Nell, You may want to rethink the "how high do ferrets jump" idea. A study was done on ferret intelligence and it was found that they have the same intelligence as a small primate... which makes them very smart. I have seen our ferrets work together to get something done. They've dragged things over to stand on. They have used each other as ladders to get over things or used each other as spring boards. They have tricked us in to doing things to "help their cause", whatever that may be at the time. A few ferrets have distracted us while the rest grabbed the treats and ran, then they all meet up to split up the booty. When you think you've figured a way to keep them in or off something you've only given them a new and momentary challenge to learn from. My husband and I are continuing to work to stay one step ahead of them in their cleverness. These are truly amazing little guys. If you want to stay active and keep your mind sharp--be a ferret owner. Nancy [Posted in FML issue 4888]