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Dolphins live in unique societies, in which
there are several subgroupings of individuals. The groups
are fluid, with smaller subgroups being more stable. The stability
of the subgroups is thought to promote social bonds between
individuals. Individuals within these groups are often out
of sight of each other, and therefore need a way of maintaining
communication.
Dolphins produce three types of sounds: broadband clicks used
in echolocation; broadband burst pulses; and whistles. Whistles
are frequency modulated narrow bands of sound, which are thought
to be used as a nametag for each individual dolphin (Caldwell,
Caldwell and Tyack 1990). Caldwell et al. (1990) described
a hypothesis in which captive dolphins would produce individually
distinctive and stereotyped whistles. These whistles were
named signature whistles due to their individually distinctive
features.
For more information about dolphins, see links to the right.
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