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WHAT INFLUENCES THE EXTENT OF DAMAGES TO CROP DUE TO THE EUROPEAN BROWN HARE (LEPUS EUROPAEUS)?
C. Fischer
Romain Tagand and Laure Rusterholz, University of Applied Sciences of Western Switzerland
In Switzerland, Brown hare densities have sharply declined since the 1960s and are now usually very low with a nation's mean density of 2.7 individuals per 100 ha. Canton Geneva, at the far Western tip of the country always showed the highest densities, with populations ranging between 10 and 15 individuals per 100 ha. Between 2001 and 2003 one of these populations within the canton Geneva showed a dramatic increase with a density growing 6 folds to reach over 60 individuals per 100 ha. This trend was accompanied by a sharp increase of damages to crop, especially sunflowers, soya-beans and peas. The first reaction toward this evolution was to try to reduce the local Brown hare population to reduce its pressure on the agricultural
activities. Considering the vulnerability of the species at a nation's level and also in neighboring France, and considering the image of the Brown hare in the general opinion it was however decided not to shoot any individual but rather to proceed to translocations in areas with sharply decreasing populations. A second objective was to improve damage prevention. But it was soon obvious that the costs of an efficient prevention would be higher than the potential reduction of damages. A final step was then to determine if damages were only linked to the Brown hares' densities, or if another factor was playing a role. If so, it would perhaps be possible to influence this additional factor to reduce damages.
A study was launched to assess the spatial use of the local hare population and its diet preferences. Hares were captured and fitted with VHF-collars. They were then radio-tracked and the type of habitats used was determined at a small scale as well as the proportion of time spent in each habitat. Pellets were collected to assess their diet using the macroscopic remains of vegetal items. To do so, it was first necessary to build up a reference collection of the available vegetal species, i.e. the cultivated ones. In addition, direct observations were performed, using a thermal-imaging sensor, to assess the behavior of the individuals present in different crop fields. This method gives the opportunity to assess if hares are resting, hiding, or really feeding (and to what extent they are feeding) when they are in a given crop type.
