Fig. 1. (A) Planar view of the left foot of the great cormorant showing the webbed area of the foot (gray) and its span, measured from feet of carcasses. The feet and tarsusmetatarsus (TMT) are rotated 16° clockwise in the lateral (XZ) plane during the stroke. Also shown are points 4 and 5, which were used for kinematic analysis of the foot motion in the trained birds (see text). Point 4 is the joint connecting the tarsusmetatarsus (TMT) with the foot, and point 5 is the tip of digit IV. (B) Planar and (C) lateral views of the great cormorant during swimming (not to scale), showing the digitized points used for the kinematic analysis. Black dots are actual points on the body, red and yellow circles are the glued tags, and the empty circles are points calculated trigonometrically using two other points. Points visible in lateral view are: tip of the bill (1), base of the neck (2), mid-body (3), base of the foot (4), tip of digit IV (5), base of the tail (6), tip of the tail (7) and the center of mass (8). Points visible in the planar view are: tip of the bill (9), base of the neck (10), mid-body (11), tip of digit IV (12), base of the tail (13), tip of the tail (14) and the center of mass (15). Points 16 and 17 in the lateral view are the points of maximum curvature of the ventral and dorsal sides of the body. With point 6, they are used to define the general slope angle of the curves of the back of the body. Also shown are the division of the body's long axis into three subunits (analyzed separately in the kinematic analysis), and the definition of the tilt angle of the tail (_T), body (_B) and neck (_N), relative to the mean swimming direction (red, dotted arrows).