431
the double of time found for the Abrolhos Bank, which could indicate longer underwater occurrence due by distinct habitat use, once the north coast is seen as an area of
greater movement than the Abrolhos Bank. However, even with distinct environmental features as the deeper areas of the North Coast, it does not seem to present a strong
influence on dive patterns of the humpback whale in the Brazilian Breeding ground.
15.4.1 Acoustic Parameters
Despite the long list of studies in more than 40 years of research about the singing
behavior of humpback whales (eg. Payne and McVay 1971; Tyack 1981; Payne and
Payne 1985; Helweg et al. 1998; Mercado et al. 2003; Au et al. 2006), still there are
few descriptive studies that present numeric values for frequency, duration and
sound intensity. This work brings the first song description in the Brazilian coast,
outside the Abrolhos Bank, showing that humpbacks are utilizing a broader acoustic
environment for their breeding activities than previously reported.
Frequency parameters varied from 20 Hz (minimum) to 24,000 Hz (maximum),
being the interval between mean frequencies of 224,4 a 4422 Hz, duration of 0,13
to 6,5 s (mean = 1,06) and sound energy ranging from 62 to 130,4 dB (re SNR)
(mean = 105).
Olviedo et al. (2008), studying at Las Perlas Archipelago, Panama Gulf, reported
frequency parameters for year 2006, such as the minimum frequency (129,2–
575,7 Hz), maximum (1151,7–2879,6 Hz) and note duration (0,79–5,50 s) and, for
2007, the minimum frequency (129–1076 Hz), maximum (2368–4866 Hz) and note
duration (0,66–11,4 s). Number of notes varied from 13 to 15. Same authors also
describe the environment as being calm and shallow waters, contributing to the
whale breeding cycle, similar to the oceanographic conditions we observe in the
Abrolhos Archipelago.
Arraut and Vielliard (2004), in Abrolhos Bank, reported 24 notes and 5 themes
as the humpback whale song structure, during the breeding season of 2000, bringing
only spectrograms as a physical reference for the acoustic parameters, with frequency axis ranging from 500 to 2000 Hz.
Thus the present work show similar frequency values from other geographical
areas, such as the Panama Gulf (Olviedo et al. 2008), however, apparently by the
spectrograms reported by Arraut and Vielliard (2004), song varied temporally inside
the same breeding area off Brazil.
Another relevant finding from this study is the high frequency harmonic occurrence reaching the top of the frequency response (24 kHz). Au et al. (2006) reported
high frequency harmonics for the humpbacks in the Hawaiian waters, suggesting
the species may show an upper hearing limit as high or higher than this value.
The humpback whale song in this work seems to be more diverse and complex
than other reported areas, such as in Hawaii, where Au et al. (2006) described 9
notes compounding the song of 2002. For the Brazilian coast, Arraut and Vielliard
(2004) identified a similar number of notes, grouped into five themes, in the breed15 The Spreading Message in a Noisy World: Song Behavior and Acoustic Ecology…
the double of time found for the Abrolhos Bank, which could indicate longer underwater occurrence due by distinct habitat use, once the north coast is seen as an area of
greater movement than the Abrolhos Bank. However, even with distinct environmental features as the deeper areas of the North Coast, it does not seem to present a strong
influence on dive patterns of the humpback whale in the Brazilian Breeding ground.
15.4.1 Acoustic Parameters
Despite the long list of studies in more than 40 years of research about the singing
behavior of humpback whales (eg. Payne and McVay 1971; Tyack 1981; Payne and
Payne 1985; Helweg et al. 1998; Mercado et al. 2003; Au et al. 2006), still there are
few descriptive studies that present numeric values for frequency, duration and
sound intensity. This work brings the first song description in the Brazilian coast,
outside the Abrolhos Bank, showing that humpbacks are utilizing a broader acoustic
environment for their breeding activities than previously reported.
Frequency parameters varied from 20 Hz (minimum) to 24,000 Hz (maximum),
being the interval between mean frequencies of 224,4 a 4422 Hz, duration of 0,13
to 6,5 s (mean = 1,06) and sound energy ranging from 62 to 130,4 dB (re SNR)
(mean = 105).
Olviedo et al. (2008), studying at Las Perlas Archipelago, Panama Gulf, reported
frequency parameters for year 2006, such as the minimum frequency (129,2–
575,7 Hz), maximum (1151,7–2879,6 Hz) and note duration (0,79–5,50 s) and, for
2007, the minimum frequency (129–1076 Hz), maximum (2368–4866 Hz) and note
duration (0,66–11,4 s). Number of notes varied from 13 to 15. Same authors also
describe the environment as being calm and shallow waters, contributing to the
whale breeding cycle, similar to the oceanographic conditions we observe in the
Abrolhos Archipelago.
Arraut and Vielliard (2004), in Abrolhos Bank, reported 24 notes and 5 themes
as the humpback whale song structure, during the breeding season of 2000, bringing
only spectrograms as a physical reference for the acoustic parameters, with frequency axis ranging from 500 to 2000 Hz.
Thus the present work show similar frequency values from other geographical
areas, such as the Panama Gulf (Olviedo et al. 2008), however, apparently by the
spectrograms reported by Arraut and Vielliard (2004), song varied temporally inside
the same breeding area off Brazil.
Another relevant finding from this study is the high frequency harmonic occurrence reaching the top of the frequency response (24 kHz). Au et al. (2006) reported
high frequency harmonics for the humpbacks in the Hawaiian waters, suggesting
the species may show an upper hearing limit as high or higher than this value.
The humpback whale song in this work seems to be more diverse and complex
than other reported areas, such as in Hawaii, where Au et al. (2006) described 9
notes compounding the song of 2002. For the Brazilian coast, Arraut and Vielliard
(2004) identified a similar number of notes, grouped into five themes, in the breed15 The Spreading Message in a Noisy World: Song Behavior and Acoustic Ecology…