It was dusk, early October. More than a hundred of us were seated in a small amphitheater at the opening of Carlsbad Cavern in southeastern New Mexico. We were there to witness the bat flight.

Carlsbad Caverns National Park, which many of us had toured during the day, is a series of naturally formed caves and tunnels extending 800 feet below ground. From the outside, it looks like an ordinary desert mountain, sun-bleached and dotted with cacti, nothing particularly striking for the eye to lock onto.

Inside however, it’s a whole other world. Hiking down the trail from the cavern’s opening, you begin to see all sorts of fascinating rock formations. Created from centuries’ worth of water dripping through the calcium-rich earth, they represent every shade in the spectrum from white to brown to gray. Stalactites and stalagmites, ranging from delicate to threatening, poke up from the ground and down from the top of the cavern. Small mineral-rich pools, in a rainbow of greens and golds, appear here and there. Soft artificial lights, illuminating what would otherwise be a pitch-black cave, cast a fairyland glow.

But what strikes you first is the smell. It’s neither the fresh scent of water, nor the flinty smell of rock and earth . . . nothing subtle at all. Powerful but tolerable, familiar yet strange. What could it be?

It’s guano. Bat poop. Because Carlsbad Caverns is home to 250,000 to 400,000 Mexican free-tailed bats.

Why on earth would anyone want to spend the afternoon in an enormous cave, in the middle of nowhere, hundreds of feet underground, with thousands and thousands of bats lurking overhead?

Well, it’s not really like that. Although the cavern is big, dark and a temperate 54 degrees year-round, the ideal summer home for a large colony of bats, the paved, faintly-lit trails don’t lead the public anywhere near the bat cave itself.

Bats, who roost during the day and come out to feed at night, don’t like to be disturbed. And since the average visitor would stop short of having a direct encounter with a single bat, let alone hundreds of thousands, the system works pretty well. Visitors are allowed inside bat-free sections of the cavern during the day while the bats are sleeping, and as the sun sets, the lights are turned out and everyone clears the way for the bats to make their nightly exodus.

So there we sat, somewhat impatiently listening to the ranger tell us everything we ever wanted to know about bats, eyes fixed on the cavern opening, waiting for those tiny winged mammals to emerge. We waited, and waited, until the ranger had run out of things to talk about, and had pointedly reminded us that on an unspecified evening each October, the bat flight just doesn’t happen, because rather than of returning early the previous morning, without warning the entire colony instead migrates to Mexico.

Lucky for us, that wasn’t the case. A hush came over the crowd (we were instructed to sit in silence while the bats were flying), and then one bat, then several, and finally a steady stream began to emerge. They poured out from the cave, swooping in circles as they floated on the wind, up and away into the desert, a ribbon of black in the sky as far as the eye could see. We watched for five minutes, ten, fifteen, and the bats continued to pour out. At twenty minutes they were still pouring out, with no sign of stopping.

I didn’t stay to see the end of the bat flight. Like many of the other visitors, I was a little bit bored and a little overwhelmed by the seemingly never-ending stream of bats. It was a lot to contemplate on a rumbling stomach with 100 miles to drive before dinner. For certain, it was an experience I will never forget.

by Kezia Bacon Bernstein, Correspondent
October 2001

Kezia Bacon Bernstein’s articles appear courtesy of the North and South Rivers Watershed Association, a local non-profit organization devoted to the preservation, restoration, maintenance and conservation of the North and South Rivers and their watershed. For membership information and a copy of their latest newsletter, contact NSRWA at (781) 659-8168.