Tweet of the Day is a series of fascinating stories about our British birds inspired by their calls and songs.
Kate Humble presents the story of the black grouse. A black grouse lek is one of Nature's spectacles. Charged with testosterone, the males, known as 'black cocks', compete on 'jousting lawns' for the females or grey hens. Fanning their lyre-shaped tails and displaying a flurry of white undertail feathers, the males rush towards their rivals with harsh scouring sneezes and bubbling cries, known as 'roo-kooing'.