"Flapping for migrating: energy expenditure quantification" by G. Vitucci, 27/08/19 (ASAB 2019)

Modern high-resolution technology allows tracking migrating birds over long distances. Depending on species, duration of displacement, environmental conditions, social organization, etc., different flock topology and flight dynamics arise.

Two main flying styles are typically used: soaring/gliding and flapping flight. The former’s performance has been studied in details for single birds as it is achieved with fixed wings, whose modelling relies on the aeronautic tradition. Soaring/gliding is cheap, as it harvests all the energy from upwards 'thermals'. Social implications for the flock have recently been pointed out.

Nevertheless, a range of circumstances makes the choice of flapping flight a preferable or unavoidable option: absence of near thermals, size of the animal, and strict time requirements, e.g. seasonal availability of food at destination.

Our current work focuses on flapping flight. In particular, we intend to unveil observed flock spatio-temporal synchronization through the quantification of the mechanical power required for flying in group - and related disparity in energy consumption between leader and follower.

For this purpose, we developed a novel aerodynamic model that achieves a trade-off between computational affordability for a large number of birds and essential features of collective flapping flight: 3D motion, bird-wake interaction and unsteadiness. Stable configurations, representative of formation flight, and transient ones predicting the cost of maneuver are analysed. Where available, comparison with field-data are reported. Finally, application of our cheap computational technique in light of decision-making strategies implementation are prospected.

Acknowledgements:

This work has received funding from the Belgian Joint Research Activity RevealFlight.