Northern long-eared bats call Nantucket home!

The Nantucket Biodiversity Initiative (NBI) is a collaboration of scientists from local conservation organizations, government agencies, and educational institutions. One of our main goals is to support and facilitate biodiversity research on Nantucket, Tuckernuck and Muskeget Islands and surrounding waters and share results with the scientific community and the general public. Each year, the NBI awards small research grants to scientists wishing to include Nantucket as a study site on wide variety of topics ranging from algal blooms in our ponds, to gall-forming insect diversity, and salt marsh invertebrates, all in an effort to increase our knowledge on the incredible biodiversity of the island we love.

Most recently, NBI has awarded Zara Dowling, a Ph.D. student at UMass-Amherst, a grant to study the bat populations on Nantucket. While the Maria Mitchell Association housed a few bat specimens in their collection that had been found on island, very little was known about the bat species that call Nantucket home. In particular, Zara was hoping to find evidence of the northern long-eared bat (Myotis septentrionalis), a small, insectivorous, forest-dwelling bat.  Historically common, populations of this species have declined by over 90% in the northeastern United States over the last 10 years because of the spread of a fungal disease, White Nose Syndrome (WNS). This fungus grows on the bodies and wings of bats during hibernation, leading to unusual behavior including awakening and activity in the winter, which leads to loss of water and fat reserves, and eventual death. The northern long-eared bat typically hibernates in caves in high densities – up to several thousand individuals. The cool, moist environment of a cave is conducive to the spread of the fungus and is very easily passed among bats during hibernation. Because of the devastating impacts of white-nose syndrome, this once very common bat is now listed as “Threatened” federally and “Endangered” in the Commonwealth of Massachusetts.

I suppose owing to their nocturnal behaviors, humans have construed all sorts of evil ideas about bats, most of which are unfounded. The benefits of having bats in the area far outweigh their drawbacks. They are very important consumers of insects, providing far greater services to agricultural areas than any pesticide ever could. They are voracious mosquito-eaters, protecting us from annoying bites and mosquito-borne illnesses– if only we could get them to acquire a taste for ticks! In many places, bats are important plant pollinators and their guano is still used for fertilizer.

Before the outbreak of WNS, northern long-eared bats were common on Cape Cod, Martha’s Vineyard and Long Island but were not known to occur on Nantucket. While bat populations were declining rapidly in the northeast, it appeared that they were doing fine in these other coastal areas. Healthy, breeding female bats and juveniles were documented on Martha’s Vineyard which led researchers to wonder what is it about these coastal areas that seem to be protecting them and could they be found on Nantucket too? Could they possibly be hibernating on the islands rather than in large colonies in caves where WNS is so prevalent? Indeed, Zara Dowling reported that “In February 2016, a healthy female northern long-eared bat was found roosting under the rakeboard of a house on Martha’s Vineyard, supporting the notion that at least some individuals are remaining on the island over the winter”. It seems plausible that these coastal areas might be providing refuge for this species from White Nose Syndrome.

In 2015, in an effort to determine whether Nantucket might also be providing a safe haven for these bats, Zara placed acoustic detectors in several locations across the eastern end of the island including Squam Farm, Medouie Creek, Milestone Cranberry bogs, and Norwood Farm. The recorded sounds are processed by software that can recognize the particular calls of each bat species – after manually vetting these results, Zara confirmed that northern long-eared bats were present on island in almost every location in which she placed the detectors. Adding further evidence, a single dead bat was found on a trail in a pitch pine forest on the northeastern edge of Hummock Pond that same summer. That specimen was given to a US Fish and Wildlife bat researcher and was determined to be a female northern long-eared bat!

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Acoustic  bat detector at Squam Farm

The next step in 2016 was to discover whether the bats were breeding and successfully rearing pups here and, if so, document what structures female bats used for roosting and maintaining maternity colonies. To accomplish this, Zara set up nets made of a very fine mesh across trails near the acoustic detectors that had recently recorded calls from probable northern long-eared bats. The nets were checked every 15 minutes beginning just after sunset in mid-July. Within an hour, Zara had captured her first northern long-eared bat on Nantucket! By 10:30pm, she had so many bats, the nets had to be closed. Each bat was identified, weighed and measured. The largest bats weighed a mere 7 grams! All captured bats were either adult lactating females or juvenile bats, providing solid evidence indicating breeding populations here on island. And none showed any sign of damage from White Nose Syndrome.

Adult female Northern long-eared bat captured on Nantucket

Adult female Northern long-eared bat captured on Nantucket

Zara placed tiny transmitters, called nano-tags, on the backs of three of the largest female bats. The frequency of each nano-tag has an individual signature that allowed us to track each bat to it’s roost tree, or house, in one case. Once the roost was identified, we returned at sunset to watch and count the bats as they emerged for the evening. The roosts had 10-12 bats each and it was fascinating to watch them emerge and begin to feed, often circling right over our heads, feasting on the plethora of mosquitoes. Their flight is fast, silent and fascinating.

Pitch pine snags are used for maternity roost sites by northern long-eared bats.

Pitch pine snags are used for maternity roost sites by northern long-eared bats.

From just a small amount of money invested by the Nantucket Biodiversity Initiative to fund some of Zara’s research, we now know so much more than we did just a year ago about what bat species share the island with us and that our protected conservation lands as well as private homes are providing critical, breeding habitat for a threatened species. Next, we would like to determine whether the bats are also actually hibernating here. We would love to know if you find bats under the shingles or trim boards of your house, or in your basement or old wells. Please contact the Nantucket Conservation Foundation to share this information!

As for White Nose Syndrome, researchers believe they have identified a bacterium that will attack the fungus, which provides hope of a cure if we can find and inoculate bats before it is too late. Given that some European bat species also have been exposed to, and survive, WNS, there is hope that given enough time, US bats may recover if enough of them are naturally resistant to WNS. In the meantime, hopefully, our coastal islands will continue to provide some refuge for northern long-eared bats.

You can help! If you, or anyone you know, finds bats in your barns, basement, old well or cisterns, in the late fall or winter, PLEASE call us here at the Nantucket Conservation Foundation at (508) 228-2884 or email dodell@nantucketconservation.org. Evidence such as this could help us determine if bats are hibernating on Nantucket through the winter – a major missing piece of our bat puzzle!

 

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The Nantucket Conservation Foundation is a private, non-profit land trust that depends contributions from our members to support our science projects, conservation property acquisitions and land management efforts. If you are not already a member, please join us!  www.nantucketconservation.org

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