Congress Avenue Bridge bat colony

The Ann W. Richards Congress Avenue Bridge hosts a large colony of Mexican free‑tailed bats; peak estimates commonly cited by researchers and the city reach roughly 1.5 million bats. The bats' evening emergence from under the bridge is a well‑documented natural spectacle that attracts nightly viewers during the summer months; population counts vary by year and methodology. Popular accounts sometimes exaggerate numbers or impacts, and scientific monitoring continues to refine estimates.