Millions Of Bats Take To The Skies At Jornada Caves

Sep 22, 2015

During the summer months, southern New Mexico hosts one of the largest bat populations in North America. The Jornada Bat Caves, just west of White Sands Missile Range, are now becoming more accessible to the public.

The flying mammals are about the size of the palm of your hand with their webbed wings spread out. At dusk, they emerge from the caves to hunt for insects, taking to the air in what looks like a dark vibrating plume as tiny bats zoom through the air every which way.

Tom Waddell manages the Armendaris Ranch were the caves are. He said out of everything he’s witnessed in Mother Nature, this experience takes the cake.

“It’s pretty impressive,” Waddell said. “This is like the caribou migrations or the big wildebeest migrations in Africa. You know, this is the most mammals you’ll ever see in one spot.”

Waddell said this year biologists think there are about eight and a half million bats inhabiting the caves.

“One of the biologist told me that there’s 260 bats per square foot on the walls in the bat cave,” Waddell said. “They’re packed!”

Waddell said that you can’t predict what time the bats will fly out every night—he’s seen that vary dramatically over the years—but he thinks they’ve figured out some explanation for the animal’s behavior.

“In ’93 we had no rain, in ’94 there was no rain, in ’95 there was only three inches,” Waddell said. “It was a really serious drought. They flew out of here at 5 o’clock cause they had to go a long ways, and they had to stay out a long time, to find insects.”

When pickings are slim Waddell said the bats fly as far as Las Cruces and Albuquerque to catch bugs, and can rev up to 60 miles per hour in sustained flight. This year with all the moisture though, he said they don’t have to fly nearly as far to feast.

But the bats aren’t the only ones feasting here.

“Part of what we are hearing is the hawks,” explained Hawks Aloft executive director Gail Garber as we watched a Swainson’s hawk going in for the kill, trying to catch a bat in mid-air.

“Look at her,” Garber said. “She’s just diving right through the bats. They don’t always get them though.”

Robin Silver is with the Center for Biological Diversity and said when Waddell, the ranch manager, told him about the Swainson’s hawks preying on the bats he didn’t believe it.

“When he first told me about it I thought it was total BS,” Silver said. “I said no, there’s no way, those birds didn’t evolve that way. He goes ‘No, it’s real!’’’

Unlike falcons that hunt in the air, Swainson’s hawks have thick bodies and are known to be prairie feeders, plucking most of their prey off the ground.

"They hunt rodents or possibly small rabbits, that’s what they’ve evolved to do,” Silver explained. “They’re hawks, not falcons, so this is really bizarre.”

Silver said he had to see it to actually believe it.

“You could see the Swainson’s, they’re like 1,000 feet high, and then the bats came out, and then they’re diving through the streams of bats and then reaching out, and you can hear the whack of them grabbing a bat,” Silver said. “It is one of the world's more incredible phenomena you’ll ever see.”

An explanation for this? Well, Silver said, Swainson’s hawks are clearly opportunists, and this a testament to evolution.

“I mean these bats have been out here probably since the glaciers receded,” Silver explained. “So this population of Swainson’s has learned at this time of year there’s food.”

Up until recently only people studying the colony could come and see the bats since the caves are on private land owned by Ted Turner. But that’s all changing. The Armendaris Ranch is starting to run eco-tours to the caves. You’ll have to wait until next year to get out there because the bats, along with the Swainson’s hawks, are flying south for the winter.