Bones of guillemots like this scull, together with feathers, are typical finds from the lower layers at the Borgsumburg excavations on Föhr. Photo: NIhK Wilhelmshaven.

Guillemots are arctic sea-birds and rock-breeders, e.g., on Heligoland.
Source: Boaworm, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons.

Common Guillemots in the stronghold

When the excavations in the early-medieval fortification Borgsumburg were continued this summer, it became obvious, that the lower settlement layers, being water-soaked, provide excellent preservation conditions for organic finds. Textile fragments and egg-shells occurred as well as numerous bones of guillemots, a penguin-like sea-bird. Not only skulls appeared, but also whole skeleton parts with feathers still in place. CT- scanning of the recovered turf-blocks and DNA-analysis will follow. As guillemots are rock-breeders, their only habitat in the southern North Sea is Heligoland. It can be assumed, that the soldiers in the stronghold had sea-worthy ships at hand, which allowed to sail to the remote island. Obviously, the birds were hunted to be eaten, is it is still the custom in e.g., Iceland and Newfoundland.