Since white-nose syndrome was first identified, just twelve years ago, it has spread to thirty-one states. The consequences for bats, humans, and the U.S. economy could be disastrous.
Late last summer, the biologist Mark Gumbert began flying over the farmlands of Iowa, looking for bats. As the animals foraged and moved through the night, he followed from above, circling the rivers and fields in his single-engine Cessna 172, trying his best not to lose the signals from their transmitters. Over the past decade or so, Gumbert has pioneered the study of bat migrations using radio telemetry, a method of wildlife tracking typically reserved for caribou, moose, and other big game, which tend to travel at moderate speeds. “A wolf running across the ground can move pretty quick, but they’re not going to run all night,” Gumbert told me recently. A bat, on the other hand, can be nearly impossible to trail on foot or by truck. Gumbert and his team at Copperhead Environmental Consulting were the first to observe an entire migration from the air, and they have since conducted surveys in New York, North Carolina, Ohio, Tennessee, West Virginia, and elsewhere. But the project that brought Gumbert to Iowa was unlike any he had undertaken before—tracking the northern long-eared bat, Myotis septentrionalis, a species that is among those most threatened by a dangerous fungal disease called white-nose syndrome.
Since the syndrome was first identified, twelve years ago, it is estimated to have killed more than six million bats nationwide, a number that has undoubtedly risen since the U.S. Fish and Wildlife Service issued its most recent official estimate, in 2012. As of September, 2017, the disease had spread to thirty-one states, some of which have suffered ninety-per-cent declines in their bat populations; the crisis, which began in New York, now extends as far west as Washington. “I think most states would say it’s not a matter of if white nose is going to show up but when,” Kelly Poole, the endangered-species coördinator for the Iowa Department of Natural Resources, told me. The disease disrupts the bats’ hibernation, causing them to wake up in winter, exert energy looking for food, and, in time, starve. It is almost always fatal, leaving caves full of bones in its wake. Scientists have yet to find a cure or treatment. “I get a sense that we may actually be witnessing the extinction of a couple of species, at least regionally,” Gumbert said. “We may not lose a species completely, but it wouldn’t surprise me if we did.”
In a state such as Iowa, where the economy is based largely on agriculture, white nose is particularly worrisome. According to a study published in 2011 in the journal Science, bats consume enough insects to save U.S. farmers an estimated $22.9 billion a year in pest control and crop damage, a conclusion echoed by a follow-up study in 2015. The findings suggest that a nationwide decline in bats could result in higher food prices, owing to an uptick in pesticide use and a reduction in crop yields. “That cost gets passed down to the consumer, and you start seeing it at the grocery stores,” Piper Roby, Copperhead’s research director, told me. She also noted that increased pesticide use means more harmful chemicals in the ecosystem. “It’s just this cascade effect if you remove a top-down predator, and you start to see the effects of it years later,” she said.
Gumbert’s efforts in Iowa, which began last August, were something of a stopgap measure. The thinking was that, if he could track the northern long-eared bats, often known simply as northerns, along their migration routes, he would be able to identify where they ended up hibernating. This, in turn, would allow state officials to protect the animals from human encroachment, including wind-energy development, while they were at their most vulnerable. As Poole, who is overseeing the project for the D.N.R., put it, “We don’t know where the bats are hanging out.” The fact that they are small and secretive complicates the process. Unlike the bats of campy horror films, northerns tend not to form large clusters in caves. If they did, Poole said, “then you’d have, like, one cave to protect.” Instead, Gumbert told me, “They may actually be roosting in the ground and in little crevices they can crawl into.” They might be in groups of two or three, or they might be alone. He and his team fitted thirty bats with transmitters in the course of the project, seven of which were active in the field at the time. None, it seemed, had ended up in the same winter refuge, known as a hibernaculum, or had really migrated much at all; they were mostly making small jumps. “We’re not exactly sure what they’re doing yet,” Roby said.
To track those thirty bats required months of near-sleepless nights. When conducting an aerial survey in the summer or fall, the team first has to catch the bats one by one, by setting up nets in areas of known bat activity. Once they catch one, they document its sex, weight, and over-all health, then put a numbered band on one forearm and fit it with a radio transmitter roughly the size and shape of a Tic Tac. Gumbert takes off at dusk each evening. He searches for one bat at a time, following the beeps from a receiver in the Cessna. Once he pinpoints one bat’s location, he begins looking for the next; he will cycle through the group again and again for the next four or five hours, waiting for one to make a move. When that happens, Gumbert leaves the rest behind and follows the bat however far it travels—in one case, more than two hundred and twenty miles in the course of several days. It is mentally exhausting work, he told me. “Not only am I listening to the beeps and going through the frequencies of the bats that are out there; I’m also looking for other aircraft,” Gumbert said. But he also finds flying at night peaceful. In Iowa, as he tracked the bats, he picked out porch lights scattered across the otherwise black fields of corn and soybeans. “If there’s not a lot of haze, you can see the reflection of the moon on the river below,” he said. Sometimes people will notice his plane circling their property. “Then they get their big flashlight out and they spotlight us, or they get their laser pointer,” he told me.
Aside from the practical concerns of protecting the species, one of the biggest challenges moving forward, Poole said, will be getting the public to recognize the threat that white nose poses. It doesn’t help the bats’ case, she added, that they’re not what most people would consider charismatic megafauna. When a conspicuous creature, such as a lion or wolf, teeters on extinction, folks tend to take notice. Last November, the outcry over the U.S. Fish and Wildlife Service’s plan to allow the import of elephant trophies from two African countries was so severe that President Trump had to get involved. Neither the northern long-eared bat, the little brown bat, the gray bat, the Indiana bat, nor any of the other species now at risk from white nose has inspired such widespread support, though their loss would no doubt affect the country more severely than would the disappearance of the elephant. But Roby told me that, even now, with white nose as widespread as it is, researchers are already behind in simply trying to understand the lives of bats—the northerns, in particular. “All of a sudden, we’re starting to lose these populations, and we don’t know how to help them because we don’t know what they need,” she said.
By November 1st of last year, Gumbert and the Copperhead team had concluded their aerial monitoring and were wrapping up the last of their field work. They had confirmed the location of only one hibernaculum. The bats had not migrated far—about twenty miles. Ultimately, the project had led to more questions than it had answered, Roby told me. Gumbert speculated that, for the time being, the most effective way to help the bats, at least in Iowa, would be to protect the forested areas along the major waterways where the animals are known to forage and hibernate. Unlike most other endangered or threatened species, he noted, northerns are generalists; they do not require a specific habitat to thrive. Since Iowa isn’t short on bat habitat, what northerns need most remains a mystery. Still, Gumbert said that he is encouraged by signs that some species in the United States and abroad may be developing an immunity to white nose. “I’m hopeful that bats build up a resistance and they do survive,” he said. “I’m terrified to think of my two-year-old growing up and there not being bats on the landscape.”