"We do not live next to open space."

Earth to Bob. You're in Colorado. The entire damned state is open space as far as wildlife is concerned, especially foxes and coyotes. If you're going to put a tasty snack out for them, expect them to sniff it out and go for it like a plate of unguarded brownies as a Weight Watchers convention or an unguarded six-pack of beer at a fraternity party.