Black-capped Chickadee nest?

We saw this Black-capped Chickadee going in and out of the hole in this tree. Did not know if was a nest or it was just feeding on bugs. The light was terrible and dull and there were a lot of branches in my way so I shot more wide open  to soften the branches that were in front of the bird. Sort of focusing past the branch and concentrating on the bird hiding or softening the branches.  I could not change position because the lake was on my left and a observation tower was on my right, but at least I got a few shots. Not great but interesting.