What would cause crows to be attracted to a human body? On another SE site, there was a comment that told me something about biology that I already know: "A man left murdered in the fields would soon have a flock of crows mobbing his fragrant corpse." But I don't quite understand why. Is it the "death" part,the fact that someone was injured/bleeding or just the fact the he was immobilized,that would attract the crows? That is suppose you tied up someone and left him on the field. Would that attract the crows? Suppose this person fell down, was bleeding, and immobile, but not seriously injured? Or is it the death part?

I think the key is _"his fragrant corpse."_ When an animal dies and begins to rot, a number of quite smelly chemicals are given off, including putrescine and cadaverine. Crows and other carrion birds like vultures are probably very sensitive to these compounds, rather like sharks are to the smell of blood.