Walter Burkert writes,
It is striking how widespread the practice of bird-watching is in divination: observation of the flight of birds, especially birds of prey, is evident in the dominant practice of ancient ornithomanteia, as well as ancient poetry. To explain how this came about one might speculate about aboriginal humans or proto-hominids being scavengers: if so, it was helpful – indeed necessary – for them to observe birds of prey, especially vultures, in order to find food. In foundation legends, the hero is often instructed to follow an animal; this seems to recall a hunter’s practice. If so, we would be able to see a shift from practical to purely symbolic and hence much more generally applicable behavior in divination, to “superstition” in the full meaning of the word.
Now I have a few problems with this, too many “ifs” strung together for one thing. To be sure, Burkert clearly labels his speculation as such. I also wonder about the range of the “full meaning” of superstition. By the way, I’m not sure that Burkert’s speculation requires that our ancestors be scavengers. Birds of prey might also direct hunters to living game. While I’m not sure how to confirm any of this, I do like the attempt at a natural explanation of the origins of divination.
Burkert might have noted the association between birds and mortality and role of eagles as the massagers of Zeus. Although I’m not sure what to make of it, one might also want to check out the vulture carving from Neolithic Göbekli Tepe.