Spatiotemporal Dynamics of the Local Population of Black Sea Bottlenose Dolphins (Tursiops truncatus ponticus Barabash, 1940): Visual and Acoustic Description Methods

Abstract

The local Sudak–Novyi Svet (Crimea) population of Black Sea bottlenose dolphins was studied. Observations and acoustic recordings were made throughout 2014 and 2015. This study is the first in Russia to use acoustic identification of individuals based on a “signature whistle” catalog in addition to visual identification. Bottlenose dolphin signatures consisted of tonal signals (whistles) with a frequency contour shape unique for each dolphin. These whistles predominated in the acoustic repertoire of each individual. In this aspect, the signatures can be regarded as acoustic markers of individuals. Analysis of the entire set of dolphin whistle recordings (nearly 30 000 signals) revealed 206 dominant types, i.e., signature whistles. Visual and acoustic data were compared to characterize groups constituting the studied population, to describe the seasonal pattern of visits of different groups to the water area, and to identify transient and resident groups.