The Secret Lives of Parks

The Undiscovered Cave

Episode Summary

Explorers in a remote area of Grand Canyon National Park discovered a cave they believe human beings had never entered before. Inside this maze of limestone passageways, researchers found thousands of fossils that could change our understanding of one of the country’s quirkiest animals — bats!

Episode Notes

At Grand Canyon National Park, explorers discovered a trove of lifelike bat fossils that provide a genetic record spanning 30,000 years. Experts reflect on why these particular remains are so rare and special, and how the National Park Service has spent years documenting and learning from the ancient life that surrounds us in our parks. Host Jennifer Errick explores the issue with guests Shawn Thomas, volunteer caver and Subterranean Team Manager at Bat Conservation International; Vincent Santucci, Senior Paleontologist and Paleontology Program Coordinator for the National Park Service; and Dr. Carol Chambers, Professor of Wildlife Ecology at Northern Arizona University.

Learn more about National Fossil Day at and read about other recent significant findings in our national parks at and

Original theme music by Chad Fischer

Night sounds at the Grand Canyon by Jeremy Tregler

The Secret Lives of Parks is brought to you by:

Todd Christopher – Producer & Host
Jennifer Errick – Producer & Host
Bev Stanton – Online Producer
Ismael Gama, Jr. – Creative Content Specialist

The Secret Lives of Parks is a production of the National Parks Conservation Association. With more than 1.6 million members and supporters, NPCA is the nation’s only independent, nonpartisan advocacy organization dedicated to protecting national parks. Learn more at

Episode Transcription

The Secret Lives of Parks

Episode 4
The Undiscovered Cave

Jennifer Errick: Explorers in a remote area of Grand Canyon National Park discovered a cave they believe human beings had never entered before. Inside this maze of limestone passageways, researchers found thousands of fossils that could change our understanding of one of the country's quirkiest animals, bats. I'm Jennifer Errick, and this is The Secret Lives of Parks.

The Grand Canyon is one of the world's most famous and beloved national parks. With millions of people visiting the site each year, you might think that every square inch of it has been hiked, paddled, climbed, and Instagrammed. But a little over a decade ago, an explorer named Jason Balinsky spotted what appeared to be a previously unknown opening in a limestone cliff in a remote area of the park. Staff at the park issued a research permit, allowing a team of experienced cavers to visit the site and investigate.

Shawn Thomas: Prior to that I'd been in hundreds of caves. And I instantly recognized this one as being really special.

Jennifer Errick: That's Shawn Thomas, a volunteer caver at the Grand Canyon, who is one of the first people to set foot inside the newly discovered cave. Thomas worked for the National Park Service for 10 years, and currently serves as the Subterranean Team Manager at Bat Conservation International, though he was part of the expedition in his role as a volunteer with extensive caving experience.

Shawn Thomas: The Grand Canyon is not particularly well known for caves. People think about the Colorado River and rafting down the canyon and some of the hiking trails, but the caves are equally grand, in my opinion.

Jennifer Errick: And this cave was no exception. It's important to note that I can't tell you the name of this cave or any details about how to find it because, for one thing, I just don't know. Very few people do. And everyone involved in this story is careful with this information, both to protect the cave and to protect the public.

Caves are extremely delicate environments. And if I were to go wandering through one unannounced, I could inadvertently harm the ecosystem by breathing, touching, or stepping on things. But beyond that, I'm an experienced hiker and there is no way I would feel safe on this journey.

Shawn Thomas: There are no trails that lead to this cave or anywhere near it. It involves scrambling down cliffs using ropes. It's a bit of a haul, it takes a good day just to get staged to go into the cave. So that's just day one, is getting to our camp. And then day two is actually going underground.

Jennifer Errick: And then comes the fun part.

Shawn Thomas: First of all, you have to do a really scary rappel. This was one of the longest rappels I'd done in broad daylight on the surface. So you back over the red wall limestone, where it goes vertical into a cliff, and you can see down hundreds and hundreds of feet. Far beyond where we're going to actually get into the cave. And it's definitely pretty alarming. You kind of have to get over that moment of panic.

And then rappel down the wall. The wall kind of vanishes away where it turns into the overhanging cave entrance. And then you land actually down below the cave. At that point, you have to climb up a big pile of rocks and breakdown and scramble up into the entrance. And then as you go through that area, it gets into this big maze cave.

Jennifer Errick: All of that leaping and scrambling turned out to be worth it. Once the team of explorers made it to the entrance, they were surprised by what they found. According to Thomas, there were no signs that any humans had ever been inside the cave. No footprints in the soft sediment or prehistoric artifacts that are common in area caves, such as tools and figurines. The cavers did see something else, however.

Shawn Thomas: Lots of bats.

Jennifer Errick: Lots of mummified bats, to be precise. The animals had been preserved intact by the dry cave air. No one can currently say exactly how many, but Thomas gave me his best estimate.

Shawn Thomas: There are likely thousands of mummified dead bats inside the cave. Easily, I've seen hundreds just in the parts of the cave I've visited. No one person has seen the entire cave, but all of these teams are coming back, reporting these bats in all these different places.

Jennifer Errick: To find this many mummified bats in one location is not just uncommon, but unheard of.

Vincent Santucci: No one has totaled all of the known mummified bat remains. There's at least 100 from Carlsbad Caverns. But it seems as though treasures that we found in this remote cave in Grand Canyon National Park collectively exceed all of the known total of other bats together from North America.

Jennifer Errick: That's Vincent Santucci, Senior Paleontologist and Paleontology Program Coordinator for the National Park Service, a role he describes as “the best job in the world.” He learned about the discovery while conducting an inventory of all the known fossils at the Grand Canyon several years later. He was impressed, not just with the quantity of bats, but also the quality.

Vincent Santucci: It turns out that this collection of bats is unprecedented. These mummified bats, some which are still attached to the wall, look like they're living bats, or they passed away yesterday. And they're in very good condition.

Jennifer Errick: In fact, these bats have remained so lifelike and intact, all three of the people I spoke with for this story said the same thing about them, that they looked like they could fly away at any minute. I saw photos of some of the animals and I'm no expert, but they looked to me like regular bats getting ready to go out for a night of pollinating and eating bugs. But these bats hadn't taken wing in a very, very long time.

Dr. Carol Chambers is Professor of Wildlife Ecology at Northern Arizona University and Co-Director of the school's Bat Ecology and Genetics Lab. She first began researching bats at the Grand Canyon while radio tracking the habits of a species known as the spotted bat in the 1990s. She's understandably enthusiastic about her studies.

Carol Chambers: Bats are fascinating. We have over 1,400 species in the world today. We're discovering more every year. And I just think they're cool animals. Even some of the ones that are what you might call plain, little brown bats. The fact that they can fly at night through the air, capture animals on the wing to eat, migrate long distances, move up and down in elevation daily, they are just amazing animals.

Jennifer Errick: Staff at the Grand Canyon contacted Dr. Chambers for her expertise when researchers discovered the new cave and she was able to study 24 of the mummified bats that explorers, including Thomas, had collected in 2010. Researchers weren't sure if the bats in the cave had all died at once from a sudden event, or whether they had died individually over a period of time.

Chambers wanted to carbon date the specimens to find out how old they were, but the process is expensive, and she didn't have funding for the project until just a couple of years ago. And even then, she only had enough to date about half of the samples.

Carol Chambers: I remember looking over the collection of 24 animals that I had, trying to figure out how to send in the right ones to get information. How do I know which ones are maybe older? You can look at things like, do they look a little faded? Do they look different? But these bats were in pretty good conditions. So it was hard to pick ones that looked old versus new.

Jennifer Errick: When the results finally came back, they were significant.

Carol Chambers: The youngest bat that we had was 3,500 years before present. And the oldest one was almost 34,000 years before present. It kind of blew us all away with the age of these bats.

Jennifer Errick: Although Chambers had suspected that the bats probably varied in age and hadn't died from a single event, she was surprised that every single specimen was thousands of years old and that there was such an enormous range in ages.

Carol Chambers: I mean, I had no expectation that every single bat would be that old.

Jennifer Errick: Santucci was similarly enthusiastic about the findings.

Vincent Santucci: The opportunity that we have here is we're able to look at about a 30,000-year span of bats, mummified bats with soft tissue, that enable us to put a date on the age of these bats. To see if over that 30,000 years we see changes, evolutionary changes that are reflected in the genomes. There's no other source of biological material spanning 30,000 years that we have available to evaluate DNA anywhere on the planet. And so this is a very unique opportunity.

Jennifer Errick: That part about the specimens having soft tissue is also an important aspect of these bats. They're lifelike appearance, the fact that they look like they could just fly away, means that there is more of their remains available for scientists to study.

Vincent Santucci: In the fossil record, mummified remains are known, but they're relatively rare. And so for a paleontologist that studies bones all their life, if they have an animal that has all the soft tissues, the fur, the skin, the internal organs so you can see what's in the gut contents, what was their last meal? All the aspects of the tissues that inform us more about what these animals look like and perhaps aspects of their physiology or behavior. Really, this was an exciting opportunity.

Jennifer Errick: Researchers are just beginning to consider what they might learn from these bats.

Vincent Santucci: We're right at the foundation of trying to see what questions we might be able to address through this research. But there's so much potential that will likely resolve from this.

Jennifer Errick: Chambers is interested in comparing the specimens to their modern counterparts to learn how they may have changed over time. She also wants to know if bats may have adapted their flying abilities and other habits to thrive in different cave environments.

Carol Chambers: Genetically, are they the same as our bats today? They look the same as the bats we have in the same area today. Are they genetically similar? It just seems like an exciting opportunity to get a feel for a big bat community in an area that hasn't been disturbed.

Jennifer Errick: These 12 carbon dated bats are just the beginning of this research. Explorers have been returning to the cave almost every year since its discovery to continue mapping passageways and identifying the fossils, in hopes of learning more. Though the cavers have had to cancel their trips for the last two years, first due to wildfires, and then due to COVID. Fortunately, a team is returning this fall, and Chambers, Santucci and others are hoping to gain more data on how old and genetically diverse these bats are and what their DNA might teach us.

The team will also continue learning about the cave itself, an intricate maze of twisting limestone tunnels. Thomas and his fellow explorers have currently mapped more than 40 miles of the cave with no end yet in sight. Here's Thomas again, putting this fall's trip in perspective.

Shawn Thomas: These expeditions, they take a lot of planning, they take a lot of time, and lot goes into this. And yeah, especially after the last couple years of having the expeditions canceled for various reasons, it does feel like a long wait. But of course, these bats have been there for thousands of years, so they're going to be ready for us.

Jennifer Errick: Of course, for those who study paleontology, this is representative of how the process works. Living organisms die, and their remains spend countless years lingering behind rocks, buried under soils, and encased in other stable environments until, if the conditions are just right, someone discovers them, often unwittingly. Fossils are hidden all around us, like time capsules with secret messages from when the world looked and felt very different from the way it does now.

One of the reasons I really enjoy talking with Santucci is because he serves as an enthusiastic translator, sharing these secret messages that national parks hold from eons gone by. Last year, his office released major findings on shark fossils at Mammoth Cave National Park in Kentucky, bones dating back 325 million years from when the site was covered in a giant inland sea. And at least five of those species are completely new to science.

He also helped discover the longest and oldest known set of human footprints from the ice age, which researchers uncovered in the crystallized gypsum dunes at White Sands National Park in New Mexico. Those human tracks coexisted alongside the footprints of giant ground sloths, extinct mammals the size of small cars that appeared to react to the humans.

My colleagues, Christa Cherava and Katherine De Groff reported on these findings last year. And you can find links to their stories and to the Park Service press materials in the show notes. Santucci emphasizes that there is much more for us to learn.

Vincent Santucci: We only knew about dinosaurs for about 160, 170 years in human history. And there are new discoveries made every year all across the planet. We're in the infancy of the science of paleontology. And again, most of what is to be discovered is still out there. It's still laying beneath the ground or exposed at the surface.

Jennifer Errick: When the National Park Service first began inventorying fossils at national park sites in 1985, Santucci was a graduate student just beginning his career as a fellow at Badlands National Park in South Dakota. At the time, staff only knew of 12 national parks with fossils. Today, researchers have documented fossils at 282 national park sites. And those are just the ones we know about.

Even accounting for the increase in the overall number of national parks, this represents an enormous wealth of knowledge spanning more than a billion years of life on earth. That we know so much more now about the ancient life in our parks, is thanks in large part to the work of Santucci and many others to document every single known fossil across the park system. These fossils are non-renewable resources, and gathering this baseline data helps park staff preserve them so that we don't lose this irreplaceable history.

Vincent Santucci: We are getting out there into the field and trying to identify the scope, the significance, the distribution, and the management issues associated with fossils. Everything that would be important to understand about these resources, to provide to the park leadership, so that they can incorporate that information to inform their decision making.

Jennifer Errick: Only about 10 full-time staff serve as paleontologists at the Park Service, and of those 10, eight are based in specific parks, leaving just Santucci and one other scientist to conduct the work on a national level. Though, of course, many park staff and partners contribute to the research and help monitor fossils over time to make sure they're safe from erosion, development, looting, and other threats.

Still, just 10 people devoted to more than a billion years of life on Earth is some pretty staggering math. And this small team keeps coming out with impressive new discoveries.

Vincent Santucci: We've really been rewarded with new discoveries of things that weren't understood. And there are many examples within the past five, six years that we've come upon resources that have gathered the attention of the public, the media, of scientists, sometimes globally significant discoveries that prior to this inventory work, no one on the planet knew that these existed.

Jennifer Errick: According to Santucci, the fossil inventory work at Grand Canyon National Park, which began in 2018, is the largest and most complex such project he has ever been involved in. And those thousands of mummified bats were just one of the major findings.

Santucci's team of more than 30 specialists didn't just make a new discovery. As part of the inventory, the team reanalyzed previously discovered fossils that a Smithsonian paleontologist named Remington Kellogg had excavated from a different cave in the 1930s.

Scientists had long believed that two of the partial skulls Kellogg had found were the remains of pumas, common animals in the area. The new research recently confirmed, however, that those skulls are actually from American cheetahs, ice age felines that were previously not known to have lived in the Grand Canyon region.

Vincent Santucci: Why this is significant ... we think, first of all, many people in the American public probably were unaware that there was an American cheetah in north America during the end of the ice age. It went extinct along with many other animals like mammoths, mastodon, camels, saber tooth cats, and ground sloths.

However, those specialists that study fossil cats put a lot of research into trying to interpret what the life, habit, behavior, and the environments in which the American cheetahs lived during the ice age. And a lot of those interpretations assumed that these were savanna dwelling, open country dwelling organisms, whereas here, finding the remains of both a sub-adult and a juvenile American cheetah within Grand Canyon puts them in a wholly different environment in Canyon Country. Providing evidence that there was more to these mysterious cats than we had previously understood.

Jennifer Errick: This month, Santucci and many others will be celebrating the joys of paleontology as part of an annual celebration known as National Fossil Day, held during the second week of October each year. The event largely focuses on engaging school children and encouraging budding young scientists. Park Service staff host art contests and events, give out coloring books, and have even developed a Junior Paleontology Program modeled after their popular Junior Ranger Program.

But the event captures the interest of people of all ages and gives those of us who are less young a good reason to stop what we're doing and learn something new about mastodons, trilobites, camelops, pterosaurs, and the many other curious creatures that once lived in our world.

It's just a coincidence that the team is revealing their Grand Canyon findings during a month when people also like to talk about bats, mummies, and the mysteries of the dead. But then I think it's always a good time to celebrate bats, because as Dr. Chambers put it so well ...

Carol Chambers: They are just amazing animals.

Jennifer Errick: The Secret Lives of Parks is a production of the National Parks Conservation Association. Episode four, The Undiscovered Cave, was produced by Todd Christopher, and me, Jennifer Errick, with moral and technical support from Bev Stanton and Ismael Gama, Jr. Original theme music by Chad Fisher. Recordings of night sounds of the Grand Canyon by Jeremy Tregler. Learn more at

For more than a century, the National Parks Conservation Association has been protecting and enhancing America's national parks for present and future generations. With more than 1.6 million members and supporters, NPCA is the nation's only independent, nonpartisan advocacy organization dedicated to protecting national parks. And we're proud of it too.

The Secret Lives of Parks is overseen by Amy Hagovsky, who was looking forward to our second season, but almost couldn't listen.

Shawn Thomas: It's definitely pretty alarming. You kind of have to get over that moment of panic.

Jennifer Errick: You can join the fight to protect places like the Grand Canyon and all of its amazing bats and fossils. Learn more and join us at