One distinction thats sometimes made is that a beak is more like the hooked beak of a hawk or an owl, while bill fits better with little birds like warblers. Whether you say bird beak or bill ...

For example, the cactus finch has a long beak that reaches into blossoms, the ground finch has a short beak adapted for eating seeds buried under the soil, and the tree finch has a parrot-shaped ...

It's the hypnotic, piston-pumping genre from late 1960's Germany where American psychedelica meets icy Germanic detachment. The key to a typical Beak> song is repetition, be it a note or a phrase.