This is the best summary I could come up with:

Twenty minutes from downtown Fredericksburg—on a long, winding stretch of Old San Antonio Road that snakes past historic country schools, a vineyard with safari tours, and at least one ghost town—lies Old Tunnel State Park.

Instead, bats do us a favor by consuming vast quantities of mosquitos (which the Centers for Disease Control and Prevention calls “the world’s deadliest animal”) and other pests, saving up to $1 billion a year in crop damage and pesticide costs.

A handy, slightly cheeky flowchart posted at the park entrance guides unprepared visitors, letting them know these migratory bats are only in town between May and October (and noting that the rest of the year, “there’s nobody home!”).

Park staff update Facebook and X pages with the most recent emergence time so visitors can arrive approximately an hour earlier for an educational program led by a volunteer, when available.

Since the tunnel’s temperatures (even in a sweltering Texas summer) remain too cool for the mothers to give birth inside, they leave the colony briefly for warmer spots in caves or under bridges nearby.

Within a couple weeks of giving birth, the mothers return to Old Tunnel with their little native-born Texans in tow, and the numbers reach their apex in late summer before the colony migrates back to Mexico in the fall.

I’m a bot and I’m open source!