Old Tunnel State Park

Texas hill country Region

Old Tunnel State Park is home to up to 3 million Mexican free-tailed bats and 1,000 to 3,000 cave myotis bats from May to October. This 920-foot, abandoned Fredericksburg and Northern Railway railroad tunnel was purchased by Texas Parks and Wildlife Department for the specific purpose of protection and management of the bats. The bat colony at Old Tunnel State Park is considered a pseudo-maternity colony. While pregnant and lactating females use the tunnel, pups are not born in the tunnel but in nearby caves or bridges with more stable temperature and humidity levels. Because of this, the size of the colony fluctuates greatly throughout the season. In June, the population of bats can be smaller, after the females leave to give birth. However, by early August, females and juveniles will return to Old Tunnel and the colony size will continue to increase through mid-August. The largest population of bats can be seen during the months of August and September. The bats will usually begin migrating back to Mexico in late October. The state park also offers a 1.5-mile nature trail through woodlands of live oak, escarpment black cherry, black walnut, hackberry, and Ashe juniper. Birds along the trail include yellow-billed cuckoo, Carolina wren, Carolina chickadee, and painted bunting. Several species of raptors can also be seen soaring over the adjacent canyon.

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Bat Fact

Bats are incredibly long-lived for their size, with the oldest confirmed insectivorous bat living 41 years!