Photo/Illutration A wind farm is planned in a sea area in the background between Oshima island, right, and Meshima island, which make up Shirashima. An oil storage facility is located near Oshima. (Asahi Shimbun file photo)

KITA-KYUSHU--Collisions with the propellers of windmills at a planned offshore wind power plant could further reduce populations of rare birds on islands here, the Wild Bird Society of Japan warns.

The society in November submitted a set of recommendations to the Kita-Kyushu city government, calling for a review of the project planned by wind farm operator Glocal Corp.

According to the plans of Glocal, a contractor based in Kure, Hiroshima Prefecture, two 6-megawatt windmills will be set up several hundred meters to 2 kilometers west of Oshima island, one of the two main isles comprising Shirashima.

Each windmill will have two blades with a rotating diameter of 141 meters.

The company aims to begin construction in 2021 and start operating in 2022.

“We are not against wind generation itself for the sake of preventing global warming,” Shinichi Maeda, secretary-general of the Wild Bird Society’s Kita-Kyushu branch, said. “As things stand, however, we have no choice but to say that it may be friendly to the Earth’s environment, but it is harmful to birds.”

The entire Oshima island and surrounding areas, excluding an oil storage facility, are designated as a bird sanctuary (special protection zone) by the Fukuoka prefectural government.

The bird society said it has ascertained 46 varieties of bird species on Shirashima and 34 varieties around the islands.

An environmental impact assessment compiled by Glocal said the two windmills will have a minimal effect on bird habitats and populations, and there will be enough space around the windmills for birds to circumvent the blades.

Glocal’s document said although there could be a temporary impact, the company will conduct a field survey to consider measures.

The bird society sees the impact on birds as inevitable.

Shirashima is one of the few breeding sites for the streaked shearwater in Japan. The society pointed out that the birds feed in a sea area located across the planned site for the wind farm, and they fly as high as the rotating turbine blades when moving in and out of the islands in flocks.

Glocal said the Japanese wood pigeon does not travel to sea areas, but the society says it is possible that the endangered species goes back and forth between Shirashima and the neighboring islands.

In addition, the Japanese murrelet, another endangered species designated as a natural treasure by the central government, and other birds migrate through the surrounding waters, the society said.

Bird strikes have been reported at wind farms across the country.

In Hokkaido, many white-tailed eagles, a government-designated natural treasure, have been killed in collisions with the blades. More than 20 birds, including streaked shearwaters and ospreys, a type of raptor, have been confirmed dead in collisions in the past five years at a wind farm in Kita-Kyushu, officials of the society said.

“I hope (Glocal) will take time to conduct a survey to find out about the impact on birds before the plant is built, and that it will continue monitoring after it is built,” said Noriyuki Yamaguchi, a Nagasaki University associate professor well-versed in bird life. “If the impact is significant, measures will be necessary, including reconsidering the operation of the windmills and the location of the site.”