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Birds face increased blade threat

New study says up to 12 times more gannets could be killed by turbines

Birds face increased blade threat image

Offshore wind farms off the UK coast could kill up to 12 times as many gannets than previously thought, according to a new study.

The research, by the universities of Leeds, Exeter and Glasgow, suggests that the protected gannets (pictured) fly at a higher height than previously thought, which could mean more birds could be killed than current figures suggest.

Gannets, which breed in the UK between April and September each year, were generally thought to fly below the minimum height of 22 metres above sea level swept by the blades of offshore wind turbines.

But the study says, while this is the case when the birds are simply commuting between their nest sites and distant feeding grounds, gannets fly at an average height of 27 metres above sea level when actively searching and diving for prey.

Also the birds’ feeding grounds overlap extensively with planned wind farm sites in the Firth of Forth, heightening their risk of colliding with turbine blades, the study, published today in the Journal of Applied Ecology, said.

The researchers estimate that up to 12 times more gannets could be killed by turbines than current figures suggest.

However, they added that the figure is based on calculations using current typical turbine sizes, which could be different to those actually installed, and that there is great uncertainty over actual turbine avoidance rates.

Previously data on gannet flight heights were obtained by one of two methods: trained surveyors on boats estimating heights by eye, or radar, which usually has a limited range of about 6km and is costly, the report said.

The researchers called for more sophisticated methods of assessing risk.

Professor Keith Hamer, of the School of Biology at Leeds, oversaw the study

He said: “Our study highlights the shortfalls in current methods widely used to assess potential collision risks from offshore wind farms, and we recommend much greater use of loggers carried by birds to complement existing data from radar studies or observers at sea.”

The study was funded by the Natural Environment Research Council and the Department of Energy & Climate Change (DECC).

A further, more extensive tagging study to improve understanding of gannet flight heights and behaviour has been funded by DECC in 2015.

Image: Pixabay

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