5. Acoustics and Social Behavior
239
emanate forward from the melon in a cone of directional sound (Au, Floyd
and Haun 1978; Norris et al. 1961). Although echolocation and click trains
have been associated with the gathering of environmental information and
navigation, the intense level of energy emission has recently been the topic
of discussion in functional aspects of cetacean life, including the ability to
stun prey (Norris and MlZihl 1981), the herding of fish (Hult 1982), and in
tactile stimulation (Johnson and Herzing 1991). Intense echolocation trains,
termed "buzzes," have also been described during interspecific encounters
between dolphins and sharks (Wood 1953; Wood et al. 1970). Since S.
frontalis use genital buzzes during foreplay, and, at a distance, it is possible
that this vocalization may have a tactile effect on the recipient ranging from
pain to pleasure during conspecific interactions.
3.4 Vocalizations Associated with Agonistic
and Aggressive Behavior
The predominant vocalizations produced during agonistic or aggressive
behavior are burst-pulsed sounds. Squawks are by far the dominant vocalization during head-to-head confrontations, body charges, and open-mouth
posturing. Torus bubbles displays (bubble rings) are also observed. Squawks
are broadband, burst-pulsed sounds, and range in frequency from 0.2 to 12
kHz, although the main energy is found in the lower frequencies of 1.1 to
2.4kHz. Duration ranges from 0.2 to LOs with repetition rates from 200 to
1,200 clicks per second. No consistent classification scheme exists for burstpulsed sounds, and the literature is replete with common names as seen in
Table 5.2.
Barks, a low-frequency, burst-pulsed vocalization that ranges from 0.2
to 2.0kHz and from 0.5 to LOs in duration, and screams, overlapping
frequency-modulated whistles that range from 5.8 to 9.4 kHz and 2.5 to
4.0s in duration, are also produced during highly escalated agonistic or aggressive behavioral sequences described above.
Many researchers have suggested that pulsed sounds may playa significant role in odontocete communication (Caldwell and Caldwell 1967; Gish
1979; Herman and Tavolga 1980). General associations between behaviors
and burst-pulsed sounds have been reported for T truncatus, including a
high-intensity, broadband "crack" or "pop" in alarm and fright (Caldwell
and Caldwell 1967) and during the herding of females by male coalitions
(Connor and Smolker 1996); squawks in head-to-head and agonistic and
open-mouth encounters (Caldwell and Caldwell 1967; Gish 1979; Overstrom 1983; Herzing 1988,1996) and in play encounters (Caldwell and Caldwell 1967); and "thunks" during disciplinary behavior between mothers and
infants (McCowan and Reiss 1994).
Reports of burst-pulsed vocalizations in other odontocetes include exchanges between S. longirostris (Watkins and Schevill 1974; Norris et al.
239
emanate forward from the melon in a cone of directional sound (Au, Floyd
and Haun 1978; Norris et al. 1961). Although echolocation and click trains
have been associated with the gathering of environmental information and
navigation, the intense level of energy emission has recently been the topic
of discussion in functional aspects of cetacean life, including the ability to
stun prey (Norris and MlZihl 1981), the herding of fish (Hult 1982), and in
tactile stimulation (Johnson and Herzing 1991). Intense echolocation trains,
termed "buzzes," have also been described during interspecific encounters
between dolphins and sharks (Wood 1953; Wood et al. 1970). Since S.
frontalis use genital buzzes during foreplay, and, at a distance, it is possible
that this vocalization may have a tactile effect on the recipient ranging from
pain to pleasure during conspecific interactions.
3.4 Vocalizations Associated with Agonistic
and Aggressive Behavior
The predominant vocalizations produced during agonistic or aggressive
behavior are burst-pulsed sounds. Squawks are by far the dominant vocalization during head-to-head confrontations, body charges, and open-mouth
posturing. Torus bubbles displays (bubble rings) are also observed. Squawks
are broadband, burst-pulsed sounds, and range in frequency from 0.2 to 12
kHz, although the main energy is found in the lower frequencies of 1.1 to
2.4kHz. Duration ranges from 0.2 to LOs with repetition rates from 200 to
1,200 clicks per second. No consistent classification scheme exists for burstpulsed sounds, and the literature is replete with common names as seen in
Table 5.2.
Barks, a low-frequency, burst-pulsed vocalization that ranges from 0.2
to 2.0kHz and from 0.5 to LOs in duration, and screams, overlapping
frequency-modulated whistles that range from 5.8 to 9.4 kHz and 2.5 to
4.0s in duration, are also produced during highly escalated agonistic or aggressive behavioral sequences described above.
Many researchers have suggested that pulsed sounds may playa significant role in odontocete communication (Caldwell and Caldwell 1967; Gish
1979; Herman and Tavolga 1980). General associations between behaviors
and burst-pulsed sounds have been reported for T truncatus, including a
high-intensity, broadband "crack" or "pop" in alarm and fright (Caldwell
and Caldwell 1967) and during the herding of females by male coalitions
(Connor and Smolker 1996); squawks in head-to-head and agonistic and
open-mouth encounters (Caldwell and Caldwell 1967; Gish 1979; Overstrom 1983; Herzing 1988,1996) and in play encounters (Caldwell and Caldwell 1967); and "thunks" during disciplinary behavior between mothers and
infants (McCowan and Reiss 1994).
Reports of burst-pulsed vocalizations in other odontocetes include exchanges between S. longirostris (Watkins and Schevill 1974; Norris et al.