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Mobile Acoustic Monitoring of Bats

Mobile Acoustic Bat Survey Program


Bat MicrophoneThe Mobile Acoustic Bat Survey Program in Indiana was created to monitor the statewide distribution and relative abundance of bat populations in their summer range. Bats maneuver through their environment and detect prey using echolocation, a process in which they emit ultrasonic sound waves typically too high in frequency for humans to hear. If the waves strike an object, a reflected wave is created that returns to the bat. Advances in technology have resulted in equipment that is able to record echolocation calls which can then be used to identify different bat species. A specialized microphone (pictured) can be used to record bat echolocation calls. This device can be attached to the roof of a vehicle.

Project personnel use an ultrasonic bat detector and vehicle-mounted microphone to record echolocation calls emitted by bats in the environment. Surveyors drive a predetermined route (15–25 miles in length) shortly after sunset when bats become active. Surveys are conducted two times in a given area across a 6 week survey period that begins in June and ends in mid-July. The same routes are surveyed each summer, allowing biologists to monitor multiple species of bats at different locations in the state and across years.

Wildlife Science staff oversee numerous projects with decades of invaluable data that are used to understand population trends of nongame and endangered species or groups. The Mobile Acoustic Bat Survey Program has collected nearly 10 years of data that verify the substantial impacts of white-nose syndrome on bat populations during the 2010s. These data also provide vital information in the ongoing management and conservation efforts to preserve one of the state's most valuable resources.


Mobile acoustic bat surveys were completed in 76 Indiana counties by wildlife biologists and citizen surveyors from 2011-19. Starting in the summer of 2020 our surveys will be conducted in smaller areas within counties adhering to standardized protocol set forth by the North American Bat Monitoring Program. This program will help agencies collect consistent data that can be analyzed across the entire range of many North American bat species.

Wildlife Science staff also use stationary equipment to monitor bats at state properties. Learn more.


Individuals interested in taking on a route, or placing a stationary detector on their property, can contact the nongame mammologist for more information, including how to sign up: helpbats@dnr.IN.gov.