Australian long-finned pilot whales (Globicephala melas) emit stereotypical, variable, biphonic, multi-component, and sequenced vocalisations, similar to those recorded in the northern hemisphere

Abstract

While in the northern hemisphere, many studies have been conducted on the vocal repertoire of long-finned pilot whales (Globicephala melas), no such study has been conducted in the southern hemisphere. Presented here, is the first study on the vocalisations of long-finned pilot whales along the southern coast of mainland Australia. Multiple measures were taken of 2028 vocalisations recorded over five years in several locations. These vocalisations included tonal sounds with and without overtones, sounds of burst-pulse character, graded sounds, biphonations, and calls of multiple components. Vocalisations were further categorised based on spectrographic features into 18 contour classes. Altogether, vocalisations ranged from approximately 200 Hz to 25 kHz in fundamental frequency and from 0.03 s to 2.07 s in duration. These measures compared well with those from northern hemisphere pilot whales. Some call types were almost identical to northern hemisphere vocalisations, even though the geographic ranges of the two populations are far apart. Other call types were unique to Australia. Striking similarities with calls of short-finned pilot whales (Globicephala macrorhynchus) and sometimes sympatric killer whales (Orcinus orca) were also found. Theories for call convergence and divergence are discussed.

The first three records of killer whales (Orcinus orca) killing and eating blue whales (Balaenoptera musculus)

“…During Events 2 and 3, groups of pilot whales closely approached large aggregations of (presumably vocal) mammal‐eating killer whales feeding on recent kills. These observations support the notion that adult long‐finned pilot whales are not threatened by mammal‐eating killer whales and will approach feeding/vocalizing groups, perhaps as mobbing behavior or possibly in search of feeding opportunities (Courts et al, 2020; Pitman et al, 2017). Addressing how and why pilot whales interact with killer whales and whether they are immune to attack will require more field observations.…”

Sounding the Call for a Global Library of Underwater Biological Sounds

“…Fin whale (Balaenoptera physalus) calls, for example, differ among populations (Delarue et al, 2009) between the Northern and Southern hemispheres (Gedamke and Robinson, 2010;Širović et al, 2013Aulich et al, 2019), as well as over seasons (Morano et al, 2012b). Pilot whales (Globicephala melas), on the other hand, produce similar call types across the hemispheres even though populations' home ranges do not (or no longer) cross the equator, raising interesting questions about their acoustic ecology and evolution (Courts et al, 2020). Fishes may also develop "dialects, " such as the different acoustic characteristics of agonistic sounds produced by the skunk anemonefish (Amphiprion akallopisos) in Madagascar compared with those in Indonesia (Parmentier et al, 2005).…”

Detection and Classification Methods for Animal Sounds

“…Among marine mammals, blue, bowhead (Balaena mysticetus), fin, humpback, minke, and right whales, Weddell seals (Leptonychotes weddellii), harbor seals (Phoca vitulina), and walrus (Odobenus rosmarus) have all been reported to sing (Payne and Payne 1985;Sjare et al 2003;McDonald et al 2006;Stafford et al 2008;Oleson et al 2014;Crance et al 2019). The songs of blue, bowhead, fin, minke, and right whales are simple compared to those of the humpback whale and little is known about the behavioral context of song in any marine mammal species besides the humpback whale.…”