What might’ve killed one of my chickens?

[Snakebiteholloway]

I have a flock of about 60 chickens who free range all day everyday, im surrounded by some woods which unfortunately some of my chickens seem drawn to. 1 1/2 weeks ago when I did a head check at night I noticed one of my marans was missing, I went looking for her in my barns and some of the surrounding areas but it was too dark and I just didn’t know where to even start looking, the next day I went into the woods and found piles of her feathers but no body (which makes sense, her body was left out overnight). Tonight the same thing, just one chicken missing but this time it was my chocolate orpington hen. I checked the same place I found the other and I found piles of her feathers and she seemed to be dragged just a couple steps away, ate from a little (not the crop & the head was still attached, her skin was flapped off and I could see some of her exposed ribs) The weird thing is she was partially buried so whatever killed her was definitely coming back later, and she was a big bird too very chunky. I’ve never dealt with something that took the time to bury their kill AND never came back for more chickens because it definitely could’ve, my chickens go everywhere. Please help !! I live in southern Michigan if that helps.

Sound like fox or bobcat kills. Both bury, both start at the gut sack. I think fox because it's not in a tree. Up here, bobcats raise their prizes of the ground. Also bobcats are far less likely to approach dwelling areas.
In 7 years I've seen dozens of bobcats but lost no birds to them.
Foxes, on the other hand, are ravenous. It's also birthing season. But they will come back repeatedly to kill and cache away everything they can catch.
Don't forget foxes are more feline than canine. We have literally hundreds up here in N Maine and (sorry animal lovers) i shoot every one i see because they will return again and again and again until you have no more chickens. You have to sit in a high hide and snipe them at night over bait. Exhausting. They are very canny. Supernaturally so!
Here they're always mangy and nasty, too, and disease vectors. Rabies is bad here.
Traps DO NOT work. Poison bait does not work. Plus I'm opposed to random poisoning for dangers to other non- invasive animals.
I lock my girls into hardware cloth protected coops at night. Double secured. I no longer let them free range. Sadly.