We also heard from Charlotte Uhlenbroek, a wildlife presenter who has been lucky enough to see the apes in their natural environment.
BBC News Online environment correspondent Alex Kirby has compiled the following report for News Online:
The orang-utan, Asia's "wild man of the forests", could disappear in just 20 years, a campaign group believes.
WWF, the global environment network, says in the last century the number of apes fell by 91% in Borneo and Sumatra.
Globally, it says, there were thought to be somewhere between 45,000 and 60,000 orang-utans as recently as 1987.
But by 2001 that number had fallen by virtually half, to an estimated 25,000- 30,000 of the animals, more than half of them living outside protected areas.