In the Field — Part 2
Bat Blitz
Welcome back! If you haven’t already, I suggest reading Part 1 where I laid the groundwork for this series and talked about my first field job.
“…anyone who has spent some time in an enclosed space with an excited bat knows what it is to encounter a fundamentally alien form of life.”
— Thomas Nagel, philosopher
Today, we move to the mountains and hills of Tennessee and Kentucky to find the ever elusive bat. I’m ecstatic about this. Bats are one of the most peculiar groups of wildlife on the planet and one of my favorites. As Nagel says above, they truly are an alien form of life. They are the only truly volant (ability to fly) species of mammal (flying squirrels and sugar gliders can’t actually keep themselves in the air). They have been estimated to to consume one thousand mosquitoes per hour (the implications of this are incredibly important for agriculture). Believe it or not, they aren’t blind despite the phrase “blind as a bat”. It’s actually believed that their vision is about as good as humans or even slightly better. Obviously, since they are active at night, they can’t see very well. Imagine being outside at night, where there is no light pollution, and trying to cook dinner. It isn’t going to happen. Rather, bats use echolocation (echo = “sound repeated by reflection”) to catch insects during the night. Insane. This group adapted to exploit an unused spot in this vast food web of life. And lastly, they are one of the most imperiled groups in the United States due to a disease called white-nose syndrome. Stay tuned for a piece dedicated to this devastating disease.
Bats are so much more than “rats with wings”. As pollinators and a natural pesticide for crop pests, bats have a lot to offer. Hopefully through this post I’ll spread a little curiosity and awareness for a group of animals that has a special place in my heart and are in dire need of help.
Tennessee: Bat Blitz
So I had gotten a taste of the field life. I was approaching the end of my undergraduate career. What am I going to do? During the spring semester of my senior year, I began looking for another field job. I had this plan. Work a few field jobs, go to grad, get a PhD/permanent job (more on this later). Graduation was approaching and I was struggling to find another field job. This is where my hard work paid off again and probably a bit of luck. Another professor in the department offered me a summer job working for two new graduate students she was taking on. Score! During my search, I had mainly been applying to positions working with birds. So when my professor approached me to help in her lab, I was surprised. She’s a bat biologist, taking on graduate students for a bat project. I had no experience with bats. No rabies shot. Nothing. And yet, she gave me an opportunity that I took and am extremely grateful for. I even got my rabies vaccination for free! This is the point at which I went from bird-centric to bird-and-bat-and-everything-centric. And guess where it was?
The Great Smoky Mountains of Tennessee and North Carolina. That’s where I’d be spending the next few months of my life working. Holy shit!
The Great Smoky Mountains are some of the most awe-inspiring and breathtaking landscapes in the entire world. The iconic haze that sits over the mountains is forever etched into my memory (if you’re interested, here is the science behind why they are hazy and blue). The cool, crisp air, the eerily dark trails, the different hues of green, and diversity of life gives these mountains a magical and otherworldly presence. There’s a reason that it’s the most visited national park in the country. For the summer, I would assisting two graduate students on their graduate research. One project focused on the roosting habitats and hibernacula selection of tri-colored bats (Perimyotis subflavus). The other focused on how bats use the historical buildings that are scattered throughout the park.
The project studied tri-colored bats which are currently one of the most imperiled bats due to white-nose syndrome and is currently being considered for listing under the Endangered Species Act. This project was similar to my first field job in that it was a telemetry study. We would capture bats at night using what’s called a mist net. A mist net (pictured below) is a fine mesh net that is strung between two poles across an area. It’s typically placed in corridors where one would assume bats to travel. Over streams, above roadways in forest, large openings in forest, basically traffic lanes that bats are able to fly through. Some mist net setups can reach up to twenty-four feet tall and cover an area up to about 20 meters wide (that’s about 65 feet in freedom units)! Once a bat flies into a net, one must carefully and quickly remove it. Time is of the essence. Bats are susceptible to capture myopathy, which is a fancy way of saying it died while being handled by a person. Being captured and handled is a very stressful situation!
Once a bat has been captured, standard measurements and observations (including signs of white-nose syndrome) are taken and a radio transmitter is attached. The weight, forearm length, age, and sex are all important factors to measure. How radio transmitters are attached to bats is a little interesting. For songbirds, little harnesses are typically wrapped around the legs and back of the bird. For a bat, the transmitter is glued on after cutting away the fur on its back (don’t worry, the glue eventually dissolves). The video below shows a demonstration of how the fur is removed before attaching a transmitter. From there, the bat is able to be tracked to its roost. Just like any other telemetry study, bats are tracked to their roosts daily. Obviously the bats aren’t active because it’s daytime. But where do they go? What is a roost? For tree bats, a roost is, well, a tree. Think of a roost as where the bat lives when it’s not flying around eating all the mosquitoes that you curse during those hot summer nights. In the leaves, under the bark, in a hollowed out snag, different species have different preferences for where they like to roost on a tree. Not to be confused with hibernation, roosting is just where bats go to sleep during the day.
So as we know, bats are nocturnal. And as we might not know, not all bats use caves. And even fewer might know that some bats migrate. Rarely does a species hibernate and migrate (although evidence of a migratory bat hibernating has recently been discovered). Instead of hunkering down in some cave or under the bark of some tree, migratory bats move to warmer climates where insect populations are more abundant.
Once a bat has been tracked to its roost, vegetation measurements are taken. Canopy cover, tree species, diameter at breast height or DBH (what is the diameter of the tree at 4.5 feet above the ground), roost height (how high up the tree is the bat roosting), tree height, among others are all important measurements to take if you want to understand how a bat selects the tree in which it roosts.
“Hey bear!” Not an uncommon phrase to say at night while trapping for bats. Or in the Smoky Mountains for that matter. American black bears (Ursus americanus) run rampant throughout the hills and hollers of those hazy mountains. If you’ve ever been to Gatlinburg, TN or Cade’s Cove in the park, chances are you’ve seen a bear. They’re so abundant in Gatlinburg that people view them as nuisance animals comparable to raccoons! Digging through dumpsters, climbing up on people’s patios and balconies, these bears have adapted to the encroachment of human civilization on their turf. But, unlike raccoons, bears are dangerous. VERY DANGEROUS. Seen as more timid compared to their cousin in the west, the grizzly bear (Ursus arctos), black bears are more than capable of killing a person.
Black bears exhibit an interesting behavior called bluff charging. Bluff charging is where a bear makes a short rush or pounce, slamming their feet down and blowing loudly. Believe it or not, this isn’t a sign of aggression. This is a sign of nervousness. Maybe the bear is a female and has cubs nearby. It’s a highly stressful situation for a bear with young to encounter a person. “Hey bear!” Imagine. It’s twilight in the middle of the smoky mountains. You’re sitting in the dark checking your traps every 10 minutes. You hear something rustling in the underbrush nearby. It’s a bear. “Hey bear!” You let it know you’re there. “Hey bear!” You get loud. Get big. “Hey bear!” Don’t come over here. And as always, be respectful and admire these creatures from afar. Please do not be the person in Cade’s Cove in the Great Smoky Mountains National Park who gets out of their car and approaches a bear. Again. THESE ARE DANGEROUS ANIMALS AND SHOULD BE RESPECTED AS SUCH.
The second project involved going into the historical buildings that are scattered throughout the national park, finding maternity colonies, i.e. groups of female bats producing and rearing young, that have established themselves within the buildings, measuring individuals, and placing iButtons that measure the temperature and relative humidity where colonies are found. iButtons are able to measure what is called a microclimate which essentially describes the climate of a relatively small area. For a bat, that might be in the attic of a house, in a cave, within a tree canopy or cavity, or shoved in a crevice (pictured below). Microclimates are especially important during hibernation as well as for breeding. Hibernation is all about reserving energy or fat stores. Choosing a location that’ll best conserve those resources is a life or death situation. As for breeding, it’s similar. Having stable temperatures increases chances of breeding success and survival. In other words, the pups have a better chance at surviving if they aren’t freezing at night or overheating during the day.
So our job was to run around the park, go into old buildings, look for maternity colonies, measure individuals, and measure the microclimate of their roosts. So cool! But. Safety first. Guano (bat poop) contains the fungal spores of Histoplasma capsulatum. These spores cause the disease histoplamosis which infects the lungs and can be deadly if not treated quickly. Therefore, we would don respirators before climbing into buildings that are upwards of 200 years old! And I’m glad we did. In one particular building on the North Carolina side of the park, we found a colony of bats that had a five foot pile of guano underneath it. FIVE FEET! It was massive and probably contained trillions of fungal spores.
It was a great experience jumping into the bat world on two different projects. One allowed me to gain invaluable experience in handling and working with many bat species, including endangered species, and to see the beautiful landscapes that the Smokies have to offer. Oh and snakes. There are always snakes.. The other allowed me to take a glimpse into the past and history of that region of Appalachia and see how nature has, in part, reclaimed those buildings back into her care. From these projects, I continued to learn and improve upon the skills that I had learned during my first field job. Although the differences between the animals I was working with were night and day (get it? bats vs. birds), the job was basically the same. Capture the animal and measure it, attach a radio transmitter, track it, and measure the habitat where you found it. However, it was definitely a stark difference from waking up at 4 in the morning to track birds to working until 3 in the morning to capture bats. Luckily, for the vast majority of my life, I’ve been a night owl and this job worked great for my sleep patterns! Also, for those interested in working with bats, you’ll need to get used to being bitten. Obviously, a bat is not too happy that you are holding it and is going to try every way of escaping which mostly involves biting. I’m not going to lie, it hurts. But it doesn’t hurt that bad. You’ll get used it. One effective way of getting a bat to stop biting you is to blow hard in its face. There’s a good chance it’ll let go if you do and you can get on with your work.
So what did I take away from these jobs? First and foremost, I found a passion for bat conservation. I’d been unexpectedly thrust into this unknown world and came out with a new appreciation for a group that provides so much, but receives little in return in terms of public opinion. Secondly, white-nose syndrome is a serious threat and presents one of the largest ecological challenges of today. Once an abundant species, tri-colored bat populations have plummeted since the arrival of white-nose syndrome experiencing population declines of over 95%. It’s the same story for other species as well including the northern long-eared bat and the little brown bat. Additionally, I believe this is around the time that I started developing a passion for education and public outreach. Being in the most visited national park in the country, interactions with the public occurred frequently. Oftentimes, we would have a mist net strung across a roadway and would have to take it down to allow park visitors to pass through. Many of these instances turned into opportunities to educate park visitors on what we were doing, why we were doing it, and why they should care. Passing on knowledge and instilling curiosity. Curiosity is everything.
Originally, this piece was going to contain both my time working with bats in Tennessee and Kentucky. However, I wrote much more than I expected I would about my experiences in the Smoky Mountains of Tennessee. Therefore, my experiences in Kentucky will be coming later.
So stayed tuned for Part 3 — Bat Blitz 2: Electric Boogaloo. Join me as we explore the largest cave system known in the world and the forests surrounding them in Mammoth Cave National Park!
