Sounds like dogs killed your flock. Only a Dog or Dogs kill 50 birds. Skunk smell may mean they tangled with the skunk too. Too bad we cant breed chickens that can spray like a skunk! The feeding is most likely someone feeding on free pre-killed food. Racoon, Skunk or other. very sorry for your loss. Best wishes in catching the killers. Dogs may come back looking for more fun. Keep your eyes open.