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.

Predation by the red fox Vulpes vulpes is believed to be threatening the little penguin Eudyptula minor on Phillip Island in Victoria. Polymorphism at seven microsatellite loci was examined to estimate the extent of differentiation between Phillip Island and mainland populations of V. vulpes. Loss of alleles has occurred on Phillip Island where foxes first appeared approximately 88 years ago compared with mainland populations. Genetic differentiation between the Phillip Island and mainland populations was high. The relatively high differentiation found between the two populations could be due to either low migration rates, the effect of the composition of founder animals or both effects. Further ecological and historical information about the populations is needed to explore the likely significance of these effects.

Selection of natal dens and diurnal shelters by red foxes (Vulpes vulpes) was investigated within the metropolitan area of Melbourne. Of 72 natal dens, 61% were in residential, public park, school or industrial lands. Most dens were beneath buildings (44.4%) or in earth banks (30.6%). The habitat categories in which dens were sited did not differ significantly from those described for London. Dens were more common beneath weatherboard buildings and were associated with properties that did not contain domestic dogs (Canis lupus familiaris). Diurnal shelter positions for 20 radio-collared foxes were obtained, and home-range data collected for 11 foxes. Estimated areas of adult home-range, for 100% minimum convex polygons (MCPs), varied between 11.5 and 45.8 ha, with from two to five diurnal shelter sites used in each home-range. Foxes showed a consistent preference for diurnal shelters associated with exotic weed infestations over ornamental and native vegetation or built habitats. Within these categories a diversity of substrates were used, including buildings, drains, graves, cypress trees, ornamental rockeries and garden beds. A preference for exotic weed infestations is an identifiable resource requirement for foxes in Melbourne and its removal may assist in reducing the abundance of urban foxes. Home-range size and selection of natal den and diurnal shelter sites by urban red foxes (Vulpes vulpes) in Melbourne

Context. Scat genotyping has not been routinely used to measure fox (Vulpes vulpes) abundance and our study sought to provide a benchmark for further technique development and assessment of field methods.Aims. This study sought to provide a comparative assessment of some common methods used to determine fox density and contrast their success with scat DNA genotyping.Methods. DNA recovered from fox scats was used to genotype individual red foxes and determine their abundance at four transects. Population indices were also developed from bait take, scat counts and sand plot tracks using index-manipulationindex (IMI) procedures on the same transects. Known samples of foxes were taken from two treatment transects using cyanide delivered in the M-44 ejector to manipulate the population and to recover foxes at the end of the trial.Key results. Replicated counts on a 41-km-spotlight transect at the field site before and after the population manipulation had low variance and good correlation (r 2 = 0.79, P < 0.01). Scat genotypes revealed 54 foxes in eight days and, when combined with biopsy DNA from recovered foxes, a minimum known to be alive (KTBA) density of between 1.6 and 5 foxes km -1 was calculated for the transects. Overall, 15/30 (50%) of all recovered foxes had not been detected by scat genotyping, 23/53 (49%) of KTBA genotypes were detected only once and 5/54 (9.5%) of foxes were found to have moved between two transects.Conclusions. At transects where population manipulation occurred, surviving individuals contributed significantly more scats than at the control transects and some individuals were detected at bait stations at a much greater frequency. This strongly suggested that they had contributed disproportionately to some IMI density estimates that were probably influenced by a change in the activity of some individuals rather than changes in population density alone. At one transect, eight foxes were confirmed to be present by spotlight surveys and were detected by scat and KTBA genotypes, yet were undetected by scat, bait station and sand plot indices.Implications. Scat and other DNA-based survey techniques provide a great deal of information about the identification and movement of individuals and if DNA sampling methods can be made more efficient they have the potential to provide accurate abundance estimates that are independent of the control technique.

Red foxes (Vulpes vulpes) are widely distributed throughout the Melbourne metropolitan area. Density estimates indicate that fox populations would be capable of maintaining the endemic persistence of rabies. Oral vaccination of foxes by baiting is a technique that has been used successfully overseas to manage rabies epizootics. This study assessed the uptake by foxes of baits containing biomarkers in three urban field sites in winter 1993 and summer 1993/94. Baits were dosed with 200 mg of tetracycline in the winter trial and 5 mg of iophenoxic acid in the summer trial, and distributed at a density of 8 baits ha −1 in open areas within each field site. In the winter trial, 8 of 11 (72.7%) radio-collared foxes known to be in the field sites during the distribution of baits were marked. In the summer trial, 45 of the 49 foxes (92%) recovered from the combined field sites had consumed at least a single bait, resulting in bait acceptance of 80–97% for each field site. No bias existed between plasma iodine levels due to sex, although first-year foxes had a significantly higher level than older age groups combined. There were no significant differences in mean age of foxes collected at the three field sites, yet significant differences existed in mean plasma iodine concentrations between all three sites. These results are discussed with reference to rabies contingency planning. The high rates of bait uptake in this study are encouraging and suggest that oral vaccination may be a viable strategy for rabies containment in urban areas and is worthy of further assessment at reduced baiting densities.