Flexibility in Animal Signals Facilitates Adaptation to Rapidly Changing Environments

Charles Darwin posited that secondary sexual characteristics result from competition to attract mates. In male songbirds, specialized vocalizations represent secondary sexual characteristics of particular importance because females prefer songs at specific frequencies, amplitudes, and duration. For birds living in human-dominated landscapes, historic selection for song characteristics that convey fitness may compete with novel selective pressures from anthropogenic noise. Here we show that black-capped chickadees (Poecile atricapillus) use shorter, higher-frequency songs when traffic noise is high, and longer, lower-frequency songs when noise abates. We suggest that chickadees balance opposing selective pressures by use low-frequency songs to preserve vocal characteristics of dominance that repel competitors and attract females, and high frequency songs to increase song transmission when their environment is noisy. The remarkable vocal flexibility exhibited by chickadees may be one reason that they thrive in urban environments, and such flexibility may also support subsequent genetic adaptation to an increasingly urbanized world

Data from: Song playback increases songbird density near low to moderate use roads

Many songbird species avoid roads. Although acoustic masking, vehicle collision, and edge effects are likely culprits, spatial avoidance also occurs along low use roads and at locations distant from the pavement. Neophobia may be one factor contributing to avoidance in these regions. In this case, playback of bird song, generally a signal of high-quality habitat, may reduce avoidance and increase territory establishment. We investigated whether playback of song from 6 migratory species increased territory establishment along low to moderate use roads in a community of songbird species. We determined whether the intensity and regularity of anthropogenic noise altered the pattern of response, and whether particular life-history traits predicted which species were responsive to playback. Territory density was significantly higher where song playback was present. Species-specific responses were variable, with 11 species increasing territory density by >30% at playback sites and 6 species decreasing in density. Noise level did not significantly impact establishment. Foraging behavior, habitat, and song frequency predicted which species were most responsive to playback. These results are similar to a companion study conducted near forest edges that did not contain roads, and suggests that song playback may be a viable method for increasing songbird use of near road habitats. Although additional work is needed to understand the variable responses of particular species and to address vital issues, such as the reproductive success of lured birds, this study highlights a behavioral management technique that may have significant conservation implications along the vast worldwide network of roads

Raw territory and noise data

Data is provided for average territories/ha for 30 bird species; broken down by the control and experimental (playback) treatment. Raw noise event data is also provided, followed by PCA1 and PCA2

Noise, avian abundance, and productivity at banding stations across the Continental United States

Noise is an increasingly common component of the natural world, due in large part to human activity. Anthropogenic noise negatively impacts abundance, health, and reproduction in many songbird populations. A few studies have reported altered abundance at larger scales. But whether continental trends are being detected at banding stations, which also offer data on productivity and survivorship, is unknown. Further, it is not known whether localized trends correlate with population trends observed at larger scales. We used breeding season data from 1160 constant-effort banding stations (Monitoring Avian Productivity and Survivorship; MAPS) and a spatially explicit noise model to determine whether abundance and productivity were related to mean noise level or spatial heterogeneity (SD) in noise within a 1-km station radius for 72 passerine species. We also determined whether particular life history traits were predictive of noise responses, and compared continental results to those from local studies. Increasing mean noise level was associated with declines in abundance for 27.1% of species and productivity in 22.1% species. Increasing heterogeneity was associated with declines in abundance for 14.3% species and productivity in 14.7% species. The relationship between noise and abundance was not correlated with the relationship between noise and productivity, and acoustic and life history traits were not related to noise responses. Continental results were similar to localized data in 43.1% and 21.4% of species for abundance and productivity, respectively. Although some patterns differed between the local and continental scale, our results indicate that the MAPS banding dataset is capable of detecting noise-associated impacts on abundance and productivity. This is currently the only large-scale dataset capable of quantifying the relationship between noise and productivity in the continental USA, although other datasets exist elsewhere that may also contribute to our understanding of noise impacts at the larger scale

Relationship between song duration and instantaneous noise.

<p>The line predicting song duration is derived from a general linear mixed model and data points correspond to the observed mean song duration at each decibel (±1 SE) averaged for all songs in all sites on weekend (black circles) and weekday (grey triangles) recordings.</p

Relationship between <i>bee</i> note peak frequency and average ambient noise levels.

<p>The line predicting <i>bee</i> note peak frequency is derived from a general linear mixed model and data points correspond to the observed mean <i>bee</i> note peak frequency at each decibel (±1 SE) averaged for all songs in all sites on weekend (black circles) and weekday (grey triangles) recordings.</p

A dataset of acoustic measurements from soundscapes collected worldwide during the COVID-19 pandemic

International audiencePolitical responses to the COVID-19 pandemic led to changes in city soundscapes around the globe. From March to October 2020, a consortium of 261 contributors from 35 countries brought together by the Silent Cities project built a unique soundscape recordings collection to report on local acoustic changes in urban areas. We present this collection here, along with metadata including observational descriptions of the local areas from the contributors, open-source environmental data, open-source confinement levels and calculation of acoustic descriptors. We performed a technical validation of the dataset using statistical models run on a subset of manually annotated soundscapes. Results confirmed the large-scale usability of ecoacoustic indices and automatic sound event recognition in the Silent Cities soundscape collection. We expect this dataset to be useful for research in the multidisciplinary field of environmental sciences

A dataset of acoustic measurements from soundscapes collected worldwide during the COVID-19 pandemic

International audiencePolitical responses to the COVID-19 pandemic led to changes in city soundscapes around the globe. From March to October 2020, a consortium of 261 contributors from 35 countries brought together by the Silent Cities project built a unique soundscape recordings collection to report on local acoustic changes in urban areas. We present this collection here, along with metadata including observational descriptions of the local areas from the contributors, open-source environmental data, open-source confinement levels and calculation of acoustic descriptors. We performed a technical validation of the dataset using statistical models run on a subset of manually annotated soundscapes. Results confirmed the large-scale usability of ecoacoustic indices and automatic sound event recognition in the Silent Cities soundscape collection. We expect this dataset to be useful for research in the multidisciplinary field of environmental sciences