Surveyors of the Night

By Naturalist, Licia Johnson

With the threat of White-nose Syndrome knocking at our door, the latest discovery of the WNS fungus just detected at Maquoketa Caves State Park, Iowa,  just 30 miles from the SW corner of Wisconsin, it is important now more than ever to get an understanding of Wisconsin’s bat population.  

One way citizens can become involved in this effort is to monitor our local bat population with an acoustic monitoring detector. 

While we have trained over 60 volunteers in the past 3 years who conduct these night-time surveys from May-September, I rarely get a chance to take the equipment out myself to partake in this awesome experience.  Well, this past Tuesday was my chance to get out there.  I met Discovery Center member and trained bat surveyor, Ed Marshall, at his house on Squaw Lake in Lac du Flambeau. 

I arrived at 9pm (we have to start the surveys ½ hour after sunset) to get all the equipment ready and to load up in the boat, and Ed was ready to go - the sun setting and temperature at a comfortable 64 degrees.  He had his electric Duffy boat, aptly named the ‘Lac du Flambeau Queen,’ after its resemblance to a certain famous 1951 action-adventure-romance flick, charging all day, so we would have enough power to last throughout the survey.  

We settled in, put all the equipment together, shoved off from the dock….and the motor wouldn’t start.  Curious.  I quickly reached out, grabbed a half-submerged pipe to keep us from drifting too far out into the lake.  We docked the Duffy, and decided to try out the Alumacraft fishing boat.  The motor started right up and we began our survey route along the edge of Squaw Lake. 

We had only about seven minutes of no bat activity before the detector started going crazy.  We could see the bats flying over the surface of the lake-over 20 surrounded us at one point.  By looking at the sonogram that showed on the equipment, I could tell they were little brown bats.  This kind of activity continued for the next hour and a half, I believe we also had big brown and hoary bats. 

As we conducted the survey, the temperatures began to drop.  I believe that it got down into the upper 40’s, low 50’s towards the end.  The water temperature was over 71 degrees F.  This led to the occurrence of a steamy lake surface.  As we glided over the lake, my hands were so cold, but I could actually feel the warmth of the steam on my face as we cut through it.  It was such an amazing feeling, and only could have been experienced while out surveying our nocturnal flying mammals. 

The best part of doing these surveys is the results we receive.  After the survey is completed, I download all the information stored in the detector on our route and all the bats that we encountered.  DNR folks in Madison then analyze the data and send back a map of the route, along with the location and species of all the bats we encountered during the survey.  

We are anxiously awaiting our results and will share them when we get them!