You ended up being right. The turkey experiment is failing. She was down to 3 chicks yesterday. She is apparently walking a 2 acre circuit so much that they’re dropping away from the group from exhaustion one at a time. I have found two such chicks by themselves over 100 yards away from the turkey hen and clutch. Oh well.
The terrorfowl growouts are doing well. No negative effect I can see from the dog fennel. I turned them back out a couple of days ago. Free ranging them has cut their daily feed intake by half, and I may be too generous with how much I am giving them now.