On the early-morning drive to Sepilok Orang Utan Rehabilitation Centre our guide keeps us awake by telling us hair-raising tales about what happens to visitors who stray within reach of probing primate hands.
Everyone comes here determined to get a close-up photograph of an orang-utan's incredibly expressive face. One tourist, more determined or more fearless than most, hid away until the morning feeding session was over and the viewing platform was quiet. Then he whipped out his camera and began to shoot. To his delight a young orang-utan came over to check him out. He moved closer. Click, click, click went the camera. He moved closer still. Grab, grab, grab went the monkey. In a matter of seconds the man had been relieved not only of his camera but also of his T-shirt and shorts.
A dutiful chuckle ripples through the bus - followed by a series of gasps as Yahya casually runs through a list of the kind of things a one-and a-half-metre-tall male orang-utan might do to you, if you happened to tickle his fancy. They're not nicknamed "wild men of Borneo" for nothing.
Besides, he goes on, many of the items to be found in your average tourist bumbag - sun cream, tropical-strength insect repellent, even mobile phone - aren't very good for orang-utans, and might even be lethal.
So here are the Sepilok rules. No brightly-coloured cameras, no shiny, dangly things of any description, and definitely no food inside the gate. We're to slather ourselves in sun cream and leave all our stuff on the bus.
We arrive at 9am, just as the centre is opening. Within minutes a clutch of other tour buses have pulled in alongside ours, and tourists are piling out, cameras clutched to sweaty chests. Sepilok Orang Utan Rehabilitation Centre was established on a 43sq km patch of lowland rainforest in 1964 by the wildlife section of the Malaysian forestry department. It is now managed by the ministry of tourism and environmental development, and although its primary purpose is still to return orphaned apes to the wild, Sepilok orchestrates a slew of educational campaigns and research projects on various endangered local species, including the rhinoceros.
What draws people here in droves, though, is the prospect of seeing orang-utans. Nowadays most of the traumatised young apes that turn up at the centre have been rescued from palm-oil plantations. Under the watchful eyes of trained staff, they acquire more and more of the skills they need to survive in the forest, and they are gradually given more and more autonomy until they're able to go off, build nests and forage for themselves.
Orang-utans are solitary animals. They're also extremely smart. So even the ones that are living in various corners of the forest around Sepilok know exactly when the keepers are likely to turn up bearing bananas and milk - twice a day, at 10am and 3pm. We tourists are to attend the morning feeding session. Nobody knows how many orang-utans will attend. Perhaps lots, perhaps none; this is not, as Yahya points out with a smile, a zoo.
On the viewing platform, tourists are crowded into the shady spots, so I wander over to the railing and gaze into the empty forest. At once sweat begins to trickle down the back of my neck. The heat seems to rise from the floor of the forest (this, Yayha will explain later in the day, is exactly what it does - the forest sweats, adding another layer of mugginess to the moisture-laden air) and attach itself directly to the skin, prompting every pore to burst in turn with an almost audible ping.
In an attempt to distract myself I stare at the bushes below me; I am rewarded by a faint scurrying: a lizard going about its morning business. Over the next few days I will learn that, in the forest, waiting is not a prelude to something but the thing itself. Such is the rainforest experience. It involves looking, listening, learning to be still and quiet in the face of this teeming natural environment.
Suddenly, out of nowhere, they come. First one, then two orang-utans swing lazily towards the platform and promptly go into a clinch so that we can see nothing except an untidy, hairy pile. Even so, everyone surges forward, and the whirr of cameras begins. The apes are joined by a third, smaller and more agile, which obligingly makes faces at the tourists. By the time the wardens arrive with the food, five orang-utans are in action. "Five," exclaims Yahya. "You've been blessed: five is a lot."
I feel blessed, but I am also on the verge of tears. In Malaysian, orang-utan means "man of the forest", and when you watch these magnificent animals standing tall in the trees, their silhouettes uncannily like our own, you understand why. Yet here they are, queuing up for bananas and milk like kids at McDonald's. We did see wild orang-utans in the trees around Sukau, but estimates of their numbers vary so wildly - from 3,000 to 10,000 - that the truth about their future is anybody's guess.
I know that Sepilok and other animal sanctuaries are doing terrific work, but what they, and the other endangered species of the earth, really need is space, and lots of it. Are we going to give it to them? Well, are we?
Arminta Wallace