Large-scale sampling of small mammals throughout the year

dance of small mammals was measured with indirect methods, i.e. field signs and track plates in four regions in Switzerland. We sampled field signs like runways, holes and molehills along transects of 5 m length and set a track plate during three days close to each transect. Our results show that the abundance of small mammals not only fluctuated in annual cycles but also highly between seasons and habitat types. Over larger areas, fluctuations were not synchronous but highly variable between the sampled regions and habitat types. Small mammal populations crashed down in agricultural fields after harvesting, while populations remained more stable during the whole year in less disturbed structures such as hedges and ditches. Such large annual, seasonal and spatial variation patterns might highly determine prey availability for predators and are of major importance for many endangered farmland species feeding on small mammals such Barn Owls and Stoats. Monitoring small mammal populations through indirect methods is a good alternative compared to live-trapping because it allows covering much larger areas with similar efforts. It provides a temporal and spatial resolution which cannot be achieved by live-trapping. Such large-scale samplings of small mammals could help improving conservation measures on larger scales, especially for predator species living in farmlands.