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.

1. 海洋哺乳动物的水下深层行为信息虽具备核心研究价值，但通过直接目视观测获取却极为困难。动物佩戴式多传感器电子标记，为这类行为的观测提供了独一无二的研究窗口。
2. 电子标记搭载的传感器可用于估算动物的三维（3D）方位、下潜深度与运动速度。本研究借助标记的流动噪声水平估算动物运动速度，对现有三维轨迹重构方法进行了拓展，允许运动方向与动物纵轴方向存在差异。
3. 研究采用分层贝叶斯模型处理多源数据，可兼顾测量误差因素，并通过模型比对检验有关动物运动的各类假说。
4. 我们以巴哈马海域一头佩戴数字标记（DTAG）的成年雄性布氏中喙鲸（*Mesoplodon densirostris*）为例，对其持续52分钟的深潜行为开展了三维轨迹重构。观测结果显示，该鲸在深潜过程中交替呈现两种运动模式：高速（>1.5 m·s⁻¹）的规则运动，以及低速（<1.5 m·s⁻¹）的复杂运动，且运动方向与纵轴方向的最大偏差可达28°。重构得到的三维轨迹与独立声学定位结果高度吻合。
5. 本方法具备广泛应用潜力，可用于研究各类佩戴三轴磁强计与加速度计标记的海洋哺乳动物的水下行为，例如探究其对人为干扰的响应。