They built the tunnel for the train, but since the train’s been gone, it’s been serving a new purpose: a perfect roosting place for millions of bats. Old Tunnel State Park (near Fredericksburg) houses to up to 3 million Mexican free-tailed bats and 3,000 cave myotis during the warmest half of the year.

The park is open for bat viewing during those months, from May to October. Like the bat emergences at other Hill Country bat roosts, it’s one of the great wildlife spectacles in Texas.

At the park’s lower viewing area, visitors can get a close look at the bats streaming out of the tunnel in their nightly search for food, even feeling wind generated by the bats’ wings.

At the upper viewing area, visitors can watch the rising swirl of bats.

“It looks like a tornado,” says Superintendent Nyta Brown.

Ranger-led nightly programs focus on the fascinating life history of the Mexican free-tailed bat.

“This year is shaping up to be a great year for bat viewing because it’s been hot and dry — the bats tend to come out earlier because they have to go farther for food,” Brown says. “It’s a hard year for bats but a good year for bat viewing.”

Tickets, purchased in advance, are required for viewing. Check the bat emergence times for the latest information; they don’t always come out at sunset.  

Beyond the Tunnel

At 16 acres, Old Tunnel is Texas’ smallest state park.