DIAL, K.P.*; TOBALSKE, T.W.; Univ. of Montana, Missoula; Univ. of Portland, Portland: WAIR Flow: Ontogeny of wing aerodynamics during incline running in birds.

A survey of diverse avian clades (e.g, Tinamiformes, Galliformes, Columbiformes, and Passeriformes), shows wing-assisted incline running (WAIR) to be a plesiomorphic locomotor behavior. This includes Australian brush turkey chicks that are capable of aerial flight the day they hatch but preferentially perform WAIR and are more proficient and effective at it than adults. To further our understanding as to how incipient and fully developed wings function during WAIR, we present preliminary data from digital particle imagery velocimetry (DPIV) for three age-classes of chukar partridge: 5 day (23 g), 42 day (200 g) and adult (600 g). We measured circulation in the wake of the birds as they ran up inclines varying from 65 � 90 degrees above horizontal, and we estimated lift production using the measured circulation coupled with 3D kinematic analyses of wing movement. All three age classes produced lift during downstroke, but lift scaled proportional to M^1.8, representing only 30% of body weight in the youngest birds and 3.5 times body weight in the adults. Impulse per downstroke revealed that lift was directed 12 � 34 degrees into the substrate. This is consistent with the hypothesis that wings function to increase traction during WAIR. Peak vorticity and circulation scaled positively with body mass (M^0.26 and M^0.72, respectively). These patterns reveal, for the first time, the effects of wing ontogeny on forelimb aerodynamic function during incline running in birds. NSF IBN-0327380 and IBN-0417176.