A 2011 WINTER CENSUS OF BATS OF THE LEWISBURG LIMESTONE MINE

In cooperation with the ODNR Division of Wildlife, ESI has participated in biennial bat surveys of the Lewisburg Limestone Mine since 1996.  This mine is an important hibernaculum for many species including the Indiana bat and is the only known Priority II (1000 to <10,000 individuals) Indiana bat hibernaculum in Ohio. 

Despite range-wide Indiana bat population decline, the population at Lewisburg Limestone Mine appeared to remain stable until the 2006 survey indicated a 22 percent population decrease from the 2004 survey; however, the 2009 survey showed a 22 percent increase over 2006. Since 2002, the total number of bats (inclusive of all species) has seen a downward trend, with a decrease of 23 percent from 2002 to 2004, 5.6 percent from 2004 to 2006, and 6.7 percent from 2006 to 2009. Because many bat species are declining throughout their ranges, frequent winter hibernacula counts are one of the most important and effective tools to gauge long-term population trends. 

Surveys at the mine are typically conducted every 2 years; however, 3 years elapsed between the 2006 and 2009 survey.  Information recorded during the census included number of Indiana bats, location of Indiana bats, temperatures throughout the mine and near Indiana bats, and locations and numbers of other species.  The survey revealed the actual number of bats wintering in the Lewisburg Limestone Mine decreased from their high of 36,818 in 2002, to 26,717 in 2006 and decreased again to 24,931 in 2009.

On 19 February 2011, ten biologists conducted an abbreviated survey to census Indiana bats and inspect for signs of White-nose Syndrome (WNS).  The goal of the 2-hour survey was to reduce disturbance on hibernating bats while ascertaining the status of WNS on the Indiana bat population in the mine.  Indiana bats were censused in areas historically containing the majority of the population.  Census methods emphasized photo-documentation of hibernating Indiana bats in an effort to decrease survey time and aid in remote WNS surveillance.  Areas historically containing large populations of little brown bats, another species widely affected by WNS, were inspected for bats with symptoms of WNS.  No WNS-symptomatic bats were found during the 2011 survey.  ESI is currently processing the census data.

 

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