The one-offs that make Edinburgh brilliant
Bracken Cave, Texas
It’s hard to imagine 20 million animals living huddled together in one cave little bigger than a football field. But that is exactly what can be found at Bracken Cave, near San Antonio, which contains the biggest bat colony in the world and the largest known concentration of mammals on the planet. At twilight, an immense river of bats – all 20 million of them – stream out of the cave in a column so thick that it shows up on air traffic control.