Luanne Johnson on bats and COVID-19



To: Bluedot Living

From: Luanne Johnson, BiodiversityWorks

Subject: Keeping bats safe from COVID

While we all know that COVID-19 impacted the Vineyard community in many ways, the pandemic also impacted wildlife and those of us in wildlife conservation. As COVID-19 restrictions were implemented in March 2020, we at BiodiversityWorks were preparing to begin spring mist-netting to capture Northern long-eared bats (Myotis septentrionalis, MYSE). MYSE were once the most common forest bat in New England but more than 95 percent of its population has died during winter hibernation since a non-native, cold-thriving fungus (Pseudogymnoascans destructans, or Pd) was first found and identified from dead bats at a cave in New York State in 2006. Bats have since spread the fungus to other hibernation sites across North America, killing millions of other bats.

MYSE survive winter by entering caves and mines where they go into a torpor and live off their fat reserves. The high humidity and cool temperatures of caves and mines are perfect for a bat to reduce energy requirements and rest, but bat immune systems are also at rest during winter. Thus, our native bats were not prepared for a novel fungus from Europe. Pd thrives in the high humidity and cool temperatures where it colonizes and digests bat skin, especially on their wings and muzzle. Pd embedded in bats’ skin tissue is known as white-nose syndrome (WNS). The infection rouses bats from their winter rest and disrupts their metabolism such that they run out of fat reserves. While not a threat to humans, Pd and WNS threatens our native bats with extinction. 

With support from the U.S. Fish and Wildlife Service, we have been collaborating with biologists on Nantucket and Long Island to understand how small populations of these now-rare bats are persisting amid Pd and WNS. We learned that they are not flying to caves or mines on the mainland, choosing instead to remain on their respective islands, and hibernate in crawlspaces, and cinderblock walls or basements with bulkhead doors. Bat detectors at these sites tell us that MYSE wake up and feed during warm periods in winter, which awakens their immune systems. Thus, we believe their persistence is related to our shorter and milder winters. 

While so many people were looking at bats as the potential cause of the global pandemic, our team of biologists was focused on how to conserve some of the only bats surviving their own ongoing crisis. Federal and state agencies restrictedt all handling of bats in 2020, to prevent any human researchers from passing COVID-19 to the bats. We canceled our netting efforts for the spring and summer of 2020, and used only acoustic detectors to record bat calls and document presence or absence and overwinter survival of this species at monitoring sites around Martha’s Vineyard. Early in 2021, we learned that several research trials attempted to infect big brown bats with COVID-19 and failed, offering some scientific support for moving forward with a 2021 field season for bat research. By late April 2021, our staff were fully vaccinated against COVID-19, which allowed us to launch our spring mist-netting efforts.

We netted areas with MYSE activity to capture the bats, collect swabs of their wings and muzzles to test for the fungus and estimate fungal loads, and to take DNA samples that will tell us how they might be responding to fungal exposure. We captured three Northern long-eared bats in May, and all showed signs of the fungus on their wings, but were otherwise healthy. The male and two females likely recovered as the May weather warmed and they began roosting behind the bark of trees exposed to the sun and warm temperatures. The Pd fungus does not survive in hot, dry environments, which is what female bats seek for pup rearing.

By August, the bat pups born in May and June will be flying, and more bats will be feeding heavily on beetles, moths, mosquitoes, and other insects in our forests and night skies than were feeding this spring. Northern long-eared bats have only one pup a year, so it will be decades before their populations recover. 

We continue to search for any basements or crawlspaces under homes on Martha’s Vineyard where bats were seen in winter, or found in the spring. Because hibernating bats do not leave excrement, nor do they chew wiring or insulation, they are good tenants, but difficult to find. Bluedot readers who have old cinderblock or stone foundations with dirt-floor crawlspaces, or a damp basement that has a bulkhead door entrance are urged to reach out if they will allow us to investigate for potential bat occupancy. Contact us at

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