Vocalizations produced by southern right whale (Eubalaena australis) mother-calf pairs in a calving ground off Brazil

Abstract

Aiming to gather information on southern right whale (Eubalaena australis) mother-calf pairs' vocal behavior, archival acoustic recorders were deployed at a calving area off Brazil. Manual inspection of spectrograms revealed seven call classes: upcall, downcall, down-upcall, tonal variable, tonal constant, hybrid, and pulsive calls, which are consistent with those previously described for this species in Argentina. Gunshots and warbles, vocalizations described from other right whale species, were not detected. Mean values of start, end, maximum, minimum and peak frequencies, frequency bandwidth and duration were calculated for each call class. Start and end frequencies, frequency bandwidth and duration of upcalls recorded off Brazil were compared to those from other right whale populations and species. Only mean duration of upcalls from Brazil were significantly different from upcalls from all other populations. Differences in call duration may be driven by differences in demographic factors or background noise features among study areas. The repertoire characterization presented in this study will contribute to increase the utility of passive acoustic monitoring as a tool for conservation and research of southern right whales off Brazil as it provides important baseline information on the vocal behavior of this species.

Review of Underwater and In-Air Sounds Emitted by Australian and Antarctic Marine Mammals

“…Descriptions of the sounds of southern right whales have been published from the South Atlantic, off Argentina and Brazil [21][22][23][24] and from the South Pacific, around New Zealand [25]. CMST has been recording southern right whales in Fowlers Bay (SA) during the austral winter [26].…”

“…All of the populations produce FM sounds, with fundamentals ranging from 30 to 500 Hz, harmonics up to 5 kHz, and durations of 0.2-3.8 s ( Fig. 5a; [21][22][23][24][25]). The most frequently reported FM sound is a 0.2-2.7 s upsweep from 30 to 450 Hz plus harmonics (referred to as the "upcall" in the right whale literature; Fig.…”

“…The most frequently reported FM sound is a 0.2-2.7 s upsweep from 30 to 450 Hz plus harmonics (referred to as the "upcall" in the right whale literature; Fig. 5b; [21,24,25]). It seems to be the primary contact call, with variability in the call structure potentially coding caller identity [21].…”

“…All populations also emit CW sounds, with fundamentals ranging from 30 to 500 Hz, and harmonics up to 3.5 kHz, and durations of 0.2-6 s [21][22][23][24][25]. An exception is a low-frequency CW sound of up to 15.5-s duration, recorded off New Zealand [25].…”

“…An exception is a low-frequency CW sound of up to 15.5-s duration, recorded off New Zealand [25]. Pulsed sounds last 0.2-6.3 s with energy in the band 30-3300 Hz [21,22,24,25]. Finally, southern right whales also emit brief, broadband (30-8400 Hz) pulses, called "gunshots" with source levels of 172-187 dB re 1 µPa rms @ 1 m, and 0.1-0.4-s duration [21,22,25].…”