Let's flap together : benefits of formation flight in relation to energy savings in the Northern bald ibis

Elisa Perinot

doi:10.34876/ksa6-j803

Title (eng)

Let's flap together

benefits of formation flight in relation to energy savings in the Northern bald ibis

Author

Elisa Perinot

Description (eng)

PhD thesis - University of Veterinary Medicine Vienna - 2023

Abstract (eng)

Migration represents a long and extenuating journey for several bird species, which significantly increases their mortality rate. To enhance their chances of survival, birds have developed a wide range of adaptations, including specific flight strategies such as gliding, soaring, intermittent flight, and formation flight. While prior research has demonstrated that gliding and soaring reduce birds’ metabolic rate, strong evidence for intermittent flight and formation flight is still lacking. Specifically, it has been suggested that during formation flight birds can save energy by flying in the upwash of another individual. In this project, we investigated formation flight and intermittent flight in a migratory species, the Northern bald ibis (Geronticus eremita). To better study formation flight, we designed and built novel Global Navigation Satellite System receivers, collected raw satellite data and post-processed it to achieve centimeter- level accuracy in positioning. To estimate energy consumption in free-flying birds, we collected acceleration and heart rate data. We successfully collected positional and acceleration data for 29 birds along six migration flights and heart rate data for 5 birds. Then, we implemented a new modelling approach based on fuzzy logic to classify birds that were flying in the wake of another individual, i.e., in-wake and checked for reduced metabolic rate. We showed that birds saved energy when flying in-wake as they presented lower heart rate and Dynamic Body Acceleration (DBA), especially during flapping flight. Additionally, birds flying in-wake skipped wing flaps more often. Northern bald ibises also used intermittent flight during migratory flights. During the gliding phases they presented decreasing heart rate and DBA, which suggests energy saving. To conclude, the project provides the first strong evidence of energy saving for formation flight and intermittent flight in migrating birds. Additionally, it offers new methodologies to collect accurate positional data and classify birds flying in-wake. Future studies should apply these innovative approaches to deepen our understanding of the behavioural ecology of collective flight strategies in migratory birds.

Description (deu)

PhD Arbeit - Veterinärmedizinische Universität Wien - 2023

Type (eng)

Dissertation

Language

[eng]

Persistent identifier

https://phaidra.vetmeduni.ac.at/o:4611

AC number

AC17640344

DOI

10.34876/ksa6-j803