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Maine’s Struggling Bats – Part Two

Tuesday, October 6th, 2015
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With Halloween coming up in a few weeks, October is a great time to talk about bats. Our furry, flying friends are in trouble. Following is part two of a series on bats we are featuring this month. Please read and share – fostering an appreciation for bats will do wonders to help make their conservation and protection a priority.

- Doug

The following article appears in the fall issue of Habitat, Maine Audubon’s member newsletter. Interested in receiving Habitat in the mail? Join us today!

Bats That Live in Maine

Cave Bats

Maine’s five species of cave bats include two that you might see in your attic, garage or barn. Big brown and little brown bats typically gather in colonies in late spring through summer where the females raise their single pups. You are unlikely to encounter the other three species (Eastern small-footed, Northern long-eared and tri-colored bat) as they spend their summers alone or in small groups in the nooks and crannies of trees during the day and forage for insects at night. But, if conditions are right, especially on an older house with loose shingles or siding, these bats will roost in human structures.

northern long-eared bat

A scientist shows off a Northern long eared bat. This cave bat (one of five species found in Maine) was added to the federally threatened species list in 2015. (Photo: U.S. Fish and Wildlife Service)

All these bats, however, spend their winters together, typically hibernating in large groups in caves. Although we know that some overwinter in human structures, we don’t know the size or extent of those wintering populations. All five species of cave bats have been affected by White Nose Syndrome.

The deadly, cold-loving fungus (Pseduogymnoascus destructans) that causes White Nose Syndrome arrived in Maine in 2011 and has since killed 90% or more of the bats hibernating in Maine’s three known hibernacula (caves).

However, there is good news on the horizon for this group of bats. Researchers from the U.S.D.A. Forest Service, the University of Georgia and Bat Conservation International recently tested a common North American bacterium that inhibits fungal growth on a group of 75 little brown bats in Missouri that were exposed to White Nose Syndrome. These bats were found to be free of the fungus and were released back into the wild this past spring. While there are no guarantees these bats will not contract the disease again (and killing the fungus left on cave walls also remains an issue), the fact that there is a potential treatment offers a glimmer of hope.

In addition, wintering cave bat mortality rates in Pennsylvania, New York and Vermont appear to be dropping off, with residual populations of hibernating cave bats now small, but holding steady. This may indicate either resistance to the disease or an ability to live with it without severe impact. Researchers in New York and Vermont put radio transmitters on 450 little brown bats last year to track their movement (and survival rate) and there are bats that were banded in Vermont in 2006 (pre-White Nose Syndrome) that are still alive. With further research, the glimmer of hope for our cave bats may just start to grow.

Tree Bats

Maine has three species of tree bats– hoary, red and silver-haired. These bats roost and have their pups individually or in small groups under the bark or in the cracks, crevices and cavities of trees, and occasionally within human structures like houses and barns. These bats leave Maine each fall to spend the winter in the southern United Sates, and return each spring. New wind developments can pose a threat to these bats, but Maine has developed strong guidelines that significantly reduce bat mortality by stopping the blades from spinning at low wind speeds, the time when bats are inexplicably attracted and most often killed at turbines.

Studies have shown reductions of up to 40-80% of bat mortality when “curtailment” is in place and MDIFW’s strong curtailment guidelines have been a condition of wind permitting over the last several years in Maine. Maine Audubon has supported the curtailment guidelines, which are stronger than those in most of our neighboring states. We believe actions like curtailment allow wind development to proceed while minimizing potential risk to bats.

What are we doing to track bats in Maine? Find out in Part 3! 

Doug Hitchcox Head Shot - please credit  M. Kathleen Kelly (1)Meet Doug Hitchcox, Maine Audubon Staff Naturalist

A Maine native, Doug grew up in Hollis and graduated from the University of Maine in 2011. Throughout college Doug worked at Scarborough Marsh Audubon Center and was hired as Maine Audubon’s staff naturalist in the summer of 2013, a long time “dream job.” In his free time, Doug volunteers as one of Maine’s eBird reviewers, is the owner and moderator of the ‘Maine-birds’ listserv and serves as York County Audubon board member and Secretary of the Maine Bird Records Committee.

Submit your question for Doug:


In the Community – The Ongoing Consideration of Birds

Monday, November 4th, 2013
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sky golden eagle

Western Maine Audubon Chapter Event – An Evening with Wind Over Wings
Wednesday, Nov 13, 2013 7 – 8:30pm, Room C 23, Roberts Learning Center, University of Maine at Farmington, Free

Wind Over Wings is an environmental organization that rescues injured birds that are no longer able to survive in the wild. At this special event you will meet Maine’s largest owl, the Great Horned; a beautiful Red-tailed Hawk; a bird considered most intelligent of birds, the Common Raven; and the king of all birds, the Golden Eagle. Learn more »

Heron Observation Network of Maine: Fall Colony Visit – An update blog post from Maine IF&W Wildlife Biologist Danielle DAuria. Read »

Watch: COUNTING ON BIRDS premieres on NHPTV PRIME November 21st at 8 p.m.

How did a Christmas-time tradition of shooting birds change to one of counting them? Willem Lange travels to Keene & Errol, NH, Ecuador and Cuba to meet people dedicated to the National Audubon Society’s Christmas Bird Count.
Learn more »

Good News: Peregrine falcon set free along Kennebec

It didn’t take long for a peregrine falcon to rediscover his wings on Monday, as a young male bird was released into the wild after a two-month rehabilitation stint. DIF&W biologists estimate there are 25 pairs of peregrine falcons living in Maine. Read about this falcon »


In the Community – October and Bats

Thursday, October 17th, 2013
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A bat with White Nose Syndrome. The fungus has wiped out close to 6 million bats in the northeastern United States alone.

Bats are an important part of the ecosystem in Maine. With Halloween around the corner, it is a great time to learn about our local bats and why we should be scared for, not scared of, them.

Listen: MPBN: Feds Propose Listing Bat as Endangered
A species of bat native to Maine may be going on the Endangered Species list. The U.S. Fish and Wildlife Department today proposed Endangered Species Act protection for the northern long-eared bat, which has been devastated by the disease known as white-nose syndrome. The decision was in response to pressure from the Center for Biological Diversity in Vermont. Mollie Matheson, a conservation advocate at the center, speaks about the proposal with Maine Things Considered host Tom Porter.
Listen at MPBN »

Watch: Battle For Bats: Surviving White Nose Syndrome
This video shows how government and private agencies have come together to search for solutions to help our bat populations overcome white-nose syndrome. The public can also play a role in the future of bats by providing habitat and surveying their populations. Bats are a critical component in a healthy forest ecosystem, plus they provide significant agricultural pest control and pollination. Their survival is essential for a sustainable natural environment.
Watch now »

Attend: Signs of the Season: 2013 Update On The Plight of Bats
Maine Audubon staff biologist, Susan Gallo presents Join biologist Susan Gallo as she shares her latest report and discusses the challenges facing our cave hibernating bats that could lead to their extinction by 2026. Join us to learn what is being done to help them and how you can lend a hand.

Stay tuned for more fall and bat themed activities at Maine Audubon.


Listen: Maine Bats Hit Hard by Deadly Fungus

Wednesday, July 18th, 2012
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Susan Sharon covered the alarming declines in Maine’s bat population and the need for survey volunteers in her recent MPBN radio piece.  She talks to Acadia National Park’s Bruce Connery as well as to two Mainer whose bat colonies in their garage and barn have all but disappeared.  FMI, visit Maine Audubon’s bat monitoring website.


Should I build a bat house?

Thursday, July 12th, 2012
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A multi-chambered bat house like this can provide a safe place for mother bats to raise their young.

With great press about the plight of Maine’s bats (see recent article in the Sun Journal, and also check the MPBN website for a piece due out later this week), I’ve been getting lots of calls and e-mails from folks asking for advice about bat boxes.  Should they put them up?  Will they work? Where should they get them?  Will they keep the bats out of their attic? Lots of good questions, and I’ll try to provide some answers here.

It’s tricky to get a bat house right, in terms of size, temperature, and location, and even if all those things are spot on, boxes may not get used if the habitat around the box is not right.  Bats like water, they avoid thick forest, and of course they need a ready source of insects to feed on.  The best scenario for a successful box is if you have an existing colony in a house or barn and you want them to move out.  In this case, it may take several seasons for the house to be discovered and occupied by the local bats.

The best place to go for advice is Bat Conservation International, the go-to organization for all things batty.  They have an excellent handbook for building bat houses, or several free plans on their “Install A Bat House” webpage.  See the Resources section for lots of information about how, when and where to put these up, or the Buy A Bat House section for links to retailers who are certified to build quality boxes to BCI specifications.

Quickly, a few tips I’ve gleaned from all the information at BCI: Bigger boxes are better…many of the bat houses on the market are too small to function as maternal roost colonies.  The four-chambered nursery boxes are the size that our mother bats are looking for so they can get together with other mothers and leave their pups in a large group during the night.  Boxes should be in a sunny location, and for our climate, should be painted a dark color.

If you want bats out of your house, you’ll need to do some work to exclude them from the cracks and crevices they are using to access your space.  BCI has a great information sheet on how to go about this, or there are several professional excluders listed for Maine.  The basic idea is to make the exits one-way out, so bats can get out of your space but can’t get back in.  You don’t want to simply seal up active colonies or you’ll end up with a mess of dead bats.  It’s best to avoid working on excluding bats from June through mid-August, the time when mother’s and young bats are using the roost.

Ideally, sealing up your space and excluding bats should be done in conjunction with a bat box.  Bats do use the same area from year to year, so if you seal up a space, they’ll be back looking for new access when they return.  By providing an easy-to-use space in a bat box near the entrance to the old roost, they may never resort to searching out a new entrance to their old space. And again, bat houses may take some experimenting to get just right.  You can try different external walls, or a pole mount, if the box seems to get too hot.  Or try raising or lowering the box.  It may take some patience, but it will pay off if you can get a thriving colony to occupy the box.

If you know of a bat colony and want to help with our maternal roost surveys, be sure to visit Maine Audubon’s bat page at FMI.