(Above) Spectrogram of the recording we made of the little brown bat. Myotis is part of its scientific name, Myotis lucifugus, which means “mouse eared bat that flees from the light.”
Last Saturday night, I led a friend and her family on a bat walk. She said it was the only thing she wanted for her birthday, so I met her at her house near Ranson, West Virginia around 8:30 pm. It had rained all day but started to clear up in the late afternoon. Perfect “batting” weather.
I attached my Echo Meter Touch 2 bat detector into the lightning port of my iPhone while we stood talking in the front room of her house. Her daughters, aged 4 and 5, were excited to see the color pictures I gave them of the bats we were likely to record. It wasn’t yet dark outside but almost immediately, bat vocalizations showed up on my screen and I pressed the “record” button. My bat detector can isolate and pick up most sounds bats make, create a visual spectrogram of the sounds, record them at various speeds, and sometimes identify the bat species.
By then half a dozen family members of various ages were ready to go on our bat walk. I explained echolocation, how bats use their voices to navigate in total darkness by making rapid, high-pitched squeaks or clicks and then listening to the reflected sound, or echo, as it bounces off objects. That’s how bats find a flying moth to catch for dinner, or avoid crashing into the wall of a cave or a projecting stick that might be in their flight path.
Bats also communicate with each other by making social sounds. But the bat detector can’t determine the bat’s identity by these sounds, and labels them as “No I.D.” Just after I explained why we wouldn’t be able to identify all bat sounds, reference pictures of two bats popped up on my phone screen. We had recorded either a silver haired bat or a big brown bat. The silver-haired, listed first, was the most likely choice. Each bat’s picture was linked to a Wikipedia description of the bat species, which I read to the group. Everyone seemed excited. Somebody said, “I didn’t even know there was more than one kind of bat.”
Capitalizing on this excitement, I flipped down the menu to a GPS view. Superimposed over a satellite photo of our location, the flight path of every bat we had recorded so far appeared in bright magenta-red. The group was impressed that bats passed directly over our friend’s house.
For the next half hour, we walked down the road through the subdivision. We paused at the edge of an adjacent field and again in front of an abandoned shed. Bat recordings continued to appear on my phone screen. By the end of the evening we had made about 200 bat recordings and yet we never went more than a few hundred yards from the house.
As we returned, I told the story of the little brown bat. Once the most common bat in our area, it is now very rare because so many of them have died of a fungus disease that attacks bats in the winter during hibernation. I described how the disease causes the bats to wake up and fly around during the day, depleting their energy so they can’t survive the winter. Just then, a picture of a little brown bat flashed on the screen, along with its recording. A rare little brown bat had just flown overhead!
Back on the front porch I played back some of the recordings we had made, explaining how the spectrogram slows down the recording so it is within the range of human hearing, distorting the sound. Both little girls were fascinated by the slowed-down bat sounds, which sounded more like tolling church bells than high-pitched clicks.
Our friend was ecstatic that we had recorded a little brown bat as well as eastern red bat, big brown bat, silver-haired bat, hoary bat, tricolored bat and evening bat. Next day, she texted me that she was just thrilled to do this on her birthday and that she would do it again.
When I show people my bat recordings, they’re often surprised at how many different kinds of bats we have. And I’ve learned that bats are virtually everywhere.
Doug Pifer is an artist, naturalist, and writer. He has a Master’s Degree in Journalism from Penn State and has been an editor and art educator. His illustrations have appeared in various books and magazines and he has been a contributor to The Observer for several years. He lives with his wife and assorted animals on 5.7 acres in a historic farmhouse near Shepherdstown.By Doug Pifer