Figure 3.

The effect of corticosterone treatment on tolerance to infection estimated using (a) body mass, (b) haematocrit and (c) haemoglobin. Open triangles and dashed line represent birds in the control group, open squares and dotted line represent the low-dose group, and solid circles and solid line represent the high-dose group. (a) Among birds implanted with the high dose, body mass was lower in birds with higher parasite burdens, and the slope was significantly different from the low-dose group or the low and control groups combined, indicating lower tolerance. (b) Birds in the high corticosterone group had lower mean haematocrit than birds in the other treatment groups. There was no difference in the slope of the relationship between haematocrit and parasite burden among treatment groups, indicating no difference in tolerance. (c) There was no difference in mean haemoglobin concentrations or the slope of the haemoglobin–parasite burden relationship among treatment groups.