Increasing brown hare (Lepus europaeus) densities in farmland without predator culling: results of a field experiment in Switzerland

In a field experiment in Northwestern Switzerland, we managed one part of each of four experimental areas in order to improve leveret (Lepus europaeus) survival and used the remaining part as control. The experimental areas were dominated by arable farming with a high diversity of different crops. Potential leveret predators were numerous and not controlled by gamekeeping. Management elements were wildflower patches, partly with an optimized antipredator design, and wider-sown cereals (to allow hares to enter the fields from May to July). We assumed that leverets are relatively safe in these two types of fields because these are seldom processed by agricultural machinery and potential leveret predators rarely forage there. The management lasted 7 years in two experimental areas and 3 years in the other two. Hare numbers and locations were monitored by spotlight counts, starting at least 3 years before the beginning of the experiment. In three out of the four experimental areas, we found a more positive development of hare densities in the managed area compared to the control area. Furthermore, the distribution of the hares within the experimental areas could be best described by a model including the percentage of wildflower patches, the percentage of arable land, and the percentage of cereals in wider-sown rows suggesting that hares predominantly occupied the surroundings of the management elements. We conclude that—irrespective of high predator densities—brown hare populations in agricultural landscapes with previously low hare densities can be considerably increased by offering a total area of about 3% wider-sown winter cereals or wildflower patches within the agriculturally used area.