My boars keep dying. I come to the pen, and several are gone, just vanished. Sometimes there will be leather and meat, sometimes not. I have a large pen for them, with two shallow ponds; log fence against predators, spikes on the outside, and several workbenches inside to stop enemies from spawning inside the pen. And YET my boars keep dying. I should actually write a song about it, but I am too annoyed. Is it possible that they kill each other??