Meeting Abstract
Increased oxidative stress associated with avian migratory flights could have a strong impact on energy stores (primarily fats) and in consequence, metabolism during and/or after migration. Migration-related adjustments and the strategies of energy usage could differ between seasons, but may also depend on the different possibilities and limitations of antioxidant capacity in autumn and spring. We used a dietary antioxidant manipulation (AO-low or AO-high) and wind-tunnel flight training over autumn and spring to examine its consequences for basal metabolic rate (BMR) and organ sizes. Female European starlings were flown over a period of 15 days, a total of about 600 km. We found an interactive effect between diet and season that resulted in about ~20% higher BMR in AO-high diet birds in autumn, but with no difference in spring. A similar pattern was observed for the pooled mass of heart and flight muscles (~5% higher in AO-high). Pooled mass of kidney, liver and gut differed only between seasons (~9% lower mass in spring). This indicates that dietary antioxidants can modulate the avian energetics through changes in organs capable to generate a high workload, however, this effect is season-dependent. Improved flight machinery may allow faster migration, but with higher energetic costs. The need for greater energetic reserves upon the arrival at breeding grounds may constrain physiological adjustments during spring migration, although birds may still profit from a high antioxidant capacity and refuel or recover faster after migratory flights. Supported by NSF (IOS-0748349 to S.R.M. and B.J.P.) and NSC Poland (2015/19/B/NZ8/01394 to U.B.)
