We have had a food waste caddy outside for some years now and the contents have always stayed undisturbed in between collections. It has a handle which pushes from the back, up over the top and down the front of it to lock it securely. It is not easy to open and requires some strength and dexterity. For the first time ever 'something' has managed to unlock it, tip it over and eat the contents.
What is the 'something'?!
PS UK-based, no bears - AFAIK.