432
ing season of 2000. This may represent the gradual modification described in literature (eg. Payne et al. 1983; Payne and Payne 1985) e o aporte de dados dos anos
subsequentes poderá contribuir com uma melhor interpretação deste resultado.
The values for maximum frequency were larger than previously reported, which
could indicate a better signal adaptation to the specific Brazilian acoustic environment. In this case, there is a big difference between the depth gradient utilized by the
whales in places like the Abrolhos Bank and the environment of the narrow continental shelf from Itacaré to Aracaju. This consideration is strengthen by the harmonic values reported for Hawaii (Au et al. 2006), where the depth is similar to part
of our study area, which include deeper waters. Biological implication of this would
be a maximization of the reproductive signal travelling across the acoustic environment to increase the mate opportunities during the time-limited breeding season.
Thus, beyond the descriptive analyzes of the acoustic parameters for the song,
this work bring information of the relations between song frequency and duration
with the acoustic environment in which it is produced, stating that differences may
occur even in a smaller geographic area, such as inside the same breeding area,
where environmental differences may result in distinct song components, as shown
with the maximum frequency and note duration.
Also, seems to be obvious that the advance in technology in the last decades have
shown a broader frequency spectra utilized by humpback whales. In this way, the
first decade in the “boom” of humpback song research was the 1970s, where notes
were registered below 5 kHz (eg. Payne and McVay 1971; Winn and Winn 1978) as
well as during the 1980s (eg. Payne and Payne 1985). The digital recording “Era”
increased more than twice the previous frequency response, bringing the higher
frequencies identifiable to the humpback repertoire (eg. Au et al. 2006, Mercado
et al. 2003, present work).
15.4.2 Song Form
Diverse and complex song structure along the time was found for humpback whales
off Brazilian waters, resulting in remarkable differences within a 6 years period of
study (2005–2010). Such differences are broader than previously commented, even
considering the differences inside the same breeding area, where environmental
characteristics may contribute with signal diversity and specificity.
Payne and Payne (1985) analyzed and compared humpback whales songs in
Bermuda for 13 years, between 1957 and 1975. They found that song changed conspicuously and progressively with time, being the songs separated by a number of
years were very different in content. Furthermore, all the songs showed basic structural similarities making possible to define a song form, which characterizes songs
from many years. Such analyses demonstrated high inter and intra-individual variability, none of which is as great as the variation between songs of consecutive
years. Our study is the first long term acoustic description to both Atlantic and
M.R. Rossi-Santos
ing season of 2000. This may represent the gradual modification described in literature (eg. Payne et al. 1983; Payne and Payne 1985) e o aporte de dados dos anos
subsequentes poderá contribuir com uma melhor interpretação deste resultado.
The values for maximum frequency were larger than previously reported, which
could indicate a better signal adaptation to the specific Brazilian acoustic environment. In this case, there is a big difference between the depth gradient utilized by the
whales in places like the Abrolhos Bank and the environment of the narrow continental shelf from Itacaré to Aracaju. This consideration is strengthen by the harmonic values reported for Hawaii (Au et al. 2006), where the depth is similar to part
of our study area, which include deeper waters. Biological implication of this would
be a maximization of the reproductive signal travelling across the acoustic environment to increase the mate opportunities during the time-limited breeding season.
Thus, beyond the descriptive analyzes of the acoustic parameters for the song,
this work bring information of the relations between song frequency and duration
with the acoustic environment in which it is produced, stating that differences may
occur even in a smaller geographic area, such as inside the same breeding area,
where environmental differences may result in distinct song components, as shown
with the maximum frequency and note duration.
Also, seems to be obvious that the advance in technology in the last decades have
shown a broader frequency spectra utilized by humpback whales. In this way, the
first decade in the “boom” of humpback song research was the 1970s, where notes
were registered below 5 kHz (eg. Payne and McVay 1971; Winn and Winn 1978) as
well as during the 1980s (eg. Payne and Payne 1985). The digital recording “Era”
increased more than twice the previous frequency response, bringing the higher
frequencies identifiable to the humpback repertoire (eg. Au et al. 2006, Mercado
et al. 2003, present work).
15.4.2 Song Form
Diverse and complex song structure along the time was found for humpback whales
off Brazilian waters, resulting in remarkable differences within a 6 years period of
study (2005–2010). Such differences are broader than previously commented, even
considering the differences inside the same breeding area, where environmental
characteristics may contribute with signal diversity and specificity.
Payne and Payne (1985) analyzed and compared humpback whales songs in
Bermuda for 13 years, between 1957 and 1975. They found that song changed conspicuously and progressively with time, being the songs separated by a number of
years were very different in content. Furthermore, all the songs showed basic structural similarities making possible to define a song form, which characterizes songs
from many years. Such analyses demonstrated high inter and intra-individual variability, none of which is as great as the variation between songs of consecutive
years. Our study is the first long term acoustic description to both Atlantic and
M.R. Rossi-Santos