Deep beneath Oklahoma’s rolling hills, something fascinating is happening in abandoned coal and copper mines. These forgotten industrial spaces have become the unlikely sanctuaries for bat colonies across the state.
The transformation of Oklahoma’s into critical wildlife habitat tells a story of adaptation, conservation, and ecological balance. These underground chambers now house some of the state’s most important bat populations, creating an intricate relationship between human industrial history and wildlife survival.
The Silent Migration Underground
This disturbance has caused many bat colonies to abandon natural caves they have roosted in for generations, prompting bat species that rely on subterranean environments to seek shelter in abandoned mines. The shift has been profound across Oklahoma’s landscape. Oklahoma bats may seek out a variety of daytime retreats including caves, rock crevices, old buildings, bridges, mines and trees.
What makes these abandoned mines so appealing? The controlled environment and temperature stability mirror the natural cave conditions bats have depended on for generations. The microclimate, most importantly the temperature, determines whether bats will use a particular mine. Warm sites are selected for maternity roosts, while cold sites are chosen for hibernation.
Oklahoma’s Underground Bat Hotels
At least 23 species of the flying mammals have been documented in Oklahoma, though recent studies suggest even higher numbers. Approximately 23 different species of bats are native to Oklahoma. Each species has different roosting preferences, making the variety of abandoned mine environments particularly valuable.
A majority of our bat species stay in Oklahoma and hibernate in caves and mines but others choose to migrate to locations where insects are still abundant. These underground spaces provide year-round shelter for resident populations while serving as critical stopover points for migrating species.
Conservation Success in Dark Places
Conservation efforts have recognized the crucial role these old mines play. Abandoned mines pose a risk to the public and a significant liability to owners and land managers, which is why abandoned mine lands (AML) closure programs exist – to eliminate these hazards from the landscape. BCI’s Subterranean Team partners with land management agencies such as The Bureau of Land Management, U.S. Forest Service, National Park Service, and more to safeguard abandoned mines.
Abandoned mines and caves that undergo our biological assessments are often candidates for closure and are frequently modified with the installation of bat-friendly gates. These gates serve a dual purpose: first, to promote human safety by restricting access to potentially hazardous environments; and second, to preserve critical habitat for bats by minimizing human disturbance.
Temperature-Controlled Wildlife Havens
The underground environment of old mines provides ideal conditions that many surface habitats cannot match. Bats that roost in smaller groups typically require temperatures between 70 and 90°F for maternity use. Big-eared bat (Corynorhinus spp.) maternity roosts have sometimes been recorded in colder sites where ambient temperatures are as low as 60°F.
Mining operations created these perfectly climate-controlled spaces unintentionally. Approximately one-quarter of the bat species in the United States and Canada are believed to hibernate almost exclusively or caves (Tuttle and Taylor, 1994). Suitable hibernation sites for bats in all regions must protect bats from freezing, and for most species, should provide stable temperatures.
The Ecological Benefits Bats Bring
Bats provide many services to Oklahoma’s diverse ecosystems, including plant pollination and reducing insect populations. Because insects are their main food source, bats act as nature’s pest control. In fact, a single bat can consume hundreds of mosquitoes and other insects in one hour!
Bats are primary predators of night-flying insects, and many such insects rank among North America’s most costly agricultural and forest pests. These include cucumber, potato, and snout beetles; corn-earworm, cotton-bollworm, and grain moths; leafhoppers; and mosquitoes. A single little brown bat (Myotis lucifugus) can catch hundreds of mosquito-sized insects in an hour.
Oklahoma’s Most Spectacular Mine-Roosting Colonies
The caves on the SLL protect the largest population of hibernating cave myotis (myotis velifer) in Oklahoma (70,000 bats) and they also harbor big brown bats, tri-color bats, pallid cave bats, and the Townsend big-eared bat (which has declined dramatically).
Alabaster Caverns State Park personnel made a count of the bats in the caverns in January 2024 and reported over 12,000. In 2016, the count reported about 16,000. The cave system is surveyed yearly for white nose syndrome, and as of 2024 none has been detected.
Advanced Technology Protects Underground Habitats
Modern conservation uses sophisticated methods to study and protect these underground bat colonies. On the subterranean team, Jackson assists in coordinating projects with federal agencies and private partners inventorying abandoned mines for bat habitat. The team then conducts internal biological surveys to assess habitat quality – whether bats or other wildlife are present, and to what extent they are using the site.
Bat-friendly gates are constructed out of steel and include horizontal bars spaced wide enough (typically 6 inches apart) for bats to fly through but too narrow for humans. These gates are constructed in the entrances of abandoned mines and caves and are specially designed to avoid impacting the internal environment which bats depend on.
Economic Value Hidden Underground
Bats provide critical ecosystem services to humans, including eating insect pests, pollinating plants, and dispersing seeds. The economic impact stretches far beyond conservation dollars. Bats are primary predators of night-flying insects that cost American farmers and foresters billions of dollars annually, therefore, threats to bat survival are cause for serious concern.
For example, native pollinators enhance agricultural crops, and insect-eating bats provide pest control services worth billions of dollars to farmers annually. This natural pest control service has particular value in Oklahoma’s agricultural regions.
Threats and Conservation Challenges
The available evidence suggests that millions of bats have already been lost due to these closures. Bats are found all throughout Oklahoma and have experienced population decline as a result of habitat loss and climate change.
Human disturbance at a bat roost can lead to stress, displacement, and, in some cases, complete abandonment of the site. This makes the protection of mine habitats particularly critical, as these represent some of the last remaining undisturbed underground spaces.
Oklahoma’s old mines have become more than abandoned industrial sites. They’re thriving ecosystems supporting incredible bat diversity. The collaborative efforts between government agencies, conservation groups, and mining companies show how human ingenuity can work alongside natural adaptation. These underground sanctuaries prove that sometimes the most unlikely places become the most important wildlife havens. What started as holes in the ground for extracting resources has evolved into Oklahoma’s most valuable bat real estate. What do you think about this remarkable transformation? Tell us in the comments.
Jan loves Wildlife and Animals and is one of the founders of Animals Around The Globe. He holds an MSc in Finance & Economics and is a passionate PADI Open Water Diver. His favorite animals are Mountain Gorillas, Tigers, and Great White Sharks. He lived in South Africa, Germany, the USA, Ireland, Italy, China, and Australia. Before AATG, Jan worked for Google, Axel Springer, BMW and others.
