Late this afternoon, I decided to take a short walk along one of my favorite trails – the nature trail at the Pearl Brook State Forest in Townsend, Mass. It’s just a short loop along the banks of a small, swift flowing stream, but I always find something interesting, and today was no exception. This time I found my way blocked by a pool of water … just in the past two months or so, beavers had built a chain of small dams. A footbridge that had crossed the brook now sat in the middle of the water, literally a bridge to nowhere.

I cursed myself for not taking my camera.

I took a good long time admiring their work, the way all the sticks and logs are intertwined, holding together just so. It raises an interesting question – just how much conscious planning goes into this? There are those who caution against anthropomorphising too much. No one has yet witnessed beavers in a planning meeting to decide where to build, and who will do what. They just seem to do it. But still, I find it difficult to imagine that this is solely the result of some instinctual impulse.

And then, are some better builders than others? Do they learn from experience, in the way that rookie nest builders among birds improve as they go along? Do they learn to choose a better spot? Which trees to drop? How to get them to drop just where they want them? If so, that would argue against a strictly pre-programmed skill.

This particular spot has the potential to hold back a lot of water, and other beavers have done so in past years, both upstream and down. Just a little ways upstream, the banks bend around to form a large bowl, which could make a sizeable pond, if the beavers choose to continue their building. It’ll be interesting to follow their progress.