Volume 38
Issue 3

Jason Corbett crawls or drops into unmapped caverns and crumbling abandoned mines, a portable poisonous gas detector clipped within his quick reach, to document critical underground bat habitat. Michael Schirmacher scales wind turbines 30 stories high and then crawls around the top of the turbines, the nacelle, on his hands and knees to install bat monitoring sensors.

Both men lead important programs for Bat Conservation International, placing themselves in unusual and potentially risky places as they incorporate solid research methods and leading-edge technology to see that the worlds bat population is preserved and protected.

Schirmacher is a longtime researcher in BCI’s Wind Energy Program. Corbett leads BCI’s Habitat Protection and Restoration Program. Both spend at least as much time in the field as in their offices. And both frequently find themselves in sticky spots: Schirmacher on a rain-slick catwalk buffeted by high winds, Corbett on the floor of a dark cave possibly inhabited by snakes.

High Above the Landscape

By Schirmacher’s 40th ascent climbing wind turbines of 260 to 320 feet, the heart-pounding exhilaration had subsided. Today, moving hand-over-hand up the rungs inside wind turbines is simply part of his job.

In 2006, Schirmacher directed the first of 13 years worth of research projects that involved installing technology on the top of wind turbines. The high tower work requires that Schirmacher and his colleagues complete fall protection training, a type of rigorous physical and classroom preparation demanded of firefighters, cell tower and electrical power workers.

The overarching question Schirmacher and his team ask is: How can bats coexist with wind turbines? Their research seeks to answer why bats are attracted to turbines. Is it the swishing sound of the turbines or, maybe, the heat exhaust from the turbine generators? Are some bats mistaking turbines for roosting places, and if so, why? Why are some species more at risk than others? And how do seasonal migration patterns, weather configurations, geography and insect activity factor in?

We need to remember that bats are cryptic. They’re difficult to study, Schirmacher said. Bats produce sounds we cannot hear, and their activity is in the dark, where its difficult to see them. That’s why technology is so important.

Schirmacher and his team make use of a range of technologies, including high-speed thermal imaging to record detailed bat flight behavior, night-vision, thermography, solar-charged battery systems to reduce the number of trips up and down the turbines, ultrasonic microphones that record high-frequency sounds (such as bat calls), and acoustic identification software for analyzing those calls.

This audio identification system works similarly to popular downloadable apps like Shazam, which can identify (human) recorded songs within a couple of notes. Only instead of comparing music notes, the system compares recordings to BCI’s library of echolocation data to identify bat species and activities like foraging or commuting.

Collecting the echolocation data was a major accomplishment, achieved over years by researchers who have compiled a call library of known bat calls. Researchers can now keep better tabs on specific species, like hoary bats, that tend to be lured to turbines.

Temperature, barometric pressure, precipitation and humidity all may play a part in bat interactions with turbines. When we pair thermal readings with night videography, we often see patterns that predict risks for bat mortality, said Schirmacher. We know, for example, that risk is higher when insects are active.

That kind of information advances smart operational practices with energy partners. Schirmacher points to win-win coordination with Duke Energy on a wind energy development in West Virginia. Based on our conversations with Duke Energy, we learned how turbines determine to start up or shut down by measuring wind speed over 10 minutes time.

Combining his knowledge about bat behavior with the information on how turbines operated, Schirmacher’s team came up with a simple but potentially novel way to change turbine operations to reduce bat fatalities. We had the turbines measure wind speed over 20 minutes, rather than 10, and not only did we find it reduced bat fatalities as much or more than before, it also reduced power loss and turbine wear-and-tear by lessening the number of times turbines started and stopped.

Supported by a number of studies, Schirmacher said bat deaths due to wind turbines can be substantially curtailed if turbines are stopped for brief periods of time, particularly during warm nights and migration periods when winds are under 15 miles per hour.

BCIs work is leading to improved decision-making regarding where turbines are located and the use of bat deterrents. Can ultrasonic technology be employed to jam bats echolocation, thus keeping them from flying too close?

Research and technology are only two-thirds of the whole, said Schirmacher. He highlighted the merits of the Bats and Wind Energy Cooperative, a seemingly unlikely partnership of diverse interests including land and wildlife managers, energy developers, academic institutions, researchers and conservation organizations like BCI.

The cooperative, celebrating its 15th anniversary, shares research and fosters open dialogue. Sharing what we learn is essential, Schirmacher said.

Spectacular Tech

Jason Corbett is a prolific surveyor of bat caves and abandoned mines. In his nearly 12 years of work for BCI, Corbett has surveyed thousands of natural caves and abandoned mines, exploring and documenting the dark unknown.

By necessity, Corbett packs lightly for his work, not knowing the tight spaces he may encounter. What he carries, however small, is leading-edge technology which helps guide important decision-making on how caves (and the lands above them) are preserved and how abandoned mines are made safe for the public and saved for bats.

On a recent BCI trip to Jamaica, Corbett and his colleagues used high-tech tools to survey the only known cave to shelter the critically endangered Jamaican Flower Bat (Phyllonycteris aphylla). Corbett and his colleagues also use that same technology throughout the western United States to collect indispensable information about bat occupancy in old and deteriorating mines that might otherwise be backhoed and filled in, destroying roosts and, possibly, trapping colonies of bats.

Corbett’s tech tools are compact, carried in a drawstring pouch slightly larger than a rock climbers chalk bag. Some of the equipment is relatively ordinary: a laser distance meter (commonly called a DISTO); an infrared thermometer to measure surface temperatures; and an anemometer, typically used for measuring wind speed, used underground to determine air flow and measure relative humidity and ambient temperature. All of these items can be found affordably at most home improvement stores.

The rest of his equipment is more expensive and anything but ordinary. A 3×5-inch LIDAR device enables remote sensing of a caves or mines interior, by sending out pulsing laser beams to provide a precise composite image of distance, height, width and geological features. Corbett collects this detailed data and then loads it onto high-powered computers to be synthesized with other data to create 3D maps of the underground surface features and other useful measurement information. The cost for one LIDAR device is $50,000 to $75,000.

Equally vital are thermal cameras. Heat-mapping will be an essential part of BCI’s research above ground or below, he said. Corbett points to National Geographic as an example for the pioneering use of thermal cameras to find and photograph wildlife. We plan to utilize this technology in a different way that is incredibly helpful for understanding how and why bats favor certain roosts over others.

Bats live in all sorts of environments and also create their own warmth by huddling together. It’s not unusual to see 150 to 200 females and pups clustered in one square foot. Warmth is conducive to raising their young.

In Jamaica, LIDAR and other tools were used to document the only known cave inhabited by the critically endangered Jamaican Flower Bat. Corbett recounted the time his team mapped a small cave system only a few feet below a highway and a gravel road. What was most alarming, he said, was that their scan also identified a private home situated above a warm-air roosting chamber.

One well-intentioned homeowner, who didn’t know the home was over this important cave, and one well-intentioned home improvement project, like digging a new septic tank, could spell catastrophe for this species with a known population of fewer than 1,000 bats, said Corbett. A surface breach opening a second entrance into the cave could allow the warm air to vent and allow cool air into the roosting chamber, putting this species in greater peril, he said.

In the continental U.S., Corbett and his team hit the road two weeks of every month to survey long-forsaken mines the Bureau of Land Management (BLM) considers deadly and dangerous. Corbett’s team determines if the mine was, is or might be inhabited by bats and makes recommendations regarding bat gates that can seal the mine entrance from human entry while keeping it accessible for bats and other wildlife.

Most often, the conditions of the mines they survey are unknown. For example, there might be no record indicating whether the mine runs horizontally to the land surface or it drops vertically, precipitously.

Safety protocols are strict. No one enters an abandoned mine without a trained partner. A third colleague waits at the mine entrance, on point to help if necessary. In addition to all their high-tech gadgetry, Corbett and colleagues carry gas detectors, radon detectors and occasionally Geiger counters to detect gamma radiation.

Poisonous gases in abandoned mines are always a potential danger, said Corbett. Radon is prevalent in abandoned uranium mines and can present serious respiratory hazards for the team, though not so much for bats. Corbett explained: Radon gas settles low, falling to the floor of the mine. Radon decays from a gas to solid particles. Those particles adhere to dust that can be stirred up when a researcher enters and moves along the floor of the mine, creating a serious health risk if proper precautions are not taken.

Gas detectors and Geiger counters have been around for a long time and used to be among the most sophisticated technology a researcher would carry into a cave or mine, said Corbett.

While we now have a lot more technology for our research, those detectors can’t be forgotten in our list of tools.