These little birds are often in my trees but are very skittish and flit away when I approach. When I went outside to walk my dog, this one didn’t immediately fly off. I went back in to get my camera. Of course I had to change lenses so fully expected it would be gone by the time I returned. Happily, it sat for a few shots. It was subzero temperatures and a bird's body heat warms the air between its feathers. It was all fluffed up in the cold to trap the air in its feathers to stay warm.