Quantification of aggressive displays by wild, male grey seals (Halichoerus grypus) using seismic monitoring

Abstract

Communication via substrate vibrations can convey information on conspecific presence, individual quality, group cohesion, and/or allow for predator avoidance. The grey seal (Halichoerus grypus) breeding colony at Donna Nook, UK, is part of a limited geographic region where the Body Slap (BS) behaviour is performed during male-male conflicts. This behaviour is thought to have a mechanical component. We examined if the magnitude of the BS substrate vibrations contained reliable information on male mass and size as measures of RHP, and if reliability varied across environmental conditions. Our results demonstrate the BS generates a stereotyped seismic signature, and we found a positive correlation between the maximum and mean magnitudes of the substrate-borne vibrations and a male’s length. Dampness of the sand substrate had no effect on magnitude. Results of this study confirm that the maximum magnitude substrate vibrations generated by the Body Slap behaviour is an indicator of male size and that the substrate-borne vibrations are reliable across varying environmental conditions.