Harbour seals use rhythmic percussive signalling in interaction and display

• DOI: 10.1016/j.anbehav.2023.09.014
• Publication Date: 2023-11-18T16:06:13Z
• Authors: Kinga Kocsis; Diandra Duengen; Yannick Jadoul; Andrea Ravignani
• Keywords: 0301 basic medicine; flipper slap; Life Sciences; Marine Biology; 03 medical and health sciences; Animal Sciences; isochrony; 14. Life underwater; nonvocal communication; Phoca vitulina; flipper slap; isochrony; nonvocal communication; Phoca vitulina; pinniped; Biology; pinniped

Multimodal rhythmic signalling abounds across animal taxa. Studying its mechanisms and functions can highlight adaptive components in highly complex rhythmic behaviours, like dance, and music. Pinnipeds, such as the harbour seal (Phoca vitulina), are excellent comparative models to assess rhythmic capacities. Harbour seals engage in rhythmic percussive behaviours which, until now, have not been described in detail. In our study, eight zoo-housed harbour seals (two pups, two juveniles, and four adults) were passively audio-video monitored during their pupping-breeding season. All juvenile and adult animals performed percussive signalling with their fore flippers in agonistic conditions, both on land and in water. Flipper slap sequences produced on the ground or on the seals’ bodies were often highly regular in their interval duration, i.e., quasi-isochronous, at a 200-600 bpm pace. Three animals also showed significant lateralization in slapping. In contrast, display water slaps, performed only by adult males, showed slower tempo by one order of magnitude, and a rather motivic temporal structure. Our work highlights that percussive communication is a significant part of harbour seals’ behavioural repertoire. We hypothesise that its forms of rhythm production may reflect divergent adaptive functions such as regulating internal states and advertising individual traits.