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Each year, humpback whales migrate thousands of miles across vast expanses of open ocean. Scientists are now learning more about their long-distance journeys with the help of new tracking technologies. And one thing they've noticed is that the whales often swim in amazingly straight lines.
NPR's Nell Greenfieldboyce reports on the mystery of how whales can chart such a steady course.
NELL GREENFIELDBOYCE: Biologists have been tagging humpback whales off Brazil for years to follow their seasonal migrations to the Antarctic. They've published maps of the whales' routes. And recently, an environmental scientist named Travis Horton saw these maps and thought: Wow, lots of the time, they're going as straight as an arrow.
Mr. TRAVIS HORTON (Environmental Scientist): They're out there in the open ocean with the sea surface currents, with its storm events, et cetera, et cetera. And they're able, over 28 days, to maintain a near-perfect straight line over 2,200 kilometers of distance. It's just absolutely remarkable how straight these courses are.
GREENFIELDBOYCE: Horton works in New Zealand, at the University of Canterbury. He studies how animals navigate. And he says: If you were out in the ocean in a rowboat and tried to keep a straight course, it would be hard. There's no landmarks, just water, water, and more water. He asked himself: If I were a humpback whale...
Mr. HORTON: What's available to me? What could I possibly be using to orientate so precisely by?
GREENFIELDBOYCE: Decades of experiments on other migrating animals, like birds, suggested two possibilities: The whales might be using the position of the sun or the Earth's magnetic field. Horton tested those ideas by analyzing both in relation to the whales' paths, but no dice.
Mr. HORTON: What we found is that the two leading theories of animal orientation don't necessarily work all that well for humpback whales.
GREENFIELDBOYCE: He thinks it is possible that the whales might be using a combination of the two strategies, although that's just a theory. He and his colleagues have published their finding in the British journal Biology Letters.
Mr. PATRICK ROBINSON (Biologist, University of California, Santa Cruz): The paper is actually very interesting.
GREENFIELDBOYCE: Patrick Robinson is a biologist at the University of California, Santa Cruz. He says not many people study navigation in marine mammals.
Mr. ROBINSON: Most of the work has been done on birds and other terrestrial animals.
GREENFIELDBOYCE: And lot of that work has been artificial experiments, not studies of creatures out in the wild.
Robinson wasn't entirely surprised by the whales' abilities. He's recently been tracking the long migrations of northern elephant seals that travel from California out into the middle of the North Pacific. It takes the seals several weeks.
Mr. ROBINSON: And what's interesting is that we do have animals traveling in near-perfect straight lines, meaning a navigationally perfect straight line, a great circle route, which is different than simply following a straight compass bearing.
GREENFIELDBOYCE: He says ocean dwellers are clearly expert navigators, and it will take a lot of scientific expertise to figure out how they do it.
Nell Greenfieldboyce, NPR News.
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