I have lost one rooster (went first) and two hens across three weeks now. I'd gone almost two years without anyhting happening. Now I'm losing one a week.
I generally let them out of the coop & run to range all afternoon & evening, and they come back into the coop themselves at dusk. I suspect it's a fox, and am pretty sure it's happening in the evening.
I'm not letting them out to range right now, until I figure out how to handle this. My run is VERY secure, and I know it's happening when they are out in the yard. I have 10 acres, some of it bordered by fields. If it were a hawk, I think I would have heard it.
How do you take care of a fox? I rarely see them, once in a while by surprise when I am in the car.