Through a shimmering clump of leaves you can see him, sunshine gleaming off his orange plumage.

He's a Cock of the Rock, as his breed is known here, a proud alpha male who for five years has beaten off rivals for this prime forest grove within range of the mist of Kaieteur Falls.

While he can feel its spray from his perch, some 200 metres of trees and rocks keep the falls from the big bird's sight, as if he's jealously aware of his runner-up looks.

Because the beauty of Kaieteur is transporting.

At 222 metres (741 feet) it's the highest single-drop waterfall on Earth and the black water of the Potaro River peels off in fluttering curtains of white as it descends over sandstone caverns into the green valley below.

``This I believe is how God would have made this,'' says captain Malcolm Chan-a-Sue, a veteran pilot who flew us up to the falls in his twin-engine plane from the mining town of Bartica.

``I only hope we can keep it as it is. We don't need wax museums here.''

We lunch at the lip of the falls, then it's departure time. A 30-minute flight takes us next to the Orunduik Falls on the Ireng River, which descends in terraced steps over semi-precious jasper on its way to the Amazon. The Orunduik, whose south flowing waters form a section of the border with Brazil, is the second jewel in the Guyana's 276 waterfall trove.

A swim in a whirlpool relieves the heat before the final leg of our flight to the mountaintop village of Paramakatoi and the canopied Pakaraima rain forest.

``Don't worry if you hear the stall alarm go off,'' Chan-a-Sue yells over the twin Rolls-Royce Continental turboprop engines as they strain to reach Paramakatoi's airstrip.

``We have to come in over a ridge before the runway and bring it down fast. It's a short strip.'' When it comes into sight, it appears impossibly short. But Chan-a-Sue brings us down without incident.

A swarm of killer bees sent passengers diving for cover as they disembarked here several days earlier. But only MacCulloch, his three expedition colleagues and about 30 curious villagers are here to greet us in this semi-autonomous aboriginal settlement.

There's Kathy Coates, assistant curator in charge of invertebrate zoology at the ROM and her technician Don Stacey. And there's 24-year-old University of Toronto masters student Jan Locke, who has paid her own way to join Coates, her teacher, on this journey.

Introductions made and visitor papers presented to the Amerindian village ``captain'' or touchau, we head down toward the forest edge and a dusty ledge that clings to a hill. For the next six days we will camp here with the ROM team and share in their adventures.

Like most of the people here, Isaacs is a part-time farmer, a part-time hunter, a part-time fisherman and a full-time partner in Amerindian cultural traditions that reach back thousands of years.

For the next week he will be our guide on the steep descent through the forest trails. Isaacs is small man of few words or extraneous movements. His considerable energies, we will soon discover, are reserved for the work ahead.

The work ahead is walking ­ the arduous birthright of the Amerindian peoples who in habit Guyana's four mountain ranges. For them it defines distances ­ the number of hours or days it takes to walk is the measure of mileage ­ and it poses the main toll on their lives.

``This has made me old,'' says Isaacs, pointing with his machete down the long, winding path to Monkey Mountain. The trail begins with a precarious 240-metre drop at the outskirts of his village before disappearing into the forest.

``My farm is down there and I come up here with heavy loads of food all the time.'' His ``farm'' is like most Amerindian agricultural operations, a slash and burn clearing in the forest. And its thin soil will sustain crops for no more than three years before another plot must be cleared.

``We plant banana, bean, cassava, whatever we can get seed for,'' says Isaacs, who was taught English by Anglican missionaries at age 14.

``But this has made me old,'' he repeats, then takes off down the offending slope.

For the uninitiated, the mountain is a leg slayer. Isaacs must stop a dozen times to allow us to catch our breath.

Along the path, MacCulloch will keep an eye out for any lizard, snake or frog species he can spot. But our real goal today is the Yawong River falls about 2 ¹/₂ hours away.

There, Stacey and Locke will collect the river mud that bears the tiny aquatic worms they're seeking, MacCulloch will look for tadpoles and frogs.

``There are three typical museum biology roles,'' MacCulloch says.``There's the identification of the species that are here, description of new species and determining the relationships among species.''

MacCulloch actually discovered a new, finger-sized lizard of the family gymnophthalmidae during his last trip in 1992. He estimates there are several hundred species of reptiles and amphibians to be identified in Guyana.

But it's not the discovery of the new that really interests the ROM team. It's the identification of what's in an area that's never been seen through the eyes of their particular sciences.

At the falls, Stacey and Locke get busy digging through the river bed and banks with a trowel. They store the mud in plastic bags for inspection back at camp and haul out their Magellan global positioning system (GPS) receiver, which will tell them exactly where on Earth these samples came from.

``This is high-tech mud,'' says Stacey, as he waits for the receiver to contact enough satellites to triangulate our co-ordinates. The receiver must access at least four of the 24 GPS satellites now in orbit to calculate the longitude, latitude and altitude on this Yawong River location.

Those co-ordinates will later be used to plot the species we find on a computer map being created by the Smithsonian Institution, which along with the University of Guyana is leading the Biodiversity of the Guyanas project in which these ROM scientists are participating.

While the ROM curators will add most of the samples they find to their vast collections at the University Ave. museum, they have agreed to share their information with the Smithsonian-lead project.

The upward gait back to camp seems less arduous at first. But gravity soon takes its toll and the climb becomes an almost unbearable ordeal. About halfway up we stop for the umpteenth time to rest and suck iodized water out of our canteens.

Just then two women in their early 60s walk past. Each carries a huge load of produce up the hill in a homemade wicker backpack. We can still hear them chatting as three barefoot children run up from behind.

As we lurch toward the mountain's summit, we see the name `Toronto' coming toward us. Here in the heart of the rain forest is a Toronto Maple Leafs cap, and it sits on the head of a man named Dolphin.

``What's hockey?'' he says when asked if he's a fan. We assure him that people in Toronto haven't known in a while either.

Dolphin has a gun slung over his shoulder, a breach loader of ancient vintage. He'll use it, he says, to kill any ``snakes or jaguars'' he comes across during the long journey ahead of him.

He's headed for Monkey Mountain, some four hours' walk away, to deliver medicine to a woman.

The next morning our walk down a southeast path is marked by parrot calls. Our talk is of snakes and their venom.

``The cobras, coral snakes, sea snakes and their relatives have a neurotoxin that affects the nervous system and kills by suppression of respiration,'' MacCulloch says.

``The other snakes like the rattle snakes and pit vipers use what they call hemotoxins, which affect the blood and tend to coagulate the blood . . . and stop the heart.''

Guyana's poisonous snakes include the labarria, large bush masters, a tropical rattle snake and the colorful coral snakes. There are also giant boa constrictors and anacondas.

MacCulloch, who's dealt with hundreds of snakes in his collecting life, has never been bitten by a venomous one. ``You just have to know how to capture them properly.''

Capturing a small anolis lizard Isaacs sees crawling up a giant greenheart tree proves a bit trickier. ``Oh damn, I just got his tail,'' MacCulloch curses.

``There are many, many types of anolis around the Caribbean, so it could have been a new one.''

The lizard, a tiny bug eater, has evolved a little survival device of his own - a detachable tail that can be broken off and grown back again and again.

``The cartilage splits between two vertebrae in the tail and the blood vessels close up right away,'' MacCulloch says.

``The ones that grow back is never quite as long or as nice as the original one.'' MacCulloch pockets this one for DNA analysis back at the ROM.

In many places along the trails, the majestic jungle is losing a war to this homely little plant. We see the results about an hour and a half from camp, where the rain forest stops and breaks into the vast western savanna.

Isaacs says the scrawny grass in this unyielding strip of land by the Brazilian border is susceptible to large fires sparked by the farming blazes in the rain forest.

After stopping for worm mud at a dry stream bed, we turn back for the largely upward journey home.

"I tell you, if you are walking here, you are walking up or you are walking down," Isaacs says. "There are always bumps, everywhere you go."

Half way down one particularly difficult hill, we run into 47-year-old Gary Lewis, who holds an 2 ¹/₂-metre blow gun over his shoulder. A deadly accurate weapon, he uses the ancient wooden tube to hunt birds along the trail. Lewis can bring down a small bird at 40 metres with a single breath.

For centuries Amerindian hunters used the slime from a local frog to poison their darts and make them even more effective. But over-hunting has put the colorful Poison Dart Frog on the endangered species list and few can be found near human settlements today.

After testing Lewis' blow gun, we trudge on toward camp and a late lunch.

To get to Paramakatoi from the camp you walk up through a grove of giant ferns and past a murky pool in which the local women launder and bathe.

It's a shoeless village, where hard paths of hot clay run between small, thatched huts.

Outside the medical clinic, village captain Gideon John speaks to some aid consultants there to inspect the facilities.

``There are 1,527 people scattered in the area, most of them live by farming and a bit of mining,'' says John, whose position is put to a vote every two years.

``It is really subsistence level farming just to feed themselves.''

But John says hunger is rare among his people, as is crime and unrest.

Injury and disease, however, make frequent appearances and nurse Mathilda Saigo is poorly armed to combat them. Her own 14-year-old son almost lost his foot earlier this year after a labarria snake bit him and the wound became infected.

``We had anti-venom at the time but we had no antibiotics, which we are often out of,'' says Saigo, whose well-thumbed volume of Gould's Pocket Pronouncing Medical Dictionary is the only book in the clinic.

``And right now there is a very bad stomach illness that has affected many people.''

Over at the schools, nine grades of classes are crammed into two, single-room buildings.

Teacher Patty Daguir, whose 14-year-olds form the school's senior class, lets us in for a look, provided we teach the children something.

``We're having science and I'm trying to teach them what an eclipse is but I don't really know,'' she admits.

``Can you teach them?'' she asks.

We agree to try. We explain that the Earth is round and orbits the sun and that the moon orbits the Earth. Then, with the help of a chalk board, we show how these orbits sometimes intersect to block the sun's light.