Assessment of the factors for the presence of wild boar near outdoor and extensive pig farms in two areas of Eastern Europe

Expanding wild boar populations associate to conflicts with human activities, being a threat to livestock and public health. Particularly, the emergence of African Swine Fever (ASF) in Europe is of major importance. To better understanding the dynamics at the interface between wild boar and domestic pigs in Europe, which is essential to prevent the risk for ASF spread, this report describes (i) the use of extensive pig farm resources by wildlife (wild boar and other mammals) and domestic pigs, and (ii) the factors involved. We studied two regions of Central-Eastern Europe with different farm management of pigs in Serbia, in low biosecurity farms in forest/bushland habitats, and Hungary, characterized by more industrial and professional farming in fenced pastures. Camera traps (CTs) were placed at a priori risk points for interspecies interactions and in random points in 4 representative outdoor pig farms in different seasons during 2022 (2 farms in Serbia and 2 in Hungary). Also, questionnaires were distributed to 37 farms (17 in Serbia and 20 in Hungary, respectively) to describe the main features and risk factors for wildlife-pigs interaction on outdoor pig farms. CTs revealed that the wild species that more frequently used the study farms resources were golden jackal (Canis aureus) and wild boar in Serbia, and red fox (Vulpes vulpes) and red deer (Cervus elaphus) in Hungary (at the periphery of fenced farms). The use of extensive farm resources by wild boar was frequent and widespread throughout the study area of Serbia (over 33 % of daily presence per farm, 3.70 visits detected per week) whereas it was rarely detected in our sampled Hungarian farms. Wild boar visit frequency (Serbia) peaked during spring (7.5 visits per CT and day, CT*day), mainly associated with water point use (2.1 visits per CT*day). In Hungary, the greater number of direct interactions occurred between pigs and red deer during summer. Even when a higher average number of risk points were identified inside Hungarian farms, they were less permeable due to effective perimeter fencing, which prevented the entrance of wild boar and other big sized terrestrial wildlife. The study exemplifies contrasted outdoor pig farm managements, and associated risks for interaction with wild boar in ASF infected or at-risk regions. Management, characterized by almost absence of external biosecurity in the specific type of production in Serbia raise health concerns, and indicates the need to develop efforts to improve biosecurity. Several strategies and specific measures adapted to environmental conditions and farm management could reduce the interactions at the wild boar-pig interface in Serbia (and similar production systems in Eastern Europe). This should be materialized in farm-specific biosecurity programs and protocols, which requires the evaluation of their effectiveness, costs, and practical value. The type of farming practiced in marginal agricultural/forest lands in Eastern Europe, often connected to backyards production, is a highly priority for biosecurity issues at European level. However, the focus should not be only on improving technical aspects of biosecurity, but also on socio-economic and educational determinants.