Wednesday, July 11, 2007

Penguin Diet Change Caused by People?


Around 200 years ago, a group of Antarctic penguins started a dramatic new diet: they switched from eating mostly big fish to a diet of tiny crustaceans.

And, new research suggests, humans might have forced the change.

Researchers Steven Emslie and William Patterson analyzed more than 220 fossilized penguin eggshells ranging in age from 100 to 38,000 years old. The scientists collected the shells from abandoned Adelie penguin colony sites from three major regions in Antarctica: the Ross Sea, East Antarctica and the Antarctic Peninsula.

The scientists expected to find that the birds' diets shifted with the ever-changing climate. Instead, they discovered a "dramatic shift in penguin prey high on the food chain, such as fish, over most of the past 35,000 years to prey — krill — lower on the food chain occurring very recently, within the past 200 to 300 years."

At precisely that time, humans began an unprecedented killing of seals and whales in Antarctica.

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