Out of the woods

When miners dug into rich deposits of graphite and iron ore in New York’s Adirondacks region in the 19th century, they carved out a place in history — providing the raw materials that shaped the nation and world in the industrial age.

The entrance to an abandoned mine, gated off to protect hibernation space for bats. Lyme Adirondack Forest Company

But they also left something behind: enormous underground cavities that have become the setting for an important chapter in our natural history. Today’s stewards of these mines — and the forests around them — may help determine how that story ends.

When miners left, bats moved in.

“It happened pretty quickly,” said Carl Herzog, a wildlife biologist for the New York State Department of Environmental Conservation. “We have evidence of bats inhabiting mines within a decade of their closing.”

The mines, some of which comprise dozens of acres, “with miles of underground passageways,” literally expanded the horizons for native bat species in the region. Scientists presume most of the bats that moved in had previously been living in caves. But since there aren’t extensive natural caves in New York, the mines provided room to grow. “It’s hard to conclude otherwise than that these mines aided the expansion of at least some of these species’ populations,” Herzog said.

The little brown bat had declined 90 percent in New York State in the era of white-nose syndrome. USFWS

At one point, a graphite mine in Hague, New York, boasted the largest documented population of the little brown bat anywhere in the species’ range, which spans from central Alaska to the southern U.S.

In addition to hibernation space beneath the ground, the sites offered complementary forests above. After the mining industry bottomed out, forestry companies bought the surrounding land for the valuable resources that remained on the surface.

“For decades, these mines have been surrounded by sustainably harvested working forests, and that offered bats habitat for foraging and rearing young,” said Eric Ross, general manager for the Lyme Adirondack Forest Company, which owns more than 200 thousand acres in the six-million acre Adirondacks Mountains region.

“It got to the point where some of these mines had hundreds of thousands of bats,” he said. “Then white-nose syndrome came along.”

The white fuzz on this bat’s muzzle is an indication of white-nose syndrome, a fungal disease that affects hibernating bats. Marvin Moriarty/USFWS

In the winter of 2006 to 2007, the fungal disease that has since devastated populations of hibernating bat species in the Midwest and eastern U.S. was discovered in a cave south of the Adirondacks region, in Schoharie, New York.

In that same two-year time span, the Lyme Forest Fund acquired approximately 278,000 acres of land in New York’s Adirondack State Park from International Paper. They sold a working forest conservation easement to the State of New York.

“We sold them the development rights, the subdivision rights and recreation rights,” Ross said. “That means these forests will be forests forever.”

That commitment to conserving a forested landscape is in Lyme’s best interest. “Being good foresters means more than just healthy trees,” Ross said. “As large landowners, it is incumbent upon us to be looking at landscape-level habitat and wildlife needs for a whole host of species.”

And that long-term vision has created a safety net for bats in tough times.

Lyme’s lands encompass three mines that have become both refuges and indicators for hibernating bat populations in the region. Among them is the graphite mine in Hague, which the previous owner, International Paper, had protected through a conservation easement with The Nature Conservancy.

Healthy forests provide habitat for bats to forage, rear pups, and roost, sometimes in cavities in old trees. Lyme Adirondack Forest Company

Bill Martin, the conservation easement program coordinator for The Nature Conservancy in the Adirondacks, explained that bats were the conservation priority for that easement when it was put in place in 1992. “It still seems forward-thinking today,” he said.

One of the first management actions was to gate off the entrances to the mine to prevent people from entering, both for their safety, and the safety of the bats. Hibernation is a critical period in the life cycles of bats — a time when they are most vulnerable to disturbance, whether from a disease or human curiosity, because they must conserve energy to survive the winter.

The management plan also included tiered harvesting buffer around the site to minimize disturbances to foraging and pup-rearing habitat, and permission for the Department of Environmental Conservation to regularly monitor the population. That access allowed scientists to chart the precipitous decline of hibernating bat species in the wake of white-nose syndrome.

Herzog estimates there were 200,000 or more little brown bats in the graphite mine when white-nose syndrome arrived. Three years later, they counted 2,000.

The graphite mine was affected worse than average, and the average was staggering. Statewide, the little brown bat population declined 90 percent, and other species have fared worse. The population decline for the northern bat and tri-colored bat in New York is closer to 99 percent.

However, some bats have weathered the storm. The big brown bat seems to be mostly unaffected by the disease.

They’re not out of the woods yet, but the population decline for little brown bats in New York seems to have leveled off. James Weliver/USFWS

And the population of the little brown bat has started to exhibit, if not a recovery, at least a leveling off. The population in the graphite mine is now 4,000. “They are clearly dealing with the disease better than they did in the early years,” Herzog said. “Every individual gets the disease every winter, but they are not dying in anything like the number that they used to. The infections are much milder.”

While no site is immune — Herzog said white-nose syndrome is everywhere in New York — the conditions created by these mines could help bats endure in the long run.

“There is both laboratory and field data that suggest bats that hibernate at colder temperatures, and in drier conditions, fare better with the disease,” Herzog said. “In these deep captivity mines, when the entrance is high up in the structure, cold air settles into these depressions, leading to these favorable temperatures.”

Areas that were once thriving mining towns are disappearing into the forests, providing communities for bats instead. Lyme Adirondack Forest Company

Martin, who has never been inside the graphite mine, has nevertheless experienced its unique climate.

“It’s so interesting to see — or to feel, rather — when standing outside one of the openings on a hot July day, this 50-degree current coming out at you. In the winter, it’s the opposite; it’s relatively warm air coming out,” he said. “It’s different. It’s a place like no other.”

Thanks to the partnership between Lyme, The Nature Conservancy and the state, it’s also a place where bats will be protected forever.

“There are some things that are out of our control, like white-nose syndrome and its presence in these mines,” Martin said. “But we can continue to maintain these sites. And when treatments become available, or resistance becomes more prevalent, these places will still be there for them.”

Seeing the bat habitat through the trees

Bats aren’t out of the woods, but forest owners, like Lyme, play an important part of the effort to support the needs of bat species on a landscape scale, in part by understanding those needs better. Here are a few more examples of private forest owners collaborating with others to conserve bats:

A research site in the Southern Appalachians for a study on bat activities associated with opening canopy and other harvesting techniques. University of Kentucky

Exploring bat-safe timber harvest near Allagash Ice Cave:

• Partners: The Seven Islands Land Company, the U.S. Fish and Wildlife Service Maine Field Office, and the Maine Department of Inland Fisheries and Wildlife
• The story: In the summer of 2019, Seven Islands approached the Service and the state about to discuss a proposed timber harvest near the Allagash Ice Cave. One of only a few known bat hibernaculum in Maine, the ice cave supports the federally threatened and state endangered northern long-eared bat and two other state-listed bat species. Seven Islands needs approval from the state to harvest within a quarter mile of the cave, and cognizant of the federal 4(d) rule for the northern long-eared bat, the company expressed a desire to learn more about bat habitat needs and plan a timber harvest that wouldn’t result in negative impacts on the cave or bat habitat in the surrounding forest.
• Outcome: The collaboration has prompted the partners to collect new data at this unique site, including a winter survey, and a summer visit to deploy acoustic detectors — a first in this remote location.

What Southern bats do in the off-season:

• Partners: National Council of Air and Stream Improvement, Inc., (NCASI), private forest owners, and the National Alliance of Forest Owners (NAFO)
• The story: In the southeastern U.S., bats are not as severely impacted by white-nose syndrome as their northern counterparts because they are active year-round. Although they don’t hibernate, they still need to forage and roost, and NCASI is funding two studies to understand how they meet these needs in managed forests in the winter. One, in Louisiana and Texas, found eight bat species using managed forests with no caves. Instead, species that are associated with caves, like the northern long-eared bat and tricolored bat, were found using alternative roost structures, such as culverts. In the second study, researchers plan to sample winter bat communities throughout the southeast Coastal Plain to examine the influence of site and landscape characteristics on winter bat activity.
• Outcome: Understanding how bats use managed forests in the Southeast today may help forest landowners support their long-term year-round habitat needs.

Harvesting and habitat in the Southern Appalachians:

• Partners: University of Kentucky, The Forestland Group, The Kentucky Department of Fish and Wildlife and the U.S. Fish and Wildlife Service
• The story: A team of scientists at the University of Kentucky is conducting an ongoing study to evaluate sustainable timber harvesting options that affect the distribution and amount of canopy structure available for foraging bats across eastern Kentucky in different ways. The goal of the project is to identify harvesting prescriptions that are compatible with, or result in positive changes to, foraging habitat of Myotis bats, including species vulnerable to white-nose syndrome.
• Outcome: The initial results show that, among other things, bat activities associated with canopy openings, shelterwood harvests, and forest roads and skid trails varied significantly by species, but that maintaining a matrix of canopy openings, shelterwood areas, and uncut stands maximized the presence of a wide variety of forest-dwelling bats.

A How-to Guide for Forest Management and Bats

• Partners: Bat Conservation International, USDA Forest Service, National Council for Air and Stream Improvement, Inc. (NCASI), and U.S. Geological Survey
• The story: Millions of bats have died since white-nose syndrome first appeared in the northeastern U.S., and the fungus has since spread throughout a large portion of North America. While researchers continue to look for new ways to combat the disease that has devastated our native bat populations, it’s important that we take care of the ones we still have. Managing forests with bats in mind can help keep populations from declining further, and because more than half of the non-industrial forest lands are privately owned, private landowners play a big part in this effort.
• Outcome: Bat Conservation International and partners produced a guide as part of the White-nose Syndrome Plan to demonstrate how basic forest-management practices that improve forest health and productivity can also maintain and enhance habitat for bats.