Nuthatch Nest Attempt Confirmed

A few days ago I reported that a pair of White Breasted Nuthatches had been checking out one of my nest boxes. Today I can report that these birds are definitely building a nest. I have now seen at least one of the pair deliver nest building materials. At that time the other bird was inside the box. I also observed a peculiar behavior by the deliverer of supplies: occasionally this bird would peck at or drum on the edges of the box. I have no idea what that's all about. But no matter, as we have at least one nest going on the property. And I am sure that my effort to pack boxes with some pine shavings paid off. In this case the box was only filled half way, and at least as of Friday afternoon I found no signs of material having been ejected. That gives our nuthatches a nice cushy surface for the nest and one with excellent insulating properties. Will any other nest boxes be claimed in upcoming days or weeks? I haven't seen any signs yet.