This summer I crossed another thing off my bucket list and went to visit Bracken Cave outside San Antonio. Bracken is the largest concentration of mammals in one place, with 20 million bats in a cave - mothers and pups. These are Mexican Free Tail bats - quite small. Photos can't do the experience any justice - but you can arrange to visit through Bat Conservation International and see the bats depart the cave at night or return in the morning. With the concentration of bats, there are also predators - I saw skunks, snakes and birds of prey. Photography was a severe challenge. There is a live webcam you can watch and many videos and photos by professionals if you want a better capture of the experience. I highly recommend it and hope to go back.