Pigeons’ Brain Cells Sense Earth’s Magnetic Field to Find Home

Homing pigeons, the earliest form of e-mail, can find places thousands of miles away because of nerve cells in their brain stems that react to magnetic sensors that may be located elsewhere around their head, a study finds.

Scientists have long known that the birds navigate using the earth’s magnetic field. The latest research, reported yesterday in the journal Science, has uncovered subtle mechanics in the brain that allow pigeons to find their way home even when the sky’s directional markers are hidden by clouds.

Pigeons were released in a black room with an artificial magnetic field that was manipulated by scientists, who used electrodes to determine which neurons were firing. They found that different neurons in the brain stem became active, depending on the direction of the magnetic field. That’s what helps the birds determine latitude, half the information needed to navigate, said J. David Dickman, at the Baylor College of Medicine in Houston.

“They’ve been used for centuries to carry news home,” said Dickman, a study author, in a telephone interview. Pigeons brought from Central Park in New York to Texas would find their way back home, he said, adding, “It might take them a while, but they’d get there.”

It’s still not clear how pigeons determine longitude, though the experiments show the birds have limited access to cardinal directions, according to Dickman. There may be intensity gradients to the earth’s magnetic fields, he said. The magnetic field is located at different angles to the earth depending on the latitude, with a 0 degree angle at the magnetic equator and 90 degree angles at the poles, Dickman said.

The research was inspired by previous work suggesting that magnetic fields may be detected by a part of the birds’ ears. Dickman’s research didn’t look directly at how the birds sense the magnetic fields, he said.

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