OutdoorNebraska

6 Listening to Ultrasound Calls Yields New Discoveries By Shaun Dunn, Zoologist, Nebraska Game and Parks Commission B iologists use all sorts of gear to collect data: pencil and paper, traps, cameras, binoculars, and even microphones and audio recorders to collect the songs and calls of many species. Audio recorders (or 'acoustic monitors' as biologist call them) have been used for decades to collect bird songs, frog calls, and even cricket calls. But acoustic monitors can also capture sounds that humans can't hear, like the ultrasonic calls of bats. Humans can typically hear sounds as low as 20 hertz and as high as 20,000 hertz (or 20 kilohertz [kHz]); however, as humans age we lose the ability to hear sounds on the higher end of the spectrum and will have difficulty hearing sounds above 15 kHz. This is where the latest in acoustic technology helps biologists 'hear' the calls of species we would otherwise miss. The Wildlife Conservation Fund supported the purchase of 12 ultrasonic acoustic monitors to help locate and track bat populations across the state. They are deployed across Nebraska, from Omaha in the east to Ponderosa Wildlife Management Area in the west. Bats are notoriously difficult to track. Acoustic monitors allow us to learn more about the activity patterns of our native bats, many of which are in need of conservation, like the endangered northern long-eared bat (Myotis septentrionalis). The data collected from these monitors have already given us a better understanding of bat distributions in the state and will continue to do so for years to come. Bats aren't the only small mammals to be heard making ultrasonic calls on acoustic monitors. Biologists in North Carolina were recently able to tell the difference b e t w e e n the ultrasonic calls of two species of flying squirrel. The southern flying squirrel (Glaucomys volans) is a threatened species in Nebraska with a very limited range in southeastern Nebraska, most notably around Indian Cave State Park. Recently, we were able to record the calls of some southern flying squirrels near Nebraska City in an area where they haven't been documented before. The recent discovery of a population of flying squirrels in Lincoln has given us another opportunity to use our acoustic monitors to identify the areas of the city the flying squirrels inhabit. Using the most advanced technology can be costly, but the results are worth it. Every month, we are collecting enormous amounts of data that help us learn more about our threatened and endangered species; and more importantly, we are learning more about the species at-risk of becoming threatened or endangered. 4 Biologists with Nebraska Game and Parks Commission and the National Wild Turkey Federation deploy an ultrasonic acoustic monitor along a fence to survey for bats. The monitor (at the bottom) will record the sounds from the microphone (at the top of the pole) and will be deployed for up to four months at a time. PHOTOS BY SHAUN DUNN

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