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Small energy benefits of in-wake flying in long-duration migratory flights
University of Veterinary Medicine Vienna / Waldrappteam
Waldrappteam / University of Bern
University of Veterinary Medicine Vienna / University of Vienna
University of Veterinary Medicine Vienna
Alexei Vyssotski ETH Zurich
Ca' Foscari University of Venice / University of Milano-Bicocca
University of Veterinary Medicine Vienna / Waldrappteam
University of Vienna / Waldrappteam
The Royal Society
During long-distance migrations, some bird species make use of in-wake flying, which should allow them to profit from the upwash produced by another bird. While indirect evidence supports energy saving as the primary benefit of in-wake flying, measurements are still missing. We equipped migrating northern bald ibises (Geronticus eremita) with high-precision global navigation satellite system data loggers to track their position in the flock. We estimated birds' energy expenditure through different proxies, namely dynamic body acceleration (DBA), heart rate and effective wingbeat frequency. During active flapping flight, DBA estimates dropped off when in-wake compared with when not-in-wake. In addition, effective wingbeat frequency decreased, suggesting an increased use of intermittent gliding flight during in-wake periods. Heart rate varied greatly among individuals, with a clear decrease during gliding-corroborating its energy-saving function. Furthermore, we found consistent proof for decreased heart rate during in-wake flying, by up to 4.2%. Hence, we have shown that flying in the wake of another individual reduces birds' DBA, heart rate and effective wingbeat frequency, which could reflect reduced energy requirement.
Englisch
2024
Dieses Werk bzw. dieser Inhalt steht unter einer
CC BY 4.0 - Creative Commons Namensnennung 4.0 International Lizenz.
CC BY 4.0 International
http://creativecommons.org/licenses/by/4.0/
Animals; Flight; Animal Migration; Energy Metabolism; Birds; Heart Rate; Wings; Acceleration