Make sure that in your orders menu, "Dwarves collect refuse from outside" is turned on, and that you have a big-enough refuse stockpile. I use two refuse stockpiles right next to each other, at least 20 spaces each. Set one to accept ONLY bones, skulls, and shells, and the other to accept everything EXCEPT bones, skulls, and shells.
In my experience, if your refuse stockpile is full, hunters won't return kills, they'll just let them rot instead of taking them directly to the Butcher's Workshop.
The "He doesn't care about anything anymore" is actually a good trait for a hunter, it means he won't get a negative thought for "witnessing death" or whatever.
Good advice.
I should explain, however, that he doesn't actually "witness death" anymore, he just maims the animal and leaves it there to bleed, throw up, pass out, bleed, wake up, throw up, bleed, pass out, wake up, crawl a few spaces in a desperate attempt to reach its little groundhog hole, throw up, and bleed to death. He can't return anything that isn't dead, as far as I can tell, though it still shows up under his kill list.
Then you would have had monkey pieces filling up your refuse pile. And although im not that experienced in the Adventure mode nor tend to give my dwarves blunt weaponry, i think the corpse needs to hit an obstacle to explode, which is completly possible as i have no cluse how the combat zone looks like.
Anyway. a butcherer needs to process the rangers victims for the cook to make it into some edible, and the dwarves need to have the order to gather outside refuse to fetch any corpses lying around.
In Adventurer mode, I once had a guard play golf with me.
He chopped off all my limbs save one only because another guard was holding me by it, and swung his hammer so hard that I ripped off of my arm and was sent flying an entire screen north into a plain, where my body exploded.
There's no possible way this could happen, as far as I could tell, but it does at least prove the the ground is, in fact, an obstacle.