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Durham University

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Publication details for Dr Sean Twiss

Bishop, A.M., Lidstone-Scott, R., Pomeroy, P.P. & Twiss, S.D. (2014). Body Slap: An Innovative Aggressive Display by Breeding Male Gray Seals (Halichoerus grypus). Marine Mammal Science 30(2): 579-593.

Author(s) from Durham


Aggression in male gray seals has been extensively studied; however it is often
simplistically assumed that threat signals are mainly cephalic in nature for this species.We report on an undescribed and apparently new kind of threat signal used by male gray seals we term a Body Slap. The behavior has been observed at breeding sites
in eastern England since 1993 but has not been studied ethologically or reported elsewhere.The aims of this study were to describe the behavior, test the influence of topographic variation on its frequency of occurrence, examine if it is used to signal dominance or submission, and to place it in intra- and interspecific contexts. Our results show Body Slaps were performed in 66.3% of interactions and by 57.2% of males; it was not performed by females. The Body Slap was positively associated with the Approach and Open-Mouth Threat behaviors but was not related to dominance; nevertheless, display rates were greater for subsequent winners. These findings suggest that the Body Slap carries information about male resource holding potential and does not signal submission. This study furthers our understanding of geographic
variants of male threat behaviors and of pinniped nonvocal communication.