New study finds wild animals will use an exercise wheel if it is provided for them.
Don't know if you have seen this-- I have read several versions now. They did a big one which wild cats used, and one big enough for dogs,the slugs seemed to choose it and stayed on quite a while. Frogs and toads got on and off, and back on.
I bet they could put them in zoos. Bored animals would like them.
People like them too, of course.
http://www.nytimes.com/2014/05/21/science/study-shows-that-mice-run-for-fun-not-just-for-lab-work.html?hpw&rref=health