Saving Bats One Cave and Mine at a Time

Merlin Tuttle

Caves are a critical resource for America’s bats. But thousands are no longer available for bats. Early American settlers relied on saltpeter from bat caves to produce gun powder. Then caves became lucrative for tourism, and many others were buried beneath cities or flooded by reservoirs. Even caves that were not destroyed often were rendered unsuitable for further bat use. Not surprisingly, the most cave-dependent bats quickly crashed to endangered status.

Today, nothing is more important to their recovery than identifying, restoring, and protecting key caves of past use. At that, Jim Kennedy is an unsung hero. Early in his career he joined me in critical research on the needs of cave-dwelling bats and worked with master bat-gate-building engineer, Roy Powers, to become an expert builder.

Kennedy became an expert at detecting evidence of past use by bats, and he has helped build gates to protect many of America’s most important remaining bat caves. He has also led workshops to train others. In 2013, he founded his own company, Kennedy Above/Under Ground, LLC. His teams have built 56 protective gates at 43 caves and abandoned mines where hundreds of thousands of bats have since recovered from severe losses.

Illustrative of the impact of protection at key locations, endangered gray bats at Bellamy Cave in Tennessee, increased from 65 to more than 150,000 once protected. And when a bad gate was replaced at Long Cave in Kentucky, gray bat numbers grew from zero to over 300,000. At Saltpeter Cave in Kentucky, endangered Indiana bats increased from zero to 7,000 when poor gates were replaced, air flow was restored, and winter visitor tours were terminated. Jim was involved in restoring each of these caves for use by bats. 

Jim Kennedy (right) and endangered Indiana Bat Recovery Team Leader, Rick Clausen, documenting recovery of Indiana bats (Myotis sodalis) in Saltpeter Cave, Kentucky. The species began rapid recovery in this cave following installation of an improved gate and airflow led by Jim.
Heather Garland, Tennessee Nature Conservancy Cave Specialist, and Merlin Tuttle conducting a winter census of recovered hibernating gray bats in Bellamy Cave.
Bellamy Cave in Tennessee provides both cold and warm roosts permitting year-around use by endangered gray bats (Myotis grisescens). Dramatic recovery occurred following protection. A 100-foot-long, 10-foot-high, perforated steel fence ensures long-term protection. The bats chose to fly over the fence instead of through the gaps. Photo Copyright Jim Kennedy

Protection can be a real challenge. Even good gates, if wrongly located, can force abandonment partly because different species have unique needs. Gray bats, and other species that form large nursery colonies in caves, cannot tolerate full gates across entrances. Newly flying young slow down and become easy prey for predators. Jim has three ways of dealing with this. When a cave entrance is large enough, he leaves fly-over space above, relying on a perforated metal lip to prevent human entry. Alternatively, he sometimes builds a metal chute at the top, using perforated metal. When entrance size or shape precludes such approaches, he surrounds the entrance with a 10-foot-tall, perforated-steel fence. At Key Cave in Alabama, the Tennessee Valley Authority contracted Jim’s team early in 2021 to build a 390-foot fence that required 21 tons of steel. Its entrances were too small to permit young bats safe exit through gates.

This 390-foot-long fence now protects a nursery colony of endangered gray bats in Key Cave, Alabama. Photo Copyright Jim Kennedy
Jim Kennedy's crew unloading some of the 21 tons of steel required to build a fence to protect an important gray bat nursery colony at Key Cave in Alabama. Photo Copyright Jim Kennedy

Cave entrances on cliff faces can be especially difficult. At Bat Cave in Missouri’s Mark Twain National Forest, the U.S. Forest Service contracted Jim and his team to haul tons of steel and equipment up a cliff face to gate the cave’s two entrances.  A chute gate and a fly-over gate were necessitated to accommodate the cave’s gray bat nursery colony. For his success, Jim received a prestigious “Wings Across America” award.

In July 2020, Jim and his team encountered a new challenge when gating New York’s Barton’s Hill Mine. The 200-year-old mine includes miles of passages with multiple entrances at different levels, creating strong “chimney-effect” air flow. Though the gate was built in mid-summer, Jim’s team had to use a chain saw and jack hammer to remove ice that was blocking the work area. Then, despite summer heat, they were forced to wear snow mobile suits while working in a strong 38-degree Fahrenheit breeze exiting through the entrance!

This mine shelters the largest hibernating bat population in the Northeast, approximately 120,000 bats of at least four species. As bats have lost natural roosts in caves, abandoned mines have become increasingly important. In fact, they now shelter millions of displaced bats. This gate will protect both bats and humans. The ice-covered floor drops approximately 100 feet nearly vertically into a pool of water, a dangerous trap for the unwary. The Barton’s Hill Mine is now safer for both bats and people.

This chute gate was used to protect the second entrance to Bat Cave. Chutes allow quick and safe access for maternity colonies that are unable to use traditional gate designs. Photo Copyright Jim Kennedy
Bat Cave in Mark Twain National Forest, Missouri, showing difficult access. Tons of material had to be raised up cliff-face terrain using a pulley system. Protection of the cave's gray bat nursery colony required two kinds of gates. Photo Copyright Jim Kennedy
Builders constructing the first of two gates at Bat Cave in Mark Twain National Forest in Missouri. This gate employs perforated steel extending at right angles outward from the top to prevent visitors from climbing over while allowing bats ample fly-over space above the gate. Photo Copyright Jim Kennedy

Protection and restoration of traditional, but long-lost hibernation sites may be the single most important option for restoring bats, especially those recently lost due to white-nose syndrome. Loss of key caves has forced millions of American bats to seek alternative shelter in less suitable locations where inappropriate temperature, and sudden shifts, can increase both the cost of rearing young in summer and that of hibernation in winter. This makes them less able to survive the stress of higher metabolic rates and forced arousals caused by white-nose syndrome and human disturbances. Furthermore, as the number of suitable roosting caves diminishes, bats are forced to expend more energy on longer travel between summer and winter roosts, leaving less and less for emergencies.

Preparing to gate New York's Barton’s Hill Mine. Home to the largest remaining hibernating bat population of the Northeast. Work here was especially challenging. Large amounts of ice had to be removed before work could even begin, and workers had to wear heavy coats in mid-July. Photo Copyright Jim Kennedy
Heavy fog periodically created by cold air from the Barton’s Hill Mine. Photo Copyright Jim Kennedy

The value of protecting key cave roosts has already been proven for gray bats. When I began my conservation efforts on their behalf, nearly six decades ago, the species was in precipitous decline and America’s leading experts were predicting extinction. Today, due to the combined help of federal, state, and private organizations, volunteer cavers, and expert gate builders like the late Roy Powers and his protégée, Jim Kennedy, we have millions more gray bats than when their extinction was predicted. Nevertheless, additional cave-dwelling species, especially the endangered Indiana bat and little brown bat, remain in widespread need of help, and invaluable opportunities for restoration remain.

Welders progress at Barton’s Hill Mine. Photo Copyright Jim Kennedy
Jim Kennedy and his team pose at the completed Barton’s Hill Mine gate. Such gates have been extremely successful in protecting bats hibernating in caves and mines. However, identical gates are generally not tolerated by summer nursery colonies. Young bats must slow down to pass through, making them vulnerable to predators. Photo Copyright Jim Kennedy

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Thai Adventures Part 4: Khao Chong Pran


By Merlin Tuttle

For me, our trip highlight was the visit to the Khao Chong Pran Cave in Ratchaburi Province. Nearly 40 years ago Buddhist monks who owned the cave had asked my advice. Their monastery relied on bat guano fertilizer sales for support. But in 1981 production was plummeting. Of course, and the monks wanted to know why.

Merlin and Surapon reminiscing about their first visit to Khao Chong Pran Cave nearly 40 years earlier.

Before dawn the next morning, my then young field assistant and interpreter, Surapon Duangkhae, and I discovered poachers using large fish nets to capture bats at the cave entrance. They were selling them to local restaurants. We hired two of the poachers to help us document the extent of the problem, then advised the monks to hire a game warden to protect their bats.

Merlin answering game warden’s questions in 1989.
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Thai Adventures Part 3: Cave Bats


By Daniel Hargreaves

We arrived at sunset at the OurLand Nature Reserve in Kanchanaburi Province, our home for the next 5 days. We quickly set up a few mist nets and a harp trap and were rewarded with a brace of lesser false vampire bats (Megaderma spasma) and several cave nectar bats (Eonycteris spelaea). Merlin took the opportunity to show the group how to train a bat. Unfortunately, the chosen bat was unusually difficult. However, just over an hour later it eagerly permitted Merlin to approach, enticing it to drink from a syringe filled with sugar water.

The next morning, we climbed 200 steps in search of roosting bats located in two caves above a monastery occupied by Buddhist shrines.

Group climbing the steps to the cave with Kate in the lead.
Group entering cave.
Daniel Hargreaves showing the first tiny bumblebee bat to our group.

Initially, we captured a long-winged tomb bat (Taphazous longimanus) but as the group was looking at that one, I netted two bumblebee bats (Craseonycteris thonglongyai). Both were females weighing around two grams. They were delicately held by group participants while I explained the species’ anatomy, ecology, and conservation status.

Mindy excited to be holding a famously tiny bumblebee bat.
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Cave Management Workshop with Bat Survey Solutions

By Merlin Tuttle

Merlin explains “chimney-effect” air flow and its key importance in providing cave-dwelling bats with cold roosts for hibernation and warm ones for rearing young.

Loss of essential roosts, especially those in caves, appears to be the most important cause of North American bat decline and endangerment. Millions of bats have been lost from single caves, initially due to saltpeter extraction for gun powder, and later when they were further altered for tourism. Some caves were even burned due to exaggerated fear of bats.

In recent decades, there have been numerous opportunities to recognize mistakes from the past as well as opportunities for the future. One way to address these issues is through cave management training.
Bat Survey Solutions held a workshop in San Marcos, Texas from May 7-9, where attendees were provided with examples of a variety of case histories and what they’ve taught us. 


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Monitoring Impacts of WNS

Monitoring Impacts of White-Nose Syndrome (WNS): Decline and Stabilization in a Little Brown Bat Nursery Colony,

A Case History from New York

By Merlin D. Tuttle


A New York nursery colony of little brown myotis (Myotis lucifugus) offers a window of opportunity for monitoring the impact and hoped for recovery of this recently devastated species. The colony occupies seven four-chamber, nursery-style bat houses provided by Lew and Dorothy Barnes. The houses were mounted on two sides of their barn near Lake Erie in western New York in the spring of 1995. By July 16, 1997 they had attracted 1,075 little brown myotis. Often aided by professional biologists, regular emergence counts were made between 1997 and 2013, providing potentially invaluable baseline data on WNS-induced population impacts.


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