Use of Water for Swimming and its Relationship to Temperature and Other Factors in Farm Mink (Mustela vison)

An investigation into swimming behaviour and its relationship to outdoor temperature was conducted in 40 ranch mink. Two different cage sizes were used and all animals had access to a basin filled with water 15 cm deep. During the years 1994-1998, water loss from the basin and temperatures at a nearby weather station were recorded once a week. In the last year 11 mink were video-recorded for 24 h. Using the monthly average daily water loss as an indicator, swimming activity showed a clear annual variation over 4 years and was positively correlated with average monthly temperature. With regard to swimming activity, a large individual variation existed: average water loss varied from 10 ml to nearly 4 litres per day, with those in large cage units having the greatest water loss. The video-recordings confirmed this variation: the number of swims ranged from zero to 177 during 24 h and there was an indication of more swimming bouts in the mink in the large cage units. The duration of swims varied from 2 to 55 s per bout. The relationship between swimming and general activity is discussed, along with the importance of water for swimming as a means of thermoregulation.