Cross-modal impacts of anthropogenic noise on information use

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms The adaptive, stronger response exhibited towards predator faeces compared to 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].Many prey species respond to secondary predator cues, such as urine and faeces, with inspection and over-marking, increased vigilance, reduced feeding and changed habitat use [5]. To investigate whether anthropogenic noise disrupts responses to a secondary predator cue, we conducted a 2x2 repeated-measures experiment on dwarf mongooses in their natural habitat. As a consequence of their small size, dwarf mongooses are threatened by a wide variety of predators [4]; they are also known to have well-developed olfactory-based communicative abilities [6]. In a given trial, either predator or herbivore (control) faeces were placed near the overnight sleeping burrows of groups that had been habituated to the close presence of observers [4,6], and the behaviour of the mongooses on emergence was monitored during playback of either ambient or road noise (full details in Supplemental Experimental Procedures).We found a strong trend for the dwarf mongooses to take longer to approach the faecal presentations when experiencing road-noise playback compared to ambient-noise playback (LMM: χ 2 1 = 3.672, p = 0.055; Figure 1A), but no significant effect of faecal type (Table S1a; full model outputs and effect sizes in Supplemental Results). Once the first mongoose had approached the faeces, subsequent behaviour by the group was significantly influenced by the interaction between sound treatment and faecal type. During ambient-noise playback, mongooses were more likely to approach (interaction term, LMM: χ 2 1 = 6.910, p = 0.009; 3 Table S1b; Figure 1B), sniff (GLMM: χ 2 1 = 5.487, p = 0.019; Table S1c; Figure 1C) and over-mark (χ 2 1 = 5.675, p = 0.017; Table S1d; Figure 1D) predator faeces compared to herbivore faeces; these differences were not seen during road-noise playback. While approaching behaviour could result from visual or olfactory cues, sniffing and over-marking are most likely responses to the olfactory information [5].One previous study has shown how anthropogenic noise can affect signalling in another sensory modality: common cuttlefish (Sepia officinalis) adjusted their visual displays by colour changing more frequently during ship-noise playb...

Anthropogenic noise alters dwarf mongoose responses to heterospecific alarm calls

“…Greater reliance on visual vs acoustic cues in conditions of increased noise represents an example of cross-modal perceptual weighting (Halfwerk and Slabbekoorn, 2015;Gomes et al, 2016); anthropogenic noise may also cause cross-modal interference (Halfwerk and Slabbekoorn, 2015;Morris-Drake et al, 2016). Increased vigilance likely means greater acquisition of accurate personal information about the current situation; social information, such as that arising from heterospecific alarm calls, can be irrelevant, unreliable or outdated (Giraldeau et al, 2002;Dall et al, 2005).…”

“…Previous experimental work has demonstrated that anthropogenic noise can disrupt dwarf mongoose use of information about predation risk, including that provided by the surveillance calls of conspecific sentinels Morris-Drake et al, 2016).…”

Integrating multiple disciplines to understand effects of anthropogenic noise on animal communication

“…In a recent playback study of road noise, dwarf mongoose ( Helogale parvula ) took longer to detect the presence of predators in noise treatments compared to ambient treatments (Morris‐Drake et al. ).…”

Why does noise reduce response to alarm calls? Experimental assessment of masking, distraction and greater vigilance in wild birds

“…Noise could distract receivers and so compromise responses to other sensory input (Chan & Blumstein, ; Chan et al, ). For instance, road‐noise playback disrupted the adaptive responses of dwarf mongooses to predator faeces; since there was no auditory element to the predator cue, this cross‐modal effect of noise implies distraction (Morris‐Drake, Kern, & Radford, ). Similarly, fathead minnows ( Pimephales promelas ) subjected to motorboat noise failed to respond to conspecific chemical alarm cues (Hasan, Crane, Ferrari, & Chivers, ), and crabs distracted by boat noise responded with a greater delay to a silent looming object (Chan et al, ).…”