Where can you find the most mammals in any single location on the planet? The answer is…in Bracken Cave. We recently visited the cave and were stunned by what we saw.

Well, if you are looking for the highest concentration of mammals in the world, look no further. Seriously? We imagined the most mammals in the world would be in Africa on the Serengeti during the Great Migration. All those wildebeests, zebras, and gazelles coming together, but we were wrong.

So where is this cave and why should we care?

Bracken cave

Visiting bats at Bracken Cave. Photo: Teresa Nichta/Merlin Tuttle.org

Bracken Cave

It turns out, the largest concentration of mammals anywhere in the world is right here in the United States, in Texas to be exact. And what mammal would be in Texas in large numbers?  You probably wouldn’t have guessed bats. And yes, bats are mammals.  Bats happen to be one of the most important mammals/animals on the planet. But more on that in a minute.

Bracken Cave

A Brazilian free-tailed bat. Photo: Merlin Tuttle

Every spring, fifteen to twenty million female Mexican (also called Brazilian) free-tailed bats descend on Bracken Cave near San Antonio, Texas.  They all come from Mexico with one purpose, to give birth to a single pup (baby bat), raise their baby and then go back to Mexico. So it is not only the largest group of mammals in one location, it is also the largest maternity ward. Very cool.

Bats are Mammals and Great Mothers

First, it is helpful to remember bats are our only true flying mammal.  They make up about 20% of all mammal species. Generally, females have only one pup a year, making them one of the slowest reproducing animals. This makes bats even more vulnerable if catastrophe strikes.

Bracken cave

A mother little-epauletted fruit bat carrying her pup in flight in Kenya.

But back to Bracken Cave. Inside the cave, the babies are packed onto the cave walls to the tune of 500 per square foot. That is a lot of baby bats. And unfortunately, only about 50% of the babies survive. Flying collisions, predators (think hawks, carnivorous beetles, snakes, raccoons, and a bunch of other critters), all take a toll on the little pups.

Luckily, bats are some of the best mothers of all. They groom, nurse, and teach their youngsters to fly and protect them as best they can.

All the while, they are eating literally tons of insects every night, helping keep mosquito and other pesky insect populations at bay. In a single night, the bats from Bracken Cave can eat 140 tons of insects, saving farmers thousands of dollars in unneeded pesticides for their crops.  How impressive is that!

Merlin Tuttle

Bracken Cave

Merlin Tuttle calling a Little big-eared bat to his hand for mealworms

Bracken Cave is owned by Bat Conservation International (BCI) who limits access to the cave in order to minimize disruption to the bat colony. The property surrounding the cave was saved from development through a joint effort by BCI, The Nature Conservancy,  and the City of San Antonio. Talk about a conservation success story.

We had the honor of visiting as a guest of the world-renowned bat expert, Merlin Tuttle (the founder of Merlin Tuttle’s Bat Conservation) and his wife, Paula. Merlin has done more to save bats worldwide from wrongful persecution and harm from false myths than any other human so it was quite an amazing experience to be visiting the caves with Merlin and some of his team.

For us, it was one of the most moving, mind-blowing experiences either of us have ever had. Ever! Who knew 20 million (give or take a few million) bats live in a cave and come roaring out every night in search of insects. And each one of those bats is caring for a pup inside the cave when they return at dawn.

We also learned more about Merlin’s continued conservation initiatives through his website (where you can see some additional amazing photos) and his inspiring, informative book, “The Secret Lives of Bats”.

Bracken Cave

A lesser long-nosed bat pollinating saguaro cactus in Mexico.

Dale also got a number of ideas for bat sculptures from our visit at Bracken Cave. All the money raised from future bat sculptures will be used for bat conservation.

bracken cave

Cliff Hanger, a bat sculpture by Dale Weiler

The Most Important Mammal?

We believe bats are one of, if not the most important, mammal on the planet!  Help us debunk the myths, provide habitat and spread the word about these incredibly beneficial creatures. Become a bat advocate and make a difference in wildlife conservation.


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