Looking for a sunset bird in winter-Frost

The west was getting out of gold, the breath of air had died of cold,when shoeing home across the white, I thought I saw a bird alight. In summer when I passed the place I had to stop and lift my face; a bird with an angelic gift was singing in it sweet and swift. No bird was singing in it now. A single leaf was on a bough, And that was all there was to see in going twice around the tree. From my advantage on a hill I judged that such a crystal chill was only adding frost to snow as gilt to gold that wouldn't show. A brush had left a crooked stroke of what was either cloud or smoke from north to south across the blue; a piercing little star was through.