My name is Totoro!

This is Totoro, I found him outside of a dollar general aimlessly wondering and asked staff and customers if he had an owner or if anyone knew any thing about him. I was told that he’d been there all morning and that was all, I took him home and immediately scoured the internet for missing dog posts that resembled him but wasn’t able to find a match. I don’t know the exact breed but guessing by physical appearance he’s either an American Pit Bull Terrier or Staffordshire Terrier. Totoro has been with us for 2 months and has shown no sign of behavioral issues towards adults, children or our small pets, HOWEVER, he HAS killed 5 free range chicken (wont eat them). I’d resolve that with proper enclosure but they're my grandfather’s and he’s not keen on that idea and restraining dog via leash to tree is restricting him to one quarter of the yard which I am not comfortable doing. I have bathed, carried AND force fed him dewormer, hasn’t once growled or attempted to bite.