Wildlife Research, Monitoring & Mentoring

Northern Long-eared Bats

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Do you have bats roosting in your bat box, your barn, or at your house on Martha’s Vineyard?

We are very interested in hearing about your spring/summer bat roost or any place where you have seen bats in winter on Martha’s Vineyard.

Please email Liz Olson with information about your bat roost:     LizO@biodiversityworksmv.org

Gathering Critical Information for Recovery and Management of an Imperiled Species

Bats play a very important role in many ecosystems by controlling insect populations, which is a valuable service to humans. For example, one bat can consume up to 3,000 small insects a night, and some of these insects include mosquitos and crop pests. Historically, northern long-eared bats (Myotis septentrionalis) were one of the most abundant bat species in New England. Tragically, their populations have declined by 95% in the Northeastern U.S. since the arrival of a cold-loving fungus (Pseudogymnoascus destructans) in 2006 that colonizes the muzzle or other exposed body parts of bats during winter hibernation. The fungus causes white nose syndrome (WNS) where infected bats exhibit unusual behavior during winter such as flying outside of hibernacula during the day, or clustering near the colder entrances of hibernacula. This unusual winter activity uses limited energy reserves and most infected bats die at or outside of winter hibernacula. WNS has killed over 5 million bats since it arrived in the northeastern United States, and it typically kills over 90% of bats in each hibernacula. Thus, our forests and fields are missing the important insect predation services bats typically offer each summer as they forage and roost in the Northeast. The estimated value of bat predation on insect pests in the agriculture industry was $23 billion annually.

Otter at Dawn
Otter at Dawn

A Northern long-eared bat we found roosting in a bird nest box in Edgartown, MA in September 2015

Photo courtesy of AlHicks_NYDEC

A Northern Long-eared Bat in hibernation

Islands of Hope

While many biologists in the Northeast were reporting dismally low numbers of Northern Long-eared Bats (Myotis septentrionalis, MYSE) in their states, a glimmer of hope surfaced on Martha’s Vineyard in 2012. In August of 2012 and 2013, The Nature Conservancy (TNC) stewardship staff at the Hoft Farm Field Station found roosting MYSE in blue bird boxes during bi-weekly checks. In summer 2013, BiodiversityWorks  began collaborating with the Northeast U.S. Fish and Wildlife Service to learn more about the status of MYSE on MV. We deployed a bat detector at sites where Kendra Buresch detected MYSE during her M.S. thesis study in 1997 and 1998. The acoustic data we recorded showed echolocation calls in the appropriate frequency for MYSE at several sites in July and August of 2013, as well as at the Hoft Farm. We have continued to detect MYSE at multiple sites around the Island in the spring, summer, and fall.

Coastal Otters

Bats infected with Pd fungus in winter hibernacula.

Coastal areas in the Northeast (Martha’s Vineyard, Cape Cod, Nantucket, and Long Island continue to have small breeding populations of  Northern Long-eared Bat. BiodiversityWorks has been collaborating with the Fish & Wildlife Service (FWS), local landowners, conservation groups, and Zara Dowling at UMass Amherst (IGERT PhD candidate) to study these remnant populations. We have been documenting their current distribution, locating maternity colonies and assessing productivity, attaching nanotags to females to document roost characteristics during pup rearing, and using nanotags to track movements of MYSE during the fall to determine if they remain on the Vineyard or leave.  Sheriff’s Meadow Foundation and The Nature Conservancy allowed us to set up temporary nanotag tracking towers that allowed us to determine whether or not tagged bats left the Island.

Otter at Dawn

A bat detector that records bat calls

Photo courtesy of AlHicks_NYDEC

Measuring the forearm length of a NLEB

Field Research

Mist nets are fine nets with a 1.5-inch mesh that biologists set across footpaths or bodies of water in areas where bats are known to forage. Free flying bats are captured when they fly into the net and become tangled. Biologists monitor the nets for bat captures every few minutes and carefully extract the bats. Bats are marked with tiny tags, measured, weighed, and identified by species and gender and then released at the site of capture. Nets are removed at the end of each night of trapping as they must be disinfected per WNS protocols.  We are studying maternity colonies of MYSE at sites in Vineyard Haven, West Tisbury, Edgartown and Chilmark.  In the late summer and fall, we try to connect with people who may have bats roosting in deck umbrellas as those are sometimes this species.

Between June and October 2015 and 2016, our Northern long-eared bat (Myotis septentrionalis, MYSE) project focused on daytime roosting and migration behavior, using nanotags (tiny transmitters) to track individual bats. This study was funded through the Martha’s Vineyard Vision Fellowship and we are collaborating with the U.S. Fish & Wildlife Service, the USGS Cooperative Research Units at UMASS (Amherst) and Virginia Tech, BOEM (Bureau of Ocean Energy Management), and Mass. Fish & Wildlife. Locally, we have permission from The MV Land Bank (MVLB), The Nature Conservancy (TNC), Sheriff’s Meadow Foundation (SMF), Vineyard Conservation Society, and Vineyard Open Land Foundation (VOLF) to capture and study bats on their properties. Several private landowners also granted us permission to study bats on their properties.

In June 2015, we captured and attached nanotags to 3 pregnant female Northern Long-eared Bats near Cranberry Acres and the Hoft Farm Preserve. These females led us to roost trees (red maple, white oak, black oak, beetlebung, sassafrass, black locust, and standing dead trees) as well as several houses where they were roosting under the trim boards near the peak of the roof.  We were able to mist net at two of the houses and captured 6 additional lactating females who were part of the same maternity colony.  In all, these mother bats led us to 24 roost sites in the Lambert’s Cove Road area of Vineyard Haven.  They moved their pups every few days until early July when most of the females stayed in one roost site at a house.  We suspect this was because the pups were older and too heavy to move any longer.  Within several days, the evening emergence count numbers at the roost increased to where we were seeing many more bats emerge than 6 or 8 when it was just the females. This indicated pups were becoming volant, which was exciting to see.  We had one of very few successful breeding colonies documented this summer in the Northeast for MYSE.  In July, near the west end of Edgartown Great Pond, we captured a lactating female in oak woodlands who was sharing a roost tree with at least 3 other bats.  In Oak Bluffs, near Major’s Cove, we captured a newly volant juvenile male at a roost site on a deck in mid-July.

Otter at Dawn

A Northern long-eared bat roosting in deck umbrella

Otter at Dawn

attaching a temporary nanotag 

Otter at Dawn

releasing a bat with nanotag

 We returned to these colonies annually, and all remain active with a few bats (3 – 11) in each colony. Perhaps the most exciting moment of the summer is when we net a maternity roost and have the opportunity to check for volant pups of the year – confirming a successful maternity season. This is also a great opportunity to re-capture females and document their survival from year to year.


a tree cavity used as a day roost



tracking a nanotagged bat to a daytime roost


a bat with a nanotag was roosting under the loose bark of this tree

Northern Long-eared Bats

Attaching a temporary nanotag to a female we tracked in 2015

Photo courtesy of AlHicks_NYDEC

Nets set at a house roost


The life history information we gather on MYSE will assist the U.S. Fish and Wildlife Service in developing recovery and management recommendations where MYSE still exist in the Northeast. It will also inform land management decisions on the Vineyard to protect maternity roosts for these bats. BOEM has used data gathered on offshore movements of bats tagged on the Vineyard to assess potential impacts of offshore wind development in this area on MYSE and other bats.


Fall and Winter 2015 – 2017

In Fall, 2015 and 2016, we captured, tagged and tracked female MYSE to several roost sites, but not to any roosts where they could spend the winter. One female was still roosting in large beech trees as late as November 9, 2016, which is when New Hampshire and Vermont bats are already in hibernation. None of our tagged females were picked up by tracking towers in the region, so we believe they are hibernating locally.

In February, 2017, we captured an adult male Northern Long-eared Bat during a warm weather event and attached a nanotag to him. This bat died within 36 hours when the weather turned cold abruptly and it did not seek shelter. While the bat did not have fungus on its nose, we did see signs of fungus in its wing tissue. The National Wildlife Health Center confirmed that the bat had died from White-Nose Syndrome, and it was the first confirmed case of the syndrome in Dukes County.

In November 2017, a homeowner reported a bat flying in a cinder block basement with a bulkhead door. Upon investigating, we documented at least three Northern long-eared bats using this unfinished, damp and cool basement as a hibernation site. They remained all winter, emerged in the spring, and returned the following winter. Since that time, our colleagues on Nantucket and Long Island documented this species of bat overwintering in crawlspaces under houses in 2018 and 2019. Because the bats do not cause any damage or leave many droppings during winter hibernation, most homeowners would never know these bats are hibernating under their home.

Current Priorities

With so many older homes being sold and demolished, the types of underground hibernation sites these bats have been using are becoming quite scarce. Our primary concern as that the few Northern long-eared bats surviving amidst the white-nose syndrome crisis could be killed during a winter demolition unintentionally. With funds through a U.S. Fish & Wildlife Service White-nose Syndrome grant, we will be building underground hibernation sites for these bats on conservation land in the late summer of 2022. We hope to attract the bats to these sites using acoustic lures.