Factor analysis of behavioural tests in farmed silver and blue foxes

Abstract

We recorded and analysed behaviour of farmed silver and blue foxes in the open-field with a computer-based system. In addition, the reaction towards humans and the capture time were recorded for the animals in their home cage. Factor analysis with VARIMAX rotation produced four independent factors. In the silver fox, the first factor was loaded from general activity in the open-field and accounted for 42% of the variance; the second factor was mainly loaded from initial activity (24%). The third factor was related to the reaction towards humans (19%) and the fourth was the capture time (15%). In the blue fox, the factors were: general (41%) and initial activity in the open-field (26%), capture time (17%) and reaction towards humans (15%). A 5 min exposure to the open-field was sufficient to provide the information needed. In the spring in comparison with the autumn a higher proportion of silver foxes did not come out of the start box to the open-field at all, while fewer young blue foxes emerged than old ones, such reaction thus being an additional behavioural test. The open-field Factor 2 (initial activity) was higher in adult silver foxes and in the autumn compared with juveniles or the same adults about 5 months earlier. The adult individuals in this group were more passive towards humans in the spring. Adult blue foxes were more active in the open-field than the young and their initial activity was higher in the spring. In the spring there were more passive blue foxes while in the autumn the number of fearful individuals was greater. In the autumn, juveniles were more aggressive than adults. Adult blue foxes were more easily accessible to a capturer than young blue foxes. The effect of cage environment on behaviour of the foxes was assessed in animals housed in empty wire-mesh cages or in cages provided with resting platforms and nest boxes or platforms only. There were no other differences between these groups in their open-field behaviour except that the initial activity was lower in the control blue foxes. Blue foxes in the control group were more fearful and passive towards humans, whereas no differences were found among silver foxes. The capture time was always longest in the nest box groups, due to the obstacles that the nest boxes presented to the capture. Our results confirm that behaviour of foxes is subject to changes detectable by the behavioural tests used. However, in this study the behaviour of both fox species appeared to be affected more by season and age than by housing conditions.