Nuthatches Back At Same Nest Box

Our one nest box success in 2010 appears to be headed for a repeat. The White Breasted Nuthatches are back! I found them inspecting the nest box they used last season. One bird went in and out of the box several times, both birds were observed in the area of the box over a period of time, and at least twice I observed a bird removing material. What was removed did not look like the pine shavings I added last month, but I can't think of anything else they could take out this early in the nest season. In any case I'm persuaded the White Breasted Nuthatches are keenly interested in repeating a nest here, and I am looking forward to see what comes! I may even site a camera permanently to observe their behavior. Can't wait!