The mechanical power output of the flight muscles of blue-breasted quail (Coturnix chinensis) during take-off

Blue-breasted quail (Coturnix chinensis) were filmed during take-off flight s. By tracking the position of the centre of mass of the bird in three dime nsions, we were able to calculate the power required to increase the potent ial and kinetic energy. In addition, high-speed video recordings of the pos ition of the wings over the course of the wing stroke, and morphological me asurements, allowed us to calculate the aerodynamic and inertial power requ irements. The total power output required from the pectoralis muscle was, o n average, 390 W kg(-1), which was similar to the highest measurements made on bundles of muscle fibres in vitro (433 W kg(-1)), although for one indi vidual a power output of 530 W kg(-1) was calculated. The majority of the p ower was required to increase the potential energy of the body. The power o utput of these muscles is the highest yet found for any muscle in repetitiv e contractions. We also calculated the power requirements during takeoff flights in four ot her species in the family Phasianidae. Power output was found to be indepen dent of body mass in this family. However, the precise scaling of burst pow er output within this group must await a better assessment of whether simil ar levels of performance were measured across the group. We extended our an alysis to one species of hawk, several species of hummingbird and two speci es of bee. Remarkably, we concluded that, over a broad range of body size ( 0.0002-5 kg) and contractile frequency (5-186 Hz), the myofibrillar power o utput of flight muscles during short maximal bursts is very high (360-460 W kg(-1)) and shows very little scaling with body mass. The approximate cons tancy of power output means that the work output varies inversely with wing beat frequency and reaches values of approximately 30-60 J kg(-1) in the la rgest species.