15. The Spreading Message in a Noisy World: Song Behavior and Acoustic Ecology in Humpback Whales (Megaptera novaeangliae), from the Southwestern Atlantic Ocean

In this chapter, the song behavior and acoustic ecology of humpback whales (Megaptera novaeangliae) in the Brazilian breeding ground are documented, between 2005 and 2010 (July to October). Behavioral and ecological aspects such as group composition, spatial distribution, depth, tides and moon were analyzed, through boat surveys. We sighted 370 whale groups in 123 days, during a total of 912 h of sampling effort. In 36 days, 29% of the groups (n = 44; 82 individuals) were identified containing at least one singer male. Such groups were sighted along all the study area, mostly like alone individuals (n = 21 groups, 48%), followed by groups with two (n = 8; 18%), three (n = 3, 7%), four (n = 2, 4, 5%) individuals and also groups with female-calf pairs with one escort male (n = 4, 9%) or female-calf pairs plus two males (n = 1, 2%). Groups with singer males were sighted in a depth range of 16 and 173 m (mean = 54,6 ± 34,2 SD). The narrow continental shelf associated with the coastal distribution of the whales in the study area may influence in the group compositions containing singer males. So on, this work bring for the first time an ecological perspective of this recognized important singing behavior in this species, and also show the expansion of the acoustic activity, during the Brazilian breeding season, going far beyond the core area of Abrolhos Bank. Understanding the acoustic ecology of humpback whales, in which the song is performed, is crucial to provide insights into conservation measurements aiming to protect marine vertebrate and their habitat.