NeuroPSI – Paris-Saclay University

Acoustic communication network in Cape fur seals (Arctocephalus pusillus pusillus): deciphering information encoded in vocal signals

Abstract
During the breeding season, the Cape fur seal form extremely dense colonies in which the use of vocal signals to communicate is highly constrained by a loud background noise and a high risk of confusion. However, all social interactions such as territorial defence, maternal care or inter-sexual interactions involve the production of vocalisations. This thesis aims to unravel the structure and functioning of the Cape fur seal’s acoustic communication network by studying their calls, the information they contain, and the mechanisms of vocal recognition among individuals. In the first part, I focussed on the species’ vocal repertoire and described the in-air calls produced by females, males and pups during the breeding season (structure, acoustic features and contexts of production). Additionally, I investigated both micro- and macro-geographical variations by comparing several call types recorded at different study sites in Namibia and South-Africa. The second part concerns the information encoded in Cape fur seals’ calls. I first assessed the degree of vocal stereotypy in different call types and made intra- and inter-species comparisons with other Pinnipeds. Then, I dedicated an important part to the study of the mother-pup individual vocal recognition system. Experiments were performed to test their ability to recognise each other’s calls, the timing of the onset of the recognition after birth and the acoustic features involved in the decoding of their vocal signature. Further investigations were made at the level of males and answered questions on whether territorial males use vocal signals to modulate their interactions with neighbouring males or subadult ones. Finally, I used noise playback experiments at multiple study sites to assess the impact of anthropogenic noise on Cape fur seals’ on-land behaviour during the breeding season and factors driving intra-species variation in their reaction.

The committee will be composed of

• • Pr. Marco GAMBA, Rapporteur (Université de Turin)
  • Dr. Sophie LUMINEAU, Rapportrice (Université de Rennes)
  • Pr. Caroline GILBERT, Examinatrice (Ecole Nationale Vétérinaire d’Alfort)
  • Pr. Sylvie GRANON, Examinatrice (NeuroPSI, Université Paris Saclay)
  • Pr. David REBY, Examinateur (Université Jean Monnet)

and

• Dr. Isabelle Charrier (Institut NeuroPSI, Saclay) & Dr. Tess Gridley (Sea Search Research and Conservation, South Africa)