We monitored European lynx (Lynx lynx) in a reintroduced population in the Swiss Alps from 1983 to 1988. We predicted that recolonizing lynx initially would reach a higher population density (and would kill more ungulates) than they would sustain once the population was established. We compared the home ranges and distribution of kills of 8 lynx in the established center of the population with those of 6 lynx at the expanding front of the population. Home ranges overlapped between males and females and were exclusive within the sexes in both areas, but at the front, home-range sizes were 3 times smaller. The distributions of kills were more concentrated, and distances between consecutive kills were shorter at the front. Kill rates did not differ (P = 0.411), but the proportion of carcasses consumed was 10% higher at the center than at the front (P = 0.037). We suggest that the smaller lynx home ranges at the front indicated a denser predator population and that the spatial concentration of kills there was due to a higher prey availability. Ungulates seemed to be more abundant and clustered, and lacked anti-predator behavior in areas where their natural predators had been missing for a longer period. We interpreted the decrease of the lynx population in the center of the population as a numerical response of the predator to a readaptation (numerical and behavioral response) by the prey.
