Figure 1.

The corticosterone stress response in female and male snow buntings at Thule, Greenland. Birds were sampled during arrival onto breeding grounds, incubation, the nestling stage, and during molt. Females had higher baseline corticosterone than males (P = 0.03), but were not different in integrated corticosterone (area under the curve; P = 0.92). Across stages, baselines were again similar (P = 0.11), but integrated corticosterone during molt was lower than the three other life history stages (arrival: P < 0.001; incubation: P = 0.01; nestlings: P = 0.02). Within females, baseline and integrated corticosterone were similar across stages (P = 0.01 and P = 0.34, respectively). Baseline corticosterone was similar across stages for males (P = 0.10), but integrated corticosterone was higher at arrival as compared to nestling and molt stages (P < 0.05 and P < 0.05, respectively). Sample sizes are included in parentheses.