chimpanzees... [ attenborough laughing ] manatee... sadly, this magnificent animal is getting rarer and rarer. how many of these wonderful things will still be around in another 60 years? what an extraordinary creature! although the threat to the natural world from humanity has never been greater than it is today, there are nonetheless causes for hope here and there. in recent decades, when people have become involved with the local population of animals, they have started to take part in the conservation process. and that's certainly the case here in borneo, in the caves at gomantong. the only visitors here when we first came in 1972 were the local people -- and the people came to the cave for one particular and extraordinary purpose. they collect what is surely one of the strangest commodities to be found in any cuisine. it's so valuable that they risk their lives to get it. they are harvesting the nests that swiftlets construct using their own glutinous spittle. and this is the end product of all this labor and sweat and danger and

attenborough: and that he was. and a few years after his arrival at the zoo, he took a shine to a young female. back in 1961, i went into the ape house in london zoo to see charlie, as i often did, and the head keeper came over and he said, "i've got good news," he said, "you're about to become a grandfather." "really," i said. "yes," he said, "your young charlie has fathered a baby, and it should be born in a few months' time. and as grandfather," he said, "you have the privilege of christening it." so, eventually i decided it should be called bulu, which in malay means "little hairy one." bulu? can we have bulu? now, this is charlie's daughter. all right dear, all right, all right. bulu was the first orangutan born in britain, and she was just as endearing as charlie had been. i look back on those days, when i had charlie the baby orang, with mixed feelings, because the fact of the matter is that these are not pets, these are wild animals and they should be in the wild. the problem is that, although many people i