With their long, featherless necks and stern-looking faces, vultures are an easy target for people's fear and loathing. In books and films, they usually appear as a forewarning of bad things to come.

What image comes to mind when you hear the word vulture? When I close my eyes, I picture omens of death, circling ominously overhead as if in an old Western movie. Or my stomach is turned by imagining ...