“It’s kind of like the ‘Field of Dreams’ — If we build it, they will come,” said Nanny during a recent tour of the site. “We’ll be monitoring both population and species composition. It’s designed for Mexican free-tailed bats, but we expect other species to inhabit it, as well.”

The plan calls for Ijams visitors to be greeted at dawn and dusk by the awesome sight of a vast cloud of the bats leaving or returning to their manmade home. 

“As a nature center we want to educate everyone about the natural world and the importance of it,” said Ijams CEO Amber Parker. “Over the last few years, our area has been getting residential communities of Mexican free-tailed bats, and we now have lots of colonies throughout Knox County,” Parker said. “So why not have a large community of bats here? These bats are particularly charismatic because they leave as one body every evening.”

Parker pointed out that Mexican free-tailed bat colonies in Florida and at the Congress Avenue Bridge in Austin, Texas, regularly draw large crowds of onlookers. 

“In Austin, you can sit and watch these millions and millions of bats leave at once,” she said. “So, let’s have a smaller community of them here at Ijams so visitors can bring their lawn chairs and families to watch them emerge, along with education programs.” 

The bat house itself had been stored in a barn for the better part of a decade following an abortive attempt to install it on the UT campus, according to Professor McCracken, who joined Ijams’ board of directors after retiring from UT’s College of Ecology and Evolutionary Biology.

A crew from Knox County’s Parks and Recreation department assembled the wooden tower, which has approximately 1,000 cubic feet of space, earlier this year at no cost to Ijams because it’s installed on a plot of land owned by the county but managed by the nonprofit center.

A large bathouse originally planned for the UT campus was reassembled this spring by a public works crew at Ijams Nature Center. The structure is expected to attract 200,000 bats at any given time in the summer. Ijams Nature Center

McCracken, who has been studying Mexican free-tailed bats for most of his career, is recognized as one of the world’s leading experts on the creatures and has proven they have a tremendous economic impact on the agricultural industry by consuming vast numbers of insects every night. 

“These bats are eating half to three-quarters of their body weight in insects every night,” McCracken said while walking around the recently completed bat house. “Since these bats usually weigh a half-ounce each, that means they’re going to be eating tons of insects. Flight is the most expensive form of animal locomotion in terms of energy, so these guys have huge metabolisms. They have voracious diets, and they eat the species of insects we (humans) are aiming for.”

While there are almost 1,500 bat species in the world, including 46 in the U.S., Tennessee used to be home to only 14 varieties. As the earth’s temperatures have continued to rise, however, Mexican free-tailed bats have begun moving into the region and have now become Tennessee’s 15^th species of bat.

“Most bats are tropical,” McCracken explained. “The big colonies of these are further south, but our climate is changing into what was further south and these guys are now reproducing as far north as Virginia. They were never here. They’re a subtropical species that first showed up in this area about 15 years ago. This is clearly related to global climate change.”

Now that Mexican free-tailed bats have joined opossums and black bears as fixtures of East Tennessee’s native fauna, they can be found in countless buildings and caves.

“The free-tails now are roosting in buildings all around this area,” he said. “There probably isn’t a church or school building that doesn’t have some.”

By luring as many as 200,000 of the bats into the tower by Meads Quarry, McCracken and other Ijams officials hope to not only delight the public but also continue researching the lives of these fascinating — and often misunderstood — creatures. 

“This is a perfect place because bats like water and bats like insects, and the quarry’s right there and the river’s right there,” he said. “Bats get a bad rap, and we’re going to have educational information here, nightly bat education outreach programs, and bat walks.

“It’s going to be research, too. We’re going to have cameras and bat detectors, so you’ll be able to actually hear the bats hunting and feeding. It’s going to be great.”

Cute and fuzzy and very, very important

Like all creatures, bats are very much their own things. But from a human perspective, they are often perceived as disease-carrying, winged rats whose blindness forces them to navigate using biological radar and who eat insects when they can’t drink the blood of other mammals. 

This is an utterly false picture, of course, and it’s one that bat experts take pains to discredit whenever they can.

For one thing, bats are a lot closer to primates (including humans) than they are to rodents. Also, they’re not blind, most species eat only insects, and they’re a lot less likely to carry diseases like rabies than many other mammals.

“The only bats that are blind are those that have had a bad accident or a congenital defect,” said University of Tennessee professor emeritus Gary McCracken. “They have pretty good nocturnal vision. It’s not that great because they get a huge amount of information from their ears, but they’re certainly not blind.”

Although bats haven’t been domesticated like canines or cattle, they are essential to human survival because they consume many times their own weight in insects that would otherwise devastate crops and torment people.

“Bats eat enormous numbers of insects, and many of those insects are the world’s most important agricultural pests, the pests for whom the greatest tonnages of insecticides are applied to crops.”

Mexican free-tailed bats — the species that a new program at Ijams Nature Center is focused on — are particularly fond of moths that eat corn, tomatoes and other crops.

“Each moth can lay 1,000 eggs, and the bats eat 40 to 50 moths each overnight. The numbers are vast.”

But the biggest misapprehension most people have about their furry flying cousins is that they likely carry rabies, McCracken said.

It’s not that rabies isn’t a terrifying disease. Once a person begins to show symptoms, rabies nearly always leads to a painful, prolonged death. 

Bats, however, aren’t a major reservoir species for the rabies virus, according to McCracken. 

“All mammals get rabies, all mammals can catch rabies and die from the virus,” he said. “Bats also die from the virus. They are not the asymptomatic carriers that many people think they are. If a bat gets clinical rabies it will die.”

At any one time, only a tiny fraction of 1 percent of bats are infected with the virus, he said, while the percentage of, say, infected raccoons is far higher. 

Before World War II, hundreds of Americans died annually from rabies but nearly all of those cases were spread to humans by dogs or, more rarely, cats. Since health authorities started using the rabies vaccine, however, it’s become almost extinct in domesticated mammals.

“Rabies is now found only in wildlife,” he said. “Dogs and cats are virtually rabies-free. Over the last few years, less than one person per year has died from it in the United States.”