AN INFRARED, THERMOGRAPHIC STUDY OF SURFACE-TEMPERATURE IN 3 RATITES - OSTRICH, EMU AND DOUBLE-WATTLED CASSOWARY

(1) Surface temperatures of the ostrich (Struthio camelus), emu (Droma ius novaehollandiae) and double-wattled cassowary (Casuarius casuarius ) were measured using infrared thermography at ambient temperatures ra nging from 0 to 27 degrees C. (2) The pattern of surface temperature r egulation for thermoregulatory purposes was similar in all species exa mined. Beak, lower leg and neck surface temperatures are regulated in all species to alter heat exchange with the environment. The feet and toes are also used by the ostrich and emu to regulate heat exchange. T he cassowary does not use the feet and toes to the same extent but use d the casque in a similar manner. (3) Standard metabolic rates were es timated using a geometric model of a bird and instantaneous heat loss calculated for specific body parts. (4) Up to 40% of metabolic heat pr oduction can be dissipated across these structures which comprise 12% and 17.5% of total body surface area. (5) The ostrich was able to regu late surface temperature more precisely than the other species, probab ly due to a larger body size. The large wings of the ostrich are usefu l for thermoregulation by increasing convective heat loss.