The Relationship of the External Surface Area of Birds to Skin Surface Area and Body Mass

Estimating the extent of an animal's exterior surface, and its interface with the environment, is of prime importance in thermal biology. Regardless of the mode of transfer, heat fluxes across an animal's surface are often calculated as intensive quantities (e.g. W/m?) and converted to values for a particular animal by multiplying by surface area. Thus, the accuracy of heat-transfer estimates may be directly proportional to the accuracy of surface area estimates. In studies of avian thermal biology, the skin surface area is frequently used in calculations (e.g. Veghte, 1964; Pohl, 1969; Drent & Stonehouse, 1971; Calder, 1974) and is commonly estimated using Meeh's (1879) formula with Rubner's (1883) constant of 10