Empirical Evidence for Energy Efficiency Using Intermittent Gliding Flight in Northern Bald Ibises

Birds face exceptionally high energy demands during their flight. One visible feature of some species is alternating between flapping and gliding, which should allow them to save energy. To date, there is no empirical evidence of an energetic benefit to this. To understand the physiology behind the...

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Main Authors: Ortal Mizrahy-Rewald, Elisa Perinot, Johannes Fritz, Alexei L. Vyssotski, Leonida Fusani, Bernhard Voelkl, Thomas Ruf
Format: Article
Language:English
Published: Frontiers Media S.A. 2022-06-01
Series:Frontiers in Ecology and Evolution
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fevo.2022.891079/full
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author Ortal Mizrahy-Rewald
Ortal Mizrahy-Rewald
Elisa Perinot
Elisa Perinot
Johannes Fritz
Alexei L. Vyssotski
Leonida Fusani
Leonida Fusani
Bernhard Voelkl
Thomas Ruf
author_facet Ortal Mizrahy-Rewald
Ortal Mizrahy-Rewald
Elisa Perinot
Elisa Perinot
Johannes Fritz
Alexei L. Vyssotski
Leonida Fusani
Leonida Fusani
Bernhard Voelkl
Thomas Ruf
author_sort Ortal Mizrahy-Rewald
collection DOAJ
description Birds face exceptionally high energy demands during their flight. One visible feature of some species is alternating between flapping and gliding, which should allow them to save energy. To date, there is no empirical evidence of an energetic benefit to this. To understand the physiology behind the strategy, we equipped hand-raised Northern Bald Ibises (Geronticus eremita) with data loggers during human-guided migration. We monitored the position of the birds, wingbeats, overall dynamic body acceleration (ODBA), and heart rates as a proxy for energy expenditure. The energy expenditure was significantly affected by the length of flapping and gliding bouts. A pronounced decrease in heart rate was measured after already 1 s of gliding. Additionally, the heart rate at flapping bouts up to 30 s increased steadily but stabilized thereafter. The gilding proportion during intermittent flight affected the energy saving compared to continuous flapping. At a gliding proportion of about 20%, we measured a maximum of 11% saving based on heart rate measurement. At higher gliding proportions, the additional energy saving was negligible. Furthermore, as during flight, not all energy is used for mechanical work, we found a greater decrease rate of ODBA at different gliding proportions compared to heart rate. Nevertheless, the combination of the two methods is essential to determine birds’ movement and energy expenditure. This study provides empirical evidence that intermittent flight is energetically beneficial and can reduce the high costs of flights.
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spelling doaj.art-6522be70494a4c3f86add88ef9cfc9e52022-12-22T03:25:38ZengFrontiers Media S.A.Frontiers in Ecology and Evolution2296-701X2022-06-011010.3389/fevo.2022.891079891079Empirical Evidence for Energy Efficiency Using Intermittent Gliding Flight in Northern Bald IbisesOrtal Mizrahy-Rewald0Ortal Mizrahy-Rewald1Elisa Perinot2Elisa Perinot3Johannes Fritz4Alexei L. Vyssotski5Leonida Fusani6Leonida Fusani7Bernhard Voelkl8Thomas Ruf9Department of Interdisciplinary Life Sciences, University of Veterinary Medicine, Vienna, AustriaWaldrappteam Conservation & Research, Mutters, AustriaDepartment of Interdisciplinary Life Sciences, University of Veterinary Medicine, Vienna, AustriaWaldrappteam Conservation & Research, Mutters, AustriaWaldrappteam Conservation & Research, Mutters, AustriaETH Zürich, Zurich, SwitzerlandDepartment of Interdisciplinary Life Sciences, University of Veterinary Medicine, Vienna, AustriaDepartment of Behavioural and Cognitive Biology, University of Vienna, Vienna, AustriaAnimal Welfare Division, Vetsuisse Faculty, University of Bern, Bern, SwitzerlandDepartment of Interdisciplinary Life Sciences, University of Veterinary Medicine, Vienna, AustriaBirds face exceptionally high energy demands during their flight. One visible feature of some species is alternating between flapping and gliding, which should allow them to save energy. To date, there is no empirical evidence of an energetic benefit to this. To understand the physiology behind the strategy, we equipped hand-raised Northern Bald Ibises (Geronticus eremita) with data loggers during human-guided migration. We monitored the position of the birds, wingbeats, overall dynamic body acceleration (ODBA), and heart rates as a proxy for energy expenditure. The energy expenditure was significantly affected by the length of flapping and gliding bouts. A pronounced decrease in heart rate was measured after already 1 s of gliding. Additionally, the heart rate at flapping bouts up to 30 s increased steadily but stabilized thereafter. The gilding proportion during intermittent flight affected the energy saving compared to continuous flapping. At a gliding proportion of about 20%, we measured a maximum of 11% saving based on heart rate measurement. At higher gliding proportions, the additional energy saving was negligible. Furthermore, as during flight, not all energy is used for mechanical work, we found a greater decrease rate of ODBA at different gliding proportions compared to heart rate. Nevertheless, the combination of the two methods is essential to determine birds’ movement and energy expenditure. This study provides empirical evidence that intermittent flight is energetically beneficial and can reduce the high costs of flights.https://www.frontiersin.org/articles/10.3389/fevo.2022.891079/fullintermittent flightenergy expenditureglidingheart rateODBAmigration
spellingShingle Ortal Mizrahy-Rewald
Ortal Mizrahy-Rewald
Elisa Perinot
Elisa Perinot
Johannes Fritz
Alexei L. Vyssotski
Leonida Fusani
Leonida Fusani
Bernhard Voelkl
Thomas Ruf
Empirical Evidence for Energy Efficiency Using Intermittent Gliding Flight in Northern Bald Ibises
Frontiers in Ecology and Evolution
intermittent flight
energy expenditure
gliding
heart rate
ODBA
migration
title Empirical Evidence for Energy Efficiency Using Intermittent Gliding Flight in Northern Bald Ibises
title_full Empirical Evidence for Energy Efficiency Using Intermittent Gliding Flight in Northern Bald Ibises
title_fullStr Empirical Evidence for Energy Efficiency Using Intermittent Gliding Flight in Northern Bald Ibises
title_full_unstemmed Empirical Evidence for Energy Efficiency Using Intermittent Gliding Flight in Northern Bald Ibises
title_short Empirical Evidence for Energy Efficiency Using Intermittent Gliding Flight in Northern Bald Ibises
title_sort empirical evidence for energy efficiency using intermittent gliding flight in northern bald ibises
topic intermittent flight
energy expenditure
gliding
heart rate
ODBA
migration
url https://www.frontiersin.org/articles/10.3389/fevo.2022.891079/full
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