Fig. 6. Energy consumption over the rest phase (12 h) of bats exposed to a diurnal fluctuation in T_a when heating commenced at 06:00 h (open circles), 09:00 h (triangles) or 12:00 h (filled circles) as a function of time spent normothermic (0 h represents bats that remained in torpor). The time of commencement of heating had no significant effect on the slope of the relationship between energy consumption and time normothermic [general linear modelling (GLM) slope: F_2,41=2.4, P=0.10], however, energy expenditure was greater overall on days when heating commenced at 06:00 h or 09:00 h, in comparison to 12:00 h [GLM, y-intercept: F_1,43=287, P<0.001; fitted line for combined 06:00 h and 09:00 h: rest phase energy expenditure (kJ)=0.734.0+0.513xtime normothermic (h); for 12:00 h: energy expenditure (kJ)=0.261+0.513xtime normothermic (h); r²=0.90].