Underwater acoustic signals of the narwhal (Monodon monoceros)

Underwater sound recordings of the narwhal from northern Baffin Island are analyzed and described. Frequency ranges of pulsed and pure tone vocalizations are found to be somewhat greater than previously observed. An earlier report that narwhals generate exclusively narrowband sounds is confirmed. Narwhal pulses appear to have a potential function as both orientation and communication signals. Pulse series having irregular repetition rates resemble the echolocation clicks of captive delphinids, and it is suggested that they serve a similar purpose. Pulse series having regular changes in repetition rate and distinct aural tones probably serve as social signals. The regular recurrence of a number of recognizably distinct pulsed tones suggests that the narwhal has 'signature' calls similar to several other odontocetes.