2019 年 7 巻 1 号 p. 23-31
In Chiba Prefecture, the local government has been extending protective fencing to prevent paddy damage by wild boars (Sus scrofa). However, the gross damage by wild boars across Chiba Prefecture has not decreased when considering whole area of cities, towns, and villages. To clarify the cause of this contradiction, we investigated the damage by wild boars between 2011 and 2016, in 1192 rice paddies, in Kyonan town, Chiba Prefecture. This showed that weeding around rice paddies and closed fencing was effective at reducing damage by wild boars. On the other hand, a fence that only partially surrounds the paddy had no effect on damage. The risk of damage increased with proximity to the forest edges and abandoned cultivated lands, and with a greater distance from roads. From the results of the 6-year survey, it was observed that there was a tendency for the wild boar damage to increase not only in the vicinity of, but also areas far from, the forest edge. It was suggested that the increase in proximity of abandoned land to abandoned land, and paddy fields contributed to the expansion of area of damage. In addition, it was recognized that wild boar damage to paddy fields advances their chance of abandonment, and that the increase in abandoned cultivated land and the occurrence of wild boar damage are linked.