Over the past several decades, both the unusually high rate of propagation and the abundant food supply have led to an increase in Switzerland’s wild boar population – a trend that shows no sign of abating. And the damage the animals cause has risen with their growing numbers. «We still don’t know nearly enough about wild boars, but we do know they are intelligent and that they adapt easily and can evade hunters,» says Stefan Suter from the ZHAW research group for Wildlife Management. An additional obstacle is that hunting wild boars is either prohibited or difficult in a variety of areas – for instance in water and bird reserves, nature conservation areas, in cities and where hunting is banned. Since 2013, Suter has been seeking new or improved methods of keeping the animals out of maize, potato, rapeseed and other crop fields, and he believes that the new deterrent will prove useful. The device consists of two battery-powered loudspeakers with a control box that sends random sound combinations in intervals of varying length. An integrated light sensor turns the device on at sunrise and off at sunset.

The comparison study shows that no single preventive measure tested can offer absolute protection. Nevertheless, the damage is significantly smaller in fields where such methods are used compared to fields with unprotected crops. «With the acoustic system, we now have an additional preventive measure that is flexible and intelligent,» says Suter. It is especially useful in the critical periods after sowing and when maize and wheat are in an early ripening stage (milk maturity).

Exerting greater pressure through hunting also raises the effectiveness of the preventive measures. For instance, when a young member of a wild boar herd is culled, the other animals will avoid the area in future. Despite keeping the animals away from crop fields where the culling took place, this method doesn’t drive the animals permanently out of the forests or keep them away from agricultural areas. Electric fences can also be effective in keeping wild boars out of fields, but only if they are well built and regularly maintained.

Stefan Suter points out that hunting methods can only form part of successful wild boar management – and that a holistic approach is necessary. Additional preventive measures are important as they help to make it more difficult for the animals to gain access to nutrient-rich crops, which in turn helps to slow population growth. «The compensation that the cantons pay to farmers for damage caused by wild boars is effectively a pig breeding strategy. If damages are paid out, there is no motivation to find ways to prevent the animals from entering fields,» says Suter, adding that hunting methods wouldn’t change this either. In areas greatly affected by the high wild boar population, it would also be useful to introduce crops that wild boars have an aversion to, for instance Sudangrass or the cup plant. «Forward-thinking farmers have already begun planting these species. Farmers who are prepared to take a risk and try something new should also receive support,» Suter says with conviction.