Evolutionary Ecology
© Springer Science+Business Media Dordrecht
201310.1007/s10682-013-9658-7
June 2013
http://link.springer.com/article/10.1007/s10682-013-9658-7
Title: A rain forest dusk chorus: cacophony or sounds of silence?
Abstract
A rain forest dusk chorus consists of a large number of individuals of
acoustically communicating species signaling at the same time. How
different species achieve effective intra-specific communication in this
complex and noisy acoustic environment is not well understood. In this
study we examined acoustic masking interference in an assemblage of rain
forest crickets and katydids. We used signal structures and spacing of
signalers to estimate temporal, spectral and active space overlap between
species. We then examined these overlaps for evidence of strategies of
masking avoidance in the assemblage: we asked whether species whose
signals have high temporal or spectral overlap avoid calling together.
Whereas we found evidence that species with high temporal overlap may
avoid calling together, there was no relation between spectral overlap and
calling activity. There was also no correlation between the spectral and
temporal overlaps of the signals of different species. In addition, we
found little evidence that species calling in the understorey actively use
spacing to minimize acoustic overlap. Increasing call intensity and tuning
receivers however emerged as powerful strategies to minimize acoustic
overlap. Effective acoustic overlaps were on average close to zero for
most individuals in natural, multispecies choruses, even in the absence of
behavioral avoidance mechanisms such as inhibition of calling or active
spacing. Thus, call temporal structure, intensity and frequency together
provide sufficient parameter space for several species to call together
yet communicate effectively with little interference in the apparent
cacophony of a rain forest dusk chorus.
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