North Sea wind farms could present 'higher risk' to migrating seabirds

Gannets have been found to fly higher above the sea when searching for food which makes them vulnerable to turbine blades

Gannets could face a much higher risk from offshore wind farms being built around the UK’s coasts than previously thought, a new study has warned.

New analysis of the height at which the seabirds fly has revealed that 12 times as many gannets could be killed by turbine blades than previous estimates, at planned wind farm sites which overlap with their feeding grounds.

The warning comes following reports the world’s biggest offshore wind farm could be built of the North East coast, with the potential of powering around two million homes.

The Dogger Bank Teesside A and B project would see as many as 400 turbines built in the North Sea, around 100 miles off the coast.

A similar sized scheme, also at Dogger Bank, was granted planning consent in February.

Put together, the two adjacent projects would be the world’s biggest offshore wind farm.

The UK is home to two thirds of the world’s northern gannets, which nest between April and September in spots such the 70,000-strong colony on Bass Rock in the Firth of Forth, Scotland, the focus of the study published in the Journal of Applied Ecology.

Around 1,500 gannets nesting at Bass Rock could be killed each year by collisions with turbines at two planned offshore wind farms less than 50km (30 miles) away, approaching levels which could threaten the long-term viability of the population, it found.

Researchers from Leeds, Exeter and Glasgow universities said gannets had previously been thought to fly well below the 22 metre (72ft) minimum height above sea level permitted for the sweep of turbine blade.

Previous analysis had been done by trained surveyors on boats estimating heights by eye, or by radar, both of which had limitations.

But the new assessment used miniature light-weight devices that logged GPS and barometric pressure, which were temporarily attached to the birds’ tails to allow researchers to track their flights in three dimensions while they flew out searching for fish.

While the gannets typically flew at around 12 metres (39ft) when commuting between their nesting site and feeding grounds, the typical flight height when actively searching and diving for prey was 27 metres (89ft), potentially taking them into collision with the blades, the study showed.

The paper called for more research into gannet flights and for raising the minimum permitted clearance height above sea level to 30 metres (98ft).

Co-author Dr Ewan Wakefield said: “For the first time we’ve been able to track birds accurately in three dimensions as they fly from their nests through potential wind farm sites.

“Unfortunately, it seems that many gannets could fly at just the wrong heights in just the wrong places.

“Increasing the distance between the tips of the spinning turbine blades and the sea would give gannets more headroom - so we strongly urge that the current minimum permitted clearance turbine height be raised from 22 metres to 30 metres.”

Northern gannets be seen offshore almost anywhere, especially when they migrate south between August and October, but there are no major offshore breeding grounds in the North East.


OCT 3 2015
back to top