Wintering dabbling ducks forage rice grains remaining on the post-harvest rice fields. Generally, farmers plow the soil of rice fields after harvest to stimulate decomposition of the rice stubbles. In the plowed rice fields, it is easier for ducks to land on and move around the rice field, and to detect predators, than in the unplowed rice fields. But the amount of rice grains remaining on the plowed rice fields is smaller than that in unplowed fields because rice grains are buried under the soil by plowing. I conducted an experiment to examine the effect of post-harvest plowed and unplowed fields with stubble on the foraging behavior of a domestic Mallard duck by comparing the amount of consumed rice grains, the duration for each foraging bout, cumulative time allocated for foraging, and the number of foraging bouts. Except for the intake rate, values recorded in plowed areas without rice stubble were higher than those of unplowed areas. According to the results of this study and previous reports, the combination of unplowed areas, with large amount of rice grains, and plowed areas, with easiness of movement and high efficiency of detecting predators, were thought to be effective at creating foraging sites for dabbling ducks. Considering the environment and the practice of rice cultivation in and around Kaga City, Ishikawa Prefecture, I devised the post-harvest treatment of rice fields named "Passive flooded rice fields with rainfall" or "Amamizu-tambo" and "Rice fields with a complex of plowed and unplowed areas" or "Shimashima-tambo" for the conservation of wintering ducks.
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