Tweet of the Day is a series of fascinating stories about our British birds inspired by their calls and songs.
Bill Oddie presents the snow goose. Snow geese breed in the Canadian Arctic and fly south in autumn to feed. Their migrations are eagerly awaited and the arrival of thousands of these white geese with black-wingtips is one of the world's great wildlife spectacles. Here, on the opposite side of the Atlantic, snow geese are seen every year, often with flocks of other species such as white-fronted geese. Snow geese are commonly kept in captivity in the UK, and escaped birds can and do breed in the wild. So, when a white shape turns up amongst a flock of wild grey geese, its origins are always under scrutiny.