Quantification of wild-domestic pig interactions
Taking the previous year as a reference, 2/3 of the farmers (20/30) had observed wild boars in proximity of the farm at a distance ranging between 1 and 200 m. One third (10/30) had observed evidence of incursions of wild boars on their farm in the previous year and 90% of those (8/30) had observed evidence of interactions between wild boars and their pigs. Those included reports of sexual interactions (reported by 8/30 farmers), fights (3/30) and trophic interactions (2/30) between wild and domestic boars. Five farmers reported observing hybrid litters as a result of sexual interactions between male wild boars and their respective sows Among those, four farmers kept the piglets for their own consumption and one brought the sows to the slaughterhouse before giving birth. Four other farmers declared having observed sexual and or trophic interactions between two and six years ago, respectively. Incursions of wild boars in the farm premises were mainly reported in fall (29%), followed by winter and summer (19 %) while sexual interactions were mainly reported to occur in summer (6%) and fall (6%). There was a significant difference between interactions reported in fall (P <0.05), compared with the other seasons (Fig.4).
Regarding hunters, only one reported direct (trophic) interactions in the forest. Despite none of them observed direct agonistic interaction, six of them acknowledged that this kind of contacts could occur. Two hunters had heard or observed of wild boar incursions in some farms in the region and two had observed the presence of domestic pigs in hunting grounds. Eighteen hunters recalled observing the presence of or hunting hybrids in recent years, mostly (2/3) between 2013 and 2016. The large majority (10/18) of those reports referred to animals with a phenotype of pot-bellied pigs.