The behaviour of the red fox is notable for its flexibility. Populations compared are from Ontario, Canada, and Oxfordshire, England; contrasts are more notable since the landscapes in these areas are superficially similar. Foxes in the 2 populations differed in their territory sizes, adult group sizes, dispersal distances, reproductive parameters, foraging behaviour and interspecific competition. The areas differed in 3 respects which are suggested to underline the observed variation: 1) dispersion and abundance of available prey; 2) pattern and type of fox mortality; and 3) extent of seasonal climatic variation. -from Authors