Population changes in long‐eared owls Asio otus, polecats Mustela putorius, red foxes Vulpes vulpes, stone martens Martes foina and badgers Meles meles were monitored during a water vole Arvicola terrestris scherman cycle in western Switzerland. Long‐eared owls confirmed their status of highly mobile specialist predators in responding strongly and without time lag to water vole population changes. Even though polecats are considered generalists, they exhibited also a strong response to water vole fluctuations. Their numbers tracked water vole densities with a 1‐yr time lag. Marked population changes were also recorded in red foxes and stone martens, but these changes were not related to water vole densities. Lastly, badgers did not show any significant population changes during the water vole cycle. We discuss the possible reasons for these differences and conclude that multi‐factorial approach is clearly required to understand population processes in predator‐prey systems.

Thirteen red foxes (Vulpes vulpes) were radio-tracked between September 1989 and August 1993 in the Swiss Jura mountains. Home ranges of subadult and adult resident foxes did not differ and were small (seasonal estimates 0.48–3.06 km2). A nomadic adult was also monitored; it used a significantly larger area (12.71–25.90 km2). In most cases, home range sizes did not vary seasonally and were not affected by drastic changes in food availability. That foxes maintain a constant territory size is in accordance with both the "contractor" and "obstinate" strategies. The small observed sizes suggest that after the eradication of rabies, rural areas of central Europe are very good habitats for foxes. In the absence of clumped feeding patches or constraining factors (e.g., deep snow cover), the foxes moved regularly throughout their home range, typically in a "non-oriented zigzag." The distance travelled per day seemed to be affected only by home range size (positive correlation) and occasionally, according to the individual, by weather or snow cover. On average, the foxes moved 3.9–12.0 km a day. Despite its significantly larger home range, the nomadic fox did not move more than the resident foxes; the physical characteristics of red foxes probably set a limit to the distance travelled daily.

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The resting sites of seven radio-tracked Red fox Vulpes vulpes (Linnaeus, 1758) vixens were determined in the Swiss Jura mountains. During their nocturnal active period, foxes rested above ground near their foraging areas. In daytime, some foxes always used dens in areas with little cover, while some other individuals often rested above ground when cover was abundant. Weather did not influence the choice of the resting place, except in extreme conditions. Each fox used several resting places, sometimes moving from one to another during the day, especially when lying above ground.