Aspects of the biology of suburban foxes

Abstract

The occurrence of wild canids living in close association with man is documented, and it is seen that foxes living in suburbia are a unique British phenomenon. Foxes have lived in London for at least 35 years, and have now permanently colonised most suitable habitats. The various body measurements of suburban foxes are compared with similar data for other populations. It is shown that the tail is shorter than in populations from regions with colder winters, the other body measurements varying from one population to another but with no obvious pattern. Various age determination techniques have been applied to the Red fox, but for the majority of techniques separation of year classes is impossible after eighteen months of age. The only technique that has proved of value is the use of incremental lines in the tooth cementum, particularly in the premolar teeth of the lower jaw. Growth curves have been constructed for animals up to six years of age. Using the age of the animals as determined by cementum lines, a life cable for suburban foxes has been constructed. These data are used to compare the structure of the suburban fox population (subject , to limited control operations) with that of a fox population subject to intense control. Survival curves have been constructed. It is shown that only the ratio of young : adults is affected by intense control operations, and that the rate of adult mortality is identical in both populations. The significance of this is discussed in relation to rabies and sarcoptic mange. The general health of the population is illustrated using spondylosis deformans as an example. This condition has not been reported previously in foxes. The food habits of suburban foxes have been examined. The various techniques available have been evaluated, but only stomach contents and den litter proved of value in the present study. The results are discussed in relation both to other fox food studies and the prey species available in London. The validity of the term "suburban fox" is considered, comparing the data presented here with similar data for other fox populations.