<p>Migration exerts a selective pressure for increased flight efficiency and reduced energy expenditure in long-distance migratory birds. In North America, eastern migratory flyways are longer and require flights over open seas, whereas western flyways are shorter and primarily over land. This should result in higher selective pressure for higher flight efficiency in birds using the eastern flyways. We tested this prediction by comparing the flight morphology of 47 species of North American wood-warblers (Parulidae). Interspecific comparisons using phylogenetic regression models and intraspecific comparisons using phylogenetic paired t tests showed modest differences in flight morphology between eastern and western wood-warblers, with most differences instead associated with migratory distances. We discuss the potential role of foraging behavior producing tradeoffs in the optimization of the flight apparatus of some species. Gleaners and ground dwelling species, which rarely use their wings during foraging, tend to have elongated wings and short tails suited for long-distance flights. In contrast, aerial foragers tend to have broad wings and tails better adapted for maneuverability at low speeds but may compromise migratory efficiency. This study contributes to further our understanding of how morphological adaptations related to flight performance may be shaped by different selective pressures.</p>