EMISSION RATE OF ACOUSTIC SIGNALS FOR THE COMMON BOTTLENOSE AND STRIPED DOLPHINS IN THE GULF OF TARANTO (NORTHERN IONIAN SEA, CENTRAL-EASTERN MEDITERRANEAN SEA)

摘要

Dolphins emit a large variety of acoustic signals on which they rely for navigation, communication and searching for food. Nevertheless, each species uses quantitative and qualitative species-specific characteristics for tonal and pulsed signals, and the different behavioral contexts may affect the use of these signals. The main aim of this work is to evaluate if the emission rate of acoustic signals can be used as a cue to recognize species, and as an intra-specific feature for recognizing behavioral contexts. We collected acoustic and behavioral data during 27 sightings of bottlenose and striped dolphins in the Gulf of Taranto, (Northern Ionian Sea, Central-Eastern Mediterranean Sea). 396.31minutes of recordings were considered for analysis. The emission rate, calculated as the number of vocalizations/minutes of recording per animals within the group, was compared among species and behaviors. A higher emission rate was recorded for bottlenose dolphins clicks during traveling compared to striped dolphins involved in the same behavior, and for striped dolphins whistles during socializing compared to other behaviors of the same species. However, we must consider that smaller groups were analyzed for bottlenose dolphins. Results suggest that dolphins share click echoes in larger groups and increase communication signals during social activities. Our preliminary results can help inform management and conservation actions, in the framework of EU regulations, in this high impacted area.