Bat Rehab

A big brown bat is fed formula to help get its weight up. Photo by Mark Paul.

Barry Genzlinger is up at 5 a.m. mixing the formula: one part goat’s milk to one part Fox Valley formula. As he feeds one of the pups tiny drops from a graduated syringe and talks about Izzy, one of his first successfully rehabbed bats, it’s clear that Genzlinger is passionate about the animals. It’s a passion shared by his wife, Maureen, who goes by Mo. At any given time, the couple might have dozens of bats in the cellar of their Milton, Vermont, home.

During the winter of 2014-15, the Genzlingers had 26 big brown bats and one little brown under their care. After releasing the bats in the spring, they hoped for a break before the year’s young started to arrive. Three weeks later, their break was over. The cellar hibernaculum – a makeshift cave providing a temperature gradient between 40 and 45 degrees – was once again transformed into a weaning- and rearing-room where unfurred pups weighing from 2.1 to 5.6 grams were housed in an incubator set between 90 and 100 degrees.

The young bat pups need three drops of formula every hour for the first three to four days in the Genzlingers’ care; then, feeding can be done every few hours. Next, the bats graduate to eating mashed up mealworms – heads cut off and guts squeezed out – and, eventually, whole mealworms. They also need bathing, for which Barry uses a Q-tip, and every step along the way, he collects data.

Rehab and Release

It’s around 7:30 in the evening on May 2, 2015 – temperature in the low 70s, still plenty of sunlight – when the Batmobile quietly pulls up. No big rear fins, not even a bat bumper sticker; it’s a Prius. This is the second release of the year. “When you see insects at night, flying around the streetlamps, you know it’s time,” said Genzlinger. “Besides, we’re just about out of mealworms: they’ve been eating 500 a day.” We’re at Essex High School. Two bats were rescued in town this past winter. They had fallen, for some reason, out of a roost in a building, so this is where they will be released.

Bat Rehab Image

Photo by Mark Paul.

Genzlinger lifts up the black curtain that covers one cage and reaches in. Three releases, three cages, and each bat has different-colored toenails, so there is no confusion about who is who and who goes where. Genzlinger knows how to handle the bats, how to maneuver his fingers under the bats’ wings to get a secure but gentle grip, but the bats are not exactly cooperating. He talks to them: “Come on, you little bug-eater you, get over here…There you go.”

Genzlinger doesn’t fit the stereotype of a grandfather. He’s fit – a marathon runner – and is as excitable as the bats he handles. He says that, when it comes to misconceptions about bats, his peers are “the biggest problem group, because they have been taught that bats get in your hair and that all bats are rabid.”

Genzlinger has made it his mission to set the record straight, devoting his energy as much to education as to saving bats. He’ll tell you that less than 0.5 percent of bats are rabid. And if your hair happens to be surrounded by insects, it may appear that bats are trying to fly into your hair, but they aren’t. “Younger people have grown up interacting with nature differently,” he says, “and are less inclined to believe these myths.”

Genzlinger has the bat cupped in his hands. Mo is standing by to help. “Yeah, yeah, yeah,” he says in a soothing tone, “this is Green Toes.” Green Toes twitters loudly. “He’s pissed,” says Genzlinger, as he walks toward the tree line, “shhhh.” He pauses for a picture and begins a recitation of cool bat facts: “This guy has a heartbeat, in flight, while foraging, of a thousand beats per minute. . . . Okay, here you go.” Genzlinger opens his hand and nothing happens. A little push and the bat flaps its wings and glides to the ground. “Lazy butts, that’s what happens when you’ve had too many mealworms. This guy weighs 14.25 grams, a bit overweight.” He picks Green Toes up and places him on a branch; a few minutes later, the bat flies away. Better to be overweight than underweight.

Bat Rehab Image

Photo by Mark Paul.

By the time we get to the Winooski release site, the sun is down, and mosquitos let us know we are close to the river. It promises to be a good night for hunting.

Bat Man

All of the releases were of big brown bats, Eptesicus fuscus, but back at the bat cave, a little brown, Myotis lucifugus, is recovering from white-nose syndrome. No obvious fungus on its nose, but another condition, immune reconstitution inflammatory syndrome (IRIS), is rapidly degrading the bat’s wings.

The bat is in quarantine. The odds are not in his favor. Not discouraged, Barry applies Lamisil spray – a fungicide – every day, and charts the bat’s weight and eating patterns. Collecting data is essential for guiding future practices.

A lot of things in Genzlinger’s life prepared him to become a bat rehabilitator. There was the orphaned raccoon that he and Mo raised while they were also raising their three children – Barry teaching high school math, and Mo teaching kindergarten and first grade. The raccoon came and went through the cat door and enjoyed riding off into the woods on the back of their pet husky. Eventually, it brought home a girlfriend and, shortly thereafter, never came back. There was the baby squirrel Genzlinger raised and kept in a drawer in his college dorm. He was an active Boy Scout as a kid and raced sled dogs as an adult, so it’s not surprising that Genzlinger has found a way to stay connected to nature.

Bat Rehab Image

Photo by Marvin Moriarty / USFWS.

When bats roosted in the eaves outside their first house in Goshen, New Hampshire, and made a mess of the porch, the Genzlingers didn’t have to find a way to coexist with the bats, but they did. And they didn’t stop there. They built a bat house and soon got hooked up with Bat Conservation International, which was sponsoring a National Bat House Research Project to determine the optimum bat house design, placement, and color for each region of the U.S.

The Genzlingers built bat houses, and so did thousands of other researchers around the country. They built small ones, large ones, green ones, black ones, white ones, one-chambered, three-chambered, you name it, and they put them up in different locations, at different heights, facing different directions. They counted bats, and their children counted bats, and they accumulated massive amounts of bat data on eight different prototypes. In the end, one of Genzlingers’ designs, 18 inches by 30, was determined to be the best size for creating a temperature range between 95 and 105 degrees, and thereby, the most conducive to bat reproduction. Exterior color affects temperature: in the Southwest, for example, white is best, while in the Northeast, black is best.

The family started a bat-house construction business called Chiroptera Cabin Company, and from about 1988 to 2010, Barry, Mo, and their three children made and sold more than 4,000 bat houses in six different models, all certified by Bat Conservation International. That was back when their Batmobile was a mobile classroom, a van with lots of bat bumper stickers and educational materials touting cool bat facts: “There are 9 species of bats in Vermont, 9 of the 45 species found in the U.S., 9 of the 1,200 species found in the world,” and, “One little brown bat can eat more than one thousand bugs in one hour.” Genzlinger lectured on bats to school and community groups, and led programs at Shelburne Farms and elsewhere, earning the title “Bat Man.”

When you talk with Barry, you get the sense that this project – or maybe I should say, this lifestyle – is not just a hobby or a passion. It’s a perfect mix of ideology and talent, dreams and needs, and it provides Barry with a steady supply of problems to solve – the lifeblood of any scientist.

Problem number one: what do we put the bats in? Solution: cardboard box. Problem number two: how to prevent the box from being destroyed by bat guano? Solution: plastic lining. And so it went, every day being faced with another problem to solve, and every day coming up with a new, exciting solution. An old heating pad on the back of the cardboard box helped create proper incubation temperatures; toilet paper rolls provided entertainment for bored pups; pouches of denim and foam gave the bats places to hide; babies who could not yet take milk from a syringe were fed from an eyeshadow sponge.


In their backyard, Genzlinger shows me the flight cage he built. This sturdy 16x16x7-foot structure provides the bats a place to practice flying before their release. He laughs as he describes his first flight cage, a pop-up screen house that blew away with the first strong wind.

Inside the cage is a bat house. We open it and take a peek at Izzy. She is free to leave but has chosen to stay, unlike the other bats from her cohort, who were released in the spring of 2014. Izzy kept coming back for the mealworms set out to allow the bats to transition to hunting on their own, so Barry and Mo eventually had to take her in for the winter. The door to the flight cage is open, and she hunts on her own, but Izzy still chooses to roost here, where the Genzlingers raised her. Barry and Mo are sure Izzy recognizes them.

“There is no record of bats’ imprinting on humans,” said Barry, “but I know that this bat remembers me. It was clearly evident when she came out of hibernation with all of her cronies, who would all attack the mealworms with a quick snap. Izzy, however, would gently pick the mealworm off the tweezers and then gobble it down.”

She is the cutest bat I’ve ever seen, but then again, I’ve never really seen the beauty in bats until now. I met my first bat after being awakened by my screaming wife in the middle of the night, right before I frantically tried to redirect it out our bedroom window with a tennis racket.

Bat Rehab Image

A bat takes flight on a summer night in Vermont, which is home to nine species of bats. Photo by Seann Patrick Cram.

Thanks to people like Barry and Mo, persistent petrified attitudes toward bats are changing. Every interaction they have with someone is a teachable moment about bats and disease.

It’s early June, and the little brown bat is recovering well. Weight is up and the wing deterioration is healing. Other experts Genzlinger knows are surprised. Barry and Mo are thrilled. No one really cared about a dead bat before white-nose syndrome, but now, with five of Vermont’s nine bat species either endangered or threatened, every bat seems to make a difference. The little brown, once the most abundant bat in the U.S., has been reduced to 20 percent of its original population. Little browns typically have one pup per year, but one female could easily have 10 in a lifetime. If half of those pups are females, and each female has 10 pups, you can see how one rescued bat could make a significant contribution to the local population.

Alyssa Bennett, a bat biologist with the Vermont Department of Fish and Wildlife, first suggested that Genzlinger take a baby big brown bat home and try to raise it. The Department had been working with him for some time, using his bat houses for state projects, so having someone who understood bats try their hand at rehab seemed logical. That bat was successfully released – the first of many.

“I thought it would be a good idea to practice rehabilitation on big browns,” Genzlinger says. “Makes sense; they are abundant. Make the mistakes on the bats that are plentiful.”

He isn’t making many mistakes. So far, Genzlinger has taken in 82 bats and successfully released 53. Those that did not survive were either severely injured or too small, weighing less than a dime.

By late June, Izzy apparently had left for good. Barry and Mo saw her chasing other bats. It was time. The little brown with IRIS was released with lots of energy and healthy wings, hopeful signs for other bat rehabbers.

Still, there were more arrivals. Six of the Genzlingers’ nine new pups had fallen out of a local bat house that was overcrowded. In a house designed for 15 to 20 bats, half the house was filled with paper wasp’s nests and the other half held 20 adult females with pups.

Bat Rehab Image

A big brown bat ready for release. Photo by Mark Paul.

As rehabilitators licensed by the State of Vermont Department of Fish and Wildlife and Agency of Natural Resources, Barry and Mo are qualified to do more than just feed and handle bats. They are bat doctors and, with help from veterinarians, can perform just about any procedure on a bat that could be performed on a human. So far, a necropsy to diagnose a dead bat’s bladder infection has been Genzlinger’s most complicated medical exploration.

Libraries are filled with books on how to care for human maladies, but for bat rehabilitators, there is only one: Captive Care and Medical Reference for the Rehabilitation of Insectivorous Bats, by Amanda Lollar and Barbara Schmidt-French. You name it, this book has it: how to anesthetize, treat shock, and do a general diagnosis; or treat bite wounds, pesticide poisoning, urinary tract infections, or diarrhea. There are procedures for treating fractures, blunt force trauma, pneumonia, and even for conducting amputations, though in most cases, euthanizing is the humane thing to do if a bat is not releasable. While this book is the bible for bat rehabilitation, the Genzlingers are adding to this body of knowledge daily.

They didn’t say so, but I’m guessing Barry and Mo can imagine a day when they will have interns – not only to help feed and care for the bats, but to do some rescues as well. In October 2015, the Genzlingers formed the Vermont Bat Center, a 501(c)(3), and can now accept tax-deductible donations to support their rehab and educational work. They can be reached at vermontbatcenter(at)

As of March 3, 2016, the Genzlingers have 16 bats in their facility. “The big news,” said Barry, “is that four of those are endangered little browns and three are critically endangered northern long-eared bats – all found clinging to the rocks outside their hibernation cave. They most certainly would have died if they had not been found by Vermont Fish and Wildlife Department staff.”

Mark Paul teaches biology and environmental science at Essex High School and lives in Starksboro, Vermont.

  1. Holly Killary → in Vermont
    Aug 23, 2016

    Great piece and very interesting!  Sadly, I haven’t seen a bat in years.  Decades ago, they could be seen flying through the night sky skimming across the lake water eating pesky (and now dangerous mosquitoes) and old lake camps would get their share of bats flying around inside - not now…

  2. Rick Miller → in Colchester Point, VT
    Dec 27, 2017

    I will installing a bat house on my lakefront property, spring of 2018. What is the right time of the spring to put up the house to have a better chance of a bat or bats occupying the new house?

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