Neighbor’s Backyard Chickens

My neighbors recently moved their chicken coop up against our property line. Video is from two weeks ago, but today I was out there saying hello through the fence and noticed a lot of animal bones, including a small skull. I live in the USA, SE state, and these people fit the stereotype of folks from this area. WTF are they feeding these chickens? I’d guess the skull to be possum/raccoon sized. The straight bones are the length of a chicken leg, but thicker. As long as y’all aren’t concerned, I’ll mind my own business unless I start smelling dead animals.