Fig. 1. Effects of prior exposure to restricted feeding regimes on subsequent photoperiodic induction of seasonal responses in photosensitive male Red-headed Bunting (Emberiza bruniceps). Birds (N=6–8) were first exposed for eight weeks to dim 12 h light: 12 h darkness (12L:12D; L=5 lux, D=0 lux) with restricted feeding (RF) regimes [6 h food present: 18 h food absent, P:A 6:18 (group 1, open circle) or P:A 12:12 (group 2, closed circle)] and then subsequently subjected for another 13 weeks to a highly stimulatory photoperiod (16L:8D; L=400 lux; D=0 lux) with food ad libitum (free food, FF). The vertical dashed line indicates the boundary between the 12L:12D and 16L:8D exposures. The response was recorded as changes in fat deposition and body mass, testis growth, body molt (or regeneration of feathers) and wing primary molt at intervals of 1–4 weeks during the 21-week experiment. In all figures, means (±s.e.m.) of the collected data are presented. Clearly, the exposure to restricted feeding regimes had an effect on subsequent induction of reproductive functions (e.g. testis growth and development).