Figure 4

Length of barbs in barn owl and pigeon wing feathers. The normalised length of barbs of the inner (iv) and outer vane (ov) of remiges (A, B) and coverts (C, D) from the barn owl (A, C) and the pigeon (B, D) are shown. The length was measured from the base to the tip and then normalised with respect to the whole length of vane. The area outside the dotted lines indicates regions of unconnected barbs forming the plumulaceous barbs (in both species), the fringes (in the barn owl) or serrations (p10 and gpc10 in the barn owl).