24
The distribution pattern of animals may also be investigated in an individual
basis and to assess such information the capture-mark-recapture method is the most
usual. Since the physical capture of the Guiana dolphin would not be an adequate
procedure, we made use of individual characteristics, captured on film by camcorder (de Oliveira and Monteiro-Filho 2008) or photographic camera. The photoidentification (Fig. 2.10) well known among cetacean researches, were originally
based on film revelation (Würsig and Würsig 1977). Being non-invasive and therefore unlikely to alter natural behavior of the target species, the individual identification through images can answer questions related to individuals. De Oliveira and
Monteiro-Filho (2008) reported the same individuals captured in image repeatedly
in the same place: two individuals seen frequently close to a traditional local fishing
trap, cerco-fixo, and a mother-calf association observed in two beaches in different
islands. Medeiros (2014) presented similar results for both beaches (Fig. 2.11).
In one of these areas, the Ponta da Trincheira, the author identified several individuals using the area, with no significant difference between them, while in the other,
Praia do Pereirinha, fewer individuals were captured and all but two individuals
were captured only once. These two individuals used this site significantly more
than any other individual did, constantly accompanied by calves. Thereby, it is posFig. 2.9 A calf of Guiana
dolphin (Sotalia
guianensis) is frequently
observed swimming
side-by-side with its
parental (Photo: Caio
N. Louzada)
Fig. 2.8 Examples of most frequent group structure found at Cananéia estuary Guiana dolphin
population, State of São Paulo, Brazil. (a) Solitary individual. (b) Family, composed by one adult
and one calf, and frequently a plus one adult. (c) School, which represents an association among
several families (Photos: Caio Louzada)
E.L.A. Monteiro-Filho et al.
The distribution pattern of animals may also be investigated in an individual
basis and to assess such information the capture-mark-recapture method is the most
usual. Since the physical capture of the Guiana dolphin would not be an adequate
procedure, we made use of individual characteristics, captured on film by camcorder (de Oliveira and Monteiro-Filho 2008) or photographic camera. The photoidentification (Fig. 2.10) well known among cetacean researches, were originally
based on film revelation (Würsig and Würsig 1977). Being non-invasive and therefore unlikely to alter natural behavior of the target species, the individual identification through images can answer questions related to individuals. De Oliveira and
Monteiro-Filho (2008) reported the same individuals captured in image repeatedly
in the same place: two individuals seen frequently close to a traditional local fishing
trap, cerco-fixo, and a mother-calf association observed in two beaches in different
islands. Medeiros (2014) presented similar results for both beaches (Fig. 2.11).
In one of these areas, the Ponta da Trincheira, the author identified several individuals using the area, with no significant difference between them, while in the other,
Praia do Pereirinha, fewer individuals were captured and all but two individuals
were captured only once. These two individuals used this site significantly more
than any other individual did, constantly accompanied by calves. Thereby, it is posFig. 2.9 A calf of Guiana
dolphin (Sotalia
guianensis) is frequently
observed swimming
side-by-side with its
parental (Photo: Caio
N. Louzada)
Fig. 2.8 Examples of most frequent group structure found at Cananéia estuary Guiana dolphin
population, State of São Paulo, Brazil. (a) Solitary individual. (b) Family, composed by one adult
and one calf, and frequently a plus one adult. (c) School, which represents an association among
several families (Photos: Caio Louzada)
E.L.A. Monteiro-Filho et al.