We never had a problem with hawks during the years we had our chickens pastured with our sheep. The chickens always hung out with the sheep in the pasture. They moved along with them as they grazed and lounged with them when they'd lay down to rest.
We have perimeter fencing and the chickens are locked up securely at night. Our biggest daytime problem is hawks. I do think that having a larger animal or even large birds like turkeys or geese can help keep chickens safe from hawks. It's not like they are all going to fend off a pack of wolves or a bear, but I do think they help with hawks.