http://www.edie.net/news/news_story.asp?id=21648

Researchers have developed what they claim is a new way to reduce the amount of bats killed by flying into wind turbines.

According to a team from the USDA Forest Service's Pacific Southwest Research Station (PSW) in the United States deaths of migratory bats at wind energy plants have become a 'frequent occurrence'.

Bat migration patterns are poorly understood and the relationship between deaths at wind energy sites and migratory behaviour are still being studied, says PSW ecologist Ted Weller.

Mr Weller argues that previous research has already shown adjusting the operations of turbines can reduce the number of bats killed by wind turbines but, this strategy has not yet been widely implemented.

The online tool takes into account bat activity at different times of the year and a number of environmental conditions, such as wind direction and speed, air temperature, and moon phase.

Mr Weller and his research team used devices which detected the bats' echolocation calls, then linked the presence of bats to the weather conditions measured on-site on a given night.

Researchers found echolocation detectors placed at 22 meters and 52 meters above ground were more effective at characterizing migratory bat activity then those located closer to the ground.

Moreover, multiple echolocation detectors were required to accurately characterize bat activity at the facility. They then built models to predict the presence of bats based on date and weather variables.

Mr Weller said: "Increasing the wind speed at which turbines begin to spin and produce energy to the grid has proven to be an effective way to reduce bat fatalities.

"However, bat activity levels depend on more than just wind speed, our work demonstrates the use of a decision-making tool that could protect bats when fatality risk is highest while maximizing energy production on nights with a low chance of fatalities."