Previous studies have shown that male mink (Mustela vison) removed from their mothers at seven weeks of age develop more tail-biting than males left with their mothers until six months. Mink in the wild do not damage their own pelts in this way, and such behaviour may well be
an indication of chronic stress. The aim of this experiment was to investigate further the causes of tail-biting by considering female young as well as male, and by lowering the age at which the late-weaned' mink were separated from their mother to 11 weeks, by which age their period of
socialization should be complete. This was to generate results of more practical use to farmers, who cannot leave all young with their mothers until six months of age for reasons of space. Mink removed from their mothers at seven or eleven weeks of age did indeed differ in the incidence of
tail-biting. 'Early-weaned' females were more likely than late-weaned females to have bitten their tails at six months of age. A similar result was evident as a trend for both sexes at ten months. Furthermore, at this age, some animals' tail tips were completely bald, and such animals were
all early-weaned. Where provided with plastic drinker dishes, early-weaned animals were also more likely to chew these. Thus weaning age had long-lasting effects on a number of oral behaviour patterns. These results suggest that young animals predisposed to tail-bite might be diverted by
the provision of other objects to chew, and that if problems of over-crowding are avoided, leaving mink kits with their mothers until 11 weeks might improve their welfare.