Cape fur seal vocal repertoire - acoustic parameters

Communication is primordial for survival of animal species as signals are
involved in many social interactions (mate selection, parental care, and
collective behaviours). The acoustic channel is the primary modality used
by birds and mammals to reliably exchange information among individuals.
In group-living species, the propagation of vocal signals is limited due
to the density of individuals and the background noise. Vocal exchanges
are therefore challenging. This study is the first investigation into the
acoustic communication system of the Cape fur seal (CFS), one of the most
colonial mammals with breeding colonies of hundreds of thousands of
individuals. We described the acoustic features and social function of
five call types from data collected at two colonies. Intra-species
variations in these vocalizations revealed their ability to convey
information about the age and/or sex of the emitter. Using two
classification methods, we also found that the five call types have
distinguishable frequency features and occupy distinct acoustic niches
indicating acoustic partitioning in the repertoire. The CFS vocalizations
appear to contain characteristics advantageous for discrimination among
individuals, which will enhance social interactions in their noisy and
confusing acoustic environment. This study provides a basis for our
understanding of the CFS acoustic communication system.