The New York Times
By HENRY FOUNTAIN
Published: June 25, 2009
Ever wonder what goes on inside the minds of pigeons?
No? Researchers in Europe have.
Alexei L. Vyssotski of the University of Zurich and colleagues have studied the brain activity of homing pigeons as they fly over visual landmarks.
How homing pigeons find their way back to a starting point is not completely known. Studies have shown that the birds variously use the position of the sun and the earth’s magnetic field as a compass, and sense of smell and visual cues as navigation aids. But the use of visual cues has been difficult to study, because if a bird flies over a landmark and doesn’t change its course, it’s impossible to know whether the bird has not perceived the cue or is ignoring it.
The researchers developed tiny neurologgers, to record electrical activity in the pigeons’ brains as they flew. The birds also carried small global positioning system units to track position. By matching brain activity to location, the researchers could determine the effect of flying over a landmark.
The birds’ flights began over water, a relatively featureless environment, and then continued over land to a homing point. This enabled the researchers to determine brain activity as the birds reached the coastline and then flew over other landmarks.
They found that activity in both high- and mid-range frequencies occurred as the birds passed over a landmark. The researchers, who reported their findings in Current Biology, suggest that the mid-range frequencies are linked to the perception of visual information, while the high-frequency activity may be related to cognitive processing — perhaps the recognition of a landmark as something the bird has seen before.
The researchers also observed strong brain activity at two rural locations where there were no significant landmarks. On visiting the sites, the researchers found that both had colonies of wild pigeons, which was probably what caught the homing pigeons’ interest.
A version of this article appeared in print on June 30, 2009, on page D3 of the New York edition.
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