Utilising APEM’s Vulcanair Observer twin-engine aircraft, the survey collected extremely high-resolution digital images using the Shearwater II, a state-of-the-art camera system developed by APEM.

A total of four aerial surveys took place, with the aircraft flying at over 300m to avoid the risk of disturbing the birds, therefore generating more reliable information on the movement of birds than other more invasive studies. The surveys were undertaken during the autumn migratory season; a period when large numbers of Northern gannets were on passage off the East coast and in the southern North Sea.

APEM researchers then analysed the resulting still images in order to record how many gannets were found at different distances from offshore wind turbines.

In total, 336 gannets were recorded in the images, of which only eight were recorded within the wind farm area and 328 were recorded outside it. The gannets had minimum recorded approach distances of 443m and 359m away from the nearest turbine within and outside the footprint, respectively, thus demonstrating that gannets avoid the close vicinity of wind farms.

In the UK, the Band collision risk model is used to predict the possible numbers of flying birds that collide with the moving blades of a wind farm. The final stage of the modelling process is to apply an “avoidance factor”, a figure accounting for the behaviour that a flying bird exhibits when encountering a constructed wind farm in order to avoid colliding with the turbines.

It was previously believed that the avoidance factor for Northern gannets was 98 per cent. Based on the latest research conducted by APEM, its ornithologists believe that a more realistic factor is 99.5 per cent. The number of gannets estimated to be at risk of collision has therefore changed from two birds per 100, to 0.5 per 100. This suggests that four times fewer Northern gannets would collide with wind turbines during the autumn passage than previously estimated.

a pair of gannets

Tom Anderson, offshore environmental manager at Scottish Power Renewables, said: “There is a need to increase our understanding of how seabird species interact with offshore wind farms in order to accurately assess the potential impacts of future renewable energy developments.

“We are supportive of APEM’s approach to collecting additional evidence of observed seabird behaviour in and around offshore wind farms and we hope this project will help to fill the knowledge gaps.”

Dr. Mark Rehfisch, associate director and head of ornithology at APEM, explains: “The findings of the survey have huge implications – not just for the population of Northern gannets, but for the future of renewable energy. The conclusions of the study, showing that fewer birds will collide with wind farms, means that earlier assessments have been overly precautionary.

“The lessened risk will mean more favourable outcomes for renewable energy firms seeking consent for wind farms, providing more opportunities for the creation of clean, renewable energy, and once again demonstrating the importance of good quality science.”

Dr. Stuart Clough, director at APEM, added: “The effects of turbines on wildlife is a major factor in the planning and construction of wind farms – the findings of this and other aerial surveys that APEM undertakes will become increasingly important ahead of the next round of the government’s Contracts for Difference allocation in 2019. To participate in the CfD auction, developers must have secured planning consent, which should ensure that they understand the full impact of planned projects on the environment.

“We believe that those that are prepared with scientific answers will find themselves at an advantage.”

APEM continues to research the impact of offshore renewable energy projects on birds, marine mammals, fish and turtles, and has completed over 1,500 aerial surveys on wind energy areas, both in the UK and overseas.

Main photograph: Tom Coyne

If you have any queries, please contact Steph McGovern, head of ornithology.
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