(a) Body mass (C-males n = 20, FC-males n = 23), (b) corticosterone concentrations (C-males n = 19, FC-males n = 22) and (c) glutathione peroxidase (GPx; C-males n = 19, FC-males n = 22) concentrations of males on chick days 7 and 12. Different capital letters indicate a significant difference between days 7 and 12 (Tukey's HSD post hoc tests). Thin solid lines: positive individual changes, thin dotted lines: negative individual changes, thick lines: group least squared means (±1 s.e.m.).