Don't let young (not full sized) bird free range. They are easy targets. Recently some wild game chickens that live in my yard fought a hawk. I came around a corner just in time to see 3 of the wild roos flying at the hawk while a hen tried to flee with her babies. They sucessfully drove the hawk away. It was an impressive fight! The next day, the hawk won the fight and left with a 3 week old chick dinner. So, I guess my point is, hawks are good at carrying off baby chicks no matter how brave a roo or roos are.
