Figure 2

Medium-term (within-season) effects of an experimental handicap on the trade-off between reproduction and self-maintenance in skylarks. A) – E) Adult body mass and immune parameters ca. 5 weeks days after experimental initiation. Values are expressed as the difference between second and first broods. F) – H) Nestling body mass and immune measures in the offspring from control and experimental parents; the latter were assigned to treatment during first broods. I) Average length of animal prey in droppings of nestling skylarks. J) Proportion of the main prey type (beetles, order Coleoptera) in the diet of nestlings. Bars depict mean and standard error. Numbers represent sample size of individual birds. For nestlings the number of nests is given in parentheses. Stars denote statistically significant differences. If both years or sexes are plotted, then the interaction with treatment was significant. Statistical analyses can be found in Results and Additional file 1: Table S2.