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Indiana bats equipped with radio transmitters helped biologists find maternity roost sites. Photo by Keith Lott/USFWS.

Indiana bats equipped with radio transmitters helped biologists find maternity roost sites. Photo by Keith Lott/USFWS.

Ohio Field Office Helps Metro Parks Track Bats

For a manager of a Metro Park, knowing what plants and animals occur on your lands significantly influences how you manage your lands. In 2008 a bat survey was conducted at Battelle Darby Creek Metro Park near Columbus, Ohio. During this survey several endangered Indiana bats were captured and tracked to their roost trees. During the summer, female Indiana bats form maternity colonies of typically 40 to 80 bats. These colonies are normally found in large dead trees with some remaining bark. The bats go up underneath the bark, which shelters them from the elements and predators, and helps keep them warm. When they give birth to their young, known as pups, this congregation of bats helps to keep the pups warm and allows them to grow faster.

For several years Metro Park staff monitored their colonies; this provided important information on colony size (sometimes greater than 300 individuals) and timing of arrival and departure (Indiana bats overwinter in caves and will travel up to 375 miles between summering and caves/mines each year). Eventually the trees decayed, losing all of their bark, which made them unsuitable for the bats, and the bats moved on to an unknown location.

This summer, biologists from the Ohio Ecological Services office partnered with staff from the Metro Parks in an attempt to relocate the maternity colonies at Battelle Darby. Two survey locations were established near where the bats had been found in 2008. Mist nets, which are made of very fine nylon string, were stretched across several trails and Big Darby Creek. Nets were opened at sunset, and checked every ten minutes. Bats are most active in the first few hours after dark; activity generally decreases after midnight. Between the two sites, biologists captured numerous bats, including northern long-eared (a proposed endangered species), big brown, little brown and eastern red bats.

It was not until after midnight that the first Indiana bat was captured in a net spanning Big Darby Creek. Shortly after, a second Indiana bat was captured at the other site, approximately a half-mile away. Biologists recorded weight, age (adult or juvenile), checked for signs of white-nose syndrome (a fungus causing significant population declines of bats in the northeast) and gender for both bats. Then a small aluminum band was placed on one wing of each bat. This band has a number, unique to each bat, so that if it is found again we will be able to determine how old the bat is and where it was originally captured. Finally a small radio transmitter, weighing only 0.2 grams, was attached to the bats. The bats were then released.

For the next week Service personnel would attempt to locate the bats approximately every two days by triangulating the signals coming from the radio transmitters. Neither bat could be located the day after they were released, but on subsequent visits both bats were found. The bats primarily used two roost trees, a very large cottonwood tree and a small red maple snag. Staff from the Metro Park have gone out at dusk and counted the number of bats coming out of the trees several times.  More than 100 bats were observed between the two trees. The Metro Parks staff plans to continue monitoring these trees for years to come, providing information on how Indiana bats are doing in this area.

By Keith Lott
Columbia, Missouri Ecological Services Field Office

 

Last updated: November 4, 2014