Figure 5. Corticosterone (CORT) concentrations in house sparrow feathers plucked before (pre-feeding) and after (post-feeding) five weeks of exposure to either a 1% oil (n = 8) or a control diet (n = 7).

Each animal's feather CORT value was determined by averaging feather CORT concentrations from two different flight feathers - primary 3 from the left wing and retrix 1 from the left side of the tail. Values are presented as mean ± SEM.