Traffic noise and its effect on the foraging efficiency in acoustic predators

Hunting at the highway: traffic noise reduces foraging efficiency in acoustic predators

Björn M. Siemers  and Andrea Schaub

Published online before print November 17, 2010, doi:10.1098/rspb.2010.2262Proc. R. Soc. B 7 June 2011 vol. 278 no. 17121646-1652

The effects of noise on animal communication are well documented, but our knowledge is very limited when it comes to the impact of noise on more complex ecosystem processes, such as predator–prey interactions.

In this paper the researchers show that traffic noise decreases the foraging efficiency of an acoustic predator, the greater mouse-eared bat (Myotis myotis). These bats feed on large, ground-running arthropods that they find by listening to their faint rustling sounds. The researchers measured the bats' foraging performance on a continuous scale of acoustically simulated highway distances.

Successful foraging bouts decreased and search time drastically increased with proximity to the highway. At 7.5 m to the road, search time was increased by a factor of five. The researchers conclude that as most of the bats' preys are predators themselves, the noise impact on the bats' foraging performance will have cascading effects on the food web which in turn will impact the ecosystem stability. These findings apply to other ecologically important acoustic predators like owls. The study provides the empirical basis for quantitative predictions of anthropogenic noise impacts on ecosystem processes.

The researchers sign off saying that that an understanding of the effects of noise emissions and other forms of ‘sensory pollution’ are crucially important for the assessment of environmental impact of human activities.