We investigate methods for physically-based simulation of aerodynamic forces acting on a flapping bird in free-flight. We make use of two previous studies as the basis for our work; Jeffery Wang's digital Ivory-billed woodpecker model, and Brendan Holt's high-speed kinematic motion capture data of a Red-winged blackbird (Agelaius phoeniceus ) in free flight. These studies provide an extensive framework in which to model a high-resolution, morphologically accurate Red-winged blackbird, which we animate to undergo a physically accurate wingbeat motion. To complete the geometric picture, we laser scan individual feathers to obtain the complete wing geometry. Adapting the detailed character rig of the Ivory-billed woodpecker to suit the smaller Red-winged blackbird, motion picture techniques allow us to pose and animate the digital bird to match the motion captured joint kinematics. Several methods of aerodynamic simulation were considered, including wind tunnel testing and computational fluid dynamics (CFD), before ultimately implementing a quasi-steady blade element model. Performing aerodynamic simulations on this animated mesh yields forces on the bird which support the validity of the model. Although the model is unable to account for the entire weight of the bird, it is within the bounds of error and provides an interactive first order estimate.