The effect of metabolic intensity (energy expenditure per gram) on the lifetime energy expenditure per gram in birds for DEE (a) and RMR (b). an = 92, log lifetime DEE per gram = 8.99 + 0.612 log DEE per gram, r2 = 0.511, F = 94.10, P < 0.001; bn = 321, lifetime RMR per gram = 8.52 + 0.523 log RMR per gram, r2 = 0.415, F = 226.26, P < 0.001