Hello, Janet! My chickens, ducks and geese "free range" during the day, but only in the fenced off portion of the yard where I can see them (except when a brave few escape into the sheep and goat pens) and hear them.
Before the fencing, the ducks liked to wander to the back of the property and swim in an old canoe -- until a mink put an end to Hadley and the fencing went up. Unfettered free ranging means you are more than likely to lose birds.
So, the standard "safety" advice is: coop them at night, use hardware cloth (not the badly named chicken wire) to keep out predators, and always keep your guard up because everything wants to eat your chickens. Raccoons have incredibly nimble fingers, so most of my coops have double latches -- one vertical and another horizontal -- and I run a carabiner through the slide bolts so they can't be opened.
Despite all that serious stuff, having chickens is and should be a great experience. Enjoy their antics, their eggs and all that you can learn from creatures that just live in the moment.
Welcome to BYC! Hope your birds all stay safe!