A New Kind of Night Life
Anna Lutz
alutz771@uwsp.edu
When the sun goes down the bats come out, and so do the members of the UW-Stevens Point bioacoustics group.

For several years now this group, under the direction of Dr. Chris Yahnke, Associate Professor of Biology at UWSP, has been monitoring bat populations throughout Wisconsin. They are part of a collaborative effort in conjunction with the Wisconsin Department of Natural Resources (WDNR) and private citizens throughout the state that collect data on bat activity.


The purpose of this research is to create an overall picture of the bat population in Wisconsin and to piece together the distribution and migration patterns of different bat species in the state.


“There are about seven different species of bats found in Wisconsin, but only about five of them are very common: the big Brown Bat, Northern Myoitis, Red Bat, Silver Haired Bat and Hoary Bat,” said Jennifer Gruettner, student co-leader of the bioacoustics group.


Gruettner has been working with the group for two years. The group started with Dr. Yahnke monitoring on his own in 2005. Since then, it has expanded to include many student volunteers and coordinates with five different sites throughout the state.


Two of the sites are near Madison and two are near Milwaukee. In Stevens Point, the main monitoring site is located in the Schmeeckle Nature Reserve. In addition to these permanent monitoring stations, there are mobile units that student researchers and volunteers can set up along the river or carry with them through the woods. One such tool utilized by this research group is the solar powered Anabat detector.


“The Anabat records bat calls and produces visual readings of each call,” said Gruettner. From these visual readings, or sonograms, students analyzing the data can determine the species of the bat that made the call. This can sometimes be a challenge, however. “The farther the bat is from the detector the more information is lost,” Gruettner pointed out.


This method of research is further complicated by the variety of bat calls. Each species of bat has at least three kinds of call: the search phase, used when flying around looking for food; the approach phase, used when honing in on prey; and the feeding phase, used when insects are caught and eaten. Bats can also sometimes mimic other bats calls.

As far as student involvement goes, Dr. Yahnke said the group is always looking for volunteers to help with fieldwork and data organization. Student involvement is somewhat of a challenge, as bats are most active in the summer outside of the normal academic year.

“We have a little window in October and a little window in April, the rest of the year we are analyzing data,” Yhanke said. “These surveys are wonderful for students to do,” said Dr. Yahnke because they are so interactive. “If there are people going by students can train them how find a bat signal in about five minutes.” This makes the research come to life for the public and gives students the opportunity to teach others about research.

However, this research is not just for the benefit of student experience. In the future, scientists will be able to used the data collected as a baseline to monitor fluctuation in the populations caused by weather, food shortage and disease.

“One of the major reasons we are doing this is to tie this back to white nose syndrome,” Gruettner said.

White nose syndrome is a disease characterized by a fungus that grows around the mouth, nose and ears of hibernating bats. According to the WDNR, the fungus spreads between bats hibernating in caves over the winter. It interrupts the bats’ normal hibernation, waking them up and causing them to expend the stored energy they need to survive the winter.

“Infected bats often emerge too soon from hibernation and are seen flying around in midwinter. These bats usually freeze or starve to death,” said Natasha Kassulke, a writer from the WDNR.

The first case of white nose syndrome was documented in New York in 2006. Since then it has spread quickly across the east coast. Though there are no known cases in Wisconsin, this research will help scientists prepare in the event that white nose syndrome does spread farther than it already has.