Young penguin populations in the Antarctic are declining because a warmer climate cuts back on their main food source, a U.S. study said Tuesday.
Only about 10 percent of baby penguins tagged by researchers are coming back in two to four years to breed, down from 40-50 percent in the 1970s, according to a study published in the Proceedings of the National Academic of Sciences.
"It is a dramatic change," said lead researcher Wayne Trivelpiece, of the National Oceanic and Atmospheric Administration's Antarctic Ecosystem Research Division.
"There are still two to three million chinstrap pairs in this region but there were seven to eight million two decades ago," he said.
"What's changed is young penguins surviving their transition to independence," he said. "They're no longer able to do that anywhere near the way they used to do, and we think that's directly related to
the fact that there's 80 percent less krill out there now."
Krill needs ice to survive, and as climate change causes more polar sea ice to melt, the tiny sea creatures cannot breed or feast on phytoplankton in the ice and their numbers fall, taking away an
important source of nourishment for penguins.
"If warming continues, winter sea-ice may disappear from much of this region and exacerbate krill and penguin declines," the study said.