Fig. 5. Energy expended by albatrosses to heat cold meals exceeds the actual heating demand. Here the measured energy expense () for Diomedea and Thalassarche albatrosses in warming meals from 0°C to T_b is compared with energy estimates for this demand () and for warming food from 20°C ( measured expense, estimated expense). The differences are attributable to an inherent delay in lowering MR after thermal equilibration of body and meal temperatures has occurred.