White Nose Syndrome and What it Means for Wisconsin’s Bats by Neva

Last month, I gave a presentation about White Nose Syndrome, a fungal disease plaguing North America’s hibernating bats. It went very well! After the presentation, I took the group out for a walk on our trails and showed them our acoustic bat monitoring equipment.

White Nose Syndrome was discovered in the United States in a cave in New York during the winter of 2006. It is named for the characteristic white coating that is present on an infected bat’s eyes, nose, and wings. The fungus impairs vision and flight, as well as disrupting a bat’s metabolism. It is suspected that the fungal pathogen that causes White Nose Syndrome (WNS) was brought over from Europe by humans. It is likely that it was picked up on the boots of cavers that explored caves in Europe who then explored caves in New York with the same boots on.

However, the fungus does not have detrimental effects on European bat species because the bats have lived in the caves with the fungus for thousands of year and have become immune. Is it possible that North American bats can become immune? Yes, but it could take thousands of years.

The fungus, Pseudogymnoascus destructans, thrives in caves because cave temperatures are less variable than the air temperature- caves are warmer in the winter and cooler in the summer. The fungus is spread from bat to bat by physical contact. For this reason, only hibernating bats are susceptible to this disease. In Wisconsin, the bats that are threatened by WNS include the Big Brown Bat, the Little Brown Bat, the Northern Long-eared Bat, and the Tricolored Bat. WNS has been confirmed in Ontonagon, Houghton, and Keweenaw counties of the Upper Peninsula of Michigan last winter, where many of northern Wisconsin’s bats go to hibernate in abandoned copper mine shafts. Many bats fly north to their hibernacula (a place of abode in which a creature seeks refuge) and do not survive the winter, which is why you may have not seen as many bats as usual this year.

The fungus disrupts the physiological processes of the bat during hibernation. A healthy bat must ration its energy supply to survive the winter. If it uses up its reserves too quickly, it will drop in body temperature and die. US Geological Survey found that bats that were infected with WNS used twice as much energy as healthy bats. An infected bat will have a higher body temperature and will burn through its fat (energy) supply more quickly, causing increased arousal from hibernation. When they wake up, they are hungry, and there are no bugs out for them to eat, so they either starve or try to go back into hibernation with a lack of energy. After infection, bats will die within 70-120 days, an amount of time shorter than Wisconsin’s winters.

If bats were to disappear from Wisconsin, the results would be disastrous. Mosquito populations would skyrocket. Did you know that a single Little Brown Bat eats 1000 mosquitos every hour? Agriculture production would decrease, because bats eat many agricultural pests; we would have to use more pesticide and this would create a rise in toxic runoff from farms.

5 million bats have already died in North America. The future is very uncertain for bats. There are solutions in the works, but it will be a race against time to save the bats before it is too late.