Why is the robin our Christmas bird? Maybe because it breaks the long silence of winter: no other species sings so sweetly in the cold months. Perhaps because its red breast splashes colour on grey December days. Or it could be that robins grow winter-tame. Following gardeners, they wait for us to disturb the soil and expose juicy worms – I’ve lost count of the times a little redbreast has appeared from nowhere, when I’ve been out planting trees.