Data from: Tracking marine mammals in 3D using electronic tag data

1. Information about at-depth behaviour of marine mammals is fundamental
yet very hard to obtain from direct visual observation. Animal-borne
multisensor electronic tags provide a unique window of observation into
such behaviours. 2. Electronic tag sensors allow the estimation of the
animal's 3-dimensional (3D) orientation, depth and speed. Using tag
flow noise level to provide an estimate of animal speed, we extend
existing approaches of 3D track reconstruction by allowing the direction
of movement to differ from that of the animal's longitudinal axis. 3.
Data are processed by a hierarchical Bayesian model that allows processing
of multisource data, accounting for measurement errors and testing
hypotheses about animal movement by comparing models. 4. We illustrate the
approach by reconstructing the 3D track of a 52-min deep dive of a
Blainville's beaked whale Mesoplodon densirostris adult male fit with
a digital tag (DTAG) in the Bahamas. At depth, the whale alternated
regular movements at large speed (>1·5 m s -1) and more complex
movements at lower speed (<1·5m s-1) with differences between
movement and longitudinal axis directions of up to 28inline image. The
reconstructed 3D track agrees closely with independent acoustic-based
localizations. 5. The approach is potentially applicable to study the
underwater behaviour (e.g. response to anthropogenic disturbances) of a
wide variety of species of marine mammals fitted with triaxial
magnetometer and accelerometer tags.