Pilot whale call types: a family affair?
An own study (...here...) recently analysed a total of 779 call vocalizations of short-finned pilot whales southwest off Tenerife, Canary Islands. 750 (96.3%) of all identified calls were heard more than once and some were repeated up to 34 times. Based on their time-frequency contours, these repetitive calls were grouped into structural categories resulting in 55 different call types with and without subtypes. It is possible that calls may serve an important role in identification of groups or individuals, or in maintaining acoustic contact between group members.
Click ...here... to see a realtime sonogram of pilot whale call vocalizations recorded on 31.08.1996 (.mov file with 3.1 MB).
Click ...here... to see a realtime sonogram of pilot whale call vocalizations recorded on 23.06.2001 (.mov file with 4.5 MB).
The figure above illustrates sonograms of the call (sub-) type repertoires recorded during recording session 4 (recorded on 01.09.1996 with 7 call types and 6 subtypes) and 10 (19.06.2001 with 6 call types and 4 subtypes). Call subtypes are labeled with a lower roman suffix. These two recording sessions showed the highest acoustic similarity. Numbers in parentheses give repetition rates of call (sub-) types during each recording session. Call subtype T-20ii was heard during both recording sessions. Call type T-22 can be found with two subtypes (T-22i and ii) in recording session 4 and with one subtype (T-22iii) in recording session 10.