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 more gannets could be killed by turbine blades at sites that overlap with their feeding grounds, compared to previous estimates.
The UK is home to two-thirds of the world’s northern gannets, which nest between April and September in spots such as the 70,000-strong colony on Bass Rock in the Firth of Forth, which was the focus of the study published in the Journal of Applied Ecology found.
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About 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 that 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 was carried out by surveyors on boats estimating heights by eye or by radar, both of which had limitations.
The new assessment used miniature lightweight 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 for fish.
While the gannets typically flew at about 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 research also found the seabirds’ feeding grounds overlapped extensively with planned wind farm sites in the Firth of Forth, raising the risk of collisions.
A predictive model estimating how many of the birds would be likely to avoid the turbine blades showed about 1,500 breeding birds could be killed each year at the two nearest planned wind farms to Bass Rock – though there was uncertainty over the actual numbers.
The paper called for more research into gannet flights and for the raising of the minimum permitted clearance height above sea level to 30 metres (98ft).
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.”
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.”