if a cat gets away with your stuff I believe you can find their 'stash' to retrieve it. It'll be a pile of junk with a yellow ? icon over it when you get close. If you try to gather there without having been stolen from, it just gives you a message saying there's nothing found. I believe you also have a time limit to get there and retrieve it, so if it was important (IE: your last trap on a capture mission) then head there immediately.
Oh wow. I always wondered what those were for.