New Year's Day was about 45 degrees and sunny, so I let the chickens out to run in the pasture about 2:00. That would give them a couple of hours of "play time" before dark.
When I went out to do chores about 4:00, I found Slim Jim, my Black Australorp rooster and a Rhode Island Red hen in the lower corral by the hay storage. It's not unusual for the hens to be in this area, but I'd never seen the roosters in there. As I focused on Slim Jim, I thought, what happened to your tail feathers? It seemed odd that one of the other roosters would have pulled them all out. I picked him up to exam him further as there was a bloody spot on this tail. Under the wing feathers, he'd had a whole bunch pulled out of his body and there were some bloody scratches (not deep).
After searching the area better, I found a pile of tail feathers and then another pile of body feathers.
It appears that something tried to get Slim Jim - most likely a fox. But Slim Jim is a tough old guy and managed to get away and I think give all the hens time to escape. No hens appear to be missing (although when you have 70+ of them, it's a bit hard to tell).
The next morning a dusting of snow revealed fox tracks (possibly more than one). So I won't be letting the chickens out to pasture for awhile. But with the coming cold and snow they won't want to be out anyway.