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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. At right is a picture of the specialized microphone used to record bat echolocation calls. It is 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 (25–30 miles in length) shortly after sunset when bats become active. Surveys are conducted two to four times in a given county across a 6 week survey period that begins in late May and ends in early 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 Diversity personnel 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 is relatively new, but promises to yield long-term benefits. It will 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 28 southern Indiana counties by Wildlife Diversity biologists during a 2011 pilot study. With the help of contracted surveyors, 29 additional counties were surveyed the following summer, and established routes now exist for 76 counties in Indiana.

Wildlife Diversity staff also use stationary equipment to monitor bats. Learn more.



This map shows locations of survey routes. Click on a route for details.