The word ferret has its origins in Latin and translates to little thief. With that tidbit of knowledge, it shouldn’t surprise you that ferrets like to steal things and hoard them.
My ferrets take anything they can drag. I’ve seen my little, one pound girl try to carry off the dog’s sterilized bone; the bone weighs more than she does. (The only reason she didn’t succeed is that the dog saw her dragging the bone across the room and intervened.) They have appropriated my shoes, my wrist brace, and stuffed toys. They have snatched bookmarks, balls, and food dishes. They have pilfered computer mice, tissues, and socks. They have removed apples, potatoes, and staple removers. If they can pirate an item, they will.
So, after my ferrets acquire an object of desire, they hoard it. Just about every stolen thing ends up in the same place. After I clean, they might relocate their stash, but there’s usually only one cache at a time. I’ve found the cache under their cage. One time the stash was behind the television and one time they actually put everything inside one of my husband’s speakers. Currently, my babies like to relocate objects to inside their Tower of Fun, a tube that twists up and down. The fuzzies like to slide down the slopes of the Tower of Fun, so it’s a little strange that they block their fun sliding route with toys. Yet, 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 (who our domesticated ferrets have been domesticated from) are carnivores. They’re hunters. They kill things smaller than themselves (usually smaller, but I’ve seen videos of ferrets killing things larger than they are). So, a ferret kills a mouse and eats it. When it’s done, it will hide the leftovers. If a ferret kills an animal that is too big to eat in one sitting, the ferret will stash the corpse to finish later. And, in all of these instances, ferrets are trying to prevent other animals from gaining their spoils.
I think that’s probably the best explanation for why ferrets steal, but I have one other thought. Frequently, I find ferrets asleep amidst their stolen treasures. Usually, when they sleep in their cache, the items are soft and squishy, like small stuffed toys and other fluffy things. So, my second hypothesis is that ferrets like to build cozy beds.