Photo/Illutration The device that emits high-pitched, randomly generated sounds to deter bears from entering Fukushima city limits (Kimiharu Arakawa)

FUKUSHIMA--Acoustic technology is being deployed in a city nature conservation area here to deter bear attacks following a sharp increase in sightings and mauling incidents.

The devices emit high-pitched, randomly generated sounds tailored to cause discomfort to bears and stop them in their tracks so they veer away from populated areas.

Authorities set up six units on Aug. 21 along the Arakawa riverbank within the Mizubayashi Natural Park, a known pathway that bears use to descend from the mountains outside the city.

The site lies upstream from Azuma Sports Park, where a man was injured in a bear encounter on Aug. 1. Bear sightings have also been reported further downstream, closer to residential neighborhoods, most recently in June and July.

Footage taken on the night of Aug. 21 when the acoustic devices were installed captured two bears prowling around, only to retreat hastily--a promising sign the equipment works.

Shota Mochizuki, an associate professor at Fukushima University and a specialist of wildlife management, explained that the devices are designed to irritate a bear’s hearing.

Traditional deterrents like firecrackers tend to stop being effective after a month or so as bears become accustomed to the noise, according to Mochizuki, an adviser to the city’s wildlife control project.

INSTINCT TO FLEE

“This new system randomly emits various piercing sounds that bears cannot adapt to,” said Mochizuki. “The combination of frequencies is not comfortable to their eardrums, triggering the instinct to flee.”

The devices emit a soft chirping noise from a distance, but when bears get close, they are met with a jarring mix of harsh tones--“pyan-pyan” and “kyan-kyan”--sounds designed to mess with a bear’s head.

Developed by ES Symphony, a company based in Kanagawa Prefecture close to Tokyo, the devices use overlapping frequencies within a range of 20 to 20,000 Hertz, the full range of a bear’s hearing.

Four speakers are positioned to ensure that sound reaches the bear’s ears. The units stand about 1 meter tall, matching the animal’s head height when it is on all fours. They have motion sensors that trigger the sounds, but only when a bear is detected.

The units are powered by solar panels and rechargeable batteries, eliminating the need for electrical infrastructure. They are easy to disassemble and set up elsewhere.

The technology was tested in the neighboring town of Nishi-Aizu, where early results showed fewer bear approaches.

Fukushima is the first municipality to formally allocate public funds for installation.

Officials said they received reports of 140 bear sightings in the city between April and August, twice the average for that period.

In response, the city allocated 3 million yen ($20,000) as an emergency measure.

The devices will remain in place until the bears go into hibernation around New Year. They will be reinstalled when the animals emerge from their winter sleep in spring.

Noting that bears come down from the mountains via the banks of the Arakawa river, city officials said their goal was to drive the animals back upstream.

Fukushima’s initiative could become a model for other cities looking for non-lethal, sustainable solutions to protect both wildlife and human communities.

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