Whether or not the birds sleep in flight remains unclear, though periods of decreased movement suggest that they do, indeed, catch up on a bit of rest midair. Still, the clear lack of significant resting periods suggest that the birds do not need as much sleep to perform their migration as previous research has suggested.
"We cannot rule out that the Alpine swifts may interrupt their flight for a few minutes," the team writes. "Nevertheless, they must be able to accomplish all vital physiological functions in flight over a period of several months."
The team next hopes to determine the evolutionary drivers responsible for what they consider to be an extraordinary behavior.
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