Cross-modal impacts of anthropogenic noise on information use.

Anthropogenic noise is a global pollutant, and there is rapidly accumulating evidence of impacts on a range of animal taxa [1,2]. While many studies have considered how additional noise may affect information provision and use, they have focused on the masking and consequent alteration of acoustic signals and cues; so-called unimodal effects [3]. Using field-based experimental trials on habituated wild dwarf mongooses (Helogale parvula) [4], we combine sound playbacks and faecal presentations to demonstrate that anthropogenic noise can disrupt responses to information from different sensory modalities. The adaptive, stronger response exhibited towards predator faeces compared with control faeces in ambient-noise conditions was detrimentally affected by road-noise playback. Specifically, having taken longer to detect the faeces, the mongooses interacted less with the predator cue, did not show increased vigilance following its detection, and spent less time in the safe vicinity of a burrow refuge, thus suffering a potentially increased predation risk. Our results are the first to show that anthropogenic noise could alter responses to olfactory cues, strongly indicating the possibility of cross-modal impacts of noise pollution on information use [3].