I mean something that can serve as a monster carrier pigeon between Instahard the gods, lift huge weights, abduct humans (recorded in many Indian legends) and shoot out lightning bolts doesn't sound like biology to me, rather more something artificial. Now perhaps all these legends of abducting and man-eating giant birds are nothing more than a rogue eagle or condor with too much testosterone in its system who, feeling threatened, attacked a lone Indian and like the fish that got away, the bird just grew and got embellished, and grew some more and got even more embellished until it reached ridiculous proportions and abilities. Well maybe.