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Sound emissions from a female humpback whale in Arraial do Cabo (RJ, Brazil) [abstract]

Sheila M. Simão & Sergio C. Moreira (2002). Sound emissions from a female humpback whale in Arraial do Cabo (RJ, Brazil) [abstract]. Bioacoustics, Volume 13 (2): 201



Little is known about female humpback whales' vocal emissions. On 28 July 2000 a humpback whale mother and its offspring was followed by means of a Zodiac boat for 1h close to the coast of Pontal de Atalaia (23° 03'S; 42° 02'W), a migratory corridor of the species. During the observation, 18min 36s of the female vocalisations' recordings (Sony WM-D3) were obtained using a hydrophone (Celesco LC-10; 3 m deep). The recordings were analysed with Cool Edit Pro 1.2 (44,100 Hz, 32-bit, mono). The emissions did not vary, showing only rising frequency units. The 'song' was formed from 47 'units'. The maximum frequency of background noise was 2 kHz. The units duration varied between 0.71 to 1.03 s (mean = 0.97 + 0.10 s; N = 27), the initial frequency varying from 5.0 to 5.3 kHz (mean = 4.9 + 1.0 kHz), final frequency from 5.4 to 5.7 kHz (mean = 5.4 + 1.0 kHz), and the peak with the most amplitude was -14.37 dB. Most of the units (59%) had a duration between 0.96 to 0.97 s. The interval between units had a duration between 21.49 and 21.58 s, except one unit with 14.44 s. All the vocalisations were followed by echo during ca. 10 s coming from the rocky coast. Frazer & Mercado III (1999) concluded that humpback whale song is a long-range sonar used by male humpbacks to locate other whales on the breeding ground. The echo presence in the female vocalisations and her closeness to the coast makes us believe that the reason for these emissions was echolocation. Furthermore, there was a practically constant interval duration between emissions, low frequency modulation and little variation of emissions. This conclusion is reinforced by the fact that during an 1h observation, the female kept the coast at port and its offspring at starboard, constantly emitting sounds (support: CAPES, Redley, Cetacean Society International and Whale and Dolphin Project).