Boxplots of diurnal variation of concentrations of glucocorticoid metabolites (GCM; ng/g droppings) of Blue-fronted parrots (Amazona aestiva), kept under natural light variation (sunrise: 06:23 a.m.—sunset: 06:03 p.m).

Respective median values are showed as a line in the boxes. Lower and upper boundaries of the boxes indicate the 25^th and 75^th percentiles, respectively. Whiskers above and below the box indicate the 90^th and 10^th percentiles. Outliers are show as points. Asterisks beside the box indicate significant differences compared with the 5 to 8 p.m. interval (P ≤ 0.005).