Evaluation of an odor repellent for protecting crops from wild boar damage

Wild boar populations have dramatically increased in the past decades and the species has spread all over Europe. As the wild boar expanded its activity range into agricultural land, conflicts with humans have intensified. Today, the damage caused by wild boar amounts to millions of dollars every year. In Switzerland, farmers usually protect fields with electric fences, which have proven to be effective in preventing damage, but are also expensive. Alternatively, various cheaper deterrents and repellents are commercially available. However, most of them lack scientific proof of efficacy. In the present study, we investigated the effectiveness of the odor repellent "Wildschwein-Stopp®" against wild boar. We conducted field experiments with free-ranging wild boars at baited luring sites, which were placed in three different regions of the Canton Basel-Land, Northwest Switzerland. The odor repellent was not able to prevent the wild boars from entering our luring sites. We recorded a minimal and non-significant deterrent effect of 0.4%. Our results lead to the conclusion that the repellent is ineffective and, therefore, not recommendable for crop protection. On the basis of the present study we generally doubt fear-inducing repellents to be effective against wild boars and feral pigs. Our findings may indicate seasonal variation in wild boar activity outside forests since the probability of wild boar visits at the luring sites differed according to the season. The visits at the luring sites peaked in spring and fall which coincides with the occurrence of damage to agricultural land.