I also have a free range flock.
My deturents are 3 guardian dogs a a small flock of guineas. I dont have any real close neighbors tho or guineas could cause problems because they are noisy.
I have 7 game cameras and have lots of native preditor pictures except the cougar. Hes been sighted and tracks found but has not walked I. Front of my camera yet.
The guineas are great alarm makers and will sight a preditor before anything else sees it, (including me).
The dogs patrol the yard and barn area and are off like a shot when the guineas make alarm or when they catch scent of a preditor.
Nothing is 100 persent for protecting your chickens except total confinement.
I lost about 5 chickens last year, which actually is pretty good.
I've lost plenty of roosters during my chicken raising years. A brave rooster is usually a dead rooster when it comes to fox and coyote.
Again, there real job is to alarm in time to usher everyone to safety. And I loose guineas too, and they are pretty smart and savvy.
Good luck!