THE BAT NET This specimen of Myotis lucifugus has been waylaid temporarily to be analyzed and measured. Photographs by Floto + Warner

Tom Kunz switches on his headlamp and climbs into the hayloft. Weak sunlight streams through a clouded pane, casting a yellow glow over a square of plastic stretched out on the wooden floor. "There’s some fresh stuff here," he says. The sheet is dotted with pellets of bat guano, the size and shape of scattered grains of wild rice. Kunz plucks one up between his finger and thumb to show me. "You can see how little these are." Little, in this case, is good -- very good. Little pellets mean little bats. Little brown bats, to be exact, Myotis lucifugus, which is what Kunz, founding director of the Center for Ecology and Conservation Biology at Boston University, has come looking for.

Kunz has been coming to this barn, just outside Peterborough, New Hampshire, on and off, since the early 1970s. Francis Carr and now Carr’s widow, Ruth, have allowed hundreds of visits to their property; one of Kunz’s former doctoral students, Scott Reynolds, conducted a 16-year continuous study here that has helped to create one of the most valuable bat population baselines in the region. From 1995 through 2008, a relatively stable number of little brown bats -- 150 to 200 adult females -- arrived here each summer, clustering along the ridge beam to give birth and nurse their pups. Crystallized trickles of urea clinging to the rafters like stalactites ("piss-cicles," Kunz calls them) still attest to how numerous the bats once were. But in 2008, the number of breeding females dropped noticeably, and then fell precipitously in 2009. By 2010, the bats were all but gone.

Only five years ago, it would have been impossible to imagine the disappearance of the little brown bat. If you stood outside in the gathering dark of a summer evening in nearly any part of the nation, in the city or the country, you would see flapping shadows glean and hawk the night sky as they patrolled for insects. Indeed, a major reason little brown bats became so numerous is precisely because they adapted so well to our presence. Though they naturally hibernate in caves, they thrived in the mine shafts of Pennsylvania coal country and the graphite mines of New England. Though they historically used hollow trees for maternity roosts, they adapted equally to the attics of drafty Victorians and the peaked roofs of hand-hewn barns. Our damming of creeks for mills and rivers for power, our irrigation ditches and stock tanks for crops and cattle, even our swimming pools and well-watered lawns -- all created breeding ponds for the insects little brown bats feed on.

In years past, when scientists like Kunz wanted to study Myotis lucifugus, it was a relatively simple proposition: the bats had multigenerational loyalty to particular hibernation caves and warm-weather roosts, and these spots were thickly and predictably populated. All that started to change in February 2006, when a pair of researchers working in a restricted-access area of Howe Caverns, a heavily trafficked tourist attraction near Albany, New York, came upon room after room of dead bats, their bodies piled on the dirt floor, faces talc white. The powdery growth, previously unknown, was eventually classified and named Geomyces destructans -- "the destroying fungus" -- and the mass mortality it caused was termed white-nose syndrome. But the coinage is something of a misnomer, because the real killer appears to be the way the infection attacks wings. The fungus causes enough irritation of the paper-thin skin between the long digits to rouse bats from hibernation, which in turn boosts their metabolism and burns critical fat reserves, making it nearly impossible for them to survive the cold months. Those bats that do manage to winter through emerge with wings so ravaged they look moth-eaten, which limits the aerial acrobatics that all bats need to hunt and lowers the chances that females will put on enough weight to nurse pups.

This piling-on effect -- killing larger numbers of bats in winter caves, starving others in the spring, and stunting the numbers of new pups in the summer -- has had an exponential effect. By 2009, more than a million bats of six different species had died from the syndrome, and new evidence of its spread is reported all the time -- to the south into Tennessee and South Carolina, westward into Ohio, Missouri, and Oklahoma, radiating northward from upstate New York into four Canadian provinces. There seems to be no defense; once the fungus arrives in a hibernation cave, the death toll can exceed 90 percent within three years.

This was enough to push Kunz and his colleagues last summer to predict the extinction of the little brown bat in the Northeast by 2025 and to forecast a similar threat for any other region the syndrome reaches. For those who would shrug off the loss of insect-eating bat populations, Kunz and his team calculated that the bats already wiped out by white-nose syndrome would have consumed roughly 700 metric tons of insects each year. If the fungus spreads to the vast cornfields of Illinois and Iowa or the cotton country of Texas, the economic effects could be crippling. Kunz estimates that white-nose deaths could cost American farmers anywhere from $3.7 billion to $53 billion each year in pesticides. Some scientists are skeptical of Kunz’s estimates, but as the fungus spreads, he insists that there is no time for equivocation. "We suggest that a wait-and-see approach to the issue of widespread declines of bat populations is not an option," Kunz and his co-authors wrote in an editorial in Science magazine in March, "because the life histories of these flying, nocturnal mammals -- characterized by long generation times and low reproductive rates -- mean that population recovery is unlikely for decades or even centuries, if at all.”

But, as new information emerges, Kunz also believes that a simple hammer-and-nails approach may offer a partial remedy: the "roost module," a wooden box containing narrowly spaced baffles. Roosting females can nestle into the tight crevices, well insulated and better able to retain heat. The fungus can’t survive above about 68 degrees Fahrenheit -- much lower than an active bat’s body temperature of well over 100 degrees. It’s only when bats go into torpor during hibernation and their body temperature drops to near ambient levels that they fall prey to the fungus. While it may not be possible to keep cave-dwelling bats warm during hibernation, Kunz believes that the chances of recovery and reproduction for each spring’s survivors would improve if they had these snug places to roost during summer nights.

Kunz snaps some pictures of the guano pellets on the plastic sheet, evidence that there may be a small group of survivors returning. Once outside, he strides up to Ruth Carr’s back deck, where she is sitting with her sister and brother-in-law, visiting from Florida.

"I’ve got a picture to show you," Kunz calls out as he approaches. "Bat poop."

He hands her the small point-and-shoot camera and says, "I don’t know how many there are here, but…"

He trails off. What follows that "but," left hanging in the air, is the unknown itself. He understands that even widespread, successful use of roost modules may not return bat numbers to previous levels, at least not any time soon, but it’s the first glimmer that there may be a way to stave off a wave of extinctions that could envelop the continent.

For the next few June days, I will join Kunz as he goes from the Carr property to a series of barns and attics where he has been monitoring bat populations for most of his career. He hopes to see whether the roost modules his team has installed are having any effect. What we will find is both encouraging and alarming. The modules appear to be more effective than anyone could have hoped, but as the fungus spreads the need for more of them is growing pressing. For Kunz, now in his seventies and working on what he vows is his last research grant, the final attempt to unravel the mystery of white-nose syndrome is not just a capstone to a career; it’s a last-ditch effort to save several species of bats he has spent a lifetime trying to understand.

The Country Boys

I've known Tom Kunz since I was a kid. More accurately, he’s known me -- or at least the back of my head, as I rushed off into the flock of sons and daughters that trailed the attendees of the annual gathering of the American Society of Mammalogists. Kunz and my father, Hugh Genoways, are both past presidents of the society and were grad school buddies at the University of Kansas in Lawrence -- two members of a legendary cohort there. Thirty-two C. Hart Merriam Awards for outstanding research contributions to the science of mammalogy have been granted over the decades, and six of the recipients, including Kunz and my dad, were either young professors or doctoral students together at K.U. in the late 1960s. They were country boys, most of them Boy Scouts and high school athletes, the last of a breed that pre-dated the lab rats most biologists are today. They were drawn to the sciences by a love of the outdoors and propelled upward by a surge of federal funding during the space race.