Backyard Naturalist: Counting bats on a summer night

I am a counter. I count my breaths in yoga, my steps when I run, sheep when I can’t sleep and when I’m nervous, I find myself searching for something solid to count. Counting helps me find order in a chaotic world. So you can imagine in our current reality, I’m doing a lot of this lately.

This summer I’ve turned my counting to something useful. I’ve been counting for wildlife. Since the spring, I’ve tallied red-back salamanders, fireflies, monarch eggs, larvae and butterflies and bats. Each species that I’ve counted was part of a larger citizen science project and the data I helped collect became part of something bigger than just my own obsession.

Recently, I completed participating in NH Bat Counts which is a joint project between UNH’s Cooperative Extension and NH Fish & Game’s Non-Game Department. I sat outside a big old barn in the summer twilight, waiting for bats to fly. My 9 year old son counted with me as we watched the bats sail out of the barn into the darkening sky. Their leathery wings, sometimes so close to us, we could hear their quiet flap and fold. He counted and I tallied. We worked for an hour until it was too dark to see them swirling up into the starlight. At the end, our tally read 271 bats.

According to the data collected from this site for the past 30 years, we were watching females and juveniles of big brown bats and little brown bats who made this barn their maternity colony. These bats, like all of NH’s bats, are insectivores, eating primarily bugs. They eat a wide range of insects, including midges, flies, moths and beetles. According to small mammal expert, Dr. Joseph Merritt, it is possible for a healthy population of bats to consume 22 pounds or 4,500,000 insects in one night alone. I think about this number, as I sit in the thickening darkness, counting these unique flying mammals, as mosquitoes land on my arms and feast on me. I had always heard that our New England bats eat a lot of mosquitoes but this is just one of the many falsehoods I’ve been told about these amazing creatures.

Bats actually don’t eat that many mosquitos. Instead they feed mainly on swarming insects, like clouds of midges and teeming flies. This bubbling-up of bugs, is easier prey for bats as opposed to mosquitos which generally fly low to the ground and hide in the thick understory.

It makes sense that bats would focus their attention on swarms of flying insects instead of hunting singular bugs buzzing in the bushes. Most insect-hunting bats use echolocation as a way to capture their prey. Bats use sound pulses that are ultrasonic. These sounds are produced in their larynx and released from their nose or mouth. Bats are then able to discriminate essential information from the echoes that return. Using this technique, bats can determine the size, shape, texture and relative motion of their prey as well as the distance to their target. No wonder there is a superhero based on bats!

Watching and counting the bats in the fading light as they swoop out of the old barn, I remember back to a time about 25 years ago, when I came to this very barn with Boston University’s bat biologist Dr.Thomas Kunz. Each year he would study several bat colonies in the Monadnock region. He and his researchers would capture bats and band them. I’ll never forget seeing a velvety little brown bat in his gloved hand with its enormous ears and a toothy mouth, opened wide in protest. With its wings folded up, it was impossibly small, like a sliver of fur, no bigger than a palm-sized fuzzy peach. Back then the barn was home to hundreds of little brown and big brown bats. It was a colony capable of eating at least 22 pounds of bugs a night.

But now, even though our count of 271 bats it better than in 2017 when they only counted 80, bats have been decimated by a fungus which results in the deadly white nose syndrome (WNS). According to NH’s Fish and Game Department, by 2012 over 5.7 million bats in the Northeast, including Canada had died from WNS. Not all bats are impacted by this fungal disease but many are including NH’s little brownbats, northern long-eared bats, small footed bats, tri-colored bats and big brown bats. The little brown bat, for example was once the most numerous bats in New Hampshire, but is now listed as state endangered due to WNS.

As I look up into the night sky and see just the slight suggestion of a bat flying over me and my son, I hope there are bats left to count for my son’s children and that they can watch them in the fading light as the bats swish through the summer skies. I’ll be counting on them.

Susie Spikol is the Community Program Director for the Harris Center for Conservation Education in Hancock.