Behavioral studies on the use of open water basins by American mink (Neovison vison)

Abstract

The aims of this study were to investigate whether farmed mink use swimming basins as an environmental enrichment factor and to identify layouts suitable to allow mink to perform their characteristic behavior to a large extent. Furthermore, an assessment of the water quality was intended. In 2006, the German “Order on the Protection of Animals and the Keeping of Production Animals” (German designation: Tierschutz-Nutztierhaltungsverordnung) stated mandatory husbandry requirements for fur animals for the first time in Germany. For mink, these include a water basin which is suitable for swimming. Forty American mink (Neovison vison) from a commercial mink farm were housed in 2 identically constructed free-range enclosures at the age of 13 weeks. In each of the 2 enclosures, the mink were offered 3 different water basins, which differed in shape, depth, and surface area and included a rectangular “swimming pool” (surface area approximately 20.5 m2, depth approximately 30 cm), a round “pond” (surface area 4.9 m2, depth approximately 80 cm), and a flowing “creek” (surface area 4.0 m2, length approximately 10.0 m, width 40 cm, depth 3-4 cm). Twenty nest boxes were placed in each enclosure (animal-to-nest box ratio: 1:1). The animal behavior in both groups was assessed by direct and video observations. Results showed that the mink generally accepted all 3 water basins and used them extensively from the beginning to the end of the study. Descriptive and negative binomial model analysis of water contact counts obtained from direct observations showed that mink preferred the swimming pool. However, in relation to the basin surface area, the preference effect is more pronounced for the pond. Overall, the animals spent a considerable amount of time at and in the water during their main activity time. On average, each mink could be observed 7 minutes per hour (12.0%) at and in the pool or 3 minutes per hour (5.5%) in the pond. The water quality was very good throughout the study. Although the mink used the water frequently, the total bacteria count and the level of Enterobacteriaceae were always very low. There were no traces of salmonella in any water sample.