In Britain large numbers of animals are taken into captivity for treatment or care and then subsequently returned to the wild, but there are few data on the effectiveness of these rehabilitation programmes. In this study, over a period of four years 251 fox cubs that had been captive-reared were tagged and released; 90 were recovered. Survival rates were low, and road traffic accidents were found to be a major cause of mortality immediately following release. Recovery distances were lower than expected. The stress associated with captive-rearing meant that released foxes weighed less than wild-reared foxes, and they suffered further weight loss in the period immediately following release, even though an analysis of the stomach contents of animals recovered dead showed that released foxes rapidly learnt to hunt successfully.

It was concluded that captive-rearing is a problematic process for foxes, and contrary to predictions they face severe problems in adapting following release. Suggestions are made for the improvement of fox captive-rearing and release programmes, and the need for similar studies on other species is highlighted.

The release of animals from captivity frequently leads to a period of erratic movement behaviour which is thought to expose the animal to a high risk of mortality. Twenty-six foxes which had been reared at a wildlife hospital or captive-bred, were radio-collared when nearly full-grown and released without site acclimation. Immediately after release there was an erratic phase of behaviour, during which the foxes travelled widely and movement parameters were markedly elevated. For those foxes which survived, a second phase was entered after an average of 17.2 days, during which one small area only was used, and movement parameters were much reduced. In a second study, nine foxes were released following site acclimation in a pre-release pen; this process postponed but did not eliminate the phase of high movement activity.

This pattern of movement was compared with the dispersal behaviour of wild-reared foxes. It was concluded that released foxes, despite being proficient in other aspects of behaviour, were moving and behaving in a markedly abnormal manner and this resulted in a high death rate. The results are used to discuss methods of improving rehabilitation techniques.