[MARMAM] New paper on dolphin whistles and ambient noise

Peter Simard simardpa at eckerd.edu
Wed Aug 30 07:50:24 PDT 2017

Dear colleagues,

We are pleased to announce the publication of the following article in the
journal Bioacoustics: *Whistling in a noisy ocean: bottlenose dolphins
adjust whistle frequencies in response to real-time ambient noise levels*
(Chantal van Ginkel, Danielle Becker, Shannon Gowans & Peter Simard).

The paper is available on the following link (or by contacting me):



Common bottlenose dolphins (*Tursiops truncatus*) use complex
acoustic behaviours for communication, group cohesion and
foraging. Ambient noise from natural and anthropogenic sources
has implications for the acoustic behaviour of dolphins, and research
shows that average ambient noise levels alter dolphin acoustic
behaviour. However, when background noise levels are highly variable,
the relationships between noise and acoustic behaviour over short
time periods are likely important. This study investigates whether
bottlenose dolphins altered the temporal and spectral qualities of
their whistles in relation to the ambient noise present at the time
the whistles were produced. Dolphin groups were recorded in Tampa
Bay (western Florida) between 2008 and 2015. Six whistle parameters
were analysed in spectrogram software (minimum frequency,
maximum frequency, bandwidth, peak frequency, duration and
number of inflection points) and ambient noise levels were calculated
immediately prior to each whistle. Linear regression analysis indicated
that the minimum, maximum and peak frequencies of whistles had
significant positive relationships with the ambient noise levels present
at the time of the whistles. These models suggested that for each
1 dB increase in ambient noise, minimum frequency increased by
121 Hz, maximum frequency increased by 108 Hz and peak frequency
increased by between 122 and 144 Hz. As ambient noise is typically
low frequency, this suggests that bottlenose dolphins increased
whistle frequency in response to real-time noise levels to avoid
masking. Future research to determine the fitness consequences of
noise-induced changes in the communication behaviour of dolphins
would be an important contribution to conservation efforts.

On behalf of the co-authors
Peter Simard

Peter Simard, Ph.D.

Visiting/CPT Professor, Environmental Studies
Eckerd College Dolphin Project


Office: 119A, Galbriath Marine Science Laboratory

Eckerd College
4200 54th Ave. South
St. Petersburg, FL 33711
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