The balance between energy intake and energy expended is critical for survival. Birds have evolved a number of collaborative behaviors to minimize individual energy expenditure and to maximize energy intake.
Formation flying is the most spectacular of these strategies. The vortex of swirling air that is shed by a bird during flapping flight includes a rising air mass. Recent research has demonstrated that the following bird flies in the “sweet spot” of this rising air and gains an energetic advantage.
Following birds must fly with wing beats synchronized to the leader to take advantage of this benefit.
The birds in the picture above are equipped with GPS devices and inertial trackers (FitBit for birds!). These hand-reared birds have been imprinted to a paraplane that they are following along a migration route. The diagram below shows how many wing flaps were in the “sweet spot” during a 7-minute flight segment. The majority were either exactly inside or just to the left of the ideal region. The birds may sense this position by perception of heart rate.
LEARN MORE ABOUT FORMATION FLYING
KIDS QUESTION: In the museum exhibit we asked: In what sports do athletes travel fast and follow each other closely?
The answer is: Cycling and running are both easier if you follow closely behind someone else.
“Drafting” in sports such as cycling and running has been shown to decrease energy expenditure for the athletes who are behind a leader. But birds are doing more than drafting; they are finding the upward part of a rotating airflow and benefiting from flying in air that helps them stay aloft.