Lummenfelsen is the bird cliff near Lange Anna, and it is one of Heligoland's great sights in spring and early summer. Guillemots, gannets, kittiwakes, and other seabirds pack the ledges, turning the red rock face into a noisy nesting wall.
Bring binoculars or a long lens if you have one. The colony is protected, and the best experience comes from watching patiently from the marked paths rather than trying to get closer.