Protecting Grain Fields in Japan from Pilferage by Birds

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Bird populations over much of Japan are small, but there may be local concentrations at certain seasons of the year and, where these concentrations conflict with farming interests by causing damage to crops, the problem of their control arises. The crop of greatest acreage and most often subject to damage is rice. Two types of damage are done to it by birds: eating the grain and trampling the seedbeds. The species most often causing damage are tree sparrows (Passer montanus), which attack the crop in the late summer during the stage, and herons and egrets, which walk through seedbeds in search of frogs, crustacea, and small fish. Grey starling (Sturnus cineraceus) flocks also feed in rice paddies and truck crops, but this species is mainly insectivorous and little damage is attributed to it. Greenfinch (Chloris sinica) and brambling (Fringilla montifringilla) are sometimes accused of damage, but their flocks are usually of local distribution and damage is small. Two species of crows (Corvus corone and C. levaillantii) occur in Japan, but flocks of as many as a hundred are rarely seen. Both species are omnivorous and damage to crops, stored foods, or animal products is usually limited to that of a few individuals. In the United States, rice or grain fields are of large acreage whereas the average field in Japan, owned or operated by one man, is less than an acre. A given farmer may have several fields, but they will usually be small and of irregular size. Since each farmer may plant at a slightly different time or use different variety of grain, the fields do not mature uniformly. Therefore in a paddy area of 500 acres there will be rice in all stages from milk to ready for harvest. This offers a variety of foods to marauding birds. Although the area of grain per farmer is small, its relative value is much higher than that of a similar size in the United States. The cost of labor appears to be much cheaper by our standards, but judged by the standard of the Japanese farmer the costs of labor and production are high. He has little cash to devote to control methods, and his margin of profit when he sells the grain is so narrow that any increase in production costs may wipe it out. In Japan the solution to this control problem rests