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Bat Surveys

Tonight marked the first night of the 2018 Bat surveys conducted on Big Oaks NWR. The surveys are acoustic and take 3 days to complete. A refuge staff member mounts an ANABAT device on the top of one of the refuge vehicles. After the acoustic device is in place, we drive one of 3 previously mapped out routes along the refuge. The surveys must start 30 minutes after sunset.

Bats use echolocation, this is the ability to locate objects based on the reflection of sound. Since bats are nocturnal, they are unable to rely on sight, echolocation allows bats to see their surrounding, at night. Bats emit a series of high-pitched clicks, so high-pitched that the human ear cannot comprehend them. How quickly the echo of the click returns, indicates to the bat how close an object is to them. The neat thing about the ANABAT device is that it makes it possible for the human ear to hear the call of a bat. So while driving the route, we were able to hear all the bats out on the refuge.

The bat calls are simultaneously downloaded onto a memory card. The memory card is then entered into a software, that is able to identify the different bat species by calls.

In the past decade, a fungal disease, known as "white-nose syndrome," has wrecked havoc on the bat populations of temperate North America. This fungus grows best in cold, dark, and damp areas. It grows on, and sometimes invades the bodies, of hibernating bats. This fungus disrupts the hibernation of bats, causing them to be more active than usual, even active during the day. This increase in activity causes the bat to burn its fat reserves, making it hard, even impossible, to survive the winter.

More often than not, people have a fear of bats. Let's be honest they're not the cutest animals on earth, but they have a vital importance, to the ecosystem and humans specifically. Bats are insectivores, meaning their diet is made up of insects. And not just any insects, bats tend to consume those insects that cause problems with crops, or are just pests in general. For example, the Big Brown Bat eats corn root worm. The more bats we have in the ecosystem, the less pests we have destroying our crops.

Since 2007, when the disease made it first appearance in America, scientists have been working hard collecting data to understand the disease, how it's effecting bats, and what can be done to eradicate the disease and save the bats. They have even established some things you can do to help. You can start by setting up bat boxes, to provide homes for the bats. You can also reduce the disturbance of natural habitats for bats, and even plant a pollinator garden! For a full list of things you can do to help, and to learn more about white-nosed syndrome and the effect it has on bats visit:


Fish & Wildlife. (2018). Bats in Indiana. DNR: Indiana Department of Natural Resources. Retrieved from

[BBC Earth Unplugged]. (2017, July 7). What is Echolocation? [Video File]. Retrieved from

White-nose Syndrome Response Team. What is White-nose Syndrome? Retrieved from

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