Young penguins in the Antarctic may be dying because they are having a tougher time finding food, as melting sea ice cuts back on the tiny fish they eat, US researchers suggested on April 11.
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, said the study in the Proceedings of the National Academy of Sciences.
Chinstrap penguins, known for their characteristic head markings that resemble a cap with a black line just under the neck, are the second largest group in the area after the macaroni penguins, and are at particular risk because their population is restricted to one area, the South Shetland Islands.
“It is a dramatic change,” lead researcher Wayne Trivelpiece, of the National Oceanic and Atmospheric Administration’s Antarctic Ecosystem Research Division, told AFP.
“There are still two to three million chinstrap pairs in this region but there were seven to eight million two decades ago,” he said.
Trivelpiece was a co-author on a study published in 1992 that suggested penguin populations were surging and subsiding according to changes in sea ice — with the chinstrap doing better in warm years and the Adelie thriving in cold years.
However, Trivelpiece and his co-authors now believe that krill are the real culprit for the disappearing penguin populations, and the damage affects both types of penguins.
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.