Bats in Austin
Media playback is unsupported on your device
Video

Bridge bat colony draws crowds to Austin, Texas

A colony of bats who live in the centre of a US city have turned from nuisance to a local treasure.

After the first of the animals moved into Congress Avenue Bridge in Austin, Texas, around 20 years ago, the number of Mexican free-tail bats has grown to almost two million, about double the city's human population.

Every evening from March to November the bats emerge from under the bridge to feed on insects.

Despite many initially regarding them as pests, some like riverboat captain Mike Pearce came to see how the bats could help the city.

Human Planet: Cities was broadcast on Thursday 3 March at 2000 GMT on BBC One. It is available to watch again on the BBC iPlayer.

Go to next video: Radar to track flying creatures