Residual SMR (W, +s.e.) in relation to sex and manipulated brood size. Statistical analysis was based on raw data, but the averages shown here were calculated as follows: (i) residuals of regressions of SMR on mass were calculated separately for the first and second measurement, (ii) the mean residual was calculated per individual, and (iii) these means were averaged per group. From left to right, n=6, 8, 13 and 16.