IMAGINE THE FINGER BONES of a human hand stretched out to something like body length, with webbing spanning between the fingers. That is, essentially, the bone structure of a bat’s wings. 

“Their wings are very similar to our hands,” says Ernest Valdez, a research wildlife biologist with the University of New Mexico. “So they’re really flying with their hands.” 

Of course, none of the detail in that anatomy is visible as the first Brazilian free-tailed bats begin rising from the Natural Entrance to Carlsbad Cavern. Those first few bats swoop and swerve above the cave, flickers of dark passing over the pale sandstone. Sometimes, one swings wide over the Bat Flight Amphitheater, where people have gathered at Carlsbad Caverns National Park to watch them since 1928 and learn a bit about bat biology and behavior. 

“This is a wildlife program,” explains Ranger Amy Brown as she kicks off the bat presentation around 7:30 p.m. on an August evening, “where we get to see wild animals in their natural habitat.” 

The Carlsbad Caverns natural entrance. Photograph by Minesh Bacrania.

Brazilian free-tailed bats spend their winters in Mexico, then migrate to New Mexico for the summer to rear their pups, she explains. The many thousands of bats clinging to the ceiling in Carlsbad Cavern’s “Bat Cave” can raise the typically 56-degree temperature inside the cave to the 80s or 90s. Bats launch into flight by dropping from that cave ceiling, then spiraling up together to aid them all in generating enough lift to fly out across the desert in search of prey.  

In 1898, bats circling up from the cave entrance like a curl of smoke first drew local cowboy Jim White to explore the area. Soon, he’d be bringing tourists to marvel at the cavern, repurposing the buckets that hauled mined bat guano out of the cave to lower passengers inside. 

Brown spends some time sorting through questions, often posed as misconceptions, from the audience. Bats are not rodents. They don’t much like people and wouldn’t be inclined to nest in anyone’s hair. Only about one percent carry rabies. A little girl in a purple shirt flaps the wings of her stuffed toy bat as she asks, “Are all bats bloodthirsty?” 

“You’re talking about vampire bats,” Brown replies. “We have none here in the park—they like more tropical areas.” 

But there are plenty of locals to admire. The Southwest hosts the greatest diversity of the winged mammals in the United States, with 29 different species living across New Mexico. Some migrate, like birds, while others make a permanent home roosting in caves, as well as in rock crevices on canyon walls, under bridges, and even in branches or under peeling bark of trees in the bosque.  

Each summer evening, Brazilian free-tailed bats emerge from Carlsbad Cavern in search of food. Photograph courtesy of NPS/Nick Hristov.

They provide several appreciable services. Bats consume insects that might otherwise plague farmers’ crops or bite people. Three species in the Bootheel region pollinate agave that distills into tequila. One New Mexican species, the pallid bat, even feeds on scorpions and centipedes. None of them are blind, they just use echolocation, a kind of radar, to assist in navigating the night, emitting a sound and listening for it to bounce back.  

“They’re calculating on the fly,” Valdez says. “It’s happening very quickly for them to read the habitat and the area, or even the particular prey item to see if they can snatch it up out of the air or glean it off a piece of vegetation.” 

These pest-eating neighbors are facing some struggles. White-nose syndrome, a fungus that can be fatal to bats, is spreading across New Mexico and causing some bat colony populations to collapse. Some bat species seem more resilient than others. Bats migrating through eastern New Mexico are now colliding with wind turbines, and scientists aren’t yet sure why, Valdez says.  

Carlsbad’s Brazilian free-tailed bats live deep enough in the cave to be in total darkness—but that also means they don’t see the sunset. “When do the bats decide to fly?” Brown asks our group. “We don’t know. That’s one of the great mysteries of bats.” 

But whatever cue tips them off, those first few are followed by pulses of many. They keep pouring out of the cavern as it becomes too dark to see the darts of their winged bodies against the deepening blue sky.