Declining survival rates of red foxes (Vulpes vulpes) during the first outbreak of sarcoptic mange in Sweden

Rapid declines in red fox (Vulpes vulpes) populations have followed outbreaks of epizootic mange caused by the mite Sarcoptes scabiei. In Sweden, the first outbreak of sarcoptic mange started in 1977/78 and affected the whole country by 1984. Here we used data on number of harvested red foxes from Gävleborg county (18 199 km2) in Sweden between 1970 and 1994. We used data on the prevalence of sarcoptic mange in harvested red foxes from 1974 to 1982. A rapid decline in harvested foxes occurred two to three years after the prevalence of sarcoptic mange first became evident. In the same period, Mark-Recovery data were used to estimate changes in survival rates, and the best model included an effect of age (young or adult) and period (annual) on the survival and recapture probabilities. The analysis was based data from 701 young foxes of which 523 were recovered, and 133 adults of which 131 were recovered. Average annual survival was 0.55 (range=0.53-0.58) for adult and 0.36 (range=0.32-0.3...