Novice bird-watcher: I don' t know much about animal tracks, but I do know that birds typically have four toes, and most birds have three toes pointing forward and one toe pointing backward. Since this track was made by an animal with four toes, of which three point forward and one points backward, we can conclude it was made by some kind of bird. The argument is flawed because it ['relies on the vagueness of the term "track"', 'depends on evidence about an individual bird rather than about birds in general', 'does not define birds as animals with four toes', 'does not establish that only a bird could have made the track']