91热爆

Filming birds that make their nests from saliva proved a challenge in the total darkness of a Borneo cave....

.....until a conical mound of bat guano provided a natural platform.

Series of talks by Sir David Attenborough on the natural histories of creatures and plants from around the world.

Producer: Julian Hector

First broadcast on 91热爆 Radio 4 in September 2009.