A buzzard pitched one of her eggs into the hawk's nest and, from that egg, a chick was hatched. Now the other chicks in the nest, being noble, did their dirt outside. But the buzzard's chick always fouled his own next. Seeing this, the hawk wanted to know, "Just who is defiling this nest?".

After a bit, the chicks told her about the buzzard's chick. So the hawk took heed and grabbed the son of a buzzard and pitched him out of the nest, declaring as she did so, "Of on egge y the brought butt of thy kind y maye naught", which is to say, "I drew you forth from an egg but I couldn't draw you away from your nature", and so the whole business was shattered.

(http://www.autoadmit.com/thread.php?thread_id=4008392&forum_id=2#36294073)