Burst-pulses in East Greenland narwhals: Further evidence for unique, individual-specific vocalizations

In August 2013–2017, narwhals from Scoresby Sound, East Greenland, were instrumented with satellite-linked transmitters and acoustic sound and movement tags (AcousondeTM) over periods of up to 8 days. The records obtained provided continuous information on the whales’ acoustic behavior during foraging and social interactions. Burst-pulses were the most easily recognizable non-feeding vocalization. They tended to occur near the surface and were more common in records that displayed higher rates of clicks from other individuals, i.e., records that presumably would include more social interactions with other narwhals. Over 100 burst pulses detected in eight subjects were analyzed in terms of their overall length and their pattern of successive inter-click intervals (ICIs). While overall length could be somewhat variable, the succession of ICIs was unique for each whale and could therefore have an identity-carrying function, as the signature whistle does in bottlenose dolphins and other odontocetes. The occurrence of these individual-specific burst-pulses in time and space will be examined in relation to other factors provided by the tags, such as the time of day, whale depth, presence of conspecifics, and behavioral state. [Work sponsored in part by the Greenland Institute of Natural Resources.]