Fig. 1. (A) Experimental setup (not to scale) and (B) anatomical points measured on the bird for kinematic analysis. (A) The height of the perches and the distance between them were adjusted to encourage birds to fly at prescribed angles of ascent and descent (Table 2). Three high-speed cameras, one dorsal, one nearer to the tall perch, and one to the side of the arena, were used to record flights (x-axis: horizontal direction between the perches; y-axis: mediolateral; and z-axis: vertical). (B) Birds were marked at several anatomical locations. The shoulder, wrist, wingtip and rump marks were digitized, as was the point on the trailing edge of the wing, directly behind the wrist in the x-coordinate. The position of the center of mass (CoM) was estimated by averaging the x- and z-coordinates of the rump and shoulder and using the y-coordinate of the rump.