Page 50 - Spring 2018

Anthropocene Soundscape Ecology
ronment. There are also reports of matches between a gap in the ambient-noise spectrum and the sound spectrum used by fish for communicating to mates and competitors. Many taxa also exhibit flexible coping strategies for fluctuating ambient-noise levels. Tamarin monkeys (Saguinus oedipus), for example, avoid noisy periods and call preferentially in windows of relative quiet, whereas some bat species raise the amplitude of their echolocation calls in response to a rise in ambient-sound levels (Brumm and Slabbekoorn, 2005).
The widespread importance of sounds taxonomically and the critical role of the acoustic environment in their func- tionality and evolution means that changes to the sound- scapes in the Anthropocene may also have widespread con- sequences. Conservation is, in that respect, an odd term because almost all ecosystems are dynamic and changes are inherent to nature. We should, therefore, not necessarily aim to stop all changes. Furthermore, we have also seen that many species are able to cope with flexible responses in cases of novel environmental factors such as elevating noise levels. However, we often lack insight into the energetic costs of ad- justing signals and whether or not there are positive fitness consequences for the animals. As a result, the link between flexibility and breeding success is not yet confirmed and may turn out to be just a temporary solution for the individual. Persistence of the species in an increasingly noisy environ- ment is therefore by no means guaranteed.
The best advice at the moment should therefore be: do not make sounds when it is not essential. Many of our activities only produce sound as a by-product of their function. Noise mitigation is, therefore, often a reasonable solution. Another sensible thing is to make use of soundscapes for monitor- ing, as discussed in an article in this issue of Acoustics Today by Miksis-Olds, Martin, and Tyack. Recordings tell more than a thousand pictures and not only report which species are present but potentially also whether they are breeding, whether they were able to get a mate, what condition they are in, and whether they have an acoustic strategy to cope flexibly with fluctuating noise conditions. Changes over time in the presence and relative prominence of anthropo- genic noise can be quantified and matched with alterations in the soundscape spectrum due to changes in the vocal ani- mal community. Hopefully, more recordings and more stud- ies will improve both our understanding and appreciation for the acoustic world around us and make such efforts not just for the record.
Acknowledgments
Lucia Berti created all the artwork for the figures. Arthur Popper and Micheal Dent reviewed an earlier draft of the manuscript.
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48 | Acoustics Today | Spring 2018