I had a chicken taken by a fox last year and there was a huge pile of feathers in the yard! It was in April and I saw it going away and my dogs found the huge pile of feathers. It was at first light, the girls were going crazy and another one came walking right by the back of my house no 15 minutes later. I think foxes hunt all times of the day when they have pups, but it is probably too early for that in most places right now. Sorry for your loss.