When you don't have huts your going to find Den holes If you are finding lots of holes they will most likely be FEED holes. The beaver goes out under the ice gets a stick and may not go to the den but will go to it's feed hole Instead.

Your going off topic. I would like to know how/when they build their bank dens. Before it after thet flood the area.

Not really I have found tons of feed holes that were under the ice. And as far as I could tell they weren't there when I was trapping open water. So they had to be dug under the ice and In most cases were just big enough so the beaver could eat with It's head above the water line. And they all had peeled sticks scattered In front of the holes. The way I discovered this situation was one spring after the water went down I was trapping this area and I found all these small dug holes up In the banks. Just big enough for a beaver to get Into and there were peel sticks in those holes. I soon took advantage of that find next winter when we had Ice. I feel I'ts more efficient To trap these holes then the actual den If you can find them. If the beaver are living In a lodge then I don't think they will build feed holes.

Beaverpeeler Is describing the same situation but with out the ice. I would venture to say that a den hole that Is dug by a beaver or muskrat Is dug from below the surface of the water. In a dam situation the dam would have to be built first to establish the water depth before the den could be dug.