Demand for swimming water and running wheel with 1 min of access per reward

The purpose of the three experiments presented here was to quantify the priorities of mink for 1 min of access to swimming water and a running wheel, respectively, by demand functions. Furthermore, the results were compared to the results of previous experiments in which mink were tested with a reward duration of 2 min. Eight 2-year-old female mink of the colour type Scan Black were kept individually in experimental cages equipped with either a box of swimming water, a running wheel, or both resources at the same time. The mink worked on a fixed ratio (FR) schedule (FR5, 10, 20, 40 and 60) for access to the resource (the reward). In experiments 1 and 2 the mink had access to only one of the two resources at a time, while in experiment 3 the mink had access to both resources at the same time. In experiments 1 and 3 the mink had free access to straw in the nest box, but in experiment 2 there was no straw in the nest box. Free access to straw in the nest box did not influence the demand for either swimming water or running wheel. In experiments 1 and 2 no differences between the two resources regarding the area under the demand curve and the elasticity and intensity of the demand function were found suggesting that mink value these two resources equally. Simultaneous access to both resources did not affect the elasticity of the demand functions suggesting that the two resources are independent. However, simultaneous access to swimming water reduced the demand intensity for a running wheel, but not the area under the demand curve. The mink worked primarily for access to the two resources in the morning. The results are discussed in relation to previous experiments in which the mink had 2 min of access to the resources per reward.