Repeated Call Sequences in Long-finned Pilot Whales: Social Setting, Modification, and Behavioural Context

Abstract

Long-finned pilot whales (Globicephala melas) are matrilineal group-living cetaceans. They often produce repeated call sequences: the same call type repeated three or more times, roughly evenly spaced with six seconds or less between calls. I used recordings from 1998-2014 from a population off Cape Breton, Canada, to examine repeated call sequence function. I found no evidence that these calls were specific to individuals or social units or could be used to allocate social units into clans. However, there was some evidence for the horizontal transmission of call types between social units. Modifications of calls (both embellishment and morphing) were common within repeated call sequences. The rate of production of repeated calls increased with group size but not with calf presence and varied with group behaviour and between years. Thus these sequences are likely not individual or unit identifiers, or primarily mother-calf contact calls, instead possibly functioning as group contact calls.