King Penguins Declining Due to Global Warming
for National Geographic News
|February 11, 2008|
King penguins near the Antarctic may be on a perilous path to extinction as a result of global warming, new research suggests.
Populations of the large birds on Possession Island in the Indian Ocean's Crozet Archipelago are declining as sea temperatures warm and the birds are forced to travel longer distances to find food.
Researchers tagged a king penguin colony and monitored it over nine years while also measuring sea-surface temperatures.
"We wanted to see what effect climate change was having on the breeding and survival of the penguins," said lead study author Yvon Le Maho, research director at the National Center for Scientific Research in Strasbourg, France.
The study appears today in the journal Proceedings of the National Academy of Sciences.
Tough Being On Top
Because king penguins are at the top of the food chain, they are particularly vulnerable to environmental changes.
Even a small shift in the numbers of fish and squid that the penguins eat could have large impacts on their population.
In recent years, many of the prey species have died or migrated as the ocean warms and the algae that those animals eat are impacted.
Warming temperatures also force fish to swim into cool waters farther away from the island, causing penguins to travel greater distances to hunt. The longer time away from home reduces chick feedings, the researchers found.
So during years when seas become warmer, penguins do not breed as successfully, Le Maho and colleagues found.
At the edge of the sea ice, where penguin adults forage during winter, just a 0.47 degree Fahrenheit (0.26 degree Celsius) increase resulted in a 9 percent decrease in the population two years later.
Le Maho said this temperature sensitivity is likely to cause problems for penguin populations,as climatologists predict a 0.72 degree Fahrenheit (0.4 degree Celsius) increase in oceans off Antarctica over the next 20 years.
(Related news: "Adelie Penguins Extinct in a Decade in Some Areas?" [December 28, 2007].)
William Fraser, an ecologist at the Polar Oceans Research Group in Sheridan, Montana, was not involved with the study.
"Here's another species, [such as] the polar bear in the Arctic and the Adélie penguin in the Antarctic, that we would have thought to be undisturbed," he said.
"Because these animals live so far removed from people, it often passes us by that they too are vulnerable to human impacts like climate change."
Ron Swaisgood, a conservation biologist at the San Diego Zoological Society, also compared the king penguins' struggles to that of polar bears.
"Polar bears traverse the ice in search of seals, [and] the sea ice is disappearing," he said. "Loss of sea ice means that polar bears will not have access to their primary prey.
"That penguins are in this situation too points to the global degree of the problem."
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