Behaviour 2019
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Sexual and Individual Signatures Encoded in Rhythm of the Vocalisations of Nesting Cape Gannets 
Kezia Sabrina Bowmaker-Falconer 1, Andréa Thiebault1,2, Maëlle Connan1, Thierry Aubin2, Isabelle Charrier2, Pierre Pistorius 1. 1Department of Zoology, Marine Apex Predator Research Unit, Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha, Eastern Cape , South Africa; 2Université Paris-Saclay, CNRS 9197, Institut des Neurosciences, Paris Saclay , Paris Saclay, Orsay, France

Vocalisations play a vital role in animal communication, which is important for mate selection and individual recognition. Seabirds often breed in large colonies and finding partners efficiently is essential for reproductive success. Several seabird species including Cape gannets (Morus capensis) are monomorphic and most likely rely on acoustic signals for successful recognition. We studied the potential use of vocalizations for sex and individual recognition. Vocalizations of nesting Cape gannets (6 males, 4 females, 6 unsexed individuals) were recorded and acoustic variables were measured in both temporal and frequency domains. Differences in acoustics parameters between sexes and among individuals were determined statistically. The fundamental frequency and average Inter-Onset-Interval between successive components of the vocalisation (i.e. rhythm) were the most important acoustic variables for sex determination. Average Inter-Onset-Interval was the most important variable for individual identification. These results show potential as a faster and less resource-intensive method to identify the sex of individuals during fieldwork.