A study of the temporal synergism of serotonergic and dopaminergic activity in the regulation of reproductive seasonality of photosensitive and photorefractory migratory Red headed bunting was undertaken. In experiment 1, groups of birds kept in natural day length (NDL) in their photosensitive phase (April) received daily injections of L‐DOPA (L‐dihydroxyphenylalanine, a dopamine precursor) at 8 and 12 hr after 5‐HTP (5 hydroxytryptophan, a serotonin precursor) administration. One control group received two daily injections of saline. The injections with 12‐hr temporal relation induced early recrudescence and full gonadal growth was achieved much in advance to that of control birds. The applications with 8‐hr temporal relation suppressed the testicular growth initially but later on this effect was eliminated by NDL of May‐June. In Experiment 2, photorefractory birds also received the treatments but the temporal relation of 5‐HTP and L‐DOPA had no effect on the regressed gonads of these birds.