Owls, natural enemies of the Japanese grass voles, have come back to apple orchards in Hirosaki-shi, Aomori prefecture. Damages of apple trees caused by the grass voles were so serious at the orchards.
By the last year, members of an apple producers’ group had fastened about 70 nesting boxes for the owls on the apple trees. Thirteen pairs of owls built their nests at the birdhouses and hollows of the trees this spring, where 35 baby birds hatched from eggs.
At the apple orchards where owls built their nests, farmers have felt that the number of grass voles is decreasing. “Owls’ effect” has been brought about in the orchards.
Behind an increase in damages to apple trees’ bark by grass voles, there was a tendency of introducing “dwarf apple” trees in recent years, which has made it possible for farmers to reduce their labor especially at the harvesting season. On the “dwarfed” lower trees, however, it turned more difficult for the owl to build a nest.
In April 2014, some 30 young farmers producing apples in the southern part of Hirosaki city set up a “Shimoyuguchi Owl Club,” which launched a project to call owls back to their apple orchards in collaboration with researchers of Hirosaki University.