Fig. 1. Graphic scheme of applied experimental design. Body mass of sand martin nestlings at the beginning of the experiment, at the antigen injection (end of day 2, marked as solid vertical line), and at the conclusion of the experiment (end of day 3) are shown. AL, nestlings fed ad libitum; I, nestlings subjected to an intermediate feeding regime; FR, nestlings fed with a limited amount of food. Mean values (connected by broken lines for each feeding regime), and s.e.m. (vertical limits of boxes) are shown. Body mass changes during days 1-2 are referred to as body mass increments before injection, whereas body mass changes during day 3 are referred to as body mass increments after injection.