325
reach sexual maturity (about 6–7 years old) (Perrin and Reilly 1984; Ramos 1997;
Ramos et al. 2000; Rosas 2000) (Fig. 13.3).
They are animals that usually form groups with an average size of 1–30 individuals (Daura-Jorge et al. 2005), although groups of over 200 individuals (Simão et al.
2000.; Flach et al. 2008) and by 400 individuals (Lodi and Hetzel 1998) have already
been reported on the Ilha Grande region, Rio de Janeiro State. Large aggregations
of this species can be characterized by cooperation for food (Flores and Silva 2009)
(Fig. 13.4).
Fig. 13.3 Mother and calf of Sotalia guianensis interacting in protected waters of the Caravelas estuary, Bahia State, Brazil. Parental care lasts usually over 5 years (Photo: Marcos Rossi-Santos)
Fig. 13.4 Group of Sotalia guianensis surfing a small wave in Pipa beach, Rio Grande do Norte
State, Brazil (Photo: Marcos Rossi-Santos)
13 Anthropogenic Noise and Guiana Dolphins (Sotalia guianensis) in Brazil…
reach sexual maturity (about 6–7 years old) (Perrin and Reilly 1984; Ramos 1997;
Ramos et al. 2000; Rosas 2000) (Fig. 13.3).
They are animals that usually form groups with an average size of 1–30 individuals (Daura-Jorge et al. 2005), although groups of over 200 individuals (Simão et al.
2000.; Flach et al. 2008) and by 400 individuals (Lodi and Hetzel 1998) have already
been reported on the Ilha Grande region, Rio de Janeiro State. Large aggregations
of this species can be characterized by cooperation for food (Flores and Silva 2009)
(Fig. 13.4).
Fig. 13.3 Mother and calf of Sotalia guianensis interacting in protected waters of the Caravelas estuary, Bahia State, Brazil. Parental care lasts usually over 5 years (Photo: Marcos Rossi-Santos)
Fig. 13.4 Group of Sotalia guianensis surfing a small wave in Pipa beach, Rio Grande do Norte
State, Brazil (Photo: Marcos Rossi-Santos)
13 Anthropogenic Noise and Guiana Dolphins (Sotalia guianensis) in Brazil…