The arbitrary assignment of different coloured leg bands to zebra finches (Taeniopygia guttata) has profound effects on mate preference, reproductive success, mortality rates, parental investment and sex ratio. Choice chamber experiments indicate that the effect is mediated by altered attractiveness to members of the opposite sex. Effects on intrasexual dominance are more equivocal. We present two experiments which demonstrate significant effects of band colour on behavioural dominance (red bands are more dominant than light green bands) and the resulting diurnal pattern of gain in mass, fat, and seeds stored in the crop. Consistent with the literature on dominance and strategic regulation of body mass in other species, subordinate (green–banded) birds maintain higher fat reserves at dawn, but dominant (red–banded) birds show the highest overall daily mass gains. The lack of obvious effects of band colour on dominance in previous studies may lie in the degree to which food can be monopolized by particular individuals.