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D.L. Herzing
1.1 History of Species Studied in the Wild
It has long been thought that dolphin communication is both complex and
contextual (Tavolga 1983; Johnson 1993). Sources of information, other
than the acoustic signal itself, are important in the definition of context and
communication for other species, specifically birds and mammals. This
includes the effect of observers or intended recipients of information, the
history of the animal, and individual differences (Smith 1977). Because of
the highly developed acoustic sense in dolphins, researchers have emphasized the recording and analysis of vocalizations (Evans 1966; Herman and
Tavolga 1980). The term "vocalizations," although a misnomer since delphinids do not possess vocal chords, is used in this chapter to describe what
should be correctly labeled, the "phonations" of delphinids.
Dolphins communicate using both vocal and nonvocal signals (Wiirsig et
al. 1990). Qualitative descriptions of behavior and associated vocalizations
of captive dolphins were reported in early years (Caldwell and Caldwell
1967). Field studies often vary in their access to animals and in the field
site conditions, such as the ability to observe from the surface or underwater. Observations of surface behavior of free-ranging dolphins are the
most accessible types of observations in the wild, and include general
categories of rest, travel, socializing, and feeding (Shane 1990). Basic vocal
repertoires have also been accumulated for a variety of species including
T. truncatus (Caldwell and Caldwell 1967), pilot whales, Globicephala
meleana (Taruski 1979), Amazon river dolphins, Inia geoffrensis (Caldwell
et al. 1966), belugas, Delphinapterus leucas (Sjare and Smith 1986), spinner
dolphins, Stenella longirostris (Driscoll 1995), and killer whales, Orcinus
orca (Ford 1991). Recently, quantitative measures of surface and underwater behavior and vocalizations have been used in studies of freeranging delphinids (Table 5.1) including S. longirostris (Norris et al. 1994;
Ostman 1994), pantropical spotted dolphins, Stenella attenuata (Pryor
and Kang-Shallenberger 1991), S. frontalis (Herzing 1996),0. orca (Simila
and Ugarte 1993; Thomsen 1995), Hector's dolphins, Cephalorhynchus
hectori (Slooten 1994), and T. truncatus (dos Santos et al. 1990; Smolker
et al. 1993; Schultz et al. 1995; Connor and Smolker 1996; Oehen 1996).
Nevertheless, underwater behavioral observations and associated vocalizations of free-ranging dolphins are difficult. Although early technical arrays
(Watkins and Schevill 1974) and later advanced methods (Dudzinski et al.
1995) attempted to localize individual vocalizers, all have had limited
success.
Although much progress has been made in understanding the acoustic
behavior of many species of dolphins and whales (Tyack and Clark, Chapter
4), associating vocalizations with underwater behavior has proved difficult
due to the lack of underwater access to dolphins and their life history, sex,
and relationship information. The four species with current underwater
and life history observation potential include S. longirostris, S. attenuata,
D.L. Herzing
1.1 History of Species Studied in the Wild
It has long been thought that dolphin communication is both complex and
contextual (Tavolga 1983; Johnson 1993). Sources of information, other
than the acoustic signal itself, are important in the definition of context and
communication for other species, specifically birds and mammals. This
includes the effect of observers or intended recipients of information, the
history of the animal, and individual differences (Smith 1977). Because of
the highly developed acoustic sense in dolphins, researchers have emphasized the recording and analysis of vocalizations (Evans 1966; Herman and
Tavolga 1980). The term "vocalizations," although a misnomer since delphinids do not possess vocal chords, is used in this chapter to describe what
should be correctly labeled, the "phonations" of delphinids.
Dolphins communicate using both vocal and nonvocal signals (Wiirsig et
al. 1990). Qualitative descriptions of behavior and associated vocalizations
of captive dolphins were reported in early years (Caldwell and Caldwell
1967). Field studies often vary in their access to animals and in the field
site conditions, such as the ability to observe from the surface or underwater. Observations of surface behavior of free-ranging dolphins are the
most accessible types of observations in the wild, and include general
categories of rest, travel, socializing, and feeding (Shane 1990). Basic vocal
repertoires have also been accumulated for a variety of species including
T. truncatus (Caldwell and Caldwell 1967), pilot whales, Globicephala
meleana (Taruski 1979), Amazon river dolphins, Inia geoffrensis (Caldwell
et al. 1966), belugas, Delphinapterus leucas (Sjare and Smith 1986), spinner
dolphins, Stenella longirostris (Driscoll 1995), and killer whales, Orcinus
orca (Ford 1991). Recently, quantitative measures of surface and underwater behavior and vocalizations have been used in studies of freeranging delphinids (Table 5.1) including S. longirostris (Norris et al. 1994;
Ostman 1994), pantropical spotted dolphins, Stenella attenuata (Pryor
and Kang-Shallenberger 1991), S. frontalis (Herzing 1996),0. orca (Simila
and Ugarte 1993; Thomsen 1995), Hector's dolphins, Cephalorhynchus
hectori (Slooten 1994), and T. truncatus (dos Santos et al. 1990; Smolker
et al. 1993; Schultz et al. 1995; Connor and Smolker 1996; Oehen 1996).
Nevertheless, underwater behavioral observations and associated vocalizations of free-ranging dolphins are difficult. Although early technical arrays
(Watkins and Schevill 1974) and later advanced methods (Dudzinski et al.
1995) attempted to localize individual vocalizers, all have had limited
success.
Although much progress has been made in understanding the acoustic
behavior of many species of dolphins and whales (Tyack and Clark, Chapter
4), associating vocalizations with underwater behavior has proved difficult
due to the lack of underwater access to dolphins and their life history, sex,
and relationship information. The four species with current underwater
and life history observation potential include S. longirostris, S. attenuata,