Creeping into a wild boar stomach to find traces of supplementary feeding

Context. Supplementary feeding and baiting of wild ungulates is a common management practice. Wild boar is among the most frequently fed species and its numbers are rapidly increasing throughout Europe. It has been suggested that supplementary feeding throughout the year can have intentional and unintentional impacts on the species as well as on European forests and agricultural landscapes, and biodiversity. It is, therefore, important to identify the dependence of wild boar on supplemental foods to determine and predict its feeding patterns under alternative population and land-use management scenarios. Aims. We investigated the diet composition of wild boar from stomach contents to identify its dependence on food resources of human origin (i.e. agricultural crops and supplemental foods) throughout the year in the Czech Republic. Methods. We collected 345 samples from four study sites during spring, summer and winter seasons, over a 3-year period, and from different wild boar ages and sex classes. Key results. Foods of human origin (mainly cereals) were the dominant food category and constituted the bulk of wild boar diet throughout the year (>50% of total stomach-content biomass), especially in winter, and in all the study sites. Cereals found in the stomachs of wild boar in summer might come from both crop fields as well as supplementary feeding. However, cereals identified in the stomachs in winter and spring come predominantly from baiting and supplementary feeding conducted by hunters. Cereals were consumed in different proportions by different ages and sexes. Males fed on cereals more than did females, whereas juveniles depended on such food less than did subadults. Conclusions. Our finding of a consistent dependence of wild boar on food of human origin throughout the year in all study sites confirmed that supplementary feeding is important in the diet, which is a potential reason for the rapid increase of wild boar numbers in the Czech Republic. Implications. Wildlife management agencies need to target feeding practices and design restrictive measures for supplementary feeding and baiting of wild boar in the Czech Republic. This should include defining maximum amounts of food and precise periods for supplementary feeding, and reducing non-target species at feeding sites.