NOCTURNAL VARIATION IN BODY-TEMPERATURE OF GRIFFON VULTURES

The variation in body temperature over 24 hr was measured by implantin g temperature measuring radio transmitters in the abdominal cavity of six captive Griffon Vultures (Gyps fulvus). Body temperature was measu red when the birds were under three different feeding regimes: within 24 hr of feeding (while digesting), 2-3 days after feeding (post-absor ptive state), and 9.5-10.5 days after feeding (food deprived). For all birds, nocturnal body temperature was significantly lower than diurna l body temperature. The decline in body temperature at night was signi ficantly greater in food deprived birds, which at 10.5 days post-feedi ng had dropped by 4-6 degrees C. We suggest that this is an adaptation to reduce energy requirements of Griffon Vultures during periods of f ood shortage.