The impact of human attitudes on the social and spatial organization of urban foxes (Vulpes vulpes) before and after an outbreak of sarcoptic mange

The red fox (Vulpes vulpes) population in the city of Bristol in southwest Britain has been studied continuously since 1977. From 1990, intensive behavioral data have been collected on the social organization and patterns of space utilization of 4-8 fox groups in northwest Bristol. The impact of a mange epizootic on the social organization and territorial behavior of urban foxes, and their inter-relationships with the resident human population has been studied. From 1990-1994, mean social group size increased from 2.25 to 6.57 adults. This was associated with a high level of food provision; around 10% of households on each range fed foxes. Feeding of the foxes commenced following regular sightings, or in response to the presence of very tame individuals. The most fundamental change following the 1994 outbreak of mange was the marked increase in mortality rates, rapidly declining social group sizes and increasing range sizes. Ranges were expanded following the loss of all animals from a neighboring group. The underlying strategy appeared to be a process of enlarging range boundaries until competing conspecifics were encountered. Range expansion was not mediated by a decline in resource availability, and the new ranges encompassed successively greater levels of resources. Following range expansion, there was no change in the level of intra-group contacts, but the level of inter-group contacts declined. Before the 1994 mange outbreak, despite the variation in territory size and hence number of households in each territory, the amount of food given to the foxes in each territory was similar both in terms of the median weekly amount of energy and in the minimum amount of food supplied. For 2 social groups, changes in the amount of food supplied by households closely mirrored changes in social group size, whereas for 2 other social groups changes in levels of food provisioning were not sufficient to match the increased energetic requirements as group size increased. The amount of food deliberately supplied for foxes by the residents appeared to have had a profound effect on the social organization of this fox population. Following the worst of the mange epizootic, by early 1999 the fox population was <10% of the pre-mange density. Groups were markedly smaller, generally comprising a dominant pair. Subordinate animals were scarce, and exclusively females. Ranges were larger than those prior to the outbreak of mange and less stable, with large-scale movements of boundaries between seasons. Such changes were probably related to changes in the availability of scavenged foods: less than 1% of households were deliberately feeding the foxes in 1999. Consequently, the foxes appeared to be utilizing habitats such as woodlands and sports fields more frequently. It is unlikely that more people will start to feed the foxes again until they see the foxes regularly. Even then, public attitudes towards the foxes may be less favorable due to concerns about the transmission of mange to both pets and humans. It will be some years before the Bristol fox population attains pre-mange densities.