Yeah, or at least there’s a running water sound nearby. If you play a recording of a sound of running water near a beaver, it will build a dam. It doesn’t even have to feel the running water. I’m not sure if it even has to be at the closest point it can get to the sound, or if it uses other cues like a narrowing of the area so that a dam will be the most effective.

In this case, the hallway may be seen like a “choke point” for flow, so it’s a good spot for a dam.

I’m curious what the thinking is for dam building. You’d think that a beaver would only build when it was actually in flowing water, but that doesn’t seem to be the case. But, what other things are they considering. Do they try to find the lowest point in an area at least? Do they consider how narrow the area is?