Change in circulating levels of (a) Beta-hydroxybutyrate, and (b) Triglycerides in plasma of European starlings over the 15-day flight-training for Trained birds (dark triangles and dashed lines) and over the same 15-day period for Sedentary birds that were not flight-trained (gray triangles, solid lines) in Experiment II. Plasma samples were collected in the early morning after an overnight without food on Day O (Pre-training), before the start of flight-training, on Day 15 immediately after the birds longest flight (Post-flight), and in the early morning after an overnight without food on Day 17 (1.5 days after recovery from the last flight). Body mass and date of measurement were included as a fixed covariate so that we report the results as least square means (LSM). Comparisons between Pre-training and Recovery indicate changes associated with the 15-day flight-training, whereas those between Recovery and Post-flight indicate changes associated with the longest flight on Day 15. Means with different letters across the three timepoints, and for the main effect of diet, are significantly different (p<0.05).