Exposure to noise pollution across North American passerines supports the noise filter hypothesis

Abstract

The noise filter hypothesis predicts that species using higher sound frequencies should be more tolerant of noise pollution, because anthropogenic noise is more intense at low frequencies. Recent work analysed continental-scale data on anthropogenic noise across the USA and found that passerine species inhabiting more noise-polluted areas do not have higher peak song frequency but have more complex songs. However, this metric of song complexity is of ambiguous interpretation, because it can indicate either diverse syllables or a larger frequency bandwidth. In the latter case, the finding would support the noise filter hypothesis, because larger frequency bandwidths mean that more sound energy spreads to frequencies that are less masked by anthropogenic noise. We reanalysed how passerine song predicts exposure to noise using a more thorough dataset of acoustic song measurements, and showed that it is large frequency bandwidths, rather than diverse syllables, that predict the exposure of species to noise pollution. Given that larger bandwidths often encompass higher maximum frequencies, which are less masked by anthropogenic noise, our result suggests that tolerance to noise pollution might depend mostly on having the high-frequency parts of song little masked by noise, thus preventing acoustic communication from going entirely unnoticed at long distances. | INTRODUC TI ONAnthropogenic noise can mask animal acoustic signals and have detrimental effects on individual fitness and on populations (reviewed by Shannon et al. [2016]). Given that noise pollution is more intense at low sound frequencies (e.g., noise power spectra in the studies by Curry, Des Brisay, Rosa, and Koper [2018], Damsky and Gall [2017],Hu and Cardoso [2010]), the noise filter hypothesis predicts that CORRESPONDENCE average, higher peak frequencies but not higher minimum frequencies than closely related species not described as regularly inhabiting urban habitats (Hu & Cardoso, 2009). The effects of using a large frequency bandwidth, particularly if encompassing higher maximum frequencies, has not been given attention in research on noise tolerance. The results provided by Klingbeil et al. (2020) and here suggest, for the first time, that this might be a key trait of animal vocalizations determining species tolerance to noise pollution.

Natural Patterns in the Dawn and Dusk Choruses of a Neotropical Songbird in Relation to an Urban Sound Environment

“…Such abilities could predispose to successful colonization of urban settlements, a proposal in line with what was previously postulated for the same species [35]. In fact, song learning and plasticity [74] and larger bandwidths in songs [75] appear to be better pre-adaptations for colonizing cities. The repertoire of the Chiguanco Thrush is composed of a wide diversity of motif and twitter elements, and, considering all possible combinations and improvisations, this situation potentially provides the previous natural ability to produce highly variable inter-and intra-individual songs.…”

“…The "noise filter hypothesis" postulates that species that naturally sing at lower frequencies are more sensitive to urban noise, affecting the composition of urban bird communities [8,75,81,82]; but see [83,84]. Therefore, the Chiguanco Thrush could be more pressured in the urban colonization process because extra-urban individuals had a mean minimum frequency around the upper limit of the dominant anthropogenic sound frequencies (2 kHz) [20], and a mean dominant frequency around 650 Hz up.…”

Background Acoustics in Terrestrial Ecology

“…Multispecies studies and meta-analyses have revealed similar patterns of habitat filtering based on acoustic signal characteristics for bird distributions in response to anthropogenic noise (Francis 2015. In these cases, the most prominent pattern is that lowfrequency noise tends to decrease habitat use most strongly among birds with low-frequency vocalizations, a pattern that has been dubbed the noise filter hypothesis (Cardoso et al 2020). More recently, an experimental study that implemented landscape-scale playback of sounds of rushing rivers identified a strong link between the strength and direction of species changes in abundance in response to background sounds and vocal frequency (Gomes et al 2021c).…”

Seasonality and social factors, but not noise pollution, influence the song characteristics of two leaf warbler species

“…Francis [ 43 ] analysed data from 183 bird species from Europe, North America and the Caribbean and found that species communicating with low frequency vocalizations tended to avoid noisy areas, but species with higher frequency vocalizations responded less aggressively. A similar comparative study shows that North American passerines using a larger frequency bandwidth were more tolerant to noise pollution [ 44 ]. However, this does not mean that species with higher-pitched songs are more likely to be more abundant in areas with noise pollution [ 44 – 46 ].…”

“…A similar comparative study shows that North American passerines using a larger frequency bandwidth were more tolerant to noise pollution [ 44 ]. However, this does not mean that species with higher-pitched songs are more likely to be more abundant in areas with noise pollution [ 44 – 46 ]. Rather, it suggests that their song will be less vulnerable to noise masking, which may allow them to get the message across a noisy environment without the need to adjust their spectral and temporal song parameters.…”