V-formation flight of great white pelicans conserves energy by each bird taking advantage of the upwake field made by the wings of the bird in front of them.

“Our results provide empirical evidence that, compared with solo flight, formation flight confers a significant aerodynamic advantage which allows birds [great white pelicans, Pelecanus onocrotalus] to reduce their energy expenditure while flying at a similar speed. In birds flying in formation, each wing moves in an upwash field that is generated by the wings of the other birds in the formation. Modelling has shown that when birds are flying with optimal spacing, a maximal reduction in power can be achieved and total transport costs can be substantially reduced. However, field observations of V formations indicate that birds often shift from their optimal positioning, perhaps in an attempt to maximize the aerodynamic advantage of flight formation, thus reducing the energy saving— so geese, for example, may make an energy saving of only 2.4%.

“In our study, pelicans often had difficulty staying within the formation, particularly when flying at the rear. But even though these birds were regularly adjusting their position, they still achieved a significant energy saving. This saving may be only partly due to effects of the wakes of other birds on the power input that results from formation flight itself. When flying in formation, pelicans appear to beat their wings less frequently and to glide for longer periods. A rough calculation based on our estimates of the proportion of time spent flapping and gliding in formation, and assuming that the overall costs of the glide–flap sequence is the sum of the gliding and flapping components, reveals an actual saving of 1.7–3.4% as a result of wake effects on power input — this value is comparable to that estimated for geese.

“The main benefit of flight formation, which until now has not been recognized, could be that by flying in a vortex wake, pelicans are able to glide for a greater proportion of their total flight time, with the total energy savings of 11.4–14.0% being achieved primarily through this strategy.” (Weimerskirch et al. 2001:697)

Last Updated May 23, 2017