I recently saw an article that suggested using twine to discourage airborne predators. It can be randomly strung across an open area to disrupt the flight pattern of hawks. If the area isn't too large, it's an inexpensive easy fix. My girls have about 100 ft by 60 ft of open area for free ranging and I was considering netting, but with trees from my yard and my neighbors yards shedding so many leaves in the fall, it didn't seem practical. I was also concerned about small song birds getting trapped. Haven't had hawk problems yet, or installed the twine, but will likely be doing that this spring.