Traffic Noise Slows Down Owls, Affects Their Hunting, Study Shows

A new study says that wild owls' efficiency in hunting decreases up to 89 percent due to traffic noise.

According to a report from Science Daily, owls, like bats, rely on their hearing to locate their prey. And with the development of transportation, there are concerns how traffic noises will affect wild animals, especially "acoustic predators."

To find out, a team of researchers from Hokkaido University's Graduate School of Agriculture, the Forestry and Forest Products Research Institute and California Polytechnic State University conducted an experiment that involved 78 owls and artificial prey sounds. Since owls are usually active at night, researchers developed artificial prey sounds that mimicked the sounds of preys to attract the owls.

However, there's a catch. Researchers also put up sounds that resemble different traffic noises together with the artificial prey sounds. The experiment happened at 103 places in Yufutsu Plain in Hokkaido and Sendai Plain in Miyagi Prefecture -- places that have a number of owls. The entire experiment ran from December 2014 to March 2015.

The results show that the rate of owls hearing the artificial prey sounds in a 40dB, the lowest traffic noise, decreased to 17 percent. Meanwhile, in 80dB, the highest level of traffic noise (similar to train noise), the rate falls down to 89 percent. The effects of traffic noise to owls finding their prey slows them down; even extended up to 120 meters.

"Behavioral changes in acoustic predators can alter the interactions between prey and predators, and possibly have negative consequences on the entire ecosystem," said Futoshi Nakamura, one of the co-authors at Hokkaido University. "It is necessary to unravel the mechanisms behind this reduced foraging efficiency, as well as possible resultant drops in survival rates and changes in distribution, in order to develop measures to lessen the impact of traffic noise on acoustic predators."