May 6, 2016

Bat Monitoring

Posted by: Ecological Management

Bat Monitoring

Since 2010 Little St. Simon’s Island has been teaming up with the Georgia Department of Natural Resources to monitor bat populations using AnaBats. As a bat is foraging, it emits a high-pitched “feeding buzz” inaudible to the human ear. An AnaBat is a device that detects and records these sounds. Each species emits calls at a unique frequency, which has allowed researchers to determine the species that are present on the island. Of the sixteen species in Georgia, Little St. Simon’s Island is host to six of them.

Some of the bats on LSSI are cave roosting bats, while others are tree roosting bats. In the summer cave roosting bats can roost in houses, under dock pilings, or other similar structures. Tree roosting bats roost under loose tree bark or in hollow trees. One species, the northern yellow bat, roosts almost exclusively in Spanish moss! During the summers of 2012 and 2013, University of Georgia graduate student, Craig Bland was studying roosting and foraging habitat preference of the northern yellow bat. This bat is fairly uncommon and little is known about its natural history. Before Craig and his technicians Bronson Curry and Lauren Austin started mist netting for the study, there were only two other documentations of the northern yellow bat on LSSI.

To study habitat preference of bats, first you need to catch them. Craig, Bronson, and Lauren set up huge mist nets over ephemeral pools on the north end of the island. The bats would then fly into the nets as they were foraging for insects and drinking water from the pools. Once the team captured a northern yellow bat they applied a permanent wing band and then used surgical glue to attach a radio transmitter, which eventually fell off. The next day, the team set out using telemetry to track the bat to its day roost. After the bat left, the team took measurements of the roosting sites, in hopes of better understanding the habitat needs of northern yellow bats.

Occasionally, when the ephemeral pools on the north end of the island dried up, the team would have to get creative. One of the few consistent, alligator-free watering holes on the island was the LSSI swimming pool. The team caught hundreds of bats over the pool during the two-year study, only one of which was a northern yellow bat. The nights were far from wasted though. Each bat captured was identified by species, gender, age, forearm length, wing damage and reproductive status. Georgia DNR biologist Trina Morris still visits LSSI each summer to mist net over the pool to collect data and monitor for the elusive northern yellow bat!

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