The function of male sperm whale slow clicks in a high latitude habitat: Communication, echolocation, or prey debilitation?

Abstract

Sperm whales produce different click types for echolocation and communication. Usual clicks and buzzes appear to be used primarily in foraging while codas are thought to function in social communication. The function of slow clicks is less clear, but they appear to be produced by males at higher latitudes, where they primarily forage solitarily, and on the breeding grounds, where they roam between groups of females. Here the behavioral context in which these vocalizations are produced and the function they may serve was investigated. Ninety-nine hours of acoustic and diving data were analyzed from sound recording tags on six male sperm whales in Northern Norway. The 755 slow clicks detected were produced by tagged animals at the surface (52%), ascending from a dive (37%), and during the bottom phase (11%), but never during the descent. Slow clicks were not associated with the production of buzzes, other echolocation clicks, or fast maneuvering that would indicate foraging. Some slow clicks were emitted in seemingly repetitive temporal patterns supporting the hypothesis that the function for slow clicks on the feeding grounds is long range communication between males, possibly relaying information about individual identity or behavioral states.

Using a coherent hydrophone array for observing sperm whale range, classification, and shallow-water dive profiles

“…The spectra of both the echolocation and slow clicks recorded here closely match those of DTAGrecorded sperm whale click vocalizations shown in Fig. 1 of Oliveira et al (2013).…”

“…These loud clicks were separated by intervals of 5 s or longer (see Fig. 4) and can be categorized as slow clicks (Barlow and Taylor, 2005;Jacquet et al, 2001;Oliveira et al, 2013;Weilgart and Whitehead, 1993). The spectra of both the echolocation and slow clicks recorded here closely match those of DTAGrecorded sperm whale click vocalizations shown in Fig.…”

“…While studies have focused on examining the function of sperm whale clicks and their behavior during their descent in deep waters (Jacquet et al, 2001;Madsen et al, 2002b;Miller et al, 2004;Oliveira et al, 2013), their behaviors in shallow water are not well understood due to the fact that sperm whales are not common in this environment. Here the depth profile is estimated for a sperm whale in the shallow waters of the Gulf of Maine with 160 m water-column depth.…”

Depredating sperm whales in the Gulf of Alaska: local habitat use and long distance movements across putative population boundaries

“…Communication among the solitary males may occur through low-frequency, highly resonant, vocalizations called clangs or slow clicks (Gordon 1987, Madsen et al 2002, which differ from the usual clicks and creaks by having a slower repetition rate (inter-click interval: 5 to 8 s). Clangs or slow clicks travel long distances due to their low frequency, and have been suggested to function as a long-range communication tool for males (Madsen et al 2002, Oliveira et al 2013, Wild 2013. Coupling satellite tracking with acoustics could provide a mechanism to understand how these whales move and travel across large ocean basins.…”

Using accelerometers to determine the calling behavior of tagged baleen whales

“…At finer scales, animal-borne tags equipped with hydrophones provide acoustic information with simultaneous information on orientation, depth and acceleration (Johnson et al, 2009;Johnson and Tyack, 2003). Sounds recorded by these multi-sensor tags have been assigned to either the tagged whale itself or nearby conspecifics based on the angle of arrival (Johnson et al, 2009;Johnson et al, 2006;Madsen et al, 2013;Oliveira et al, 2013) or a combination of consistent received level, high signal-to-noise ratio and apparent isolation of the tagged animal (Janik, 2000;Jensen et al, 2012;Oleson et al, 2007;Parks et al, 2011). Most of these methods are problematic for analyzing baleen whale sound production when conspecifics are present because tagged whale sounds cannot be easily distinguished from those of nearby animals given the typical long-range propagation of low-frequency calls.…”