Written in the spring of 2018
Read the full, unpublished story here
Today white-nose syndrome is burning into the Great Plains, into the Southwest. In 2016 it lept to Washington, shocking researchers who predicted its arrival years later. When biologists confirm its presence in a new state, often the ominous sign — white noses — doesn’t come that winter. It comes in the second winter, and in the third come the deaths. (Oddly, sometimes, in the third winter their numbers rocket instead, climbing in certain instances by 1,000 percent, before they plummet.) The greatest losses have been documented in Missouri. White-nose syndrome was confirmed here in March 2012, and by the winter of 2015-16 it had overrun half the state. Sixteen percent of the big brown bats here are unaccounted for, and that’s the lower end of the toll. More than half the tri-colored bats are missing, nearly 90 percent of the little browns have disappeared and rounding up one-tenth of a decimal point exterminates the northern-long eared on paper. In the beginning, scientists were searching for what was killing the bats. Now they’re searching for what will save them.
In February, two biologists were searching for survivors in a limestone cave on a frozen elbow of Cedar Creek in Boone County, Missouri. The first one they found was just beyond the mouth of the cave squeezed into a crack in the pockmarked walls. It had brown fur and dark skin and looked a little like a dog with its hooped ears and polished snout. It was a big brown, no bigger than a child’s fist. As it slept, a red dot swept over it and hovered, shaking, for a few seconds, and then Kirsten Alvey-Mudd read the numbers from her infrared thermometer.
“Twenty-one-point-two degrees,” she said, converting from celsius. “He is effectively hibernating.”
Savanna Shafer pulled out her phone and made the first entry: one big brown bat.
They crowded around the bat looking for signs of white-nose syndrome. Its nose and ears and wings were free of the white fuzz, and it was thin but not emaciated. It slept undisturbed, its temperature down by more than half, its breaths coming every 40 or more minutes, all in an effort to slow its metabolism to ration fat and live to spring. The epidemic has sparked a wave of research into bats, but still researchers have a lot to learn. Why, for instance, are big browns resistant to the fungus when little browns are among the hardest hit? Why do Indianas surge before they crash? And why, from here to New England, are some bats living winter to winter with the fungus but without the symptoms? Do they have a gene the dead bats lack?
“We don’t know,” said Jeremy Coleman, who, since 2009, has lead the US Fish and Wildlife Service’s efforts on white-nose syndrome. “We would love to be able to find some genetic component of resistance, or resilience, just to have some piece of mind. It looks like that might be the case, based on the counts, or at least the persistence of the populations.” There are reports of little browns, he said, that were around before the epidemic returning to Pennsylvania and New York and Vermont to hibernate each fall a little fatter. Elsewhere, too, are similar report, like in Missouri and northern Ontario. Is there a gene, then, allowing these bats to gain weight while others starve? “People are very hopeful,” Coleman said, “myself included. But the question is still, ‘What is driving that?’”
Further in the cave, the glow of daylight disappeared and Alvey-Mudd and Shafer scanned their headlamps up and down the limestone walls searching for bats. They dragged themselves on padded knees through a passage that flashed with thousands of green and gold lights — dew-clad cave fungus, the native kind, and also some fools gold refracting the headlamps — but no bats. They crawled above a stream where salamander larvae, miniature white shrimp and leopard-printed pickerel frogs swam in cold, clear water, and they ducked their heads to avoid a bat hanging from the ceiling. Shafer added it to her tally.
As they pushed deeper, Alvey-Mudd thought out loud.
She saw several bats stuffed in a crack.
“They’re like playdoh.”
She saw another bat hanging from the ceiling.
“Nope. His nose looks good.”
But now, in a crater above her head, she spotted three bats: tri colored. Their fur shined silver like tinsel: condensation. Alvey-Mudd didn’t need her thermometer to know these bats were warmer than they should be. Something had disturbed their sleep.
On the snout of one of the bats was a white fuzz.
“Oh,” she said. “This guy has white nose.”
Shafer came over and looked up, the sterile light of their headlamps spotlighting the bats like they were specimens quarantined in a lab. The one with the powdered nose also had white splotches along the edges of its folded wings.
“It’s highly likely the ones next to him have white-nose as well,” Alvey-Mudd said.
Further down the passage, the fungus was blooming on the tail and belly of another tri colored.
If evolution is rescuing North America’s bats from this epidemic, their future will be under greater threat from another. Bottleneck events like these pulverize a species’ gene pool. Largely only the animals with the genes to survive do, and when they reproduce, slowly building back the population with resistant offspring, they’re more likely to be missing genes key for adapting to climate change, say, or diseases from across the ocean. “Things that aren’t even on the horizon,” Coleman said.
Eurasia may be an example of what North America can expect. The fungus that causes white-nose syndrome, Pseudogymnoascus destructans, diverged from its last known ancestor 23.5 million years ago and probably began evolving alongside Eurasian bats. Researchers don’t know, but many believe it decimated colonies and through natural selection they slowly rebounded. Before the epidemic, the average size of a bat colony in North America was orders of magnitude larger than ones in Europe, but the average size of blighted colonies in North America are now nearly the same size as colonies in Europe.
“They may not ever recover to the numbers pre white nose,” Coleman said, if they recover at all. If there is no genetic resistance in the surviving bats, and if we assume the fungus will spread across the entire continent, as it appears to be doing, he said, “I think those species are likely to go extinct.”
Back near the mouth of the cave, Alvey-Mudd and Shafer reviewed their survey results. Zero little browns. Six big browns. Forty-three tricolored, four of which had white nose.
“In years gone by,” Alvey-Mudd said, “this cave has had between three- and four-hundred tricolored bats. So that — that would be a 90 percent loss.”
But if this cave was a crypt, its corpses were gone. Maybe the bats flew out, fleeing whatever was killing them and froze in the woods. Maybe they fell from the ceiling and dissolved in the streams. Maybe raccoons dragged them away. The two biologists could only guess, but they knew what it would have looked like. Alvey-Mudd pulled out her phone and in the darkness flipped through photos from other caves.
A dead bat hung from a ceiling like a leaf yet to fall.
A dead bat’s eye sockets and nostrils billowed white fuzz.
A dead bat crumbled on a cave floor: yellow bones, leather flesh.
Her photos were from caves in Missouri, but she could have taken them anywhere white-nose syndrome has reached. The scenes are all the same. Where there were once hundreds or thousands of bats there are few, or there are none.
She put away her phone and they walked out of the cave.