Context is critical, right? Years ago I took a second job loading trucks at night, and a few guys on the dock had what you might call “white-nose syndrome.” All I had was coffee, so they could work faster than I, although they spent a lot more time in the rest room. I hope they eventually recovered.
Addiction is a serious and potentially life-threatening matter, but from a bat’s perspective, white-nose syndrome (WNS) is something even more devastating. This disease, which is nearly always fatal, has killed 80 percent of the bats in the northeastern United States in less than a decade. Initially found in central New York in 2007, white-nose syndrome now affects bats in 25 states and five Canadian provinces. Since it was first identified, it has felled more than 7 million bats, leaving once-packed hibernation sites, or hibernacula, empty, and pushing some species to the edge of extinction.
The disease is caused by a cold-loving fungus, Pseudogymnoascus destructans, which grows on hibernating bats. Its common name comes from the fuzzy white fungal growth that develops on the muzzle and wings of infected bats. Because Pseudogymnoascus is only active between 40 and 60 degrees F, and prefers very high humidity, it does not affect bats in their summer roosts.
The fungus is not native to North America, and researchers believe it was introduced by caving enthusiasts from abroad on their clothing or gear, likely several years before its discovery. Research has shown that the fungus remains viable on clothing for long periods of time. It was initially thought the pathogen originated in Europe, but scientists now say it’s unclear whether it came from Asia or Europe.
After its introduction in a high-traffic commercial cave in Schoharie County, NY, white-nose syndrome quickly spread via bat-to-bat contact, and by contact with spores on contaminated surfaces in hibernacula where WNS is present. Fortunately, it does not appear to spread through the air.
According to Benjamin Tabor of New York State Department of Environmental Conservation’s Bureau of Wildlife, it is not the disease itself that kills bats, but rather the changes in behavior it induces. Tabor explained the white-nose pathogen irritates the skin of infected bats. They wake from torpor to scratch their muzzles, and often fly around in confusion before returning to “power-saver mode.” Hibernating bats pack a modest winter picnic in the form of fat reserves to sustain them until spring. Rousing a half-dozen times during winter to scratch their faces and fly around burns off bats’ energy reserve too soon, and they starve to death.
New York, possibly the state hardest hit by WNS, is home to six kinds of cave bats: the little brown, big brown, northern, tricolor, Indiana, and long-eared. Cave bats are most at risk because they hibernate in dense clusters in caves or mines that are contaminated with WNS spores. New York also has three types of tree bats, but these are less susceptible to white-nose syndrome. The more solitary behavior of tree bats, as well as the fact their hibernation sites are much drier than those of cave bats, protect them from the disease.
Body size seems related to mortality, with smaller species dying off in greatest numbers. Once the most numerous species in New York State, the little brown bat population has declined by over 90 percent. Populations of northern bats and tricolor bats have plummeted since 2008, down 98 percent in both species. The big brown bat, the largest New York State species, has fared somewhat better, with a decline of around 50 percent.
Along with spiders and snakes, bats are one of God’s creatures which seem to trigger an innate fear response in many people. Stories about vampires in folklore and popular culture don’t exactly help endear bats to us, either. But if you don’t like mosquitoes, especially given the recent concerns about the Zika virus, you might learn to appreciate bats a little more.
Fortunately, all bats in our region eat flying insects exclusively. In fact they consume up to 50 percent of their body weight each day in critters that may have a taste for human blood.
And they take a serious bite out of the agricultural pest population. According to the United States Geological Survey National Wildlife Health Center (USGS NWHC), insect suppression by bats saves the U.S. agriculture industry (including forestry) a minimum of $4 billion, and possibly as much as $50 billion, annually.
More information about WNS, or call your local New York State Department of Environmental Conservation or Cornell Cooperative Extension office. Stay out of caves where bats are hibernating, and keep your noses clean.
Paul Hetzler is a horticulture and natural resources educator with Cornell Cooperative Extension of St. Lawrence County.