Hummingbird Flight Speeds

Abstract

ABSTR^CT.--Long-tailed Hermits (Phaethornis superciliosus) normally fly faster than the ve-locity predicted to minimize their cost of transport. The average speed we measured for individuals flying a known 40-m course was 11.5 m/s. Rapid flower visitation yields rewards that could compensate for the extra costs of fast flight. Received 2 March 1984, accepted 30 July 1984. How fast should a bird fly? Intermediate flight speeds that minimize instantaneous power costs (Vmp), or more realistically that minimize the cost of flying a certain distance (Vm,), can be predicted from aerodynamic the-ory that is devoid of ecological context. The potential for minimization of power costs at intermediate speeds emerges from the U-shaped form of the relationship between power costs and flight speed (Fig. 1; Pennycuick 1969, 1975; Greenewalt 1975).