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Open Access CC BY V4.0
Journal article
Identification of animal movement patterns using tri-axial magnetometry
Movement ecology, Vol.5(1), 6
2017
PMCID: PMC5367006
PMID: 28357113
Abstract
Background
Accelerometers are powerful sensors in many bio-logging devices, and are increasingly allowing researchers to investigate the performance, behaviour, energy expenditure and even state, of free-living animals. Another sensor commonly used in animal-attached loggers is the magnetometer, which has been primarily used in dead-reckoning or inertial measurement tags, but little outside that. We examine the potential of magnetometers for helping elucidate the behaviour of animals in a manner analogous to, but very different from, accelerometers. The particular responses of magnetometers to movement means that there are instances when they can resolve behaviours that are not easily perceived using accelerometers.
Methods
We calibrated the tri-axial magnetometer to rotations in each axis of movement and constructed 3-dimensional plots to inspect these stylised movements. Using the tri-axial data of Daily Diary tags, attached to individuals of number of animal species as they perform different behaviours, we used these 3-d plots to develop a framework with which tri-axial magnetometry data can be examined and introduce metrics that should help quantify movement and behaviour.
Results
Tri-axial magnetometry data reveal patterns in movement at various scales of rotation that are not always evident in acceleration data. Some of these patterns may be obscure until visualised in 3D space as tri-axial spherical plots (m-spheres). A tag-fitted animal that rotates in heading while adopting a constant body attitude produces a ring of data around the pole of the m-sphere that we define as its Normal Operational Plane (NOP). Data that do not lie on this ring are created by postural rotations of the animal as it pitches and/or rolls. Consequently, stereotyped behaviours appear as specific trajectories on the sphere (m-prints), reflecting conserved sequences of postural changes (and/or angular velocities), which result from the precise relationship between body attitude and heading. This novel approach shows promise for helping researchers to identify and quantify behaviours in terms of animal body posture, including heading.
Conclusion
Magnetometer-based techniques and metrics can enhance our capacity to identify and examine animal behaviour, either as a technique used alone, or one that is complementary to tri-axial accelerometry.
Details
- Title
- Identification of animal movement patterns using tri-axial magnetometry
- Authors/Creators
- Hannah J. Williams - Swansea, SA2 8PP UKMark D. Holton - Swansea, SA2 8PP UKEmily L. C. Shepard - Swansea, SA2 8PP UKNicola Largey - Swansea, SA2 8PP UKBrad Norman - ECOCEAN Inc. (Aust.), ECOCEAN (USA), C/o 68a Railway Street, Perth, WA 6011 AustraliaPeter G. Ryan - Rondebosch, 7701 South AfricaOlivier Duriez - Université Paul-Valéry MontpellierMichael Scantlebury - Queen's University BelfastFlavio Quintana - Centro Nacional Patagónico, CONICET , Puerto Madryn, Chubut ArgentinaElizabeth A. Magowan - Queen's University BelfastNikki J. Marks - Queen's University BelfastAbdulaziz N. Alagaili - P.O. Box 2455, Riyadh, 11451 Saudi ArabiaNigel C. Bennett - Pretoria, South AfricaRory P. Wilson - Swansea, SA2 8PP UK
- Publication Details
- Movement ecology, Vol.5(1), 6
- Publisher
- BioMed Central Ltd unless otherwise stated. Part of Springer Nature.
- Identifiers
- 991005580061107891
- Copyright
- © The Author(s). 2017
- Murdoch Affiliation
- Centre for Sustainable Aquatic Ecosystems
- Language
- English
- Resource Type
- Journal article
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- Collaboration types
- Domestic collaboration
- International collaboration
- Citation topics
- 3 Agriculture, Environment & Ecology
- 3.35 Zoology & Animal Ecology
- 3.35.33 Avian Ecology
- Web Of Science research areas
- Ecology
- ESI research areas
- Environment/Ecology