Somewhere at the middle-end of the 19th century, a railroad tunnel under construction in Walhalla partially collapsed and left behind a cave that tricolor bats really took to. There used to be hundreds of the small, furry bats hibernating through the winters by clinging to the rock. By Feb. 10 of this year, there were seven.
“That’s a huge decline,” says Jennifer Kindle, the lead bat biologist for the South Carolina Department of Natural Resources.
She finds the reality depressing.
The reason for the massive drop in numbers of tricolor bats here is due almost entirely to White Nose Syndrome, or WNS, a fungus that clings to bats while they hibernate and eventually rouses them too early in the season. The bats use up huge stores of their energy and their fat stores trying to find food sources, but can’t. The bugs they mainly rely on are not out for the spring yet, and WNS can weaken their wings. They have difficulty getting around to look for food they can’t locate and usually starve to death.
WNS first showed up in New York in 2006. It spreads the way pollen spreads when bees carry it, except that the disease is wiping out tricolor bats so suddenly and so sharply, the species is under consideration for endangered status.
In the old railroad cave in Oconee County, where Kindel recently led a population count survey, there were 401 bats in 2012. The population had been hovering around 150, give or take, for years, in part due to the easy access people had to the mouth of the tunnel. In 2008, the city of Walhalla sealed off the opening with a steel gate and the population of tricolor bats rose above 400.
Two years later, Kindel and her team noticed WNS on 28 bats and the population inside the tunnel cave was 119. In 2017, her survey found just 13 bats. On Feb. 10, seven were left.
Kindel says it’s “entirely possible” that some of the bats that were here three years ago found another place to ride out the winter. But she’s sure WNS is responsible for the lack of tricolor bats here.
It’s not just tricolor bats. South Carolina is home to 14 species; six (big brown, little brown, eastern small-footed, northern long-eared, southeastern and tricolor bats) have been affected by the disease, according to DNS. It has been detected on another four, but so far no bats have shown signs of the disease.
In some populations, like big brown bats, numbers have dropped by 90% over the past decade. Susan Loeb, a researcher at Clemson University, counted 321 bats in Walhalla’s Stumphouse Tunnel in 2014. She and her team found 37 three years later.
Loeb told Clemson World magazine, “The disease [white-nose syndrome] has progressed faster than I thought it would,” Loeb says. “It’s only going to get worse and continue to spread until a treatment or cure is found. But we’re continuing to work here on campus and with our partners to understand the spread of this deadly disease and to minimize its impacts.”
The effort to save South Carolina’s bats involves 11 state and federal agencies, four universities and seven non-governmental groups (including the South Carolina Bat Working Group, which is not listed on the DNR’s page but is trying to spread the word about the toll WNS is taking in the Palmetto State).
The benefits of bats to the world at large are profound. Beyond maintaining healthy cave ecosystems where they live, bats vacuum up immense quantities of insects that, without a predator, could decimate farm crops. The National Park Service estimates that bats provide $3.7 billion worth of pest management in a year (which would be replaced by chemicals and harmful processes in the absence of voracious bats).
"Imagine a teenage boy eating 200 quarter-pound burgers," the NPS writes on its website. "That's how much a bat eats in insects in one night."
Bats are also excellent pollinators, a trait becoming more urgent as the other great pollinators, bees, are dying off rapidly as well. Bats help disperse seeds and are meals for predatory birds and mammals, which are suffering the loss of their own food sources.
SCDNR has a formal response plan, updated last year, to contend with the precipitous die-off bats are suffering. It includes passive and active monitoring, public awareness and efforts for more regulatory oversight concerning bat protections. It also has a bat protection plan, which acts as a centralized record of what is happening with bats and the fungus that is killing them.
But because WNS has no cure, there is little biologists can do about declining numbers yet.