Fig. 1

Schematic illustrating the basic principles of direct and indirect encounter mapping. The three panels show the movements of two subjects (A, B) in 2D space. Indirect encounter mapping either generates a set of unconstrained XY coordinates for tags (left panel), or records the times when tagged animals are being detected by fixed receiver stations (green triangles) (middle panel). Direct encounter mapping, on the other hand, relies on tag-to-tag (radio/acoustic) communication (right panel); usually, data are recorded in binary form (encounter yes/no), but some systems, like “Encounternet”, store raw signal-strength data that can later be converted into estimates of tag-to-tag (and hence animal-to-animal) distance; for details, see main text and [14]