MC biology professors help relocate Anderson Hall bats

March 18, 2014 

When construction crews began work last summer on the interior renovation of Maryville College’s oldest building, College officials had already made arrangements for the relocation of 45 faculty and staff members who were going to be displaced from their offices during construction.

What officials didn’t anticipate, however, is that they would need to relocate thousands of big brown bats that had taken up residence in the attic of 148-year-old Anderson Hall.

But where would these homeless insectivores go?

That’s where Maryville College biology professors Dr. Drew Crain and Dr. Dave Unger come in.

Crain, who also teaches wildlife photography at the College, inspected and photographed the bat population in the attic prior to their removal, and he was surprised by what he saw.

“We always knew there were bats in the Anderson Hall attic, although we never had any idea about the magnitude in terms of the number of bats,” he said, estimating that between 1,500 and 2,000 big brown bats had taken up residence in the attic. “They never caused any problems.”

Bats are vitally important to the ecosystem and have helped the MC campus tremendously, Crain explained, so it was important to not only safely remove them, but find them another home.

“Studies show that a single bat can eat between 600 and 1,000 mosquitoes per hour,” Crain said. “It is no coincidence that we have never had to spray insecticides on the MC campus to control for mosquitoes. Give me a choice between an insecticide and an insectivore, and I’ll choose an insectivore any day!”

An expert was called in to safely remove the bats by installing a reverse trap, which allowed the bats to leave Anderson but wouldn’t let them back in. Crain said the timing of the relocation was ideal.

“In the late spring, the pregnant female bats come together in a nursery colony; in essence, all of the females come to live together, give birth, and raise their newborns,” Crain explained. “This nursery colony disperses in early fall, so the eradication in early fall followed their normal annual cycle.”

The next step was to determine how to create a new, nearby home for the bats on campus.

Unger consulted with Merlin Benner, president of Wellsboro, Pa.-based company Wildlife Specialists, to determine what kind of home would be ideal for the bats – and where to place them.

“He has 20 years of experience as a wildlife specialist, much of it with bats,” said Unger, who has collaborated with Benner on other wildlife research projects in the past.

Together, they came up with a plan to erect 10 bat boxes and one bat condominium on campus. The boxes, located in the Maryville College orchards, each can hold an estimated 300-400 bats and were installed in November. In February, officials installed a large, 4-feet-by-4-feet bat condominium that overlooks the soccer field, softball field and tennis courts. It can hold up to 4,000 bats.

The idea is to simulate the type of roosting site that big brown bats would seek in nature.

“Historically, big brown bats would roost under large pieces of bark on old growth trees and in tight rock crevices communally,” Unger explained. “With the great reduction in climax forests and increased land development, bats shifted their roosting behavior to incorporate human dwellings.”

Anderson Hall’s attic offered an ideal substitute.

“In the summer, when pups are born and raised, the entire colony seeks a large refuge with tight spaces to maximize thermal gain through body contact – this thermal gain maximizes the growth rate in the newborn bat pups, so that when it's time, they are fully developed to be able to fly and hunt on their own,” Unger said. “Anderson Hall's high attic – with constant solar gain and tight spaces between the rafters – fit this need perfectly.”

The new housing options contain closely-spaced slats that mimic the tight spaces the flying mammals prefer.

Unger said both the bats and the College benefit from the relocation project, as the bat boxes and condominium could provide research opportunities for Maryville College students for years to come.

“By providing these bats a place to call their own, the College is showing its devotion to sustainable use of resources and the proper conservation of the life that thrives on and around our beautiful campus here at the foothills of the Great Smoky Mountains, while also attempting to solve the problem of bats entering buildings,” Unger said. “Perhaps most importantly, these bat houses, if successfully occupied, will represent a living, breathing learning tool for the students who attend our institution.”

When asked about the future of bats on campus, both Crain and Unger simultaneously smiled and say, “Bring them on!”

By Chloe Kennedy, Assistant Director of Communications


Maryville College is ideally situated in Maryville, Tenn., between the Great Smoky Mountains National Park and Knoxville, the state's third largest city. Founded in 1819, it is the 12th oldest institution of higher learning in the South and maintains an affiliation with the Presbyterian Church (USA). Known for offering its students a rigorous and highly personal experience that includes an undergraduate research requirement, Maryville College is a nationally ranked institution of higher learning that successfully joins the liberal arts and professional preparation. Total enrollment for the fall 2014 semester is 1,213.