Hard to see them (I didn't see any either when I was there), but the exhibit certainly is natural. It looks just like I imagine it would look like if I ran across one in the wild in some European national park.
@Water Dragon Funny that the BBC 2 documentary on Yellowstone showed them very much active during the day,and I also saw them very active at Wildwood a few years ago,I think you will find they are mainly nocturnal but not exclusively as you stated!
I agree with @Water Dragon -- every collection I've been to that has held beaver, the beaver are either sleeping or hiding away in their lodge. Quite frustrating. Also the only time I've seen them wild was at around 10 at night
I've only ever seen wild beavers during the day That said, they are quite common around here but have only seen them a handful of times. Not sure on European Beavers, but with American I'd agree with zg's statement. Only been to one zoo with beaver on-display in America during the time of my visit, but that visit was at the end of winter.