The effects of induced sterility on the territorial behaviour and survival of foxes

Summary 1. This paper reports on the behavioural effects of surgical sterilization when used to simulate immunocontraception in free-ranging female foxes Vulpes vulpes . 2. During 3 years of trapping, 348 male and female foxes were fitted with transmitters in two treatment (females sterilized) and two untreated areas. 3. Radio-tracking indicated that sterile and fertile vixens maintained similar-sized territories during the breeding season, but that sterile females were possibly more likely to share their territories with each other. 4. There were no consistent differences in survival or dispersal between sterile and fertile females. 5. Outcomes from the study suggest that immunocontraception in free-living foxes is feasible.