Seabirds are like feathered buoys. Gently rafting on the ocean’s surface, these birds go with the flow, making them excellent proxies for tracking changes in a current’s speed and direction.
Oceanographers traditionally use radar, floating buoys or autonomous underwater vehicles to measure ocean current velocities, which can affect the climate, ecosystems and the movement of important seafood. But some ocean regions aren’t easily accessible. Seabirds lazily resting on the ocean surface could offer a novel alternative to collecting those data, researchers report online January 10 in Scientific Reports.
“I don’t think it’s going to replace the various instruments we use,” says Evan Mason, a physical oceanographer at the University of Washington in Seattle. “It was just interesting to see what we might find.”
Mason and his colleagues outfitted 75 Scopoli’s shearwaters (Calonectris diomedea), a seabird found in the Atlantic Ocean and Mediterranean Sea, with GPS tags and tracked their movements in the Balearic Sea off eastern Spain.
On average, the birds spent only 10 percent of their time idly drifting on the water, but the team still collected 405 trajectories, the researchers say. Visually comparing wind and water velocity information with the way birds drifted, the researchers determined ocean currents, winds or both drove the animals’ direction, excluding some that preferred hitching a boat ride instead. The team then compared those tracks with satellite- and buoy-derived data of winds and surface currents and found they matched well.
As scientists increasingly use such logging devices to track the behavior and movement of animals, the method could also aid in studying how ocean characteristics change with time and location, the researchers say.