If a chicken run is built with half-inch welded wire on top, sides and bottom (buried), it will be basically predator proof.
Another alternative is to keep them inside a wooden coop and only let them roam about outside in your presence.
If you’re rural enough to have roosters, they will protect from skunks and weasels at least.
It would take some doing, but it could be done.
I’m rural enough...Live in the middle of the state forest.....Click on Hoo-mama ...pictures are small...but will replace someday.
Now I wonder if the border collie would help...She and the cat are best friends and nothing or no one bothers her cat.