January 30, 2014
Climate Change Threatens Vulnerable Penguin Chicks
Brett Smith for redOrbit.com - Your Universe Online
Lacking their parents' waterproof feathers, penguin chicks covered in down can suffer and die from hypothermia after being exposed to drenching rain – despite efforts of their concerned parents to keep them safe.While previous studies have found that singular events, like a rare Antarctic rainstorm, can threaten penguin chicks, a new study in the journal PLOS ONE has identified the additional risk long-term climate change trends have for the survival of these tiny birds.
"It's the first long-term study to show climate change having a major impact on chick survival and reproductive success," said study author Dee Boersma, a biology professor at the University of Washington.
Boersma has conducted work since 1983 at the world's largest breeding area for Magellanic penguins, along the Atlantic coast of Argentina at Punta Tombo, where 200,000 breeding penguin pairs live from September through February.
During the course of 27 years, about 65 percent of chicks died on average each year, with some forty percent starving, according to the study team. Climate change, a fairly new cause of chick mortality, killed an average of 7 percent of chicks per year. However, during some years, it was the most common cause of death – killing 43 percent of all chicks one year and half in another.
"Starving chicks are more likely to die in a storm," Boersma noted. "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."
Overall rainfall and the quantity of storms per mating season have already risen at the Argentine study site, said study author Ginger Rebstock, a UW researcher. For example, in the first two weeks of December, when all chicks are less than 25 days old and most in danger of storm death, the amount of storms raised from 1983 to 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.
The study findings are based on weather data, collected from the local airport and by scientists in the field, in addition to penguin-count data. Throughout the mating season, scientists visited nests once or twice per day to make observations and record the contents of the nest, often searching for chicks when they became mobile. When chicks vanished or were found dead, the scientists become detectives searching for proof of starvation, predators or other reasons for death such as being attacked by other penguins.
Another recent study found that climate change adds uncertainty to long-term projections for the size of penguin populations.
In that study, researchers concluded that Adelie penguins are able to adequately react to shifts in sea ice concentrations under normal conditions, but not as much during extreme events, like the presence of multiple giant icebergs. These massive icebergs lowered the penguins' ability to hunt and caused them to waste more energy in their fight for survival.
The randomness of these extreme events that appear to be driven by climate change makes them confounding factors for accurately projecting future penguin populations.