How blue foxes value an earth floor
Orjala, Hanna; Koistinen, Tarja; Mononen, Jaakko; Korhonen, Hannu T. (2007)
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Korhonen, Hannu T.
Farmed blue foxes are willing to work for access to an earth floor. However, when the foxes have free access to earth and wire mesh floors they prefer the wire mesh floor, in particular while resting. Consequently, it seems that blue foxes are motivated to access an earth floor, but in some circumstances they may even consider the earth floor aversive. We compared the earth floor use in blue foxes working to leave an wire mesh floor to enter an earth floor and foxes working to leave the earth floor to enter the wire mesh floor. The subjects were 16 blue fox males in two cohorts of eight foxes. From the age of 12 weeks, the foxes were individually housed in test cages. Each test cage consisted of two traditional fox cages (115 × 105 × 70 cm, L×W×H), with two openings (23 × 28 cm, W×H) between the cages. The openings had one-way doors. The force needed to open the one-way doors could be altered. There was a wire mesh floor in one of the cages and an earth floor with a 30 cm layer of sand in the other cage. In four test cages of each cohort, door weight was altered in the door leading from the wire mesh to earth floor (TOEF), and in four test cages in the door leading from the earth to wire mesh floor (FROEF). After 10 days of training, the foxes were exposed three times to door weighs of 0, 0.5, 1.5 and 2.5 kg. The door weights were changed after every 24h. The number and duration of visits, and the percentage of time spent on the floor materials were measured. One FROEF fox was removed from the experiment. The data for 15 foxes were analysed using Linear Mixed Model analysis (SPSS). As expected, the number of visits decreased with increasing workload (p<0.001), and no difference between the groups was found (p>0.05). As the workload increased the percentage of time spent on the earth decreased in the TOEF (29% on 0kg weight to 15% on 2.5kg weight), but increased in the FROEF (23% on 0kg to 50% on 2.5kg) (p<0.001). The mean duration of the earth floor visits did not change in TOEF (41 min on 0kg, 42 min on 2.5kg), but increased in the FROEF (15 min on 0kg to 210 min on 2.5kg) with increasing door weight (p<0.001). The mean duration of the visits on the wire mesh floor increased (TOEF: 73 min on 0kg, 155 min on 2.5kg; FROEF: 47 min on 0kg, 106 min on 2.5kg) with increasing door weight (p<0.001), but there was no difference between the groups (p>0.05) or group-workload interaction (p>0.05). The results confirm the earlier findings that blue foxes are willing to visit the earth floor, but they still prefer to stay on the wire mesh floor. TOEF did not compensate for the higher door weight by increasing the duration of the visits on the earth floor, which indicates that the value of an earth floor visit does not increase by staying longer on the earth floor. This supports the earlier findings that blue foxes value the earth floor for behaviours of short duration, e.g. exploration. Although, the FROEF accepted to stay longer (rest) on the earth floor when it became costly to leave the earth floor, we conclude that blue foxes are willing to work for leaving earth floor. A detailed behavioural analysis will clarify the reasons to enter and leave the earth floor.
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