I free range both my adult chickens and my ducks. I have a seasonal creek, lots of willow and brush to hide in but overall, a very open couple acres. I see bald eagles every day. Hawks every day.
I lost my favorite bantam to a hawk. She was in a covered run where the littles get used to the great big world. It killed her through the wire.
I lost my favorite EE and a duck to a coyote (found her feathers along with the neighbor's cat on a path they use near the property line).
I have had out of control neighbor dogs tearing apart my pens, caught one with my Welsummer in his mouth - (she lived) and chasing my birds in a free for all. The humane society won't come out for animals attacking on your property, but if you say that the owners are mistreating the dogs, THEN they show up

Dogs removed. Problem solved. That and letting the neighbor know that their dogs are going to be fertilizer if they are caught again.
I have lost a duck to a mink.
I still can't find it in me to pen up my birds. Every year, I get better at battling the predators. A .22 pellet gun works really well for most and having pigs on the property has completely gotten rid of the coyotes and mink. I have big dogs too, but those turds sleep inside.
I do make sure to have super secure night enclosures/coops and I haven't had any breaches of my coops ever.
I know that I will lose birds in the future to predators, but I also know that my birds are so happy and healthy. Nothing makes me happier than coming home from work and getting followed to the door by silly chickens wanting their daily meal worm treats...