44.5 Thursday, Jan. 5 Ontogeny of aerodynamics in Mallard ducks: comparative performance and developmental implications DIAL, TR*; HEERS, AM; TOBALSKE, BW; Brown Univ; Univ of Montana; Univ of Montana email@example.com
Wing morphology correlates with flight performance and ecology among adult birds, yet the impact of wing development on aerodynamic capacity is not well understood. To gain insight into the effects of life-history strategy and ontogeny on wing function, we used a propeller and force-plate model to study aerodynamic force production across a developmental series of the precocial-flying chukar partridge (Alectoris chukar) and altricial-flying mallard duck (Anas platyrhynchos). In both species, coefficients of lift (CL) and drag (CD) increase throughout ontogeny. The chukar generated aerodynamic forces early (<8 days), yet improved gradually throughout a 100-day ontogenetic period. The mallard delayed aerodynamic force production until just prior to fledging (day 60), yet showed dramatic improvement within a condensed two-week period. In the adult stage, mallard wings exhibit higher lift-to-drag ratios (CL:CD= 5), at lower angles of attack (α=11˚) compared to chukar wings (CL:CD= 4;α = 15). Chukar generate less lift per unit drag but produce large resultant aerodynamic forces (vector sum of lift and drag) and rely on these at an early age to rapidly accelerate and escape predation. Mallards, in contrast, generate more lift per unit drag but produce smaller resultant aerodynamic forces – optimizing economy over maximal force production, delaying wing function and seeking refuge in aquatic habitats. Throughout development, feather microstructure (feather unfurling, asymmetry and barbicel overlap) more so than gross wing morphology (aspect ratio, moment of area or camber) correlated to lift generation (CL and CL:CD). The early onset of restricted ontogenetic change in chukar wing morphology and performance compared with the delayed, but radical, change in the mallard wing, implicate life-history strategy as a possible mechanism influencing locomotor diversity in the avian clade.