Penguin-chick mortality rates have increased in recent years off the coast of Argentina — a trend scientists attribute to climate change and expect to worsen throughout the century, a new study finds.
From 1983 through 2010, researchers based at the University of Washington in Seattle monitored a colony of roughly 400,000 Magellanic penguins living halfway up the coast of Argentina on a peninsula called Punta Tombo. Each year, the researchers visited penguin nests once or twice a day from mid-September through late February to assess the overall status of the colony and the health of the chicks once they hatched in late November or early December. (Gallery of Magellanic Penguin Colony)
The resulting data set provides one of the longest-ever records of a single penguin colony. It revealed that starvation and predation were the most common and consistent chick killers over the years, but that hypothermia was the leading cause of death during years with heavy rainstorms, which became more prevalent throughout the study period — a trend that is consistent with climate models projecting the effects of climate change in the region.
Young chicks between 9 and 23 days old were particularly vulnerable to hypothermia, as they were too young to have fully grown their waterproof plumage but already too big to seek shelter under their parents' bodies, the team reports today (Jan. 29) in the journal PLOS ONE.
"They have to have waterproof feathers to survive," study co-author Dee Boersma told LiveScience. "If chicks don't have waterproof plumage, they are going to die as soon as they end up in the water."
Extreme heat — another component of climate change expected to worsen throughout the century — also challenged chicks' temperature-regulation systems and resulted in deaths, though not as many as hypothermia did, the team reports.