Every summer, outside Mason Texas, approximately 4 million pregnant female Mexican Free -tailed bats come to give birth. Over the next couple of months, the babies grow, start flying with their moms, and eventually fly home. Not quite the size of Bracken, but at that time of year it’s one of the largest bat colonies in the world. https://www.nature.org/en-us/get-involved/how-to-help/places-we-protect/eckert-james-river-bat-cave-preserve/

It’s an interesting place to get to. If you’re in a normal car, you need to pay attention to rain, as part of the directions are “turn off the paved road, drive 8 miles, ford a small river, then drive another mile or so”. The road is… not great, especially the last few hundred yards. But the bat flight is amazing. Seating is close you can get brushed by them. It’s a fantastic couple of hours.