Most preditors strike at night, I would worry about the coop itself being secure, mine freerange all day w/out a fence, but coop is SOLID(only loss was when son left the door open)
If your coop is solid and your birds go there, they should be fine. Only day predators are usually hawks, foxes, and dogs. Mine free range all day but we don't have foxes here and only two dog sightings in 10 years of chickens.