Deep, harmonic moans associated with Bryde’s whales in several locations worldwide

Abstract

Several sounds have been associated with Bryde’s whales in the Gulf of California [Cummings et al. (1986); Edds et al. (1993)]. Here, we report on harmonically rich tonal calls recorded in the vicinity of Bryde’s whales. In the eastern tropical Pacific, sonobuoys were deployed in the immediate vicinity of Bryde’s whales on 40+ occasions, and in two cases, a 1–2-s tonal signal was recorded with a fundamental of 50–53 Hz and with 3 clear harmonic overtones. In the southern Caribbean, sonobuoys were deployed in the vicinity of Bryde’s whales, and, on 20 occasions, a 2–3-s tonal signal was recorded with a fundamental of either 15–20 or 40–45 Hz and with 3–5 clear harmonic overtones. Off New Zealand, a bottom-mounted hydrophone recorded 4–7-s, 22–28-Hz tonal calls which are seasonally associated with the presence of Bryde’s whales; such calls were previously recorded in this area using a hydrophone with greater bandwidth [Kibblewhite et al. (1967)] and showed harmonic overtones that were similar to those at the other two locations. Bryde’s whales appear to produce a rich variety of calls, including these harmonic moans that had not been previously noted in the published literature.