A meta-analysis of the influence of anthropogenic noise on terrestrial wildlife communication strategies.
Human-caused noise pollution dominates the soundscape of modern ecosystems, from urban centres to national parks. Although wildlife can generally alter their communication to accommodate many types of natural noise (e.g. wind, wave action, heterospecific communication), noise pollution from anthropogenic sources pushes the limits of wildlife communication flexibility by causing loud, low-pitched and near-continuous interference. Because responses to noise pollution are variable and taxa specific, multi-species risk assessments and mitigation are not currently possible. We conducted a meta-analysis to synthesize noise pollution effects on terrestrial wildlife communication. Specifically, we assessed: (a) the impacts of noise pollution on modulation of call rate, duration, amplitude and frequency (including peak, minimum and maximum frequency); and (b) the literature on anthropogenic noise pollution by region, taxa, study design and disturbance type. Terrestrial wildlife (results driven by avian studies) generally respond to noise pollution by calling with higher minimum frequencies, while they generally do not alter the amplitude, maximum frequency, peak frequency, duration and rate of calling. The literature on noise pollution research is biased towards birds, population-level studies, urban noise sources and study systems in North America. Synthesis and applications. Our study reveals the ways in which wildlife can alter their signals to contend with anthropogenic noise, and discusses the potential fitness and management consequences of these signal alterations. This information, combined with an identification of current research needs, will allow researchers and managers to better develop noise pollution risk assessment protocols and prioritize mitigation efforts to reduce anthropogenic noise.