Feeding black-tailed gulls has been a popular activity on the sightseeing boats that cruise around the Matsushima islets, considered to be one of the three most beautiful spots in Japan, but local authorities banned the practice this month in a bid to protect the islets' famous pine trees from withering as a result of nitrogen in the droppings of the gulls, who have bred in large numbers in the area.
Tourists who looked forward to feeding the birds have expressed disappointment, but the government of Matsushima, Miyagi Prefecture, has called for visitors' understanding, saying it is the pine trees that make Matsushima (literally, pine island) what it is.
Signs reading, "To protect the pine trees, feeding black-tailed gulls is prohibited for the time being," and pictures showing the state of withered pine trees are being displayed in sightseeing boats.
A committee formed to consider ways to combat the problem-comprising such members as the Matsushima government, the Matsushima Tourist Association and sightseeing boat operators-stopped sales of the shrimp-flavored rice crackers used to feed the birds from the boats, beaches and other locations from April 1.
According to the Matsushima government, more than 30 years ago pine weevils were confirmed to be causing trees to wither in the area. However, damage from black-tailed gulls has been exacerbating the situation in recent years.
The number of gulls living on islands in the bay has increased greatly in the past 10 years or so, and there are now believed to be tens of thousands of them.
Formed last August, the committee decided that feeding by humans has greatly increased the number of black-tailed gulls, which normally eat fish and insects. It believes that absorbing too much nitrogren from the birds' droppings through the soil makes the trees vulnerable.
According to Yasoen Koen park in Sendai, pine trees can sprout and grow even in infertile soil.
However, if they absorb too much of the nitrogen that fertilizes them, it becomes difficult for the trees to ingest nutrients and they wither.
After prohibiting the feeding of gulls for about one year, the committee plans to conduct a survey of the gulls and other factors.
There have so far been no particular complaints from visitors. "We'll explain our intentions to tourists and seek their cooperation," said Kazuhiko Mano, 53, director of a union of companies operating sightseeing boats around the islets.