Fig. 4. The relationship between whole-animal oxygen consumption rate (_O2; ml O₂ h^–1) and whole-animal ATP turnover rate per unit power output (mmol ATP h^–1 W^–1, assuming either perfect, P_per, or zero, P_zero, elastic storage) to respiratory quotient (RQ). The slope of whole-animal _O2 in relation to RQ is significantly different from zero (F_1,22=10.4134, P=0.0039). The slopes of whole-animal ATP turnover rate per unit power output in relation to RQ are not significantly different from zero (assuming P_per, F_1,22=1.8537, P=0.1871; assuming P_zero, F_1,22=1.1524, P=0.2947). Note that >90% of _O2 and ATP turnover rate during hovering are accounted for by flight muscles. Example using Anna's hummingbird (C. anna) number 3.