Global increases in environmental noise levels – arising from expansion of human populations, transportation networks, and resource extraction – have catalysed a recent surge of research into the effects of noise on wildlife. Synthesising a coherent understanding of the biological consequences of noise from this literature is challenging. Taxonomic groups vary in auditory capabilities. A wide range of noise sources and exposure levels occur, and many kinds of biological responses have been observed, ranging from individual behaviours to changes in ecological communities. Also, noise is one of several environmental effects generated by human activities, so researchers must contend with potentially confounding explanations for biological responses. Nonetheless, it is clear that noise presents diverse threats to species and ecosystems and salient patterns are emerging to help inform future natural resource-management decisions. We conducted a systematic and standardised review of the scientific literature published from 1990 to 2013 on the effects of anthropogenic noise on wildlife, including both terrestrial and aquatic studies. Research to date has concentrated predominantly on European and North American species that rely on vocal communication, with approximately two-thirds of the data set focussing on songbirds and marine mammals. The majority of studies documented effects from noise, including altered vocal behaviour to mitigate masking, reduced abundance in noisy habitats, changes in vigilance and foraging behaviour, and impacts on individual fitness and the structure of ecological communities. This literature survey shows that terrestrial wildlife responses begin at noise levels of approximately 40 dBA, and 20% of papers documented impacts below 50 dBA. Our analysis highlights the utility of existing scientific information concerning the effects of anthropogenic noise on wildlife for predicting potential outcomes of noise exposure and implementing meaningful mitigation measures. Future research directions that would support more comprehensive predictions regarding the magnitude and severity of noise impacts include: broadening taxonomic and geographical scope, exploring interacting stressors, conducting larger-scale studies, testing mitigation approaches, standardising reporting of acoustic metrics, and assessing the biological response to noise-source removal or mitigation. The broad volume of existing information concerning the effects of anthropogenic noise on wildlife offers a valuable resource to assist scientists, industry, and natural-resource managers in predicting potential outcomes of noise exposure.

https://www.wildliferesearch.co.uk/Wildlife_Research/Publications_files/A%20synthesis%20of%20two%20decades%20of%20research%20documenting%20the%20effects%20of%20noise%20on%20wildlife%20Shannon.pdf

A synthesis of two decades of research documenting the effects of noise on wildlife

Roads fragment landscapes and trigger human colonization and degradation of ecosystems, to the detriment of biodiversity and ecosystem functions. The planet’s remaining large and ecologically important tracts of roadless areas sustain key refugia for biodiversity and provide globally relevant ecosystem services. Applying a 1-kilometer buffer to all roads, we present a global map of roadless areas and an assessment of their status, quality, and extent of coverage by protected areas. About 80% of Earth’s terrestrial surface remains roadless, but this area is fragmented into ~600,000 patches, more than half of which are

https://science.sciencemag.org/content/sci/354/6318/1423.full.pdf

A global map of roadless areas and their conservation status

Human activities have caused a near-ubiquitous and evolutionarily-unprecedented increase in environmental sound levels and artificial night lighting. These stimuli reorganize communities by interfering with species-specific perception of time-cues, habitat features, and auditory and visual signals. Rapid evolutionary changes could occur in response to light and noise, given their magnitude, geographical extent, and degree to which they represent unprecedented environmental conditions. We present a framework for investigating anthropogenic light and noise as agents of selection, and as drivers of other evolutionary processes, to influence a range of behavioral and physiological traits such as phenological characters and sensory and signaling systems. In this context, opportunities abound for understanding contemporary and rapid evolution in response to human-caused environmental change.

/pdf/a-framework-to-assess-evolutionary-responses-to-3xxvebxka6.pdf

A framework to assess evolutionary responses to anthropogenic light and sound.

Anthropogenic noise threatens ecological systems, including the cultural and biodiversity resources in protected areas. Using continental-scale sound models, we found that anthropogenic noise doubled background sound levels in 63% of U.S. protected area units and caused a 10-fold or greater increase in 21%, surpassing levels known to interfere with human visitor experience and disrupt wildlife behavior, fitness, and community composition. Elevated noise was also found in critical habitats of endangered species, with 14% experiencing a 10-fold increase in sound levels. However, protected areas with more stringent regulations had less anthropogenic noise. Our analysis indicates that noise pollution in protected areas is closely linked with transportation, development, and extractive land use, providing insight into where mitigation efforts can be most effective.

https://science.sciencemag.org/content/sci/356/6337/531.full.pdf

Noise pollution is pervasive in U.S. protected areas.

Decades of research demonstrate that roads impact wildlife and suggest traffic noise as a primary cause of population declines near roads. We created a “phantom road” using an array of speakers to apply traffic noise to a roadless landscape, directly testing the effect of noise alone on an entire songbird community during autumn migration. Thirty-one percent of the bird community avoided the phantom road. For individuals that stayed despite the noise, overall body condition decreased by a full SD and some species showed a change in ability to gain body condition when exposed to traffic noise during migratory stopover. We conducted complementary laboratory experiments that implicate foraging-vigilance behavior as one mechanism driving this pattern. Our results suggest that noise degrades habitat that is otherwise suitable, and that the presence of a species does not indicate the absence of an impact.

/pdf/a-phantom-road-experiment-reveals-traffic-noise-is-an-3aaeomv8x8.pdf

A phantom road experiment reveals traffic noise is an invisible source of habitat degradation.

Many authors have suggested that the negative effects of roads on animals are largely owing to traffic noise. Although suggestive, most past studies of the effects of road noise on wildlife were conducted in the presence of the other confounding effects of roads, such as visual disturbance, collisions and chemical pollution among others. We present, to our knowledge, the first study to experimentally apply traffic noise to a roadless area at a landscape scale—thus avoiding the other confounding aspects of roads present in past studies. We replicated the sound of a roadway at intervals—alternating 4 days of noise on with 4 days off—during the autumn migratory period using a 0.5 km array of speakers within an established stopover site in southern Idaho. We conducted daily bird surveys along our ‘Phantom Road’ and in a nearby control site. We document over a one-quarter decline in bird abundance and almost complete avoidance by some species between noise-on and noise-off periods along the phantom road and no such effects at control sites—suggesting that traffic noise is a major driver of effects of roads on populations of animals.

https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2013.2290

An experimental investigation into the effects of traffic noise on distributions of birds: avoiding the phantom road

Several past studies have demonstrated the effects of anthropogenic noise on populations of animals. Yet, differing effects of noise by age and subsequent changes in the age structure of populations are poorly understood. We experimentally tested the effects of traffic noise alone on the age structure of a community of migrating birds at a fall stopover site in south-western Idaho using an array of speakers – creating a phantom road – that replicated the sound of a roadway without other confounding aspects of roads. Both hatch-year and adult birds were negatively affected by noise – having lower capture rates, lower body condition and lower stopover efficiency along the phantom road when the noise was on compared to control conditions. However, hatch-year birds responded more strongly which lead to a significant shift in the ratio of hatch-year to adult birds under noisy conditions. Our previous work using the phantom road demonstrated that traffic noise can degrade the quality of a stopover site by affecting the ability of migrating birds to gain body condition. Here, we demonstrate differences between age classes such that although noise degrades habitat for both hatch-year and adult migrants, there are still differences in responses to noise between age groups. Despite alternative explanations of our results such as changes in behavior affecting capture likelihood, evidence suggests that younger birds avoided the phantom road more than adult birds perhaps because of different tradeoffs between foraging and predation risk and differing strategies of site selection during migration.

Noise from a phantom road experiment alters the age structure of a community of migrating birds

Numerous studies document impacts of roads on wildlife, and suggest traffic noise as a primary cause of population declines near roads. For migratory birds faced with increasingly human-altered habitats, noise may pose a serious threat. Using an array of speakers, we applied traffic noise to a roadless landscape, directly testing the effect of noise alone on an entire songbird community. Focusing on individuals that stayed despite the noise, we demonstrate that songbirds show a near halving of ability to gain body condition when exposed to traffic noise during migratory stopover. This marked degradation in stopover efficiency may help explain dramatic declines in migratory songbirds worldwide. We conducted complementary laboratory experiments that implicate foraging-vigilance behavior as one mechanism driving this pattern. Our results suggest that noise pollution degrades habitat that is otherwise suitable, and that a species’ presence does not indicate the absence of impact.

/pdf/traffic-noise-decreases-body-condition-and-stopover-4ls70w2x5w.pdf

Heidi E. Ware

Papers

An experimental investigation into the effects of traffic noise on distributions of birds: avoiding the phantom road

A phantom road experiment reveals traffic noise is an invisible source of habitat degradation.

Noise from a phantom road experiment alters the age structure of a community of migrating birds

Traffic Noise Decreases Body Condition and Stopover Efficiency of Migrating Songbirds