and the La Regina family. Boersma is lead author of a paper on the findings in the Jan. 29 issue of PLOS ONE.

During a span of 27 years, an average of 65 percent of chicks died per year, with some 40 percent starving. Climate change, a relatively new cause of chick death, killed an average of 7 percent of chicks per year, but there were years when 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 said.

“Starving chicks are more likely to die in a storm,” she said. “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.”

Rainfall and the number of storms per breeding season have already increased at the Argentine study site, said Ginger Rebstock, UW research scientist and the co-author of the paper. For instance in the first two weeks of December, when all chicks are less than 25 days old and most vulnerable to storm death, the number of storms increased between 1983 and 2010.

“We’re going to see years where almost no chicks survive if climate change makes storms bigger and more frequent during vulnerable times of the breeding season as climatologists predict,” Rebstock said.

Magellanics are medium-sized penguins standing about 15 inches tall and weighing about 10 pounds. Males of the species sound like braying donkeys when they vocalize. Of the Earth’s 17 species of penguins, 10 — including Magellanics — breed where there is no snow, it is relatively dry and temperatures can be temperate.

Punta Tombo is so arid that it gets an average of only 4 inches of rain during the six-month breeding season and, sometimes, no rain falls at all. Rain is a problem and kills down-covered chicks ages 9 to 23 days if they can’t warm up and dry off after heavy storms in November and December when temperatures are likely to dip. If chicks can live 25 days or more, most have enough juvenile plumage to protect them. Once chicks die, parents do not lay additional eggs that season.

The findings are based on weather information, collected at the regional airport and by researchers in the field, as well as from penguin counts. During the breeding season researchers visit nests once or twice a day to see what is happening and record the contents of the nest, often hunting for chicks when they move around as they get older. When chicks disappear or are found dead, the researchers turn into detectives looking for evidence of starvation, predators or other causes of death such as being pecked or beaten by other penguins.

Just back from two months in the field, Boersma said 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 to the breeding site later and later in the year, probably because the fish they eat also are arriving later, Boersma said. The later in the year chicks hatch the more likely they’ll still be in their down-covered stage when storms typically pick up in November and December.

Besides the coast of Argentina, Magellanic penguins also breed on the Chile-side of South America and in the Falkand (Malvinas) Islands, breeding ranges they share with some 60 other seabird species. These species also are likely to suffer negative impacts from climate change, losing whole generations as the penguins have in the study area, the co-authors say.

“Increasing storminess bodes ill not only for Magellanic penguins but for many other species,” they write.

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