Averaging just 14g these tiny little birds puff themselves up to protect against the cold. And of course sit really close to each other. They come in close to my home to forage for seeds and berries. Food gets scarce in winter. So does foliage so they remain vigilant against predators. Often I only see them when they move. On more than one occasion I have just branches and leaves in frame. The birds flew a fraction of a second before I pressed the shutter.