Published: May 15, 2020

Fearing Bats Won’t Prevent the Next Coronavirus


Those bats in your backyard? Very good neighbors.

Close-up of a big brown bat perched on a mossy surface. Its fur is light brown and its face, ears, and wings are black.

By Natalie Dalea, Public Relations and Science Communications Intern and escritora Xicana studying environmental humanities

Bats already had a bad reputation from vampire stories and rabies concerns. Now in the spotlight for their role in the spread of the new coronavirus, bats are under even greater scrutiny and face threats of extermination

It’s uncertain exactly how COVID-19 first infected humans. Genetic sequencing reveals that the coronavirus that causes COVID-19 probably originated in bats, namely a certain species of horseshoe bat. However, given the horseshoe bat’s rural habitat, it’s possible there was another animal that picked up the virus from bats and then transmitted it to the first city-dwelling human patients. But mass slaughter of bats leads to new problems—it prevents them from providing economic benefits and it disrupts their ecosystems, which can cause a domino effect of unknown problems. Still, the pandemic has only amplified people’s fears about these shy creatures of the night, putting bats in danger.

Here in Chicago, without realizing it, all of us live with bats all the time.

  Larry Heaney, Negaunee Curator of Mammals

Why are bats so notorious for diseases? All animals carry different viruses. The 1918 Spanish Influenza pandemic likely came from birds. H1N1 is commonly known as “swine flu” because it came from pigs. HIV originated from people coming in contact with infected chimpanzee blood. Yet we don’t indiscriminately kill birds. We still raise pigs. We launch campaigns to protect chimpanzees. We accept these animals as important parts of our world. Why not bats?

I interviewed Larry Heaney, the Field Museum’s Negaunee Curator of Mammals, to find some answers. “Bats are among the least well-known mammals globally,” he tells me. One thing this pandemic has emphasized is that we are much more scared of things we don’t know. And humans are diurnal creatures—with our poor night vision and lackluster hearing, we are naturally afraid of things that go bump in the night. Bats are much easier to fear than familiar primates, pigs, or birds.

Four people sit around a table under a tarp in the middle of a forest. They work with small mammal specimens.

Larry Heaney and Philippine colleagues at one of their forest camps. Heaney does much of his research in the Philippines.

Eric A. Rickart

Heaney is an evolutionary biologist. He studies mammals, with the majority of his research in the Philippines. His fieldwork has taken him from vast tropical forests to snake-infested caves. If anyone has some good bat facts, it would be him. I figured it was time to refresh myself on the bat basics and get to know my nocturnal neighbors. Sometimes the coolest conversations can come from the simplest questions.

What even is a bat? 

The simplest answer: “They’re the only mammals that fly.” Many mammals have flaps of skin that help them glide between trees. Bats are the only mammals that actively propel themselves through the air. “If it’s a mammal and it’s got wings, it’s a bat,” Heaney says. “But it’s important to know the way biologists define them is based on relationships. If you go back far enough, all bats share a common ancestor.”

Bats are all in the same group of mammals, but nowadays they come in a great many varieties. There is so much genetic variety among bats that it is unlikely COVID-19 could transfer from horseshoe bats to other bats around the world—more reason not to disturb hibernating bats in your backyard. “Bats are an extremely diverse group of organisms,” Heaney says. “Among bats, there are species as distantly related to each other as cattle and deer and giraffes are to each other.”

This fact is as intriguing as it is reassuring. I didn’t realize “bat” could be a category as wide as “four-legged, hooved animal.” From a distance, it’s hard to see the differences between them. Most bats are pretty small, so it doesn’t seem like there’s much difference between one furry flapping thing to the next. Heaney has been up close and personal with about every type of bat imaginable. Bats are not only incredibly diverse, but they also perform a range of important—and maybe surprising—services.

Megaderma spasma, also called the lesser false vampire bat, lives in South and Southeast Asia. It uses its enormous ears to listen for insect prey.

D.S. Balete

An illustration from the book The Mammals of Luzon Island that Heaney co-authored. The orange-fingered bat, Myotis rufopictus, lives only in the Philippines.

Velizar Simeonovski

We all benefit from bats

As an evolutionary biologist, Heaney studies the genetic relationships and differences between mammals. He also learns about the relationships mammals have within their ecosystems. When I ask him what role bats play in their habitats, his answer is immediate.

“Bats are tremendously important,” Heaney states. “They’re the keystone parts of a lot of communities. That takes place in a lot of different ways.”

He first tells me a story of Mexican free-tailed bats, named because they have long skinny tails sticking out behind them. One of the most abundant mammals in the Americas, free-tailed bats roost in colonies, with millions crowding together in caves in the Southwestern US. 

“People who aren’t familiar with these bats leave unusual reports,” Heaney says, “because every evening as the sun goes down, it looks like there’s a big plume of smoke going into the air. It’s actually a big swarm of bats going into the upper air layers where they feed on moths and beetles catching a ride on the winds up high. There can be so many of them that the national weather service picks up clouds of bats, as if they were rain clouds.”

These clouds of insect-eaters not only add to local reports of UFO sightings, but also they save the agricultural industry millions of dollars every year. Two important bugs they slurp up are the army cutworm moth, which infests crops of grains, and the cotton bollworm moth, which infests cotton. So if you want shelf-stable pasta, hygienic underwear, and clean face masks, you want to keep the bats around. “Those are just examples from the United States,” Heaney adds. Many kinds of bats all around the world eat moths, beetles, and mosquitoes, which damage crops and give people diseases like malaria. Keeping the bugs under check makes bats an important part of their ecosystems’ food webs.

Bats, the littlest tree-huggers

Not all bats are insectivores alone. “Some are the mammalian equivalent of hummingbirds,” Heaney says. “They feed on nectar and pollinate flowers they feed from. A lot of those plants are critically important for the forests they live in, even commercial crops and mangrove trees, which are crucial for protecting coastal areas as sea levels rise.”

Bats do a lot to naturally protect Earth against climate change. In addition to pollinating wetland trees like mangroves, many bats disperse seeds. Bats are the littlest tree planters.

“They are one of the most important agents of reforestation,” Heaney states. Bats restore forests in areas that people once cleared for agriculture and livestock. After fruit-eating bats feed on trees in nearby forests, they fly over open areas and poop. Their guano contains live, viable seeds of the fruit they’d been feeding on, with a little bit of fertilizer. 

“You see this conspicuously as you walk through the Philippines,” Heaney recalls. “There are these little splats on the ground with fig seeds, and little seedlings sprouting.”

A forested, mountainous landscape in front of a clear blue sky.

The forests of Mt. Natib, part of a protected area that is less than 50 miles from Manila, are home to dozens of species of bats with wingspans that range from about five inches to over over four feet.

L.R. Heaney

Bats help us answer medical questions

There are always risks that come with existing on a planet with other living creatures. But the truth is, Heaney explains, we are more likely to be killed by being kicked by a horse or being hit by a lawnmower than by a bat on its own. Heaney illustrates this point. “Here in Chicago, without realizing it, all of us live with bats all the time. When my wife and dog and I walk around the city in the summer, we see bats almost every evening, flying above our heads. They’re really innocuous animals. In fact, they’re very shy."

Close-up of a big brown bat perched on a mossy surface. Its fur is light brown and its face, ears, and wings are black.

The big brown bat (Eptesicus fuscus) is one species that lives in Chicago—and across much of North America. 

Michael Durham / Minden Pictures

The COVID-19 pandemic has increased interest in bat research, especially understanding their immune systems. Studies are exploring a new hypothesis: maybe the reason bats carry these viruses is because their immune systems work differently than others. Instead of killing viruses, it is possible their immune systems find ways to coexist with the virus without bats getting sick. If scientists can crack the case, who knows what solutions they might find for developing vaccines or treating autoimmune disorders.

And museum research is an important puzzle piece in answering these questions. Heaney tells me, “At the Field, we have large research collections—tens of thousands of bat specimens from around the world, collected over the past 130 years.” This abundance of bats gives our scientists plenty of data to explore bat biology. Genetic research can reveal which bats are viable carriers of diseases. Studying bat behaviors out in the field can determine how bats indirectly benefit our health, by eating pests and balancing their ecosystems. Ecological research is intrinsically intertwined with medical studies.

Heaney explains, “When catching bats, the first question any medical researcher will ask is, ‘What species of bat is this? Is it related to the bats carrying the COVID-19 virus?’ Museum-based evolutionary biologists are the ones who do the research that makes it possible to answer that question. Bats, including the horseshoe bats, are among the least-studied animals globally. There’s a tremendous need for the most basic research on taxonomy—how these animals are related to each other, or how many species of these animals there are, and where they live.”

What we do know is this: Bats perform crucial roles in our shared environments, from swooping on mosquitoes to replanting areas of tropical forests—many benefits that we rarely see because there is so much more to learn from them. They are neighbors to greet from a respectable distance, like any wild animal. They are collaborators in taking care of our planet. They are creatures worth protecting.