A major German environmental group has filed a complaint against its government with the European Commission as it seeks a shutdown of turbines at the 288MW Butendiek offshore wind farm, claiming huge damage to aquatic birds in an EU nature protection area.

The Nature and Biodiversity Conservation Union (NABU) wants to see decommissioning of at least parts of Butendiek, which has been operating since 2015 west of the island of Sylt, pointing to studies that suggest North Sea offshore arrays have a greater impact on bird life than previously thought – in particular on the sensitive gavia stellate and gavia arctica species.

“Data has shown for almost two years that rare and strictly-protected Gaviiformes are being expelled from their designated protection area,” NABU managing director Leif Miller said. “The responsible authorities finally need to act. Otherwise Germany continues violating valid EU nature protection legislation every day.”

Gaviiforme populations have diminished up to 16km around offshore arrays, the group claims, adding that two thirds of the ‘Eastern German Bight’ bird protection area is affected.

“Butendiek alone leads to a total loss of around 265 square kilometres, or 8.5% of the bird protection area,” said NABU marine protection expert Kim Detloff.

Bird conservationists have been challenging offshore wind farms for years. The UK’s Supreme Court in 2017 rejected a lawsuit by a bird charity over 2.3GW of projects off Scotland.

NABU accuses Germany’s Federal Maritime and Hydrographic Agency (BSH) and the Federal Nature Protection Agency (BfN) of knowingly ignoring the situation and failing to take damage control measures. The group says Germany is violating parts of the EU’s fauna-flora-habitat guideline.

Eighty Siemens SWT-3.6-120 turbines have been spinning at Butendiek since June 2015.

Earlier lawsuits by NABU, the municipality of Sylt (on tourism grounds) and fishery groups against the construction of Butendiek have been unsuccessful.

Germany's Wpd, which developed the project and still holds a minority stake, told Recharge it is studying the complaint and may comment in due course.