Bats and Wind Turbines: Caught on Camera

A research paper published in the August 26, 2008 issue of the journal Current Biology reports that bats are killed by wind turbines not because they hit the blades, but rather, the spinning arms cause the mammals’ lungs to explode. 

As the blades spin, they push air upward, creating a small pocket of low-air pressure. When bats fly through these pockets the cells in their lungs expand in response to the pressure change. The expansion causes the capillaries lining the bats’ lungs to burst, which results in internal hemorrhaging and ultimate death. Though this is the first paper to put a finger on what’s causing all the bat fatalities near wind farms, another paper also looking at bats and turbines – this one with wicked videos – slipped by in January 2008.

The study was published in The Journal of Wildlife Management –- co-authored by the Batman himself, researcher Thomas Kunz. It used video to demonstrate that bats exhibit “exploratory behaviors” around wind turbines; from "chasing" the tips of the moving blades, to one bat even alighting on a moving arm. The study proved to be an ominous precursor to the findings in August's Current Biology when the authors write: “It seems unlikely that aerial feeding insectivorous bats, which are capable of making remarkable aerobatic maneuvers to capture small insects, should be so frequently killed by [crashing into] moving turbines blades." But more compelling than the oracle-like nature of the research (or their conclusion, which was bats don’t run into wind turbines very often), is the video they shot while collecting data.

The researchers used three thermal infrared cameras to capture bats flying among wind turbines at night. The stylistic blue, red, purple, and yellow footage shows little bat dots darting around mammoth spinning turbines, in what we now know can be a lethal game of cat and mouse -– even if the cat never touches the mouse. I suggest loading the videos, then after playing them all the way through, use your cursor to drag the bar that adjusts your place in the clip. Depending on how quickly you move your computer mouse, you can slow the footage down, or see the bats move forward and backward. Unfortunately, or not, no explosions were captured in the making of the film.

Watch the videos here.

To check out the paper: Horn et al, 2008 Journal of Wildlife Management 72:1 123-13

Thermal infrared cameras capture bats flying around wind turbines. Photographs are still frames from the following videos (from left): "A bat repeatedly investigates and briefly lands on the turbine tower while the rotor spins slowly" and "A bat investigates the turbine tower (monopole), showing typical 'touch-and-go' behavior."

Photo credits: Thomas Kunz / CECB