Wildlife Research, Monitoring & Mentoring

Northern long-eared bat update, November 2020

Checking data from a bat detector in the field

Amber checking a bat detector

Amber and the bat mobile searching for a signal

While COVID-19 did not impact our other wildlife work this spring and summer, it did halt most of our bat research.  We were not able to handle any bats for fear of transmitting COVID-19 to them when North American bats are already struggling with a devastating disease, caused by an introduced fungus that kills them during hibernation (white-nose syndrome WNS). So, we scaled back and used only acoustic monitoring to check on maternity colonies and did emergence counts during the spring and summer. Acoustic detectors showed us that small populations of Northern long-eared bats survived the winter and were active during the breeding and swarming season around the island.

Each winter hibernation period is another chance for these bats to be infected with the fungus that causes WNS, yet our research is showing that Northern long-eared bats on Martha’s Vineyard and Long Island, are surviving infection with the fungus – probably because of our shorter, milder winters that result in shorter infection times, and because we often have warm periods in winter where they can wake up, drink water, and feed. Because these tiny bats only have one pup a year, it will take a long time to recover their populations. Thus, finding where they are hibernating locally is essential to protecting these remnant populations so that they can survive into the future.

A male northern long-eared bat captured in October 2020. Notice the radio transmitter antenna visible on his back

It has been a busy six weeks this fall searching for Northern long-eared bat activity and netting at night with hopes of capturing a few to radio-tag and track to their hibernation sites.  Each one we capture is the result of many hours of work. We place acoustic detectors in forests with streams or wetlands and leave them to record all bat calls within range for a few nights. Once we find a spot with Northern long-eared bats, we set mist nets, open them at dusk, and check them every 5 minutes until we close.

We captured and attached tiny radio-transmitters to three Northerns this fall; two males and one female. Hard to believe, but this was the most Northerns we have captured in four years of fall netting! The female left her transmitter behind in a tree, and the males disappeared on us within 48 hours of tracking. These little bats can sometimes move 5 to 7 miles from their capture site, so we drove and hiked around the island searching for their signals, covering almost all of the island. The transmitters last for 21 – 35 days but only transmit 250 yards because they are so tiny.  It’s possible these males were here only for mating opportunities during the fall swarming season and left the island.

A tiny northern long-eared bat in the hand

Each Northern we capture provides us with another piece of the puzzle to understanding their behavior and life history. As the cold weather sets in, they may be in a crawl space under a house, in an old well or root cellar, or in the cinderblock walls of a damp basement. If you have seen bats in a space like this on Martha’s Vineyard in fall or winter, please give us a call at (800) 690-0993 or email LizO@biodiversityworksmv.org.

To learn more about which types of human provided shelters provide winter hibernacula for bats in our area, you can watch Luanne’s presentation at the annual meeting of The Wildlife Society by clicking here.


<a href="https://biodiversityworksmv.org/author/luanne-2/" target="_self">Luanne Johnson</a>

Luanne Johnson


Luanne Johnson is the Director of BiodiversityWorks and a wildlife biologist. She has been monitoring, studying, and protecting wildlife on Martha's Vineyard for 27 years.

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