3D tracking of animals in the field, using rotational stereo videography

Abstract

We present a method for tracking the path of animals in the field, based on stereo-videography and aiming-angle measure, combined in a single, rotational device. In open environment, this technique has the potential to extract multiple 3D positions per second, with a spatial uncertainty < 1 m (rms) within 300 m from the observer, and < .1 m (rms) within 100 m from the observer, in all directions. The tracking device is transportable and operated by a single observer and does not imply any animal tagging. As a video of the moving animal is recorded, track data can easily be completed with behavioural data. We present a prototype device based on accessible components, that achieves about 70% of the theoretical maximal range. We show examples of bird ground and flight tracks, and discuss the strength and limits of the method, compared to existing fine-scale (e.g. fixed-camera stereo-videography) and large-scale tracking methods (e.g. GPS tracking).