Conservation News

2014 Bat Surveys

By Laura Deming,  Senior Biologist – Wetlands

This past summer, 19 volunteers across New Hampshire drove along back roads on quiet evenings to record vocalizing bats as part of the New Hampshire Bat Survey Project.  Initiated in 2012, the project is a partnership of NH Audubon, NH Fish & Game, the US Fish & Wildlife Service (USFWS) and Northeast Ecological Services, and contributes to a nationwide survey coordinated by the USFWS to monitor bat populations throughout the U.S.  Information on bat populations has become especially critical since the onset of White-nose Syndrome (WNS), which has killed over 5.7 million bats in 19 states (including New Hampshire) and four Canadian provinces since its discovery in 2006.

As a volunteer drives slowly along a route, the high-frequency calls of bats flying overhead are recorded by a sensitive microphone fastened to the car roof and linked to a specialized recorder that stores the data.   Data are later downloaded onto a computer and analyzed with software that categorizes each vocalization based on several characteristics.  Bat vocalizations can often be identified to species or, in some cases, a group of species, yielding important information on species’ distribution over large areas.
It sounds simple, and it is, if everything works.  However, over the past three years, volunteers have dealt with an array of challenges, including malfunctioning equipment, failing batteries, sudden rainstorms, getting lost, and being stopped by police wondering what the strange contraption on the top of the car might be.  Despite all this, volunteers successfully recorded nearly 4,200 bats representing seven species each season.

Sonogram red bat 1

Eastern Red Bat Sonogram. Click to see a larger image.

This sonogram of an Eastern red bat (Lasiurus borealis) was recorded along one of the routes.

Province Lake Survey Route

Province Lake Survey Route

This map shows one of the longest-running survey routes in the state.  Each dot represents a bat, which were present along almost the entire route.  Purple dots indicate either Silver-haired or Big brown bats, green are Eastern red bats, red are Hoary bats, and yellow are unknown bats, which are bat vocalizations that cannot be identified because they are too brief, too far away, or some other reason.

Another component of the NH Bat Survey Project focuses on finding and monitoring maternity colonies of Little Brown bats (Myotis lucifugus), a once-common cave-hibernating species that has been decimated by the fungus that causes WNS.  Maternity colonies are located in barns, attics, steeples, and other warm, dark sites, where female bats give birth and raise their young.  Many colonies have declined drastically or completely died out, so protecting remaining colonies is critically important for sustaining Little brown bat populations until a solution to the effects of WNS can be found.

If you are interested in volunteering for this project, or have a bat colony you would like to report, please contact Laura Deming (