You will be surprised at how long they can be gone and still return unscathed. I actually just had a Cockerel return the day before yesterday that had been missing for 4 days. I had been looking non-stop for him as he was free-ranging so I figured he had decided to sleep in the bushes instead of...
I have had them fly out and them hide for the night. Another member here I believe had one attacked and packed off but he returned a couple days later running down the road.
I would suggest getting some netting for the top of your pen for future incidents.
@RavynFallen