Oxidative balance in birds: an atoms‐to‐organisms‐to‐ecology primer for ornithologists

All air-breathing organisms must face the challenge of oxidative damage, and understanding how animals cope can lend insight into their ecology. Unlike other vertebrates, birds rely primarily on fats to fuel endurance exercise such as migration, and therefore face a greater potential for damage from the reactive by-products of their own metabolism. We review the physiological ecology of migrating birds through the lens of oxidation-reduction chemistry, underscoring how oxidative balance in wild birds may affect their dietary choices and use of critical stopover habitats during migration. Recent studies reveal that migratory birds prepare for oxidative challenges either by up-regulating endogenous antioxidants or by consuming them in their diet, and they repair oxidative damage after long flights, although much remains to be discovered about how birds maintain oxidative balance over the course of migration. We conclude by describing some of the most used and useful measures of antioxidant status and oxidative damage that field ornithologists can include in their tool kit of techniques to probe the oxidative balance of wild birds.