The only harpies ever seen have always been female, with a woman's body wed to a bird's wings and talons. Some speculate that they reproduce by mating with human men.
While they may appear beautiful, harpies are very violent and cruel. Thus, not much research has been done on them... but what of their chicks? Surely, a smaller, weaker subject would be much less of a problem to deal with...
However, the researchers were wrong. The hungry chicks devoured the researchers, and any thoughts of communicating with them have been destroyed.