The Importance of the Legs in the Thermoregulation of Birds

AbstractThe proportion of the total heat production of herons and gulls which at ambient temperatures ranging from—10° C to 35° C is dissipated to cold water or air surrounding their legs has been measured. At low ambient temperatures less than 10 % of the metabolic heat is lost from the legs. At higher ambient temperatures an increasing proportion of the metabolic heat is lost from the legs and at 35° C almost the entire heat production is dissipated through the legs. Heat loss to water was found to be about four times higher than to air of the same temperature. The degree of heat loss from the legs was shown to react within seconds to changes in ambient temperature. Likewise, panting stopped immediately when the legs were irregated by cold water. It is concluded that the naked legs of these birds serve as controlled heat conduits of great importance in thermoregulation.