Blue foxes’ motivation for access to an earth floor measured by operant conditioning

The aims of the present series of experiments were to measure farmed blue foxes’ motivation for access to an earth floor exploiting operant conditioning, and to analyse the foxes’ behaviour on the earth floor in different seasons. Six farm-born blue fox males were used in the experiments. The foxes’ motivation for access to the earth floor was measured in autumn, winter and spring. In each season, the foxes were exposed to work for access to the earth floor on a fixed ratio (FR) sequence (FR4, FR8, FR16, FR32 and FR64) in operant apparatus designed for the study. The FR sequence was repeated three times in autumn and spring and twice in winter. In each experiment, the foxes were tested every second day in 6-h test sessions. The reward, i.e. the possibility to stay on the earth floor, lasted for 4 min. The slope and intercept of the demand curve were calculated. The foxes’ behaviour during the earth floor rewards was analysed using continuous recording. The slopes of the fragment of the demand curves for the earth floor ranged from −0.40 to −0.31. The slope or the intercept of the demand curve revealed no differences between the seasons. However, the foxes’ behaviour on the earth floor varied between the seasons. The time spent digging and the number of vole jumps were lowest in winter when the earth floor was frozen. The percentage of play behaviour from the total time spent on the earth floor was highest during autumn, when the foxes were young and the earth floor was not frozen. In conclusion, blue foxes are motivated for access to an earth floor. The motivation for access to the earth floor does not change between the seasons or with age or experience of the foxes. Foxes’ behavioural profile on the earth floor varies according to the properties of earth floor and is possibly also dependent on the age of foxes.