Hubbard's cave
Encyclopedia
Hubbard's Cave is a cave
and 50-acre (0.2 km²) natural area located 10 miles (16 km) southeast of McMinnville
in Warren County, Tennessee
. It is owned by the Tennessee Chapter of The Nature Conservancy
.
Hubbard's Cave is ecologically significant because it serves as a hibernaculum
for two Federally
endangered
bat
species, the gray bat
(Myotis grisescens) and the Indiana bat
(Myotis sodalis). The cave is known to be the largest gray bat hibernaculum in Tennessee
with a population of over 500,000 gray bats. Five other bat species also hibernate
in the cave. Hibernating bats are extremely sensitive to disturbance during the hibernation period. Since they have stored up just enough energy to survive through the winter, rousing them forces the use of these precious stores. In many instances the bats will be unable to survive the winter. Consequently, the cave entrances have been gated to prevent disturbance of the bats during their hibernation. The cave consists of three entrances (branches) at the base of a large sinkhole
. It is surrounded by a mesic
oak-hickory forest.
In addition to its biological importance, Hubbard's Cave has played an extensive role in human history and prehistory. During the Civil War
, the cave was heavily mined for saltpeter
to produce gunpowder
. The west passage in particular is littered with evidence of this historic human use. Researchers are still working to record all of the signatures found on the walls of this passage. Unfortunately, many of the historic signatures have been covered by the spray paint of modern graffiti
caused by vandal
s. Artifacts from the saltpeter mining works have been found scattered throughout this passage, including a remarkable ladder that was burned and nearly destroyed by vandals in 1997. Prehistoric human use is also evident in Hubbard's Cave. Most notable are the pieces of cane torches found throughout the west passage. Incredibly preserved due to the dry conditions, these fragments have been carbon dated
to be around 2000 years old.
Cave
A cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...
and 50-acre (0.2 km²) natural area located 10 miles (16 km) southeast of McMinnville
McMinnville, Tennessee
McMinnville is the largest city in and the county seat of Warren County, Tennessee, United States. The population was 13,605 at the 2010 census...
in Warren County, Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...
. It is owned by the Tennessee Chapter of The Nature Conservancy
The Nature Conservancy
The Nature Conservancy is a US charitable environmental organization that works to preserve the plants, animals, and natural communities that represent the diversity of life on Earth by protecting the lands and waters they need to survive....
.
Hubbard's Cave is ecologically significant because it serves as a hibernaculum
Hibernaculum (zoology)
Hibernaculum plural form: hibernacula is a word used in zoology to refer to a place of abode in which a creature seeks refuge, such as a bear using a cave to overwinter. Insects may hibernate to survive the winter. The word can be used to describe a variety of shelters used by various kinds of...
for two Federally
Federal government of the United States
The federal government of the United States is the national government of the constitutional republic of fifty states that is the United States of America. The federal government comprises three distinct branches of government: a legislative, an executive and a judiciary. These branches and...
endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
bat
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
species, the gray bat
Gray Bat
Myotis grisescens once flourished in caves all over the southeastern United States, but due to human disturbance, Gray Bat populations declined severely during the early and mid portion of the 20th century. At one cave alone, the Georgetown Cave in Northwestern Alabama, populations declined from...
(Myotis grisescens) and the Indiana bat
Indiana bat
The Indiana bat is a medium-sized mouse-eared bat native to North America. It lives primarily in eastern and midwestern states and in parts of the south of the United States. The Indiana bat is gray, black, or chestnut in colour and is 1.2–2 inches and weighs about 1/4 an ounce...
(Myotis sodalis). The cave is known to be the largest gray bat hibernaculum in Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...
with a population of over 500,000 gray bats. Five other bat species also hibernate
Hibernation
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...
in the cave. Hibernating bats are extremely sensitive to disturbance during the hibernation period. Since they have stored up just enough energy to survive through the winter, rousing them forces the use of these precious stores. In many instances the bats will be unable to survive the winter. Consequently, the cave entrances have been gated to prevent disturbance of the bats during their hibernation. The cave consists of three entrances (branches) at the base of a large sinkhole
Sinkhole
A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the Earth's surface caused by karst processes — the chemical dissolution of carbonate rocks or suffosion processes for example in sandstone...
. It is surrounded by a mesic
Mesic habitat
In ecology, a mesic habitat is a type of habitat with a moderate or well-balanced supply of moisture, e.g., a mesic forest, a temperate hardwood forest, or dry-mesic prairie. Compared to a dry habitat, a mesic habitat is moister....
oak-hickory forest.
In addition to its biological importance, Hubbard's Cave has played an extensive role in human history and prehistory. During the Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...
, the cave was heavily mined for saltpeter
Potassium nitrate
Potassium nitrate is a chemical compound with the formula KNO3. It is an ionic salt of potassium ions K+ and nitrate ions NO3−.It occurs as a mineral niter and is a natural solid source of nitrogen. Its common names include saltpetre , from medieval Latin sal petræ: "stone salt" or possibly "Salt...
to produce gunpowder
Gunpowder
Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...
. The west passage in particular is littered with evidence of this historic human use. Researchers are still working to record all of the signatures found on the walls of this passage. Unfortunately, many of the historic signatures have been covered by the spray paint of modern graffiti
Graffiti
Graffiti is the name for images or lettering scratched, scrawled, painted or marked in any manner on property....
caused by vandal
Vandalism
Vandalism is the behaviour attributed originally to the Vandals, by the Romans, in respect of culture: ruthless destruction or spoiling of anything beautiful or venerable...
s. Artifacts from the saltpeter mining works have been found scattered throughout this passage, including a remarkable ladder that was burned and nearly destroyed by vandals in 1997. Prehistoric human use is also evident in Hubbard's Cave. Most notable are the pieces of cane torches found throughout the west passage. Incredibly preserved due to the dry conditions, these fragments have been carbon dated
Radiocarbon dating
Radiocarbon dating is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. Raw, i.e. uncalibrated, radiocarbon ages are usually reported in radiocarbon years "Before Present" ,...
to be around 2000 years old.