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.
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
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.
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.
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!
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.