Tweet of the Day is a series of fascinating stories about our British birds inspired by their calls and songs.
Chris Packham presents the gadwall. Gadwall were rare ducks until a few decades ago, now though, gadwall are spreading fast in the UK. Gadwall can be sneaky thieves, exhibiting what scientists call klepto-parasitic tendencies. They often wait for birds such as coot and mute swans to bring up aquatic vegetation beyond their reach and seize it before their victims can eat it themselves.