This area in the remote north is, I presume, almost managed by the beavers in some sort of sustainble cycle. Food supply is relatively poor. and as your examples suggest they move along the stream.

I came along this example when I was using Google Earth to map the southern limit of sporadic permafrost ( I believe you do glacier studies if I am not mistaken?)

I have added a bit of an interpretation to the original post.

Also I lived with beavers for at least for 20 years on the Carp Ridge near Ottawa. This area is almost exclusively managed by beavers. I had to put chicken wire around all the trees I wanted to protect. Like we have with farming, they seem to have a kind of rotational system. When the food supply is exhausted, they move on to the next best area, but will be back again when new growt has re-established itself.

In the area A beavers have been active all the time I lived there, maintaining a dam, but not always living there. In area B the started to build the dam around 1992. Before that time they occupied the area C , just downstream the present dam, for at leat 5 years.