by Sarah Stankavich
For eight years, the Ohio Division of Wildlife has been conducting mobile bat acoustic surveys across the state with the help of volunteers. These surveys began as a way to help monitor bat populations after white-nose syndrome, a disease associated with large-scale bat mortality, was found in Ohio. A survey route through Little Miami State Park was added in 2018, making it the 44th route in the program. During July, volunteers attach a microphone to the top of their car that is connected to an Anabat. As the volunteer drives, the Anabat records the echolocation calls of bats passing overhead. These data, like that on the graph at left, can later be imported into computer programs that help identify which species of bats are present along a route. Using these acoustic surveys, we can gain insight into bat population trends across the state each year.
Data from the Little Miami route in 2018 shows that big brown bats (Eptesicus fuscus), hoary bats (Lasiurus cinereus), and evening bats (Nycticeius humeralis) are likely the most abundant species in the area. The recorders also picked up possible calls from tri-colored bats (Perimyotis subflavus), silver-haired bats (Lasionycteris noctivagans), and Myotis species (like that in the photo above), although in low numbers. Because it can sometimes be difficult to distinguish species from one another using acoustic data, adding additional data from upcoming years will help paint a clearer picture of the species composition in this area.
The graph below shows the number of bat detections each survey night. The bats are grouped into categories based on the minimum frequency of their echolocation call. The low frequency group includes big brown, silver haired, and hoary bats. The mid-frequency group includes evening bats, tri-colored bats, and eastern red bats (Lasiurus borealis). The Myotis group includes all bats in the genus Myotis.
Sarah Stankavich holds a B.S. in biology from The University of Akron and a M.S. in biology from Eastern Washington University. She has studied bats in Ohio, Washington, Arizona, and Puerto Rico. Sarah currently works at the ODNR Division of Wildlife, where she coordinates several bat and pollinator projects.
April 2019