Up From the Underground

At 8:07 p.m.,

                                                                                a lone gray bat

wheels out of Bellamy Cave
                                            in western Tennessee

    
                                and disappears
           into the muggy

                                                                                                   July night.

The waking of an infected bat during hibernation triggers its metabolism and body temperature to rise. Without a food source to offset those costs, the interruption means that the bat runs through its winter energy store and dies. The disease has slashed northern long-eared bat and little brown bat populations by 90% across their ranges. Indiana bats are not far behind, sustaining an 85% decline. Bat populations were hardest hit in northern states, while those in warmer climes (with shorter hibernations) are faring slightly better. Overall, millions have died nationwide.

But, miraculously, the hit to the remaining gray bat populations never came. No one knows exactly why.

Bats play a vital role in our ecosystems. They are key seed dispersers and pollinators, and insectivorous bats can eat one-third of their body weight in moths, beetles and other bugs in one night.

One study estimates they save the U.S. agricultural industry an annual $23 billion in pesticides.

But 15 years after the juggernaut of white-nose syndrome, it’s unlikely that some bats will regain their historic numbers. “A worst-case future scenario is that we see the complete collapse of little brown bats, tri-colored bats and northern long-eared bats,” Pattavina says. “A best case would be a modest increase in abundance, but I don’t expect a big splash of a return.”

White-nose syndrome is here to stay, but so is the new collaborative approach to bat conservation it galvanized.

“White-nose syndrome gave everyone a shared purpose, and that coordination has spilled over to other bat projects, because we don’t take common species for granted anymore,” says Dustin Thames of the Tennessee Wildlife Resources Agency, a frequent partner in Holliday’s efforts.

The complicated reality of protecting bat caves

Holliday himself is at the center of Tennessee’s bat action and cave protection. After spending five years surveying life in the state’s caves, Holliday pivoted his program in the early days of white-nose syndrome’s outbreak to focus on bat research and conservation. To protect an animal is to protect its habitat, he says. Tennessee is home to 11,500 known limestone caves, the most of any state in the country; it is a bounty of underground space stemming from the region’s limestone geology.

Tracking bats in Tennessee for future conservation plans

The spirit of collaboration that’s now a hallmark of Tennessee’s bat work is on display at Bellamy Cave. The Nature Conservancy purchased the cave in 2006, when it sheltered 140,000 bats in winter and 35,000 in summer. Today, after gate installations and protection work by TNC and the Tennessee Wildlife Resources Agency, those numbers ring in at 350,000 in winter and 250,000 in summer.

Tonight, 17 biologists—representing the U.S. Fish and Wildlife Service, the Tennessee Wildlife Resources Agency, the University of Tennessee, Sewanee: The University of the South and the Department of Defense—are here to attach transmitters to as many gray bats as possible to gather tracking data.

In a nightly summer ritual, the gray bats traverse a mile of Bellamy’s inky passageways, emerging as darkness falls to forage. That is, except for those that hit the harp trap—a device that looks like its namesake, with strategically spaced strings that snag bats who attempt to fly through and deliver them (unharmed) into a trough below.

Two biologists pluck captives from the trough and pop each into a brown paper sack. Runners ferry the bags up a hill to a processing station and clip the bags onto a clothesline. Teams of biologists fetch a bat at a time to record basic information like sex and weight. Each bat receives a tiny forearm band and a transmitter glued on its back. All of this is done on a ticking timer because, according to U.S. Fish and Wildlife Service rules, these endangered bats can’t be held longer than 45 minutes to avoid overstressing them.

The data from the radio transmitters is key to learning more about these misunderstood mammals: What are critical habitats for foraging and migration? What are their biggest threats, besides white-nose syndrome?

As the tagged bats fly, they’ll pass Motus Wildlife Tracking System towers dotted across the landscape.

The towers are a recent addition to the biologist’s toolbox; they pick up signals from any passing tagged animal, logging location data that can be easily shared. Motus started as a collaborative way to track birds, but Holliday harnessed its capabilities for bats and has installed 18 towers in Tennessee. The tracking data will shape future conservation efforts, and Holliday hopes it will illustrate where to avoid building wind turbines, a looming threat.

Back at Bellamy, it’s almost 10 p.m.; headlamps illuminate five tables strewn with glue bottles and data clipboards. “We have 15 minutes before we have to release,” calls Holliday. Bags still hang from the clothesline, far too many bats to process as the minutes fly.

Soon, time is up. In total, the biologists have attached 41 transmitters. Those 41 bats will flit across the landscape, ranging 50 miles in a single night, each Motus tower they pass pinging with a data point that’s a window into a secret life. The biologists head to the clothesline, reach into the bags and withdraw the furious little mammals within. They raise an arm, open a hand and cast each bat back into the night, like an offering to the sky.