Meeting Abstract
Approximately 1000 species of bat and 80 species of toothed whales are known to use echolocation to detect and track prey. While the basic function and phases of echolocation (search, approach and terminal buzz) are similar in both laryngeal echolocating bats and toothed whales, it is currently unclear whether similarities between Chiroptera and Cetacea extend to group situations. The influence of conspecifics on echolocation signals, for example, has been widely studied in bats, but is relatively lacking with respect to toothed whales, including porpoises. Using multi-microphone arrays and multi-hydrophone arrays, we recorded the calls/clicks produced by Daubenton’s bats and harbour porpoises, respectively, while they hunted insects and fish either alone or with a conspecific. Some of the call/click parameters we measured included source level (dB re 1 µPa pp), peak frequency, +/- 10 dB bandwidth, signal duration and inter-click interval (or call period). Based on previous research, we expect that bats foraging in pairs will produce calls with shorter durations, longer call periods and more variable peak frequencies compared to foraging alone. Because porpoises are facing similar constraints and acoustic clutter when they forage in groups, we expect to see similar changes in echolocation click parameters in harbour porpoises. Deviations from these patterns could provide information regarding the ability or likelihood of porpoises to engage in jamming avoidance responses or clutter responses when hunting with conspecifics.
