The impact of local fox (Vulpes vulpes) removal on fox populations at two sites in southern England.
Abstract
The impact of known culls of foxes (Vulpes vulpes) on local fox populations at two study sites in southern England (Salisbury Plain and Dorset) was estimated for the three years 1985-87. Each site involved a core area of 5-6 km2 with intensive fox control and a surround of 6-10 km2 with less intensive control. Fox populations were estimated from two models based on mean breeding territory size and mean breeding group size, measured from adult fox radio tracking on one of the study sites. For 1985-1987 mean breeding territory size was 2.72 ± 0.27 km2 (n = 6) and mean breeding group size was one male plus 1.5 females with 4 cubs weaned per territory (n = 6). Mean annual culls were 1.7 individual foxes/km2/yr in the core area and 0.8 foxes/km2/yr in the surround zone of the Dorset site. Figures for Salisbury Plain were 3.4 and 2.9 respectively. At both sites cub production was effectively prevented within the core area. On Salisbury Plain, fox control probably achieved complete removal of the adult breeding population in the core area in each year, while adult density was only reduced in Dorset. In fox population terms, both areas became 'sinks' with negative population growth. Both core areas were recolonised each winter, and some immigration of adult foxes with cubs also occurred during late summer/autumn. On Salisbury Plain the local beneficial effects of predator control on gamebird productivity were not experienced at a further monitored site only 6 km away. We therefore conclude that the effects of fox control on the fox populations were of local importance only.