Carlsbad Caverns National Park
The Mexican free-tailed bats are there from April or May to late October or early November. They fly out of the cave in a dense group, corkscrewing upwards. They usually start flying out around sunset. The event usually lasts about three hours. Every evening from Memorial Day weekend to mid October, a ranger talks about the bats while visitors sitting in the amphitheater wait to watch them fly out.