Bats Avoid Radar Installations: Could Electromagnetic Fields Deter Bats from Colliding with Wind Turbines?

Abstract

Large numbers of bats are killed by collisions with wind turbines, and there is at present no direct method of reducing or preventing this mortality. We therefore determine whether the electromagnetic radiation associated with radar installations can elicit an aversive behavioural response in foraging bats. Four civil air traffic control (ATC) radar stations, three military ATC radars and three weather radars were selected, each surrounded by heterogeneous habitat. Three sampling points matched for habitat type and structure, dominant vegetation species, altitude and surrounding land class were located at increasing distances from each station. A portable electromagnetic field meter measured the field strength of the radar at three distances from the source: in close proximity (<200 m) with a high electromagnetic field (EMF) strength >2 volts/metre, an intermediate point within line of sight of the radar (200–400 m) and with an EMF strength <2 v/m, and a control site out of sight of the radar (>400 m) and registering an EMF of zero v/m. At each radar station bat activity was recorded three times with three independent sampling points monitored on each occasion, resulting in a total of 90 samples, 30 of which were obtained within each field strength category. At these sampling points, bat activity was recorded using an automatic bat recording station, operated from sunset to sunrise. Bat activity was significantly reduced in habitats exposed to an EMF strength of greater than 2 v/m when compared to matched sites registering EMF levels of zero. The reduction in bat activity was not significantly different at lower levels of EMF strength within 400 m of the radar. We predict that the reduction in bat activity within habitats exposed to electromagnetic radiation may be a result of thermal induction and an increased risk of hyperthermia.

Bats on the Move

“…Baerwald and Barclay (2009) relate intensity of bat activity to geographic variation in the number of bat fatalities in order to predict which locations for wind turbines would be less harmful for bat populations. Nicholls and Racey (2007) recently suggested the use of electromagnetic emissions to reduce bat fatalities at wind turbines after observing reduced bat activity in the vicinities of a strong electromagnetic field. The great responsiveness of the scientific community toward the escalating problem of bat fatalities at wind turbines will, we hope, bring about an effective method of preventing these fatalities without hindering our efforts to slow global warming.…”

Insect attraction to wind turbines: does colour play a role?

“…Some species may be assessing them as potential roost sites (Cryan 2008), however there is also some evidence of foraging behaviour around turbines (Horn et al 2008;Ahlén 2004). Bats tend to be concentrated in areas of high insect density (Nicholls and Racey 2007) and are much more likely to begin hunting when large numbers of insects are congregating (Griffin et al 1960). Reports into bat-turbine interactions frequently state the importance of investigation into the possibility of insect attraction to turbines (e.g.…”

“…Reports into bat-turbine interactions frequently state the importance of investigation into the possibility of insect attraction to turbines (e.g. Johnson and Kunz 2004;Ahlén 2004;Nicholls and Racey 2007;Rodrigues et al 2006), particularly since the recent loss of feeding habitats may be pressuring bats to feed in alternative areas (Wickramasinghe et al 2003). Turbine colour may play an important part in insect attraction (Ahlén 2004), although to date this has not been closely investigated.…”

The Aversive Effect of Electromagnetic Radiation on Foraging Bats—A Possible Means of Discouraging Bats from Approaching Wind Turbines

“…[22] also reported anecdotal evidence that bats foraging offshore in Sweden avoided an area around Utgrunden lighthouse where a powerful radar was in permanent operation. However, although it has been demonstrated that large air traffic control and weather radars appear to exert an aversive response on foraging bats [21], this has little practical application in preventing bats from colliding with turbine blades. It is therefore necessary to establish whether a deterrent effect can be replicated with a small, portable radar system.…”