If you book a tour for Bracken Bat Cave Preserve and the neighboring Natural Bridge Caverns, you will start your day with a tour of the incredible caverns. After the cavern tour, you will get to see a presentation given by highly educated naturalists employed by the top bat conservation, Bat Conservation International (Bat Con.) The presentation takes you through the history of Bracken Cave, the bats that call it their summer home, and facts about them. These tours take a combined five hours and cost $41 for ages 12 and up, and $34 for ages three to 11.

There are over 1,399 species of bats worldwide and Texas alone is home to 32 different species. These mammals, measuring only 3.75 inches are the only mammals that are capable of sustained flight, rather than only gliding like other “flying” mammals. They can fly up to 10,000 feet high and most bats can fly close to 60 miles per hour; the record-breaking Brazilian bat can fly as fast as 99 miles per hour. These high speeds come in handy for hunting their main food source: insects. The majority of bats’ diets consist of mainly insects, which is one of the ways that they impact our environment. A single bat can eat between 4,000 and 6,000 bugs per night, saving farmers $23 billion annually in pesticides.

During the summer, Bracken Bat Cave is home to the largest colony of bats in the world. It holds an amazing estimated number of 20 million Mexican Free-Tailed Bats during the bat’s maternity season, which begins in March and ends in October or early November. The bats migrate from Mexico to Texas and the pregnant females form large maternity colonies, such as the one at Bracken Cave. The males play no role in raising the babies and form smaller bachelor colonies in other places. Bats can live in places such as under bridges, abandoned buildings, bat houses and other various places.

Each female bat gives birth to only one pup per year in Bracken Bat Cave, which is good because the babies can weigh up to one third of the mother’s weight! After the mothers’ give birth, they spend around an hour with their new pups, nursing them and getting to know their unique scent and call. The pups stay in a nursery area, so the mothers being able to recognize their pups unique scent is essential to the pup’s survival as pups do not start to become independent until a few weeks after their birth. In the nursery, there are around 500 pups per square foot, but the mother bat’s nose is strong enough to find her baby through the mass.

At around 7 p.m., the tour then takes you to the face of Bracken Cave to watch as the bats begin their flight out of the cave to hunt for bugs.

They start out with just a small group of bats dropping down from the ceiling of the cave and beginning to circulate within the cave. As more bats join in the circulation, they begin to gain speed and altitude, until they can use the circulation to boost themselves out of the cave and thousands of bats head out for a long night of hunting.

There are usually around two to three groups of bats leaving the cave each night and it can take up to several hours for the millions of bats to leave the cave.

Since in the beginning the pups are so dependent on their mothers, unfortunately, if any mother bat is killed during her hunting, her pup will die as well.

Eventually, it’s time for the babies to attempt to take flight as well. They begin this process by dropping straight from the cave’s ceiling, opening their wings, beginning flight and making a sharp turn to avoid hitting the ground.

After they have successfully avoided hitting the ground, their next challenge is using their echolocation to avoid hitting other pups learning to fly.

Although, contrary to the rather common belief, bats are not blind, and the truth is that their eyes are more adapted to the darkness of caves. As adapted as their eyes may be to the dark, that does not mean that they can “see” in the dark. This is why the bats need to use echolocation for navigation in the dark.

Echolocation is actually pretty self-explanatory. Bats and other echolocating animals send out a “call” to the environment around them.

This call’s sound wave moves out around the animal until it hits an object, in which case the call is echoed back to the animal to alert them to the distance, direction and size of an object. They can then safely navigate around the object.

The bats are at risk from many different predators that wait outside of the cave for a bat to fall to the ground, as once a bat has fallen, they have a hard time getting back up. This is perfect for the snakes, skunks and racoons; in the sky they can fall prey to owls and hawks who wait near the cave for the bats to take flight. However, the bats at Bracken Cave are now facing an even bigger threat from disease.

In 2006, scientists discovered a disease which they named “White-nose Syndrome” (WNS) for the unique white growth on an infected bat’s face.

Since its discovery, WNS has killed an estimated 6.7 million bats and according to scientists it shows no signs of slowing down.

The disease causes bats in hibernation to become unnaturally active during the cold winter months, causing them to burn off all of their stored body fat and eventually die.

Recently, the fungus was detected in Bracken Cave, although the bats themselves are not currently infected by the disease.

Bat Conservation International (BCI) has explained that the Mexican Free-tailed Bats in Bracken Cave are at less risk of struggling with this disease since they migrate back to Mexico in the winter, rather than hibernating.

Regardless, BCI has been planning for over 10 years on how to deal with an outbreak of WNS and is prepared to increase surveillance on the cave and surrounding areas, along with teaching the community more about WNS.