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Bat Productivity Study


bats in a Maine cave

Bats might give you the creeps, but they have some amazing qualities. One little brown bat can eat up to 3,000 mosquitoes a night! Bats across the United States typically provide more than $3 billion worth of pest control for our croplands. Without bats, our evening campfires and summer barbecues would prove unbearable and pesticide use would be on the increase!
Bat populations, however, are threatened by White Nose Syndrome, a disease caused by a cold-tolerant fungus first discovered in upstate New York in 2006. Since that time, it has been estimated that more than 5 million bats have died from the disease. Because of concern over this loss of bats, and anecdotal observations of fewer and fewer bats active in Maine, Maine Audubon and the Maine Department of Inland Fisheries and Wildlife are looking for volunteers who know the locations of bat roosting colonies in their barns, attics, camps or other locations. Interested volunteers can also conduct a quick and easy colony survey to count bat mothers and their young (see directions and datasheet at bottom of this page).With your help, we can establish baseline information about where bats have been, where they are now and how many young they might be raising in Maine. Learn More about Maine Bats »

What Can I Do?

We are looking for volunteers who know of places where bats rest during the day and where they leave their young in the evenings. There can be several dozen bats sharing these “maternity roosts.” Knowing the location of these roosts will help us gain insight into bat productivity. Links to a detailed protocol describing the field surveys and a datasheet for recording observations are below.

Where Do I Survey?

This project covers the entire state of Maine, but for many people, there will be no need to go further than your backyard. If you want to find a bat colony, it’s best to go out at dusk on a warm evening. Look in the eaves and under roof-lines of older buildings, barns, garages or sheds.  Bats will generally fly out right around dusk, one or two at a time through the roost entrance  Landowner permission is required for surveys not on your own property.

What Do I Need to Know?

You don’t need to know how to identify bat species, or get up close and personal with them to collect meaningful data for this project. The key information we are looking for is the location of the bat colony. You are also welcome to sit and watch the colony at dusk on evening and make observations about how many pups (baby bats) you see.

Who Do I Contact For More Information?

For more information about this project, contact Susan Gallo at Maine Audubon, 207-781-6180 ext. 216, or John DePue at Maine Department of Inland Fisheries and Wildlife, 941-4473.