I ran and got my Sony camcorder to record the bird which looked like two-thirds the size of a chickadee. Flying upside-down or right-side up made no difference to the nuthatch as it worked its way among the pine trees.
While trying to follow the nuthatch, I realized I was also recording a second bird, even smaller than the nuthatch, which Sue identified as a kinglet. Speaking roughly, the yellow-crowned kinglet is about half the size of a chickadee. And the kinglet was performing complex antics all his own.
The little kinglet is small enough to perch on pine needles, that is, when calm enough to be still for a few seconds.
I have no idea how long they'll stay in the area. Already the robins are coming into full voice, and the mourning doves are cooing away. This, to say the least, is a very, very early spring!