Dozens of dead bats littered the cave floor entrance, some encased in ice, while other living bats had a white fungus covering their muzzles. In February of 2010, a team of biologists with the New Hampshire Fish & Game Department encountered this grizzly scene in a large Grafton County mine.
The biologists had discovered another case of White-nose Syndrome (WNS), a devastating disease that has killed over five million hibernating bats over the past seven years.
According to a June 2012 survey update from the United States Geological Survey (USGS), a subdivision of the United States Department of the Interior, the disease has spread at an alarming rate since it was first discovered within the caves of rural Schoharie County, west of Albany in 2006.
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“The fungus was first noticed by New York State Department of Environmental Conservation staff doing the routine bat monitoring and cave surveys they do every winter,” said Dr. Paul Curtis, an Associate Professor in the Department of Natural Resources at Cornell University and an Extension Wildlife Specialist for New York State.
The disease, caused by the fungus, Geomyces destructans, infects the skin of the ears, muzzle and wings of hibernating bats, and is now prevalent in the central United States and throughout New England.
“We suspect the fungus causes the bats to rouse during the winter months and scratch and itch. The bats have a very thin line on energy reserves, they need to go into hibernation with a certain amount of fat and any additional arousal, causes the bat to burn the fat it needs to get through the winter months,” said Curtis.
The fungus has also spread beyond American borders and is now widespread in southern Ontario, western Quebec, and the Maritimes.
“It is called White-nose Syndrome because the fungus tends to cause a white crusty area on the muzzle of bats when they’re roosting,” said Curtis. ”It also does significant wing damage and causes holes and lesions in their wing membranes,” said Curtis.
In addition to crippling the numbers of little brown bats in New York State, WNS is also currently afflicting large bat populations of tri-colored, northern long-eared, big brown, eastern small-footed, Indiana and gray bats.
“We have had about an 85 percent decline in the population at our local (Cornell University) maternity colony,” said Curtis.
According to the United States Fish & Wildlife Service, Indiana bats and gray bats are considered federally endangered and are in grave danger from the lethal fungus.
“Recent Fish and Wildlife Service figures show that we probably lost 5.5 to 6 million bats in the northeastern United States over the last five years,” said Curtis.
The implications on ecosystems throughout North America have yet to be determined due to the relatively recent emergence of this disease.
“We really have no idea of the long-term impact of this disease on the ecosystem,” said Curtis.
The catastrophic decline in the number of healthy bats could cause an increase in mosquitoes and with it the spread of deadly diseases like West Nile Virus and Eastern Equine Encephalitis. However, Dr. Laura C. Harrington, an Associate Professor at the Department of Entomology at Cornell, said these fears might prove to be unfounded.
“The die off is unlikely to have much of an impact on mosquitoes,” Harrington said. “Many people have the misconception that bats feed only on mosquitoes, but in reality they are generalists and consume large quantities of all sorts of flying insects.”
The consequences of the bat die off on agriculture may be far more severe.
“The bats of North America are all insectivorous and some of those insects have larvae that significantly impact agricultural crops,” said Curtis.
But so far, local farmers have offered a mixed report on the status of populations of insects, usually considered harmful to agrarian goods.
“Last year the bugs were not bad,” Zack Caplan-Moss, an employee for Blue Heron Farm in Lodi, NY, said. “It could have been any number of things [though], I know we have a lot of predators up on the farm. There’s all kinds of dragon flies, birds, toads – a lot of insect predators, which I think is one of the reasons we don’t have a huge insect problem.”
Todd McLane, Manager of West Haven Farm in Ithaca, has noticed an increase in the insect population on his farm last year, but he is unsure what this should be attributed to.
“I say it’s all environmental factors…I don’t even know what our bat population is around here, but it’s been a little bit of ebbs and flows for the insects,” McLane said. “Last year was a particularly rough year for [West Haven Farm] and a lot of it had to do with the previous winter and the fact that there was no rain, so I don’t know if our pest pressure was necessarily higher.”
McLane has noticed also that several species, known for their ability to destroy crops, have become much more common recently.
“I saw a really high amount of cucumber beetles last year,” McLane said. “In the fall, flea beetles were really bad. Another thing we had a really high pressure of was potato leaf hoppers…I don’t know what caused it but I definitely saw a lot more than in years past.”
According to the organization, Bat Conservation International, the big brown bat’s voracious appetite for beetles and various crop damaging bugs make the small mammals a critical aide in controlling agricultural pests across the United States.
Cucumber beetles and leafhoppers are some of the most destructive agricultural pests in the United States and are both favorite foods of the big brown bat. In one year, 150 big brown bats, a standard number for a healthy maternity colony, can easily eat 38,000 cucumber beetles, 16,000 June bugs, 19,000 stinkbugs and 50,000 leafhoppers.
In 2011 scientists from the USGS and the National Wildlife Health Center published a study confirming the cold-loving fungus G. destructans causes WNS. Since then, a number of Federal and State agencies have been working to better understand this devastating disease.
