Zyklische Bestandswechsel (Gradationen) bei der Feldmaus (Microtus arvalis), festgestellt durch Analyse von Eulen-Gewollen

Bethge, E.

Studied over 13 yr (1968/1969 until 1980/1981) were the pellets of longeared owls, which regularly winter in a park at the edge of Wurzburg West Germany . The pellets contained the remains of 51,682 small vertebrates. The numbers of the main prey animals, common vole (Microtus aravalis) and longtailed fieldmouse (Apodemus sylvaticus) and of the captured birds flucutated regularly with peaks of 3 yr intervals, except for one 2-yr interval. The yearly portion of the common vole and the longtailed fieldmouse together was rather constantly 82-95%. A reciprocal relationship exists in the occurrence of these 2 spp. These fluctuations reflect the real flucutations of the population density of the common vole. The 3-yr cycle of the longtailed fieldmouse seemed to be dependent on the course of the cycle of the common vole.