I have endless admiration for beavers and their dams. I don't like them when they take down trees in my woods, but I do respect their hydraulic engineering skills. When you are driving along and see a dam, you typically see it from the "downstream" side (from the "upstream" viewpoint all you see is a pond). From the back it look like a pile of sticks, but what you can't see from far away is the amount of mud that has been applied to the upstream side to plug leaks. The result is a sturdy structure that requires heavy equipment or dynamite when humans deem removal necessary.
This video is a time-lapse of one year of a dam in my favorite part of the country - the northwoods of Minnesota near the boundary waters. Besides the variety of wildlife, note the sturdiness of the dam.
I should pair this with another video I posted a year or so ago about wildlife using a fallen log to cross a stream,
but I can't seem to locate that post. Here it is (with a hat tip to reader Bub for helping me locate it in my own blog!).
BTW, this is another video that is more rewarding when you click the fullscreen icon in the lower right corner...
A tip of the blogging hat to reader Matt, who found the video and emailed it to me.