The review of the impacts of wind farms and other aerial structures upon birds, by Environmentally Sustainable Systems, was commissioned in Britain by Scottish Natural Heritage. It says that UK wind plant developers should treat results from the large body of Californian studies with caution. This is because the high turbine densities and turbine numbers there, contrasted with the relatively low numbers of turbines in UK wind farms, make any comparison difficult.
The review finds that disturbance leading to loss or deterioration of habitats is the issue of most concern in Europe, while American studies have concentrated on collision mortalities. Surveys around UK wind farms have found very few collision victims. However, all studies to date of bird deaths around wind farms underestimate by varying degrees the number of victims, the report says. It points out that estimates of bird mortality rates based on searches for dead birds need careful calibration to correct for factors such as inefficiency in searching and for scavenger activity. Most studies have not taken account of this in their findings, states the review. And it criticises authors of some recent reviews which have based their findings on mortality rates drawn from such flawed published sources.
Among the report's recommendations is a call for a "round table" forum in the UK to improve co-ordination of British studies. With this approach, developers' monitoring resources could be concentrated on the most sensitive sites. The highest research priority is a series of carefully designed monitoring studies involving matched wind farm and control sites, it claims. This would need co-operation between developers. More resources need to be directed to collecting baseline data and analysing data which should be co-ordinated and targeted to particular sites, it says.
¥ A new phase of a study into wind turbine impacts on birds is about to begin at the Blyth wind farm. This will gather background data in preparation for the development of two offshore wind turbines, says David Still from Borderwind. Speaking at last month's British wind conference in Exeter he said the company will take advantage of the time before the wind turbines are built to make a monitoring study mapping flight lines and assessing total impact. He pointed out that the ongoing study shows the existing turbines have only a small impact. "Birds are used as an issue by objectors to stop any wind farm development," he said. "So we need to understand how birds are affected."