Scientists have recently made a surprising discovery, with the help of a wind tunnel and a flock of birds. Songbirds, many of which make twice-yearly, non-stop flights of more than 1,000 miles to get from breeding range to wintering range, fuel themselves by burning lots of fat and a surprising amount of the protein making up lean body mass, including muscle, early in the flight. This flips the conventional wisdom on its head, which had assumed that migrating birds only ramped up protein consumption at the very end of their journeys, because they would need to use every ounce of muscle for wing-flapping, not fuel.