title: Decision-making by a soaring bird: time, energy and risk considerations at different spatio-temporal scales.
abstract: Natural selection theory suggests that mobile animals trade off time, energy and risk costs with food, safety and other pay-offs obtained by movement. We examined how birds make movement decisions by integrating aspects of flight biomechanics, movement ecology and behaviour in a hierarchical framework investigating flight track variation across several spatio-temporal scales. Using extensive global positioning system and accelerometer data from Eurasian griffon vultures (Gyps fulvus) in Israel and France, we examined soaring-gliding decision-making by comparing inbound versus outbound flights (to or from a central roost, respectively), and these (and other) home-range foraging movements (up to 300 km) versus long-range movements (longer than 300 km). We found that long-range movements and inbound flights have similar features compared with their counterparts: individuals reduced journey time by performing more efficient soaring-gliding flight, reduced energy expenditure by flapping less and were more risk-prone by gliding more steeply between thermals. Age, breeding status, wind conditions and flight altitude (but not sex) affected time and energy prioritization during flights. We therefore suggest that individuals facing time, energy and risk trade-offs during movements make similar decisions across a broad range of ecological contexts and spatial scales, presumably owing to similarity in the uncertainty about movement outcomes.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.
authors.affiliation: Movement Ecology Laboratory, Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 91904, Israel roi.harel@mail.huji.ac.il.
authors.forename: Roi
authors.identifier: 0000-0002-9733-8643
authors.initials: R
authors.lastname: Harel
authors.affiliation: CEFE UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, 1919 route de Mende, 34293 Cedex 05, Montpellier, France.
authors.forename: Olivier
authors.identifier: 0000-0003-1868-9750
authors.initials: O
authors.lastname: Duriez
authors.affiliation: Movement Ecology Laboratory, Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 91904, Israel Department of Environmental Science and Policy, University of California, Davis, CA 95616, USA.
authors.forename: Orr
authors.identifier: 0000-0001-8941-3175
authors.initials: O
authors.lastname: Spiegel
authors.affiliation: CEFE UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, 1919 route de Mende, 34293 Cedex 05, Montpellier, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Fluhr
authors.affiliation: Movement Ecology Laboratory, Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 91904, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Horvitz
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA School of Mathematical Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa.
authors.forename: Wayne M
authors.identifier: 0000-0001-8784-9354
authors.initials: WM
authors.lastname: Getz
authors.affiliation: Computational Geo-Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, 1094 XH Amsterdam, The Netherlands.
authors.forename: Willem
authors.identifier: 0000-0002-5250-8872
authors.initials: W
authors.lastname: Bouten
authors.affiliation: CESCO UMR 7204, MNHN-CNRS-UPMC, 55 rue Buffon, 75005, Paris, France.
authors.forename: François
authors.initials: F
authors.lastname: Sarrazin
authors.affiliation: Science Division, Israel Nature and Parks Authority, Jerusalem, Israel.
authors.forename: Ohad
authors.initials: O
authors.lastname: Hatzofe
authors.affiliation: Movement Ecology Laboratory, Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 91904, Israel.
authors.forename: Ran
authors.identifier: 0000-0002-5733-6715
authors.initials: R
authors.lastname: Nathan
mesh_terms: D000531:Altitude; D000818:Animals; D001696:Biomechanical Phenomena; D003657:Decision Making; D004734:Energy Metabolism; D046093:Falconiformes / Q000502:physiology*; D005247:Feeding Behavior; D005426:Flight, Animal; D005602:France; D006702:Homing Behavior; D007557:Israel
keywords: GPS tracking; biotelemetry; convective thermals; movement ecology; risk-aversion flight index; soaring–gliding efficiency