Wild boar feeding site effects on targeted and non-targeted species

Abstract: Wild boar (Sus scrofa) is an ungulate species that is increasing in Europe and Sweden, and with that causing conflicts and problems in agriculture. Wild boar are omnivores and are often rooting in the ground to find food items. It is a common management practice to establish artificial feeding sites for wild boar, and other wildlife species, as supplementary, diversionary or for baiting and hunting purposes. Such feeding sites may also influence the surrounding areas through the extra food and activities made by the animals visiting the site (rooting, trampling, etc.), including non-targeted species. In this study, situated in the Grimsö wildlife research area, South-Central Sweden, feeding sites were investigated through camera traps in September to January. The study was divided into a control year with no feeding, and an experiment year with feeding and control sites with no feeding. Rooting inventories around the sites were also conducted during the vegetation season. The research focus was laid on (1) how long time it takes for wild boar to find and use new feeding sites compared to already established, old feedings sites and control sites, and (2) if there is any relation between rooting level at a feeding site and the visitation rate of wild boar, as well as (3) whether feeding sites affect the local species richness. The results showed that wild boar presence was higher at old feeding sites than at new (50% daily presence after ~35 and ~55 days, respectively), and both were different from the control sites in which presence did not change with time. There were also more wild boar and more rooting closer to the feeding sites, but the effect seemed to cease at a distance of 50 m from the feeder. The level of rooting was directly related to wild boar presence, i.e. the more wild boar, the more rooting. Finally, there was higher species richness at old feeding sites than at control sites, while the species richness at new feeding sites seemed to increase faster than at the old sites. Rooting has been suggested to have both positive and negative impacts on plants and soil properties. A better understanding of how much area that is affected will be important for our understanding on the ecological impact on the surrounding. This study suggests that wild boar feeding sites seem to have a limited direct effect on the area and only affect the immediate surroundings, while on the other hand, attract several non-targeted species, whereof many birds. It is thus probably an important management consideration in choosing the placement of feeding sites in terms of limiting the impact on the surrounding species. However, to investigate long-term effects, a long-term study of feeding (more months) would be needed.