Anthropogenic noise has been increasing globally. Laboratory experiments suggest that noise disrupts foraging behavior across a range of species, but to reveal the full impacts of noise, we must examine the impacts of noise on foraging behavior among species in the wild. Owls are widespread nocturnal top predators and use prey rustling sounds for localizing prey when hunting. We conducted field experiments to examine the effect of traffic noise on owls’ ability to detect prey. Results suggest that foraging efficiency declines with increasing traffic noise levels due to acoustic masking and/or distraction and aversion to traffic noise. Moreover, we estimate that effects of traffic noise on owls’ ability to detect prey reach >120 m from a road, which is larger than the distance estimated from captive studies with bats. Our study provides the first evidence that noise reduces foraging efficiency in wild animals and highlights the possible pervasive impacts of noise.

The distribution of coarse woody debris in a fifth-order Cascade Range (Oregon) stream system was examined from a geomorphic point of view. The number, volume, location, orientation, decay class, and pool formation roles of coarse woody debris were investigated. The processes of coarse woody debris production, transport, and storage, which vary with channel and valley floor geomorphology, are responsible for the pattern of coarse woody debris distribution on valley floors. Channel width and sinuosity are the main factors that control production, storage sites, and hydrologic effects of coarse woody debris. The amount of coarse woody debris and the number of pool-forming pieces are relatively high in wide, sinuous reaches, where a complex structure of floodplains and riparian forests develops in association with a braided channel pattern. These relations are transferable to other systems with similar relations of coarse woody debris piece length to channel width.