Wayward Penguins Hitch Rides to U.S. on Fishing Boats

John Roach
for National Geographic News
June 7, 2007
How did the penguin cross the Equator? The question has vexed biologists ever since a Humboldt penguin, native to South America, was found off the coast of Alaska in 2002.

Now they have a likely answer: The flightless bird hitched a ride on a fishing boat.

"Penguins are kind of cute. People like them, and they're pretty easy to pick up," said Dee Boersma, a conservation biologist at the University of Washington in Seattle.

Boersma and graduate student Amy Van Buren looked at a series of possibilities for the out-of-place seabird and concluded the boat ride is the best explanation.

The penguin was likely hauled aboard in a fishing net and kept as a crew pet, the scientists suggest.

They speculate that other penguins spotted in North American waters, although very rare, may also have traveled by fishing boat.

A study on the Humboldt penguin's trek is published this month in the Wilson Journal of Ornithology.

Process of Elimination

With the exception of a population in the Galápagos Islands just a smidge north of the Equator, all 17 species of penguins are found exclusively in the Southern Hemisphere (see a penguins photo gallery).

So how did the Humboldt penguin get to Alaska?

A 5,000-mile (8,000-kilometer) swim from its home in coastal Peru is unlikely because it would have to survive a large area of warm, tropical water that doesn't have much food.

"That would be tough for a penguin to do," Boersma said.

Nor is it a remnant from failed attempts in the mid-20th century to establish penguin colonies in Norway. Within a decade all those penguins were dead, the researchers noted.

And since 1972, all U.S. zoos have bred penguins in captivity and keep close tabs on their whereabouts. No escapees coincide with the Northern Hemisphere sightings.

Nevertheless, penguins—perhaps including the one caught in 2002—have been sighted up and down the North American West Coast a handful of times since 1975.

"In this case, we think they probably first showed up in Washington [State], probably coming on tuna boats as the tuna boats came up from Peru," Boersma said.

Wayne Trivelpiece is a penguin expert with the Southwest Fisheries Science Center in La Jolla, California. He agreed that boats are the most plausible penguin transport.

Crossing the warm, food-poor tropical waters, he said, "would be a really effective barrier in keeping any of them from naturally making that migration."

Set Free

Guy Demment, the fisher who found the Humboldt penguin in Alaska in 2002, set it free once he snapped its picture.

Boersma said it probably won't survive.

"They don't live forever, and they got a lot of predators there [in Alaska]," she said.

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