This guide is based on wikipedia's list of birds of Germany with accidentals removed to keep the guide under 500 entries.
The Great Bustard (Otis tarda) is in the bustard family, the only member of the genus Otis. It breeds in southern and central Europe, where it is the largest species of bird, and across temperate Asia. European populations are mainly resident, but Asian birds move further south in winter. Portugal and Spain now contain about 60% of the world's population.