Playback Experiment

Speaker playback of “come” vocalization

To date we have performed one playback trial. We extracted a section from Mila’s whistle, altered it by removing the upper frequency harmonics, and played it to Eva through an underwater speaker. Eva certainly could distinguish this artificial, band limited whistle from a real one produced by Mila herself. Even so, Eva still started to chorus with the speaker. She stopped at approximate time 6:09, probably because the time intervals between speaker playback segments were too long.6 At one point Eva even started to swim over toward the speaker but then stopped and returned to Juan Carlos (her trainer), probably for the same reason. Compare this spectrogram with the one on the previous page. The spectrogram shown below is from our first playback of a vocalization-like signal to one of the dolphins.

6. King, S.L., Harley, H.E. & Janik V.M., 2014. The role of signature whistle matching in bottlenose dolphins (Tursiops truncatus). Animal Behaviour, vol. 96, pp. 79-86.