Texas by Nature

Bats Come Home to Roost

Amazing Mexican free-tailed bats keep insect populations in check, pollinate crops 

The Mexican free-tailed bat may have faces only a mother could love, but their eating habits are something for all of us to celebrate.

This nocturnal flying mammal literally eats its body weight in insects and agricultural pests like cutworm and corn borer moths every night!

With a range that stretches from Central America into much of the southern United States, summer populations of Mexican free-tailed bats are largely concentrated in a dozen main colonies, with one of the largest found at The Nature Conservancy’s Eckert James River Bat Cave Preserve in Mason, just two hours west of Austin in the Texas Hill Country.

“As many as 3 million Mexican free-tailed bats call this cave home each spring,” said Vicki Ritter, preserve steward. “That makes it one of the ten largest maternity colonies in the world.”

That's great news for parents looking for something fun and educational in the slow summer months. The Eckert James River Bat Cave Preserve is open in the evenings on Thursday through Sunday, from mid-May to early October. The preserve offers interpretive tours and features amphitheater seating for the evening emergence, a spectacle that has been described as a 'living tornado' of bats. 

Female Mexican free-tailed bats produce a single pup, usually in June, and the young roost in dense masses, sometimes as many as 500 pups per square foot of cave wall. Usually, an adult bat will feed within 50 miles of its day roost, but some may range as far as 150 miles. Remarkably, returning mothers are able to locate their young within inches, remembering location and responding to pups’ calls and unique scents.

Bats are only recently gaining recognition for the important ecological role they play. Not only do they munch down unwanted insect populations, they are also agents of seed dispersal and serve as pollinators for many plant species. Another popular bat colony roosts beneath the Congress Avenue bridge in Austin, and at the Bracken Bat Cave near San Antonio.

For more information on the Conservancy’s work in Texas, including the species we protect, visit

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