We had a similer experiance (only my ditzy mom just all the new birds out). Of 25 birds we got 19 back. The best trick was to go out a night with a pole and a flashlight--if you can't sneak up and grab them, knock em off and they are so much easier to catch than in the day. The last 3 came back of there own accord to try to get in the fence with the others. We have the normal preditors here (I could hear the coyoties going crazy two nights after they ran), but many roosted high up and lived on their own for a few days before being caugth or disappearing.
Yesterday at noon after church we drove into the yard, we watched the hen walk toward the garage, we drove toward her and she ran in there and I jumped out of the car shut the garage door, and caught her with a fishing net, cut her flight feathers and shes safe in sound
Yup I got them all! now I spend 5 mins a day with each trying to tame them, I put hawk netting up even know it looks super tacky, it helps them stay in and hawks out.