The feet of birds are important in the regulation of core temperature (Kahl 1963, Steen and Steen 1965, Johansen and Millard 1973) and are particularly effective in heat transfer when birds are normoor hyperthennic (Steen and Steen 1965). Under natural conditions, they must also be sites of considerable heat loss when they are immersed in cold water or in contact with cold substrates (e.g., ice...
