Tweet of the Day is a series of fascinating stories about our British birds inspired by their calls and songs.
Kate Humble presents the willow warbler. The first willow warblers return from Africa in late March. Willow warblers were once the commonest and most widespread summer migrant to the UK but in the last two decades numbers in the south and east of England have dropped by two thirds. Fortunately in Scotland, Ireland and the west, numbers seem to be holding up.