1. Fig. 4 Foraging parrotlets select takeoff angles that minimize the mechanical energy needed to extend long jumps with flapping wings.
Foraging parrotlets select takeoff angles that minimize the mechanical energy needed to extend long jumps with flapping wings. The long jumps of parrotlets and their antecedents are greatly extended by (proto)wingbeats. (A) The mechanical energy required to long jump and fly between perches depends on takeoff angle, distance, and inclination. Circles mark actual average takeoff angles used, and bolded regions denote SDs, showing that parrotlets preferred close to optimal long jumps. (B) Even one proto-wingbeat, with modest aerodynamic weight support during the downstroke and an inactive upstroke, extends the long jump range of all birds and their antecedents substantially [bird antecedent masses; (35)]. The increase in energetic cost required is offset by foraging gain. More powerful wingbeats require a smaller body mass, consistent with evolutionary trends in bird antecedents (37). Simulated proto-wingbeats were limited to those that would require a muscle mass–specific power within what parrotlets require for a downstroke with full weight support (see Materials and Methods for details). The vertical dashed line indicates 30% bodyweight support, which smaller bird antecedents were likely capable of generating with their protowings (35). The open circle (mean) and bolded region (±SD) on the parrotlet curve show the predicted increase in the long jump range based on the measured exerted impulse during 20-cm flights (N = 4, n = 5; except for two flights, where the bird did not flap its wings).
Diana D. Chin, and David Lentink Sci Adv 2017;3:e
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