Tweet of the Day is a series of fascinating stories about our British birds inspired by their calls and songs.
John Aitchison tells the story of the parrot crossbill. The Parrot Crossbill lives only in a few native pinewoods in Scotland. When they're at the top of pine trees a view of the Parrot Crossbill is tricky, so crossbill experts use the birds' calls to tell them apart from Common and Scottish Crossbills. Parrot crossbills have a deeper call than the others.