Ecologically based management of grassland small mammals
Résumé
Since 2007, the European REACH directive makes industry responsible for assessing and managing the risks for humans and the environments posed by chemicals. National plans (e.g. Ecophyto in France) and regulations more and more aim at reducing the dependence of farmers on pesticides. Small mammal population surges pose a number of problems in various domains such as agriculture, forestry, health and conservation. However, a large number of small mammal pest species are actually important key stone species in their native range. They maintain large densities of various species of predators that may be of conservation value and legally protected. Unconditional chemical control of grassland rodents often induces inacceptable consequences on non-target fauna and poses inextricable problems to various stakeholders of regional ecosystems. The water vole (Arvicola scherman) and the common vole (Microtus arvalis) are two grassland species that may reach large population densities and cause heavy damage to grassland and crops. Here we present the results of long term inter-sectorial research carried out since the late 1980s, aiming at identifying the key ecological factors that may help grassland vole control. In Franche-Comté, France, this led to the development of integrated methods (a “toolbox”), now implemented by farmers, inspiring national regulations to conduct more sustainable control of grassland rodents. Application of such methods to A. terrestris populations decreased the quantity of bromadiolone bait used per hectare by 8, the area treated by 6, and led to a subsequent drastic reduction of the impact of vole control on non-target species.