Pica pica
Unmistakable. Only black and white passerine of it's size in Europe. Short rounded wings and exceptionally long tail. Wings fan-shaped and tail graded. Tail constitutes about half of the total length in adult birds. Compact body but relatively long legs. Flat crown. White wing patches/flight feathers very conspicuous in flight.
Most notable sound a harsh, chattering "chechechecheche" used as warning call, or when mobbing predators. Rich repertoire includes soft and surprisingly varied sub-song.
Xeno-canto: map
Birdlife ecology