2015 Volume 31 Issue 2 Pages 41-49
In recent years, wild boars (Sus scrofa) have caused growing damage to farm crops in a hilly and mountainous area of the Tohoku region. In particular, in designated evacuation zones following the accident at the Fukushima Dai-ichi nuclear power plant, there are growing concerns about the expanding range of wild boars and the resulting degradation of farmland. To assess the influence of reduced human activity on encroachment on farmland by wild boars, this study selected two adjacent study sites—the Yamakiya district (40 km2) in Kawamata town, designated as the Evacuation Directive Lift Prepared Area, and the Iwashiro and Towa districts (80 km2) in Nihonmatsu city—and recorded locations of damage (feeding, trampling, rooting) to farmland and farm crops caused by wild boars during the period from June to December in 2013. The locations at which wild boar feces were found were also recorded and collected. These feces, as well as muscle tissue samples collected from individuals trapped during the period, were subjected to DNA microsatellite analysis to identify individual animals. Values for the probability of identity for siblings (PID-sib) were used to assess the accuracy of identification. More locations damaged by wild bores were found in Kawamata town (150) than in Nihonmatsu city (94) (generalized linear model, P < 0.001). The total number of feces was also higher in Kawamata town (332) than in Nihonmatsu city (62). The number of feces found within each location was 0.49–0.74 during the summer but increased to 1.70–3.67 in autumn. These results suggest reduced human activity expands the range of wild boars, particularly in autumn. The accuracy with which individuals could be identified by microsatellite analysis differed with the primer sets used. The best identification results were obtained using nine primers (six primers reported as applicable for individuals in Japan [Tamate, 2012] and three primers reported in Europe [Frantz et al., 2012]) (PID-sib = 0.011). Successful individual identification was achieved for 38 fecal samples (9.6% of total feces), including three pairs of fecal sample derived from the same individual. However, the fecal sample pairs were collected within the same location and on the same measurement occasion. Thus, they provide no evidence regarding the seasonal migration of particular animals.