138
may rely on strategies to recognize individuals in order to adjust their behavior
(Whitehead 2003).
Within the types of clicks that sperm whales emit, a series of stereotyped patter of
clicks called codas stand out. Codas have been associated to communication and
identification of a specific unit membership, besides of being used for individual
recognition and identification (Watkins and Schevill 1977; Whitehead and Weilgart
1991) and consequently reflects family relationships (Weilgart and Whitehead 1997).
Sperm whales social units in the Pacific were grouped into vocal clans based on
their coda repertoires (Rendell and Whitehead 2003a). Besides that, within vocal
clans, unit members share elements of their coda repertoire, and eventually engage
in codas exchanges in order to share a signal code (Whitehead 2003; Rendell and
Whitehead 2004). It is know that codas repertoire varies geographically (Weilgart
and Whitehead 1997) and are learnt within matrilineal social groups. Rendell and
Whitehead (2005) found that similarities among repertoires showed a negative correlation with increasing distance of clans.
Codas were mostly studied in the Island of Dominica (Schulz et al. 2008; Antunes
et al. 2011; Schulz et al. 2011; Gero et al. 2015; Gero et al. 2016), in the Mediterranean
(Borsani et al. 1997; Pavan et al. 2000), in the Caribean (Moore et al. 1993), in
Azores (Oliveira et al. 2016), in the Galápagos (Weilgart and Whitehead 1993;
Rendell and Whitehead 2003b, 2004, 2005), in the Pacific (Rendell and Whitehead
2003a, Marcoux et al. 2006) and in the North western Atlantic (Watkins and Schevill
1977). As a first effort in studying codas and social structure of sperm whales in
South Atlantic (Fig. 5.24), we have been making recordings since 2011 in the South,
Southeast of Brazil. In collaboration with researchers of University of St. Andrews,
the vocal clans and its dialects will be investigated. So far, a total of 939 codas were
marked up using a custom-written software for analyzing sperm whale sounds
called Rainbow Click (see Gillespie 1997; Leaper et al. 2000).
5.5.3 Abundance Estimation of Sperm Whales
Information on distribution and density of most marine mammals have been primarily obtained from visual surveys (Ward et al. 2012; Marques et al. 2013). However,
the traditional methods of visual monitoring have been associated with: (1) training
of qualified staff, (2) an intensive work effort, (3) a high implementation costs
(Evans and Hammond 2004; Ward et al. 2012; Marques et al. 2011, 2013). They can
be undertaken merely during daylight and in good weather conditions and, as the
individuals are available for visual observation only when at the surface, just part of
the animals present can be detected (Mellinger and Barlow 2003; Mellinger et al.
2007; Vallarta-Hernandez 2009; Ward et al. 2012; Yack et al. 2013).
PAM has been increasingly used in study of marine mammals, especially because
many of them are more acoustically than visually available (Barlow and Taylor
2005; Zimmer 2013; Yack et al. 2013). Whether simultaneously conducted, the
abundance estimates obtained through these methods are possibly more reliable
A. Andriolo et al.
may rely on strategies to recognize individuals in order to adjust their behavior
(Whitehead 2003).
Within the types of clicks that sperm whales emit, a series of stereotyped patter of
clicks called codas stand out. Codas have been associated to communication and
identification of a specific unit membership, besides of being used for individual
recognition and identification (Watkins and Schevill 1977; Whitehead and Weilgart
1991) and consequently reflects family relationships (Weilgart and Whitehead 1997).
Sperm whales social units in the Pacific were grouped into vocal clans based on
their coda repertoires (Rendell and Whitehead 2003a). Besides that, within vocal
clans, unit members share elements of their coda repertoire, and eventually engage
in codas exchanges in order to share a signal code (Whitehead 2003; Rendell and
Whitehead 2004). It is know that codas repertoire varies geographically (Weilgart
and Whitehead 1997) and are learnt within matrilineal social groups. Rendell and
Whitehead (2005) found that similarities among repertoires showed a negative correlation with increasing distance of clans.
Codas were mostly studied in the Island of Dominica (Schulz et al. 2008; Antunes
et al. 2011; Schulz et al. 2011; Gero et al. 2015; Gero et al. 2016), in the Mediterranean
(Borsani et al. 1997; Pavan et al. 2000), in the Caribean (Moore et al. 1993), in
Azores (Oliveira et al. 2016), in the Galápagos (Weilgart and Whitehead 1993;
Rendell and Whitehead 2003b, 2004, 2005), in the Pacific (Rendell and Whitehead
2003a, Marcoux et al. 2006) and in the North western Atlantic (Watkins and Schevill
1977). As a first effort in studying codas and social structure of sperm whales in
South Atlantic (Fig. 5.24), we have been making recordings since 2011 in the South,
Southeast of Brazil. In collaboration with researchers of University of St. Andrews,
the vocal clans and its dialects will be investigated. So far, a total of 939 codas were
marked up using a custom-written software for analyzing sperm whale sounds
called Rainbow Click (see Gillespie 1997; Leaper et al. 2000).
5.5.3 Abundance Estimation of Sperm Whales
Information on distribution and density of most marine mammals have been primarily obtained from visual surveys (Ward et al. 2012; Marques et al. 2013). However,
the traditional methods of visual monitoring have been associated with: (1) training
of qualified staff, (2) an intensive work effort, (3) a high implementation costs
(Evans and Hammond 2004; Ward et al. 2012; Marques et al. 2011, 2013). They can
be undertaken merely during daylight and in good weather conditions and, as the
individuals are available for visual observation only when at the surface, just part of
the animals present can be detected (Mellinger and Barlow 2003; Mellinger et al.
2007; Vallarta-Hernandez 2009; Ward et al. 2012; Yack et al. 2013).
PAM has been increasingly used in study of marine mammals, especially because
many of them are more acoustically than visually available (Barlow and Taylor
2005; Zimmer 2013; Yack et al. 2013). Whether simultaneously conducted, the
abundance estimates obtained through these methods are possibly more reliable
A. Andriolo et al.