How can they make such a perfectly circular hole?
Chickadees often act as primary cavity nesters (i.e., create their own nest holes). But since they lack the size and excavating equipment of, say, a flicker, they require a tree with relatively soft wood. A paper birch snag in an advanced state of decay is suitable, provided it’s not on the verge of collapsing. This hole is about twenty feet up, three feet below the broken top of the snag.
Chickadee entering hole.
Finally, at 10:58 (Chickadees are not only dapper, they’re punctual), a pair appeared and landed in a neighbouring tree. One darted into the hole, and disappeared for a few seconds. Out it popped, with a scrap of pulpy wood in its bill.
Click to see wood chip in bill.
It flew away, carrying the wood. Immediately the second bird flew into the hole, and it too darted out quickly, carrying a scrap of wood in its bill.
There was a lag, as they went somewhere. Chickadees are so tidy, they probably took the wood chips to a recycling depot.
This happened again and again. They arrived together, entered the hole to remove more wood in quick sequence, and then disappeared for a few minutes. Perhaps, in arriving and leaving as a twosome, instead of as two individuals with evenly spaced intervals between, they are keeping a lower profile, acting almost as a single bird, which would draw less attention to their nest. They would also be affording each other the protection of a pair of eyes on the outside--they got each other’s back. I can understand these things.
What I don’t understand is how they can make such a perfectly circular hole.