The past three days I’ve watched a downy woodpecker excavate a hole in a dead ash tree. Its characteristics are a near perfect match for the Cornell website description of a preferred downy cavity - a short section of branch around 7 inches in diameter, hole on the underside, etc.
I’m assuming this is a winter roost. What I can’t find info on, however, is whether they might then use this in the spring as a nest cavity. It seems like an ideal nest site (again, per descriptions at Cornell & Wikipedia). And we can easily see it, so a nest there would be fantastic.
We’ve intended to cut down the tree for years so it doesn’t fall on the woodshed. Our laziness has been rewarded. :-)
I have video and am planning to pull some still images from that. If I can remember to bring out my camera rather than my phone, I should be able to get better photos. :-)
I don’t know about Downies in the particular, but many birds avoid using the same cavity for too long because of the buildup of parasites. I wouldn’t be surprised if they move out in the spring, or even part way through the winter, once the parasite load becomes too much.