Ibises in flight take turns to reduce drag
DOI: 10.1063/PT.5.028613
New Scientist : Birds fly in a V formation to boost the efficiency and range of the entire flock. But how the birds decide which one will take the leading position has been unclear. Now Bernhard Voelkl of Oxford University and colleagues, who have been studying the flight patterns of northern bald ibises, say the birds pair off and take turns. The researchers tagged a flock of 14 with GPS data loggers to track the flying positions of each individual. They found that the lead bird and the one flying immediately behind it switch places frequently, taking equal turns at leading and following. Such reciprocal altruism allows the birds to help each other, and the direct reciprocation of working in pairs lessens the opportunity for cheating. The cooperation the birds exhibit in flight has not been observed when they are on the ground.
