Seabirds could face a much higher risk from offshore wind farms than previously thought, a new study has warned.
New analysis has revealed 12 times as many gannets than forecast originally could be killed at sites which overlap with their feeding grounds.
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 the Bass Rock in the Firth of Forth, which was the focus of the research published in the Journal of Applied Ecology.
It is feared around 1,500 of birds nesting on the volcanic outcrop off North Berwick could be killed each year by collisions with turbines at two huge offshore wind farms that have been proposed.
The projects, planned for construction less than 30 miles from the island, would inflict a level of casualties which could threaten the long-term viability of the Bass Rock population.
Researchers from Glasgow, Leeds and Exeter universities said gannets had previously been thought to fly well below the 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 39ft when commuting between their nesting site and feeding grounds, the typical flight height when actively searching and diving for prey was 89ft, potentially taking them into collision with the blades.
The research also found the seabirds’ feeding grounds overlapped extensively with planned wind farm sites in the Firth of Forth, raising the risk of collisions.
The paper has called for more research into gannet flights and for raising the minimum permitted clearance height above sea level to almost 100ft.
Co-author Dr Ewan Wakefield, of the University of Glasgow, 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 (98ft).”
The study’s authors stress that the figure of a twelve-fold increase in gannets being killed is based on current typical turbine sizes, which could be different to those actually installed.
RSPB Scotland has already mounted a legal challenge against the consent granted to four major offshore wind farms off the Firth of Forth and Firth of Tay, but is awaiting the result of the judicial review.
Between the Inch Cape, Neart na Gaoithe, Seagreen Alpha and Bravo developments there could more than 400 turbines standing in the sea off the east of Scotland.
An RSPB Scotland spokesman said: “This is an enormously useful study; a really valuable contribution to our knowledge about the behaviour of seabirds when they are out at sea and away from their nesting sites around our coast.
“It’s important we understand as much as we can about flight behaviour, and this study gives us further valuable insights on how they act in the marine environment.”
Hannah Smith, policy officer for Scottish Renewables, said: “It’s important to put this research into context. It focuses on developing a new method using a tiny sample of less than one percent of the total gannet population that can be found at the Bass Rock.
“I am sure that the Scottish Government will look at this latest piece of research, along with all the other work by academic researchers, renewable energy developers and environmental agencies and assess if it is relevant to how they consider any future applications for offshore wind projects.”
WWF Scotland director Lang Banks said: “Offshore wind has an important role to play in safeguarding our rich marine environment over the long-term by reducing the impacts of climate change. Research like this can help contribute to ensuring those offshore wind farms are sensitively sited.
“Home to a quarter of Europe’s offshore wind resource, it makes sense for Scotland to tap into this clean energy source.
“With careful planning it should be entirely possible to harness this resource to help cut our climate emissions while still safeguarding the marine environment.”