Meeting Abstract
Sexual dimorphism is widespread in bird species, but the consequences of this dimorphism upon flight performance is not well understood. Hummingbirds are useful models for studying the biomechanics and physiology of avian flight. Most studies of hummingbird flight are conducted in controlled conditions in the lab, and only recently have techniques made it feasible to examine details of their flight outdoors. In hummingbirds, males typically have smaller body mass, lower wing and disc loading, and larger flight muscles than females. We undertook the present study to test whether sexes differ in escape performance during free-flight in the field. We used high-speed video (three Hero3 Black GoPro, synchronized) to record 15 flights of male and 17 flights of female Selasphorus calliope escaping from a startle perturbation while they were foraging at an outdoor feeder. Peak and average velocities were almost the same in both sexes. Peak and average accelerations were higher in male hummingbirds, but only the latter difference was statistically significant (peak acceleration, p = 0.38, average acceleration, p <0.05). Overall, male hummingbirds were found to perform shorter, more accelerated flight than females in the field during escape. This result suggests sex should be taken into account when testing hypotheses of hummingbird flight performance and behavioral ecology.
