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What’s Driving Bats Batty? White-Nose Syndrome

Staff reports
The Chronicle Express

White-nose syndrome (WNS) is a fungal disease killing bats across North America. Detected in 2006, the fungus, Pseudogymnoascus destructans, is believed to have been accidentally introduced from Europe and has since spread to more than half of the United States and several Canadian provinces. WNS causes high death rates and rapid population declines in affected bat species and researchers foresee regional extinctions of species including the little brown bat (Myotis lucifungus), the federally threatened northern long-eared bat (M. spetentronalis), and the federally endangered Indiana bat (M. sodalis). As of 2019, WNS has already killed more than 90 percent of bats at hibernation sites in New York State and there is no known treatment. 

Laura Bailey – Cornell Cooperative Extension of Yates County Natural Resources Educator & Northwest Regional Director of the Master Forest Owner (MFO) Program

Several species of bats roost over the winter in caves or abandoned mines in ‘hibernacula’ where they lower their body temperature to that of the cooler, surrounding cave or mine temperatures. This allows bats to survive the winter off their fat reserves until warmer temperatures and insect prey arrive again. Unfortunately, the fungus that causes WNS grows best in cooler temperatures, and when bats are hibernating, their immune systems are suppressed and they congregate closely, making the population very vulnerable to the spread of WNS. The fungus appears as a white, powdery growth on the nose and wings of infected bats and causes them to wake up from their hibernation, depleting their fat reserves, and leading to starvation or dehydration before spring arrives.

Bats with the white fungus visible around their muzzles.

Spread of WNS can occur in a few different ways. Infected bats can share the fungus through physical contact with another bat or they can contact it from contaminated surfaces of the cave or mine. The fungus can persist on surfaces in the cave or mine even during the warmer months, allowing it to infect any surviving bats returning to the cave the following winter. Humans can also spread the fungus from one hiberculum to the next on clothing, shoes, or gear. 

There is no evidence or documented cases indicating that WNS is transmittable to humans. However, bats are known carriers of rabies and bats infected with WNS may act erratically, increasing the risk of bat-human contact and exposure to rabies. Although WNS cannot directly infect humans, there are many indirect impacts to humans associated with declines in bat populations. Bats perform very important ecosystem and economic services such as pollination and controlling pest populations. 

Little brown bat (M. lucifugus) with symptoms of White Nose Syndrome.

As research continues for treatment and/or resistance mechanisms for control of WNS in bats, we can help out bat populations in many ways:

  • Put away that broom. If you find a bat in your home, don’t kill it. Instead, open a window and let the bat find its way out or call a professional to help with safe eviction.
  • Build or purchase a bat house for your property. DIY instructions can be found at the National Wildlife Federation website: https://www.nwf.org/garden-for-wildlife/cover/build-a-bat-house
  • Stay out of bat caves. Not only can entering caves or mines where bats are hibernating assist in the spread WNS, but even a seemingly quiet visit to a hibernaculum can cause bats, infested or non-infested with WNS, to wake and expend their fat reserves to a critical level. Additionally, entering the hibernation site of the northern long-eared in NYS may be subject to prosecution.
  • If you encounter several dead bats or bats flying outside in the winter, report those observations to NYSDEC at fwwildf@gw.dec.state.ny.us. Do not touch sick or dead bats.