Sooty shearwaters migrate nearly 40,000 miles (64,000 kilometers) a year, flying from New Zealand to the North Pacific Ocean every summer in search of food, according to a new study.
The extensive summer trek is the longest animal migration ever recorded electronically.
"It was really amazing to see the distance they were traveling," said Scott Shaffer, a research biologist at the University of California, Santa Cruz.
Shaffer and his colleagues tracked the birds between their breeding grounds in New Zealand and their seasonal feeding grounds off the coasts of California, Alaska, and Japan.
The birds leave New Zealand in the Southern Hemisphere's winter—summer in the Northern Hemisphere—and take advantage of prevailing winds along different portions of their migration route.
When plotted on a map, their paths look like giant figure eights over the Pacific Ocean (see map at left).
Only the Arctic tern, which migrates between the Arctic and Antarctica, rivals the sooty shearwater in distance traveled in a single migration.
But the terns are too small to outfit with electronic tags, so the true distance they cover remains unknown, Shaffer says.
Sooty shearwaters have wingspans of about 43 inches (109 centimeters).
Conservation Implications
The 0.4-ounce (12-gram) tracking tags used on the shearwaters collected data on position, temperature, and dive depth for more than 200 days in 2005.
Shaffer and his colleagues report the results in the early online edition of the Proceedings of the National Academy of Sciences.
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