Glimmers Of Hope In the Dark Battle To Save Bats

Richard Stark, a biologist with the U.S. Fish and Wildlife Service, examines a tricolored bat (Perimyotis subflavus)near the entrance of the cave. (Credit: Geoffrey Giller) Hidden away in the woods near the upstate New York town of Lake George is a cave. The entrance of the cavern, an abandoned graphite mine, is almost perfectly round, with a trickle of water running out of it. On a weekday morning in late February, researchers, led by Carl Herzog, a wildlife biologist for the New York State Department of Environmental Conservation, gather at the cave mouth and swap hiking boots for waders before filing in. Kate Ritzko, a fish and wildlife technician for the Department, reminds everyone of proper caving etiquette: Make sure geotagging on phones is turned off, so that no one accidentally reveals the location of this sensitive site; and keep voices low, so as not to disturb the bats the team is here to count. Inside the cave, the swishing sounds of waders bounce off the low, angled ceiling, mixing with the trickle of water and the occasional fracture of ice as someone’s foot punctures the stream’s frozen surface. Icicles rise from the ground like impermanent stalagmites. But as we move deeper into the cave, the ice disappears. That’s largely why bats seek out these caves in winter: The surrounding earth, like a blanket of soil and stone, insulates the interior from the frigid temperatures outside. We spot the first bat, tucked into a corner, upside down. It appears healthy enough. Oblivious to our presence and our bright headlamps, this is a big brown bat (Eptesicus fuscus), and it’s one of the species resistant to the fungus that has killed millions of bats throughout the eastern United States since it first emerged in 2006. The fungus is why we’ve come to this cave. It grows on hibernating bats, spreading across their face, wings, and any other furless skin. Infected bats typically develop a distinctive white semi-circle of fungal growth around the nose, which is the source of the deadly disease’s rather innocuous name: white-nose syndrome. Even before the fungus appeared, Herzog and others at the state agency had been conducting surveys in caves to get a handle on bat numbers—of both common species and endangered ones. Across the country, state and federal environmental departments have long done the same thing, generally visiting caves every other year to minimize disturbance. But in the era of white-nose syndrome, these surveys have provided grim tallies of the utter devastation the fungus leaves in its wake. In some large bat colonies, more than 90 percent of bats have been wiped out since the fungus first appeared; in many smaller colonies, every individual died. While the fungus has been a threat to the very existence of some endangered bat species, it’s the ecological ramifications of losing millions of once-common bats that worry scientists most. This cave, for example, used to be filled with a different type of bat, one that until white-nose arrived was the most common bat species in the northeast: the little brown bat (Myotis lucifugus). Today, we’ll find only two of them in a cave that used to house more than a thousand. The species is now listed as endangered in Vermont; millions have perished across the animal’s range.