Texas Tech University's Liam McGuire is studying how to mitigate a fatal bat disease.
It's pitch black. The ceiling is only a few inches above your head, and if you extend your arms, you'll easily be able to touch the walls on both sides of you. You're the only person there, but you're not alone. You can hear the flapping of hundreds of wings, but it's too quiet, like your ears aren't working properly or maybe sound just doesn't carry the same here. You can feel the creatures zipping around you in every direction, invisible in the darkness.
For many people, this sounds like a scene from a nightmare. For Liam McGuire, it was the moment he knew he wanted to be a bat researcher.
“We were working at this abandoned mine in Eastern Ontario; this was a site where, in the middle of winter, about 30,000 bats would hibernate,” he recalled. “I remember standing in the adit as you come into the mine, and there were just hundreds of bats zipping back and forth all around you, and not a single one is ever touching you. I can't see my hand in front of my face, but with their echolocation, they can see just fine. They know I'm standing there, and they just swerve around me and keep on going. You can feel the wind coming off their wings as they fly past you – really neat experience. I said, ‘Yeah, I've got to do more of this.'
“To be fair, if you just pluck somebody up, blindfold them and plop them in that situation, it's pitch black dark; it's damp; it's humid. The sound in an abandoned mine is just totally different, everything is so muted and so quiet. Then there's something, and you don't know what it is, flying all around you? Yeah, I would totally understand being afraid of that.”
Fear of bats
Although many people are afraid of bats, McGuire said it's definitely a learned behavior.
“I've given bat talks from kindergarten right up through high school, and I have yet to meet a small child who's afraid of a bat. They are universally fascinated,” said McGuire, an assistant professor in the Texas Tech University Department of Biological Sciences. “What you typically see is all the kids crowding in close and all the parents backing away. I think kids notice that, especially as they start to get a little older and they're more tuned in on social cues. They learn to think bats are scary.”
That's not to say that there aren't legitimate reasons to be wary of bats, like the fact that they can carry rabies. According to the World Health Organization, bats are now the major source of human rabies deaths in the Americas, while the Centers for Disease Control and Prevention list bats as the most frequently reported rabid animals in the United States.
But McGuire believes most people's fears are attributable to simple unfamiliarity.
“How many people actually ever get to see a bat? If you're lucky, you get to see the silhouette of something flying around the sky at dusk,” he said. “When you think about what is a bat, they fly around in the dark through caves, underground, at night – none of these things line up with what we do, so it's all very unfamiliar to us, both in the sense of what they're doing and in the sense of ever actually interacting with these animals.”
He knows exactly what he would say to someone who is afraid of bats.
“Let me introduce you to one,” he said. “I've had people who've been very, very hesitant but you get them close, and they realize it's not scary. First of all, most people think bats are huge. They tend to think of ‘Indiana Jones and the Temple of Doom' where you've got the giant vampire bats, which of course are not a thing – vampire bats, yes; giant vampire bats, no. Almost universally, when they finally see one, their first comment is, ‘Oh, it's so small!'”
There are some bats, like the Australian flying foxes, that have a 6-foot wingspan. But, McGuire pointed out, their favorite food is flowers. None of the bat species in the United States get anywhere near that large.
“I've got photos of bats in my hand, where my thumb covers up most of the body of the bat,” he said. “They seem a whole lot less intimidating when you realize they fit entirely within the palm of your hand and they're not going to come do whatever you think they're going to do to you.”
Experiencing one up close, he said, can change most people's minds.
“When you get to see them and see how neat they are, their fur is so soft, and their wing membrane is really neat; it's so thin and so fragile,” he said. “You see these animals looking around and checking you out – in many cases, they're sort of puppy-like in that sense. They're just curious about what's going on.”
And for people who really need to be convinced, he recommends looking up pictures from the Australian rescue centers that raise orphaned flying foxes.
“When the bats are very young, they can't control their body temperature yet, so you have to swaddle them in a little blanket,” he said. “Also, when they're very young, the only way they're ever going to survive is by holding onto mom while she flies around, and the only place to hold on is mom's teat. So they need a little pacifier. You see these photos of these little bats wrapped up in a little swaddling blanket with a pacifier, and that's what keeps them happy and cozy.
“Bats are actually quite cute.”
That's all fine for fruit- or flower-eating bats, you may say, but how can even a bat researcher defend vampire bats? The truth is, some don't.
Years ago, McGuire and a colleague were conducting research in Belize. They had strung up nets to catch bats, and time came to check the nets. In the first one, McGuire found the first vampire bat he'd ever caught. Hearing this, his colleague responded, “Oh, well, in that case, I'll let you be the one to take it out.” McGuire had to be very careful because, if he were bitten, the anticoagulant in vampire bat saliva would make him bleed and bleed and bleed. But he got the bat out and everything was fine, so they went to the second net.
There, they found another vampire bat. His colleague, this time, said, “Why don't you get that one, and I'll go check the next net?” So McGuire got it out and they moved on again.
“We get to the net after that, and there's a vampire bat and a tiny, cute, little fruit bat,” McGuire said. “He says, ‘I'll get this one, you get that one over there.' And I'm like, ‘Hold on, I'm seeing a pattern here.' And he said, ‘Oh yeah, I don't touch vampire bats.'”
So why would even a bat researcher avoid vampire bats if they're not really the stuff of monster movies?
“They are incredibly fast,” McGuire explained. “If you think about it, these common vampire bats feed mostly on large mammals, which now means cattle, mostly. They have to sneak up on these animals in the middle of the night while the animals are sleeping. They don't actually suck the blood; they make a tiny little incision, their anticoagulant causes the blood to flow, and then they just lap it up with their tongues. Vampire bats are basically kittens.
“But if you're a little vampire bat, nipping at the heel of a horse or a cow, you have to be ready to jump out of the way so you don't get stomped on. These guys are really quick at jumping, turning, flipping and spinning. So when you're trying to get them out of the net and they don't want you grabbing at them, they just spin around so quickly. You have to be very careful and pay attention – much more than you do with other species.”
Vampire bats aren't evil, though. In fact, they're incredibly social, helpful animals.
“They eat blood and nothing but blood, and blood is actually not a really nutritionally high-quality diet,” McGuire said. “You've got to drink a lot of blood to get enough nutrition out of it, so these bats, if they don't get a blood meal, have basically got three days and they're dead.
“So the social groups they live in are one of the textbook examples of altruism. If one of the bats in that group hasn't been able to get a meal, one of the other bats will regurgitate part of its meal to share with the bat that didn't get any. The idea is that they're working on this long-term average: you didn't get a meal tonight, so I'll help you out; at some point in the future, I'm not going to be able to get a meal, and you can return the favor and help me out. There are these really complex social systems in these animals that play into that.”
In his experience, McGuire said, vampire bats generally come across as very curious animals that, nevertheless, won't take anything lying down. Mexican free-tailed bats, by comparison, are very passive.
“They are the most gentle, teddy bears of bats I have ever met,” McGuire said. “You catch these guys and they just hang out. ‘OK, fine, what are we doing? You want me to open my wing? OK, let's do that. OK, that's fine. Thanks very much,' and off they go. They're just totally calm, not fussed about anything. Other species that you catch in your net, you know you've caught one before you even see it because they're just screaming at you. So just anecdotally, different species are very different in how they respond to things.”
But there also are scientific ways of measuring bat personalities using a Hole Board Test. In the middle of a closed, square arena are holes the bats can stick their heads into to investigate.
“You can look and see what the bat does when you put it in there,” McGuire said. “Really shy, very anxious-personality animals tend to sit very still and keep to the perimeter; they don't take any risks and just try to keep out of the way. If it's a very bold, more exploratory, aggressive kind of animal, it's all over the place. It'll go out into the middle of that arena, away from the safe space of the wall, and it'll be dipping its head down into the holes to see what's going on in there.
“You can record this on different animals, and you can tell this animal was more exploratory and more aggressive; this animal was more shy and more anxious.”
Even though people generally see themselves as the victims and bats as the villains, that's not exactly an accurate worldview. In fact, McGuire's current research focuses on something that's victimizing the bats: white-nose syndrome.
White-nose syndrome essentially causes bats to starve to death during hibernation. Before bats hibernate, they build up their fat stores, then go underground and drop their body temperature to match the air around them. They expend almost no energy while cold but use significant energy to warm up. The disease causes the bats to arouse more frequently during the winter, resulting in the depletion of their fat stores. Ultimately, the animals run out of energy waiting for warmer weather to arrive.
The fungus that causes white-nose syndrome has now reached Texas on its march west.
“All the West is still an unknown quantity,” McGuire said. “We've got quite a different mix of species out there than we do in the East. So the big question is, are these different species susceptible or not? In the East, some species get 90-plus percent mortality; others, a few animals are killed by the disease but not that many. All these species out West that haven't yet been introduced to the fungus, what's going to happen with them?”
Bat scientists are hoping to use the bioenergetic model of hibernation to try to predict what will happen to these species, but there's one big obstacle in the way.
“We don't know anything about the species out West because they're hard to come by, and there hasn't been much work done out there,” McGuire said. “We don't even know the basic input parameters for that kind of model, basic energetics or how these animals hibernate.”
So for the third consecutive year, his research team is taking a mobile field lab to hibernation sites across seven states, catching bats and recording data to better understand how various species hibernate and what that means for white-nose syndrome.
In the meantime, McGuire is working on a related project here at Texas Tech.
“White-nose syndrome is a fungal disease, and fungus generally like a very specific set of conditions for growing; this fungus likes cold temperatures, unlike most others,” McGuire explained. “The right temperature and the right humidity are going to be the best for the fungus to grow. At the same time, when these bats are hibernating, they like the right combination of temperature and humidity, themselves. So one of the ideas that's been suggested as a way to mitigate some of the impact of the disease is to manipulate the microclimate of different hibernation sites – make it a little warmer, a little colder, a little more humid, a little drier – and that would shift the balance to give the bats the edge over the fungus.
“It wouldn't be curing the bats, it wouldn't be clearing the infection but shifting the environment such that the bats are favored over the fungus. Neat idea, except that we have no idea if we should make it colder or warmer or how to account for the idea that, as you change temperature, you're also going to be changing humidity.”
So, McGuire and his research assistants will modify environmental chambers into miniature bat caves, and bats will hibernate inside them throughout the winter. The scientists can set the temperature and humidity to see how the bats fare under those conditions.
A second group of bats will hibernate inside interconnected chambers, each with its own separate condition, so the bats can fly from chamber to chamber and choose which condition they prefer.
“That's the next most important question,” McGuire explained. “If we do say, ‘OK, this temperature and this humidity is ideal for giving the bats the advantage over the fungus,' then it may be that the bats make a maladaptive behavioral decision, where they prefer a condition that makes things worse.
“We can manipulate the microclimate of an old abandoned mine, for example, all we want, but if that's not a condition the bats are going to tolerate, it won't make a difference.”