Bottlenose dolphin signature whistle variation : a perspective on physical characteristics, long-term stability, relatedness, and disturbance effects
Abstract
Bottlenose dolphin signature whistles are individually specific, modulated tonal sounds
that have been the focus of interest for studying the social acoustic repertoire in this species.
However, there is still limited understanding about the factors that might drive variation in these
signals. The dolphin community in Sarasota Bay is ideal for investigating the influence of
interspecific and intraspecific characteristics as well as the social structure on signature whistles as
it has been a long-term study for over 30 years. In this thesis, I investigated whether sex, age and
size affected the acoustic parameters and modulation patterns of signature whistles. I also
determined the variation in signature whistle acoustic characteristics over a long period of time to
test the stability of contour patterns. To look at the possible influence of genetic relationships on
whistle structure, I studied the influence of maternal kinship (including mothers, grandmothers,
siblings and aunts or uncles) and associations during the first year of life on signature whistle
acoustic parameters and contour modulation patterns. Since short-term responses to
environmental changes can also be encoded in whistles and can lead to changes in whistle
parameters, I investigated the effect of carrying digital acoustic devices (D-TAGs) after brief
capture-release session on the acoustic properties of signature whistles and dolphin behaviour.
The overall results of this thesis highlighted that signature whistles are arbitrary signals that have
long-term stability allowing them to be reliable signature calls. Mother-calf relations and social
interactions during very early development were found to have the highest influence on the
crystallisation of a signature whistle modulation pattern. Carrying suction cup D-TAGs, on the
other hand, had no clear effect on the dolphins’ signature whistles and surface behaviour,
confirming that these research methods are appropriate for studying vocal behaviour in
bottlenose dolphins.
Type
Thesis, PhD Doctor of Philosophy
Rights
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