VAN SANT, M. J.; BAKKEN, G. S.; Indiana State University; Indiana State University: Do Ducklings Get Cold Feet?

Mallard ducklings (Anas platyrhynchos) take to the water shortly after hatching. Their legs and feet are completely un-insulated and submerged while swimming, providing a place for large amounts of heat transfer to take place. Studies on adult mallard ducks have demonstrated that heat loss from the legs can be conserved in cold temperatures by altering the pattern of blood flow. Minimizing heat flow through the legs and feet could be a significant aspect of duckling thermoregulation when swimming. The physiological mechanisms allowing adult birds to reduce heat loss from their legs may or may not be fully developed in ducklings. We explored this idea by using an adiabatic calorimeter (accurate to within 100mW) to measure the amount of heat lost to water from the legs and feet of 3-day old mallard ducklings. The calorimeter was sealed at the top, but had two holes for the ducklings� legs to pass through while their abdomen rested on the calorimeter�s insulated lid. A metabolic chamber was placed over the duckling. The calorimeter was filled with water at one of four temperatures (5&deg, 10&deg, 20&deg, or 25&degC). Air within the metabolic chamber was regulated at either 5&deg or 20&degC above water temperature. One run consisted of two consecutive 30-minute runs, one at the high air temperature and one at the low air temperature. Total heat lost to the water was calculated based on the temperature change of the water within the calorimeter. Most ducklings in 5&deg C water and some in 10&degC water were unable to maintain a steady body temperature and lost 200-300mW to the water. Ducklings with a stable body temperature in 10&degC water could minimize heat loss 50-150mW. Ducklings in 25&degC water could increase heat loss from their legs and feet to well over 200mW.