Are you suffering losses?
If yes, you may be able to deny fox with modest modifications to your night-time containment. Prior to present dogs, I had to tolerate fox coming into yard and patrolling pen area. I made so chickens roosted outside of fox's reach. If fox could make chicken bail from roost, then I had so fox could not work perimeter of pen easily. Fox would try to get chicken to walk to edge of pen where it could be grabbed. When fox was successful, this resulted in bird being decapetated or loosing a wing. It does not take much to make so fox cannot use this strategy. I also went out when birds were disturbed but this required opened window.
You can also use trap (live or otherwise) with penned birds used as bait. Such return foxes are easy to catch. Dispatch fox if captured live since homing abilities make relocation impractical.