title: Tracking the kinematics of caudal-oscillatory swimming: a comparison of two on-animal sensing methods.
abstract: Studies of locomotion kinematics require high-resolution information about body movements and the specific acceleration (SA) that these generate. On-animal accelerometers measure both orientation and SA but an additional orientation sensor is needed to accurately separate these. Although gyroscopes can perform this function, their power consumption, drift and complex data processing make them unattractive for biologging. Lower power magnetometers can also be used with some limitations. Here, we present an integrated and simplified method for estimating body rotations and SA applicable to both gyroscopes and magnetometers, enabling a direct comparison of these two sensors. We use a tag with both sensors to demonstrate how caudal-oscillation rate and SA are adjusted by a diving whale in response to rapidly changing buoyancy forces as the lungs compress while descending. The two sensors gave similar estimates of the dynamic forces, demonstrating that magnetometers may offer a simpler low-power alternative for miniature tags in some applications.
authors.affiliation: SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK Asociación Ipar Perspective, C/Karabiondo 17, 48600 Sopela, Bizkaia, Spain lmml2@st-andrews.ac.uk.
authors.forename: Lucía Martina
authors.identifier: 0000-0001-6587-4495
authors.initials: LM
authors.lastname: Martín López
authors.affiliation: CREEM (Centre for Research in Ecological and Environmental Modelling), University of St Andrews, Fife KY16 9LZ, UK BIOECOMAC (Biodiversidad, Ecología Marina y Conservación), Universidad de La Laguna, 38200 La Laguna, Tenerife, Spain.
authors.forename: Natacha
authors.initials: N
authors.lastname: Aguilar de Soto
authors.affiliation: SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK.
authors.forename: Patrick
authors.initials: P
authors.lastname: Miller
authors.affiliation: SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK Zoophysiology, Department of Bioscience, Aarhus University, Building 1131, C. F. Moellers Alle 3, Aarhus C DK-8000, Denmark.
authors.forename: Mark
authors.initials: M
authors.lastname: Johnson
mesh_terms: D000054:Acceleration; D000818:Animals; D001696:Biomechanical Phenomena; D005684:Gait / Q000502:physiology; D060306:Magnetometry / Q000379:methods*; D008297:Male; D012399:Rotation; D013550:Swimming / Q000502:physiology*; D014907:Whales / Q000502:physiology*
keywords: Accelerometer; Body rotation; Gyroscope; Magnetometer; Specific acceleration; Swimming kinematics