The word ferret originates in Latin and translates into little thief . With that bit of knowledge, it should not surprise you to fire like stealing things and raising them.
My fries take everything they can pull. I have seen my little one-pound girl trying to carry the dog's sterilized bone; The leg weighs more than she does. (The only reason she did not succeed was that the dog saw her banging her leg over the room and grabbing.) They have shoved my shoes, my wrist strap and stuffed toys. They have snapped up bookmarks, balls and dishes. They have pilfered computer mice, tissues and socks. They have removed apples, potatoes and staples. If they can pirate a subject, they will.
Then, after my fritters conquered an object, they cut it. Almost all stolen things end in the same place. After I've cleaned, they can move their stash, but there's usually only one cache at a time. I have found the cache under their cages. Once stash was behind the tv and once they actually put everything inside one of my husband's speakers. At the moment my babies can move objects to their Tower of Fun, a pipe that twists up and down. Fuzziesne slides down the ship in the Funen Tower, so it's a little odd that they block their fun moving trail with toys. But they do.
As I do not speak fruit, and my fries do not speak humanity, I can only guess from their natural behavior in nature. Polecats (as our domesticated fritters have been domesticated from) are carnivorous. They are hunters. They kill things that are smaller than themselves (usually smaller, but I've seen videos of fritters killing things that are bigger than they are). So a fruit kills a mouse and eats it. Once done, it will hide residues. If a fruit kills an animal that is too big to eat in one session, the seed will stop the body at the end later. And in all these cases, fritters try to prevent other animals from getting their swapping.
I think that's probably the best explanation why fritters steal, but I have another thought. Often I find fries sleeping in the midst of their stolen treasures. Normally, when they sleep in their cache, the items are soft and sticky, like little stuffed toys and other fluffy things. So my second hypothesis is that the fritters like to build cozy beds.