Upgrade to a rooster who actually do his job. Silkie roosters are pretty much useless. Get a large, aggressive rooster that can fight. My legbar boy for example is a hawk killer and he is ready to fight predators as large as dogs.
If everyone killed bird of prey because they attack their chickens, there would be no more birds of prey. I live near a national park, it's full of hawk and never had a problem. Get rid of your lazy fluffy rooster and get a real one. It's your rooster's fault if you lost birds, not the hawk. The hawk is just trying to survive.