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.
A Northern long-eared bat we found roosting in a bird nest box in Edgartown, MA in September 2015
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 a few MYSE at multiple sites around the Island in the spring, summer, and fall.
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 Bats. BiodiversityWorks has been collaborating with the U.S. Fish & Wildlife Service (FWS), local landowners, conservation groups, and doctoral students (Zara Dowling at UMass Amherst (IGERT PhD) and Samantha Hoff (SUNY-Albany, PhD) to study these remnant populations and their persistance. With funding through the Martha's Vineyard Vision Fellowship (2015 - 2016), we were able to study these rare bats during maternity season to learn more about their needs for pup rearing and whether or not they foraged over the ocean.
Liz Olson and Luanne Johnson attach a transmitter to a Northern long-eared bat
Between June and October 2015 and 2016, our Northern long-eared bat (Myotis septentrionalis, MYSE) research 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 collaborated 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, the MV Land Bank (MVLB), Nature Conservancy (TNC), Sheriff’s Meadow Foundation (SMF), Vineyard Conservation Society, and Vineyard Open Land Foundation (VOLF) granted permission to capture and study bats on their properties. Several private landowners also welcomed our research 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 behind the exterior trim boards of 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. During the course of our study, none of the MYSE we tagged flew offshore. All stayed on the island.
A Northern long-eared bat roosting in deck umbrella
attaching a temporary nanotag
releasing a bat with nanotag
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
Attaching a temporary nanotag to a female we tracked in 2015
Nets set at a house roost
The life history information we gathered on MYSE is assisting the U.S. Fish and Wildlife Service in developing recovery and management recommendations where MYSE still exist in the Northeast. It also informs 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.
Measuring the forearm length of a NLEB
How we capture bats
We use mist-nets to capture bats, and we have federal and state permits for this work. 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. We 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.
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, which supported our theory that they are hibernating locally.
In February, 2017, a Northern Long-eared Bat was reported to us at a shed in Oak Bluffs during a warm weather event. The 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. MYSE were known to hibernate in caves and mines on the mainland. But, 99% of those MYSE had perished from white-nose disease. What was this bat doing on Martha's Vineyard in February? It made us wonder if they were hibernating here and if our persisting MYSE would continue to persist amidst the WNS crisis.
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. However, we also learned that many of these older homes were quickly being purchased and demolished to build newer homes during the COVID-19 pandemic. The newer homes did not have crawl spaces with dirt floors and were build very tight, which excluded the bats. Other homes were having deep energy retrofits where foam insulation was sprayed and blocked tiny gaps the bats had used to enter. It was a housing crisis for bats!
Current Research
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 unintentionally during a house demolition in winter. With funds through a U.S. Fish & Wildlife Service White-nose Syndrome grant, we built an underground hibernation site adjacent to our headquarters, modified two underground sites on private land to be suitable as hibernacula, and supported Nantucket Conservation Foundation's effort to create a hibernation site on one of their properties.
The 'bat cave' under construction in 2022
We designed our 'bat cave' with an entrance similar to the grates in cinder block foundations of homes where our research has seen them enter and exit. We also placed it adjacent to the foundation of the building so that it would appear to be part of the foundation. In September and October, on nights with low winds when temperatures were above 45F, we played recordings of Northern long-eared bats to attract them to this winter hibernaculum.
The entrance to our bat cove with a camera trap and a lure
We capped this underground room with a grated bat entrance.
On private property in West Tisbury, the owner had an underground space with a sand floor that provided perfect hibernation conditions. We capped an opening at the top with an entrance grate and a roof to make it look more like a foundation.
We ran lures during the fall 2023 and fall 2024, and had Northern long-eared bats active outside all of the hibernacula, except for Nantucket. In February, 2025, we had our first confirmed image of a small Myotis bat at the hibernacula pictured here. Paired with recordings from inside just prior to the image, we confirmed a Northern long-eared bat occupied this hibernation site! We hope to see more in the future.
