The word ferret has its origin in Latin and is translated as pilferer. With that tidbit of knowledge, it shouldn’t surprise you that ferrets like to steal things and hoard them.
My ferrets take everything they can drag. I’ve seen my little one pound girl try to take the dog’s sterilized bone; the bone weighs more than it does. (The only reason she was unsuccessful is that the dog saw her dragging her bone around her room and intervened.) They have taken my shoes, my wristband and stuffed toys. They have taken bookmarks, balls and food dishes from him. They have stolen computer mice, handkerchiefs and socks. They have removed apples, potatoes and staple remover. If they can hack an item, they will.
So after my ferrets acquire an object of desire, they hoard it. Almost everything stolen ends up in the same place. After cleaning, they can relocate their stash, but there’s usually only one stash at a time. I found the hiding place under his cage. Once the hiding place was behind the TV and once they put everything inside one of my husband’s speakers. These days, my babies like to relocate objects inside their Tower of Fun, a tube that spins up and down. The furry ones like to slide down the slopes of the Tower of Fun, so it is a bit strange that they block their fun slide route with toys. However, they do.
Since I don’t speak ferret, and my ferrets don’t speak human, I can only guess based on their natural behaviors in the wild. Polecats (from whom our ferrets have been domesticated) are carnivores. They are hunters. They kill things smaller than themselves (usually smaller, but I’ve seen videos of ferrets killing things larger than themselves). So a ferret kills a mouse and eats it. When it’s ready, it will hide the leftovers. If a ferret kills an animal that is too large to eat in one sitting, the ferret will hide the carcass to finish it later. And, in all of these cases, the ferrets are trying to prevent other animals from getting their loot.
I think that’s probably the best explanation for why ferrets steal, but I have another idea. Frequently, I find sleeping ferrets in the midst of their stolen treasures. Usually when they sleep in their cache, the items are soft and cuddly, like small stuffed toys and other fluffy things. So my second hypothesis is that ferrets like to build cozy beds.