Regular readers will recall that I have an interest in bats and that interest drove me to volunteer with the Wildlife Division of the Connecticut Department of Energy & Environmental Protection (CT DEEP) to help it assess the bat population in the state.

There are two ways to count bats. The low-tech version is done by visiting a bat roost colony (typically a barn or outbuilding) and use two handheld counters. With one hand you count the bats as they leave the roost to feed at night and with the other hand you count when the bats return. It’s pretty easy to do if you have basic coordination and can stay focused.

The second way to count bats is decidedly more high-tech and it is the program I participate in under the supervision of CT DEEP Wildlife Biologist Devaughn Fraser, who will later analyze the data. When I do my survey, I am responsible for a 20-mile transect route on secondary roads between Putnam and Windham. I have been doing this volunteer work for the past five years or so and there are eight other volunteers in different locations throughout the state. We monitor our routes twice a month between May 1 and Oct. 15.

The prescribed backroad route requires me to drive between 18 and 20 mph with a large, highly sensitive microphone attached by a powerful magnet to the roof of my vehicle. The microphone connects to a laptop with digital recording software and a GPS that has the route already downloaded. My job is to simply plug in the equipment, make sure it is working properly, set the date and route name on a digital file to be saved on the laptop hard drive when the route is over and head off into the dark night. Sounds simple right? Well, there is more to it when you consider the science of recording bats.

The training materials provided by CT DEEP explain the science behind the equipment. It’s all based on the echolocation bats use to navigate and forage in the dark. The sounds bats’ produce can’t be heard by human ears, but microphones and recording software (bat detector) can hear the calls of feeding bats. Fraser then uses specialized bat call analysis software (SPECT’R III) that creates both a visual picture and audible experience of the bat vocalizations.

Here is where it gets technical. According to the manual, SPECT’R III plots the frequency in kilohertz (Khz) verses time in milliseconds (ms) in a display called a sonograph. The display is broken into 4 horizontal panels, each 25 milliseconds wide. Most bat calls are between 0 and 25 milliseconds. The display has a vertical scale on the right side of the graph to indicate frequency scale between 0 and 120 kilohertz. Most people can’t hear sounds above 15 kilohertz. Bat calls are typically between 40 and 90 kilohertz. The colors on the software display of each call also indicate how loud the call is with blue relatively quiet, green louder, yellow louder still and red the loudest.

With SPECT’R III recording each bat’s calls in milliseconds, kilohertz and loudness, Fraser gets visual and audible evidence she can use to identify the species of bat being recorded. This important data helps DEEP get a better understanding of the population of each species of bat in the state.

At the end of the bat echolocation recording season the equipment and saved data files from each volunteer are returned to Fraser. She downloads the data, replays and analyzes each recording to indicate the number of each bat species counted on a specific evening in each transect. Over time, the data creates a clearer picture of the number of bats in the state. It’s critical each volunteer follows the same survey protocols, has experience doing the work, documents each night with start and stop times and weather conditions, and that the research is conducted in the same location for several years. More data, correctly gathered over time, provides the reliable evidence.

This data is critical if we are to better understand what is happening to bat species in our region due to the devastating effect of white-nose syndrome, a disease first discovered in the United States in 2006. This disease has significantly impacted several bat species around the country, especially those that roost and hibernate in caves. One of the most common bats in our region, the little brown bat, has been decimated with a population decline of more than 90 percent.

I am happy to continue to volunteer with CT DEEP to help them document and learn more about the species of bats we have here in our region. To be part of the process doing “citizen science” is rewarding work, and I am glad to assist gathering data on bats.

If you’re interested in learning more about bats in our region, and the impact of white-nose syndrome, you’ll want to check out the CT DEEP website. A link is provided below.

https://portal.ct.gov/DEEP/Wildlife/Learn-About-Wildlife/Bats-in-Connecticut

My volunteer efforts also inspired The Last Green Valley’s program on bats with Fraser. We began the program last year and are enhancing it this year when we return to Lyon Preserve in Pomfret on the evening of July 23. Last summer we counted 186 bats at a roost location that is the summer home to probably more than 200 bats. This is a program designed for the whole family. Fraser is going to explain the science behind monitoring bats and why they are so important to our ecosystem. In addition, we will have kid-friendly crafts and games. Of course, all ages like to use the counters I mentioned earlier in the column. More information on the program can be found on the TLGV website at:

https://thelastgreenvalley.org/directory-events/acorn-adventure-bats-in-the-last-green-valley/

Bats are fascinating mammals and ecologically important for pest control. Some are also important pollinators. The more we learn about this important animal the better informed we are about the challenges facing not only our region’s bat population, but our entire ecosystem.

We live in a beautiful place called The Last Green Valley National Heritage Corridor. Our region is rich in natural and cultural resources, and I hope you’ll join me and together let us to care for it, enjoy it and pass it on.

Information for this column was sourced, and in parts used directly from the CT DEEP Bat Acoustic Survey training materials provided by Wildlife Biologist Devaughn Fraser.

Bill Reid is the Chief Ranger of The Last Green Valley National Heritage Corridor. He can be reached at 860-774-3300 or via email at bill@tlgv.org.

Exploring The Last Green Valley, Sunday, July 17, 2022

The Norwich Bulletin is granted first serial rights and associated electronic rights to publish the following article.  The Last Green Valley, Inc. retains all other rights to the work.