[MUSIC] [OMINOUS SOUNDS] [MUSIC] If you collected every species of mammal on
Earth, a whopping one in four would be a bat. There’s more than 1300 species around the
world, one is as small as my fingernail, and another is as wide as my arms. There’s a
lot of bats out there. There’s also a lot of bats in there. This
is a very special place. Beneath our feet is the largest gathering of mammals anywhere
on Earth. 20 million or so Mexican free-tailed bats!
For the past 10,000 summers or so, these bats have come up here for the summer in what’s
known as a maternity colony. And they get hungry. Every night around sunset, they head out to
eat, and it’s an unforgettable sight. Different species eat pretty much every kind
of food there is, but the bats that live here are insectivores. A single Mexican free-tailed
bat only weighs about as much as two quarters, but all in all, this population will eat more
than a hundred tons of insects in a single night.
By doing so, they save farmers billions of dollars every year in lost crops and pesticides
that they don’t have to use. TV weathermen around here used to see evening
storms popping up on their Doppler radar, but then people on the ground would call in
saying there wasn’t a rain cloud in the sky. That’s because the radar was seeing
this. Every night invading hordes of moths ride
high altitude winds toward croplands in the midwest. Mexican free-tailed bats bats fly
as high as 10,000 feet to intercept them in epic aerial battle. Bats are the only mammals capable of powered
flight without using airplanes, a skill they evolved separately from birds and insects.
A bat’s wing is actually a highly-evolved hand, and the flexibility of their webbed
wing means that they can generate more lift and maneuver even better than birds. As adapted as they are, those flexible wings
can’t generate enough lift to carry the bats straight up out of the cave. So they
fly in this sort of cyclone shape to create an updraft. It’s like a bat-nado! I hope
you’re listening SyFy channel? It’s a tornado, made of bats. You know the old saying “blind as a bat”?
Well, bats are anything but blind. As they pour out of that cave by the millions, they
depend on their eyesight to keep from crashing into each other. But once the hunt begins,
in the dark of night, another sense takes over. Do you hear that? Nah, me neither. Bat echolocation
frequencies are above the range of human hearing, which is a really good thing. They’re so loud
it’s like holding a smoke detector six inches away from your ear. In fact, bats have to
inactivate their own hearing system when emitting their calls so they don’t drive themselves
deaf. Their ears are actually angled to let them
hear in stereo so they can triangulate the location of their prey. Scientists found that
one moth is even able to jam bat sonar by producing clicks of its own. Hungry bats make a lot of poop. In fact, there’s
more than 19 meters of guano at the bottom of this cave, in fact scientists ran out of
drilling equipment before they found the bottom. As the guano decomposes, it creates enough
heat to keep all the little baby bats warm. Aww. In addition to eating insects, some bats are
important pollinators, or they disperse seeds from the fruit they eat. Even though bat populations like this one
have been here since probably before humans have, they are in danger. Urbanization is taking away habitats and food
sources. And imported diseases like White Nose Syndrome are wiping out whole caves in
the eastern Unites States, and spreading. This fungus irritates the skin of hibernating
bats, forcing them to wake up and fly out when there’s no food to eat. They basically
starve and die of thirst thanks to an itch. Despite their importance and how amazing they
are, these incredible species are still feared and misunderstood. If you want to know more
about what you can do to help bats around the world, and just to learn more about these
awesome animals, check out a link down in the description to Bat Conservation International.
They’re the awesome people who brought us out here today, and they own all of this land
to protect this natural treasure. If you want some more awesome bat science,
check out these videos from our friends at Smarter Every Day and MinuteEarth. Stay curious.