Data from: Dolphins simplify their vocal calls in response to increased ambient noise

Ocean noise varies spatially and temporally and is driven by natural and
anthropogenic processes. Increased ambient noise levels can cause signal
masking and communication impairment, affecting fitness and recruitment
success. However, the effects of increasing ambient noise levels on marine
species, such as marine mammals that primarily rely on sound for
communication, are not well understood. We investigated the effects of
concurrent ambient noise levels on social whistle calls produced by
bottlenose dolphins (Tursiops truncatus) in the Western North Atlantic.
Elevated ambient noise levels were mainly caused by ship noise. Increases
in ship noise, both within and below the dolphins’ call bandwidth,
resulted in higher dolphin whistle frequencies and a reduction in whistle
contour complexity, an acoustic feature associated with individual
identification. Consequently, the noise-induced simplification of dolphin
whistles may reduce the information content in these acoustic signals and
decrease effective communication, parent-offspring proximity or group
cohesion.