Fig. 4. Mechanical advantage (corrected for muscle length L) for representative species calculated with (solid line) and without (broken line) the uncinate processes. (A) A diving bird, the razorbill Alca torda; (B,C) non-specialist birds, (B) barnacle goose Branta leucopsis and (C) kestrel Falco tinnunculus; and a walking bird (D) the red-legged partridge Alectoris rufa.