The Drive for Green Energy

We need sustainable, affordable and clean energy production to fuel the economy, and the drive towards more environmentally friendly energy production versus coal and peat burning energy production has seen a large number of wind farms built across the countryside as an alternative. Wind turbines have had their share of negative press and many people don’t like how they disrupt the view of the countryside, while others complain of the negative psychological impact on their health. Wind turbines can also cause problems for wildlife species, and great care has to be exercised when planning the location of these turbines to avoid disturbance and injury to birds, bats and even insects like bees.

A new study by a team of researchers led by Linn Lehnert of the Leibniz Institute for Zoo and Wildlife Research in Berlin, Germany has been published in Plos One. The authors explain that bat fatalities can occur during the migration period, when bats are moving from their summer sites in North East Europe to hibernation sites located in Southern and Central Europe. This means that countries like Germany are directly in the migration route, and with one the highest density of wind farms in the world there is growing concern for the bat species that use this area as a corridor during migration, and also the resident populations. Concern is especially mounting for the noctule bat (Nyctalus noctula) as this bat species is found dead more often near wind turbines than any other bat species in Germany.





When dead bats are found near wind turbines it is difficult to know if it was a local bat or migrating bat that could have travelled as far as 1,600 Km. This new study used a staple isotope method that examined ratios of hydrogen found in the bat’s fur. Such ratios are found to vary along a north south gradient, reflecting precipitation and temperature levels across Europe, and hence the general geographic area where the bat had come from. In the case of the noctule bat, the breeding grounds can be inferred from this analysis as the animal sheds its fur at these sites and the new fur contains a geographic fingerprint of the general location.

The study took place in the eastern part of Germany, with searches for dead bats taking place on wind farms between July and September over a ten year period between 2002 and 2012, resulting in the collection of 136 noctule bats.

The results showed that 28% of the bats were migrating when they collided or otherwise died near the wind turbines. Amongst the dead bats, a considerable proportion were described as juveniles, suggesting that younger bats might be more likely to collide with the wind turbines. Modelling analysis of the migratory bats revealed that they most likely originated in Baltic countries, with some of the female bats thought to have come from further into Northern Europe and east into Russia.

Conservation Implications

The wider implications of this study show that wind turbines do pose a risk for bats, especially the high flying foraging species like noctules. Not only are local populations likely to be affected, but so too are distant populations migrating between hibernating and breeding sites. Furthermore, the migratory bats are from some of the most peripheral areas of the species’ distribution, and these populations are more vulnerable to population perturbation, with these losses placing additional burdens on such populations.

The authors also focused on the high number of juvenile bats killed in wind farms and they advise that wind farm sites should be placed away from breeding or maternal roosts as much as possible. They go on to say that the current practice in Germany to place wind farms at a minimum distance of 1 Km away from known bat roosts may not be enough to protect juvenile bats.

Implications for Bat Conservation in Ireland

Studies such as this also have implications for bats in Ireland as wind farms are becoming more popular and new developments will take place in the future. While the noctule bat is not present in Ireland, a relative called Nyctalus leisleri, or the Leisler’s bat has a relatively high abundance in Ireland in comparison to Britain, making the Irish population very important. This bat too is a high flying and long distance forager making it also vulnerable to collisions with wind turbines. To help planners and developers, Bat Conservation Ireland have recently outlined a set of guidelines for wind farm development in Ireland.

To date, very little is known about the potential impact of wind farms on bats in the Irish landscape, but research is currently being conducted, and talks by Will Woodrow and Una Nealon at the upcoming Bat Conservation Ireland conference will discuss findings related to bats in wind farms in Ireland. Details of the conference that will be held at Cork International Airport Hotel on October 11th and 12th can be found here.

Reference

Lehnert LS, Kramer-Schadt S, Schönborn S, Lindecke O, Niermann I, & Voigt CC (2014). Wind farm facilities in Germany kill noctule bats from near and far. PloS one, 9 (8) PMID: 25118805