This is a Brown Headed Nuthatch that was banded a few years back. We had some researchers come over and band a couple of the Nuthatches. They were researching if unmated Nuthatches helped raise other Nuthatches from another nest. We have two pairs nesting in two different boxes right next to another. They allow you to get very close to them without moving, because you are too close to their nest and they want to protect it. Knowing basic behavior like this can help you get better photos.