Distribution and density estimates for urban foxes (Vulpes vulpes) in Melbourne: implications for rabies control

Abstract

The distribution and density of red fox populations was investigated in metropolitan Melbourne from 1990 to 1993. Distribution data were collected from sightings reported by members of the public, from spotlight and active den surveys, and from trapping and road kills. Archival data suggested that resident populations of foxes have been present within the inner metropolitan area since the early 1940s. Contemporary fox populations were found to be extensively distributed throughout the urban area, with few 1-km ² grids within a 5-km radius of the Central Business District not containing foxes. Density estimates were based on nearest-neighbour analysis of active natal dens in four field sites. Observations of cubs over a 4-year period at 17 dens within the field sites revealed a mean litter size of 4.36 cubs. Mean 4-year density estimates for each field site, immediately after the breeding season, were 0.47–2.55 dens km ⁻², which was estimated to represent 3–16 foxes km ⁻². Density estimates may be conservative, as family groups may contain more than one non-breeding adult. The implications of these data are discussed with respect to the potential role of the urban fox in the epidemiology of rabies. It was concluded that fox populations at the field sites were of sufficient density to maintain a sylvatic epizootic of rabies.