State-space modelling of the flight behaviour of a soaring bird provides new insights to migratory strategies

Pirotta, Enrico; Katzner, Todd; Miller, Tricia A.; Duerr, Adam E.; Braham, Melissa A.; New, Leslie

State-space modelling of the flight behaviour of a soaring bird provides new insights to migratory strategies

dc.contributor.author	Pirotta, Enrico
dc.contributor.author	Katzner, Todd
dc.contributor.author	Miller, Tricia A.
dc.contributor.author	Duerr, Adam E.
dc.contributor.author	Braham, Melissa A.
dc.contributor.author	New, Leslie
dc.contributor.funder	U.S. Department of Energy	en
dc.contributor.funder	U.S. Fish and Wildlife Service	en
dc.contributor.funder	Lindbergh Foundation	en
dc.contributor.funder	West Virginia University	en
dc.contributor.funder	U.S. Geological Survey	en
dc.date.accessioned	2018-08-13T11:22:37Z
dc.date.available	2018-08-13T11:22:37Z
dc.date.issued	2018-06-09
dc.date.updated	2018-08-13T10:55:12Z
dc.description.abstract	Characterising the spatiotemporal variation of animal behaviour can elucidate the way individuals interact with their environment and allocate energy. Increasing sophistication of tracking technologies paired with novel analytical approaches allows the characterisation of movement dynamics even when an individual is not directly observable. In this study, high-resolution movement data collected via global positioning system (GPS) tracking in three dimensions were paired with topographical information and used in a Bayesian state-space model to describe the flight modes of migrating golden eagles (Aquila chrysaetos) in eastern North America. Our model identified five functional behavioural states, two of which were previously undescribed variations on thermal soaring. The other states comprised gliding, perching and orographic soaring. States were discriminated by movement features in the horizontal (step length and turning angle) and vertical (change in altitude) planes and by the association with ridgelines promoting wind deflection. Tracked eagles spent 2%, 31%, 38%, 9% and 20% of their daytime in directed thermal soaring, gliding, convoluted thermal soaring, perching and orographic soaring, respectively. The analysis of the relative occurrence of these flight modes highlighted yearly, seasonal, age, individual and sex differences in flight strategy and performance. Particularly, less energy-efficient orographic soaring was more frequent in autumn, when thermals were less available. Adult birds were also better at optimising energy efficiency than subadults. Our approach represents the first example of a state-space model for bird flight mode using altitude data in conjunction with horizontal locations and is applicable to other flying organisms where similar data are available. The ability to describe animal movements in a three-dimensional habitat is critical to advance our understanding of the functional processes driving animalsâ decisions. A plain language summary is available for this article.	en
dc.description.sponsorship	U.S. Department of Energy (Grant DEEE0003538); U.S. Fish and Wildlife Service (Pennsylvania SWG grants T-12 and T47-R-1)	en
dc.description.status	Peer reviewed	en
dc.description.version	Accepted Version	en
dc.format.mimetype	application/pdf	en
dc.identifier.citation	Pirotta, E., Katzner, T., Miller, T. A., Duerr, A. E., Braham, M. A. and New, L. (2018) 'State-space modelling of the flight behaviour of a soaring bird provides new insights to migratory strategies', Functional Ecology. doi:10.1111/1365-2435.13180	en
dc.identifier.doi	10.1111/1365-2435.13180
dc.identifier.endpage	11
dc.identifier.issn	0269-8463
dc.identifier.issn	1365-2435
dc.identifier.journaltitle	Functional Ecology	en
dc.identifier.startpage	1
dc.identifier.uri	https://hdl.handle.net/10468/6599
dc.language.iso	en	en
dc.publisher	John Wiley & Sons, Inc.	en
dc.rights	© 2018, the Authors. Functional Ecology © British Ecological Society. Published by John Wiley & Sons Inc. This is the peer reviewed version of the following article: Pirotta, E., Katzner, T., Miller, T. A., Duerr, A. E., Braham, M. A. and New, L. (2018) 'State-space modelling of the flight behaviour of a soaring bird provides new insights to migratory strategies', Functional Ecology. doi:10.1111/1365-2435.13180, which has been published in final form at https://doi.org/10.1111/1365-2435.13180. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.	en
dc.subject	3D states	en
dc.subject	Hidden state model	en
dc.subject	Markov chain Monte Carlo	en
dc.subject	Movement ecology	en
dc.subject	Raptor	en
dc.subject	Subsidised flight	en
dc.subject	GPS-GSM telemetry	en
dc.title	State-space modelling of the flight behaviour of a soaring bird provides new insights to migratory strategies	en
dc.type	Article (peer-reviewed)	en