LYNOTT, Aaron J.; BANTA, Marilyn; HIGGINBOTHAM, Clay M.; BAKKEN, George S.: Thermoregulation in Swimming Mallard Ducklings
Most duckling mortality occurs in the first week after hatching, and is often associated with chilling by cold, windy, wet weather, extended periods of swimming in cold water, or both. We measured the thermoregulatory ability of 3 to 5 day old mallard ducklings (Anas platyrhynchos) swimming in a flow tank with a water velocity of 30 cm/s. Water temperatures ranged from 5o to 20oC and air temperatures from 10o to 20oC. Ducklings were imprinted on a moving mallard hen decoy, and generally “followed” another such decoy placed on a pedestal which supported it just above the water. We recorded cloacal temperature with a thermocouple and skin temperature on the head directly over the brain using a FLIR PM575 radiometric thermal imager. The ability to maintain body temperature and swimming endurance depended on water temperature, the area of the body where water saturated the down, and swimming effort. Wetting of the down depended on down density and other factors. Ducklings were capable of coordinated swimming with body temperatures as low as 28oC and recovered from such hypothermia with no evident ill effect. Thermographic temperature of the shaved head was correlated with cloacal temperature and may offer a means for estimating the body temperature of unencumbered hatchlings.
