1. Overview
27
born killer whale calf and found that it learned and reproduced only the
calls of its mother and ignored the calls of other killer whales in the same
pool. Ford (1991) also observed killer whales imitating the call types of different pods, and even those from other clans. These instances were rare, but
it does show a capacity for learning and mimicry of acoustic signals.
4.4.4.2 Bottlenose Dolphin
Wang et al. (1995) have found some differences in the structure of whistles
of different populations of bottlenose dolphins, T. Turncatus, in the Gulf
of Mexico, suggesting that they also may have dialects. However, more
research is needed in order to accumulate sufficient evidence to address this
issue. Working with bottlenose dolphins may be much more difficult than
killer whales since bottlenose dolphins exist in free fission-fusion groups in
which many individual animals tend to come and go at will. Therefore, there
does not seem to be a clanlike structure to the bottlenose dolphin society
and dialect may be more associated with habitat differences rather than
clan and pod membership like the killer whale.
4.4.4.3 Sperm Whales
Sperm whales, P catodon live in a matrilineal family unit where they exhibit
cooperative behaviors including communal care of the young in ways
similar to killer whales. The family units are very stable and females may
live as long as 60 to 70 years (Whitehead et al. 1991). Codas seem to be the
primary means of acoustic communications for these animals (Watkins and
Schevill 1977). Weilgart and Whitehead (1997) recorded for more than a
year codas from a number of sperm whales around the South Pacific and
in the Caribbean Sea. Photographic identification also allowed them to
assign recording sessions to particular groups. They found that the coda
repertoire recorded from the same group on the same or different days
were much more similar than those recorded from different groups in the
same place. Groups recorded in the same place had more similar coda
repertoire than those in the same broad area but different places. Groups
from the same area were in turn marginally similar to those in the same
ocean but different than those in different oceans. Coda class repertoires
of groups in different oceans and in different areas within the same ocean
were statistically significantly different. They concluded that strong groupspecific dialects were apparently overlaid on weaker geographic variation.
P catodon, 0. Orcinus, and possibly T. turncatus are the only cataceans
known to have dialects.
5. Sound Emissions by Mysticete Whales
There are 11 species of mysticetes, or baleen whales, and sounds have been
recorded from all but the pygmy right whale, Caperea marginata (Clark
1990). Tyack and Clark (Chapter 4) present a detailed discussion of sound
27
born killer whale calf and found that it learned and reproduced only the
calls of its mother and ignored the calls of other killer whales in the same
pool. Ford (1991) also observed killer whales imitating the call types of different pods, and even those from other clans. These instances were rare, but
it does show a capacity for learning and mimicry of acoustic signals.
4.4.4.2 Bottlenose Dolphin
Wang et al. (1995) have found some differences in the structure of whistles
of different populations of bottlenose dolphins, T. Turncatus, in the Gulf
of Mexico, suggesting that they also may have dialects. However, more
research is needed in order to accumulate sufficient evidence to address this
issue. Working with bottlenose dolphins may be much more difficult than
killer whales since bottlenose dolphins exist in free fission-fusion groups in
which many individual animals tend to come and go at will. Therefore, there
does not seem to be a clanlike structure to the bottlenose dolphin society
and dialect may be more associated with habitat differences rather than
clan and pod membership like the killer whale.
4.4.4.3 Sperm Whales
Sperm whales, P catodon live in a matrilineal family unit where they exhibit
cooperative behaviors including communal care of the young in ways
similar to killer whales. The family units are very stable and females may
live as long as 60 to 70 years (Whitehead et al. 1991). Codas seem to be the
primary means of acoustic communications for these animals (Watkins and
Schevill 1977). Weilgart and Whitehead (1997) recorded for more than a
year codas from a number of sperm whales around the South Pacific and
in the Caribbean Sea. Photographic identification also allowed them to
assign recording sessions to particular groups. They found that the coda
repertoire recorded from the same group on the same or different days
were much more similar than those recorded from different groups in the
same place. Groups recorded in the same place had more similar coda
repertoire than those in the same broad area but different places. Groups
from the same area were in turn marginally similar to those in the same
ocean but different than those in different oceans. Coda class repertoires
of groups in different oceans and in different areas within the same ocean
were statistically significantly different. They concluded that strong groupspecific dialects were apparently overlaid on weaker geographic variation.
P catodon, 0. Orcinus, and possibly T. turncatus are the only cataceans
known to have dialects.
5. Sound Emissions by Mysticete Whales
There are 11 species of mysticetes, or baleen whales, and sounds have been
recorded from all but the pygmy right whale, Caperea marginata (Clark
1990). Tyack and Clark (Chapter 4) present a detailed discussion of sound