Global warming threatens king penguins, study reports
The king penguin, a species that rebounded from near extinction over the last century, could be wiped out in coming decades due to global warming, researchers reported today.
If the surface temperature of the Southern Ocean rises 0.47 degrees Fahrenheit -- an increase well below current forecasts of 0.72 degrees over the next 20 years -- declining food availability would lead to a population collapse, the scientists estimated.
"We don't have to get several degrees of increase to get a big effect," said Yvon Le Maho, a physiologist at the French National Center for Scientific Research and lead author of the study, which was published in the Proceedings of the National Academy of Sciences.
The research followed 456 adult birds with radio transponders implanted under their skin and correlated their survival rate over an eight-year period with changes in sea surface temperatures.
Christophe Barbraud, a scientist at the same center who not involved in the study, said the time period was probably too short to draw a definitive link between temperature and survival.
Still, the study supports other research, including Barbraud's own work on a dramatic decline of emperor penguins in Antarctica, that climate change can harm sea bird populations, he said.
King penguins, which can live up to 30 years, were nearly hunted to extinction in the 19th century by sailors who used their fat as stove oil. They have since bounced back and number about 2 million today.
The bulk of the population lives in colonies on the Crozet Archipelago, French islands more than 1,000 miles north of Antarctica.
During the breeding season from November to March, a pair of adults cares for one chick, feeding it lantern fish from nearby waters.
The lantern fish later migrate deeper in the ocean, leaving the chicks to survive on their fat stores, while the adults travel hundreds of miles south to the edge of the Antarctic ice sheet to feed on krill. The adults return in October to finish raising their young.
The researchers tracked how many adults returned using the radio transponders. When a pair of penguins returned, the researchers used binoculars to see if its chick was still alive.
Through the natural variation in water temperature over the course of the study's observation period, the research found that in warm years, chicks were less likely to survive the winter fast, most likely because there was not enough local fish for their parents to fatten them up, the researchers said. Chick mortality rose by as much as 50%.
