I had a fox problem earlier this year. But I actually saw the culpret. It was taking a chicken a day. I think it had kits. But my neighbor found a dead fox in the street (hit by a car) last week and I haven't had any losses this week. I have a dog but she is a senior and not as alert as she used to be.
Sounds like you may have both fox and raccoon. In my experience the fox will carry off it's kill and the only evidence you will find, if any, is a pile of feathers. But what you describe could be raccoon or mink or weasel and you need to get rid of whatever it is, or it will dessimate your flock. Trapping or an exterminator is in order as well as trying to keep your girls out of harms way by locking them up at night. Dogs are nice too. You could consider getting a dog to protect your flock. I understand the Great Pyrenees breed is a wonderful flock garding dog. But also a very big hairy dog too.