摘要Background: Unlike resident birds, migratory birds are generally believed to have evolved to enhance flight effi-ciency; however, direct evidence is still scarce due to the difficulty of measuring the flight speed and mechanical power. Methods: We studied the differences in morphology, flight kinematics, and energy cost between two passerines with comparable size, a migrant (Fringilla montifringilla, Brambling, BRAM), and a resident (Passer montanus, Eurasian Tree Sparrow, TRSP). Results: The BRAM had longer wings, higher aspect ratio, lower wingbeat frequency, and stroke amplitude com-pared to the TRSP despite the two species had a comparable body mass. The BRAM had a significantly lower maxi-mum speed, lower power at any specific speed, and thus lower flight energy cost in relative to the TRSP although the two species had a comparable maximum vertical speed and acceleration. Conclusions: Our results suggest that adaptation for migration may have led to reduced power output and maxi-mum speed to increase energy efficiency for migratory flight while residents increase flight speed and speed range adapting to diverse habitats.