When your dog buries a bone, toy or any other object he finds valuable, it's a sign he's in touch with his animal instincts. In the wild, dogs instinctively bury things they care about, especially food items like bones, to keep them safe from other animals that might otherwise steal them.
Buried for Safekeeping
If your dog doesn't finish off a bone in one sitting, he can't stick it in a drawer or the refrigerator for safekeeping, so he buries it. This is an instinct programmed in him by his ancestors, who would bury unfinished meals to hide them from predators. Sometimes, a wild dog buries, unearths and reburies his leftovers in a different spot to throw off would-be thieves. When your pet buries a bone, it means that even though he is domesticated, he still retains some of his wild animal instincts.