122
5.3.3 Burst Sounds
Burst pulse sounds are another major category of sound emissions by odontocetes.
For dolphins and small whales, burst pulse sounds are characterized by a high repetition rate (greater than about 300 pulses per second) or low inter-pulse intervals
(less than about 3 ms) (Au and Hastings 2008).
The great emphasis on studying whistles has led many to suppose that whistles
are the primary mode of communication in odontocetes. It is likely that the reason
for this relies on the wide band nature of burst pulse sounds compared to the frequency of the fundamental components of whistles, given that burst pulses can have
frequencies components that extend beyond 100 kHz (Lammers and Au 1996). The
Fig. 5.7 shows burst vocalizations with frequency components in the ultrasonic
range. So far, our data set allows basic measurements as duration, peak frequency,
center frequency and delta frequency. In addition, we have been observing the
sequential and time patterns in which burst sounds appear in the spectrograms.
Apparently, some burst sounds are emitted continuously to clicks trains (Fig. 5.7a)
or they are discrete in time (Fig. 5.7b).
The basic description of sounds produced by marine mammals in South Atlantic
Ocean, allows further investigations on geographical variation, signals classification
systems, social structure, behavior and so many other science fields that reflect on
acoustic communication. The next species sections in this chapter will present some
acoustical parameters for whistles, clicks and burst sounds of delphinid species
recorded in the South Atlantic continental shelf break.
5.4 Cetaceans Species Recorded and Identified
in the Western South Atlantic
5.4.1 Risso’s Dolphin (Grampus griseus)
Rissos dolphin (Fig. 5.8) is a small cetacean that can reach up to four meters long
and is distributed in temperate and tropical waters worldwide (Jefferson et al. 2014).
This species is distributed along the Brazilian continental shelfbreak and slope from
northeast to south region (Bastida et al. 2007; Di Tullio et al. 2016).
The acoustic repertoire of the Risso’s dolphin has not been fully detailed and
examples of whistles and clicks are preseted in Fig. 5.9. Neves (2013) described the
acoustic parameters of whistles and clicks in different regions (Australia, Azores,
California, Egypt and Gran Canaria). Gannier et al. (2008) and Rendell et al. (1999)
studied whistles in the waters of the western Mediterranean Sea and Azores, respectively. Philips et al. (2003) described the clicks emitted by the Risso’s dolphin in
captivity, and Madsen et al. (2004) studied click emissions of free-ranging animals
in Sri Lanka. Corkeron and Van Parjis (2001), in addition, describing the acoustic
parameters of pulsed sounds and whistles in Newcastle, Australia. Andriolo et al.
A. Andriolo et al.
5.3.3 Burst Sounds
Burst pulse sounds are another major category of sound emissions by odontocetes.
For dolphins and small whales, burst pulse sounds are characterized by a high repetition rate (greater than about 300 pulses per second) or low inter-pulse intervals
(less than about 3 ms) (Au and Hastings 2008).
The great emphasis on studying whistles has led many to suppose that whistles
are the primary mode of communication in odontocetes. It is likely that the reason
for this relies on the wide band nature of burst pulse sounds compared to the frequency of the fundamental components of whistles, given that burst pulses can have
frequencies components that extend beyond 100 kHz (Lammers and Au 1996). The
Fig. 5.7 shows burst vocalizations with frequency components in the ultrasonic
range. So far, our data set allows basic measurements as duration, peak frequency,
center frequency and delta frequency. In addition, we have been observing the
sequential and time patterns in which burst sounds appear in the spectrograms.
Apparently, some burst sounds are emitted continuously to clicks trains (Fig. 5.7a)
or they are discrete in time (Fig. 5.7b).
The basic description of sounds produced by marine mammals in South Atlantic
Ocean, allows further investigations on geographical variation, signals classification
systems, social structure, behavior and so many other science fields that reflect on
acoustic communication. The next species sections in this chapter will present some
acoustical parameters for whistles, clicks and burst sounds of delphinid species
recorded in the South Atlantic continental shelf break.
5.4 Cetaceans Species Recorded and Identified
in the Western South Atlantic
5.4.1 Risso’s Dolphin (Grampus griseus)
Rissos dolphin (Fig. 5.8) is a small cetacean that can reach up to four meters long
and is distributed in temperate and tropical waters worldwide (Jefferson et al. 2014).
This species is distributed along the Brazilian continental shelfbreak and slope from
northeast to south region (Bastida et al. 2007; Di Tullio et al. 2016).
The acoustic repertoire of the Risso’s dolphin has not been fully detailed and
examples of whistles and clicks are preseted in Fig. 5.9. Neves (2013) described the
acoustic parameters of whistles and clicks in different regions (Australia, Azores,
California, Egypt and Gran Canaria). Gannier et al. (2008) and Rendell et al. (1999)
studied whistles in the waters of the western Mediterranean Sea and Azores, respectively. Philips et al. (2003) described the clicks emitted by the Risso’s dolphin in
captivity, and Madsen et al. (2004) studied click emissions of free-ranging animals
in Sri Lanka. Corkeron and Van Parjis (2001), in addition, describing the acoustic
parameters of pulsed sounds and whistles in Newcastle, Australia. Andriolo et al.
A. Andriolo et al.