Noise Pollution Not an Insignificant Concern

A review of recent studies into noise pollution and biodiversity has concluded that noise is becoming a major threat, interfering with the way species communicate, mate and hunt. The authors found that man-made noise is already creating a host of problems, and worry that noise pollution is so ubiquitous that it may be a factor in some large-scale declines in biodiversity.

Many species have evolved hearing sensitive enough to take account of the quietest conditions, so noise can significantly impact how they communicate. Great tits (Parsus major) sing at higher frequencies in response to urban noise, so they are better able to hear each other. Other species have not shown a similar ability to adapt their calling habits, with female grey tree frogs (Hyla chrysoscelis) exposed to the sounds of passing traffic taking longer to locate and find calling males, and European tree frogs (Hyla arborea) calling less overall. This may potentially compromise their ability to reproduce.

Noise pollution can also effect the hunting ability of many species. One gleaning bat species, the Bechstein’s bat (Myotis bechsteinii), is less likely to cross roads than other bat species that forage in open areas, suggesting the noise of the traffic could fragment their hunting grounds. In the Amazon, terrestrial insectivores, which also hunt using sound, especially avoid areas where roads are being constructed.

The problem appears to be getting worse. In the US alone, road and air traffic more than tripled between 1970 and today. Shipping noise has similarly increased, with worrying implications for marine mammals. Systematic monitoring by the Natural Sounds Program, a research exercise carried out by the US National Park Service, confirms the extent of the noise intrusion. Noise is audible during more than one quarter of daylight hours at more than half of 55 sites in 14 National Parks studied to date. At 12 sites, anthropogenic noise can be heard more than half the time.

The authors argue that much more needs to be done to mitigate the problem, using techniques such as quieter road surfaces, noise barriers, and restriction of motorised travel in protected natural areas.

For more information, see ‘The costs of chronic noise exposure for terrestrial organisms’
J.R. Barber, K.R. Crooks & K.M. Fristrup, Trends in Ecology & Evolution.