An updated estimation of cost of transport for flying species

This project wants to provide a first assessment of the role of the physical environment in determining cost of transport in the wild. The project has been Dr. Martina Scacco’s main research focus for the last two years of postdoc and it is the product of a large collaboration involving over 55 co-authors.

Description: Cost of transport (COT) is defined as the amount of fuel needed to transport a unit of body mass for a unit distance, and flying animals are known to benefit from the energy available in the landscape, mainly in the form of wind currents, to largely reduce this cost. However, seminal works on the COT of flying animals largely ignore the effect that physical environment and variation in flight behaviour have on flight costs, identifying flight as the most costly form of locomotion per unit time. The ability to switch from flapping to passive (soaring/gliding) flight, in response to variations in the wind vectors, was assumed to be the province of selected large birds, but modern bio-logging and radar techniques now allow us to accurately estimate the proportion of flapping vs passive flight. In this study, Dr. Scacco used a large dataset of high-resolution movement data from 46 species to provide the first assessment of the role of the physical environment in determining COT in the wild. She quantified how changes in the use of flapping flight and variation in the wind vectors contribute to variation in COT, and showed how these affect species differently, according to morphology and body mass. This changes the current dogma about the cost of flight relative to other forms of locomotion, demonstrating that flight can be much cheaper but also much more expensive than expected, with the difference being driven by the interaction of energy landscape, body mass and wing morphology.

Main collaborators: Prof. Emily Shepard, Dr. Kamran Safi & data providers