When a man with a machete silently joined us at the edge of the rain forest, my sister and I weren't sure whether to be alarmed or comforted. We already had a guide and park ranger accompanying us as we set off into Way Kambas National Park in Sumatra. The mysterious machete man made five.

The Indonesian island of Sumatra is one of the few places left in the world where elephants, rhinos and - of particular interest to Heather and me - tigers live together in the wild. Critically endangered, wild tigers are fighting to survive in the face of widespread poaching and forest-clearing. With that in mind, we'd went to Sumatra to see what we could while we could.

Before the trip, the eco-lodge making the arrangements warned us it was extremely unlikely we would see any tigers. There are roughly 30 Sumatran tigers remaining in the 502-square-mile Way Kambas park in southern Sumatra, and they mostly prefer to stay in the deep interior. Across Sumatra, there are fewer than 400 tigers left, and they are extinct on the nearby islands of Java and Bali. Sumatra's tigers are smaller than their cousins elsewhere and have thicker black stripes.

Though getting a glimpse was a long shot, Heather and I were ready to try, hoping at the very least to spy a tiger paw print or claw marks on tree bark - any signs of the jungle cats would do.

From the clearing, we hiked single file into the park with the mysterious machete man at the rear, the ranger at the front. Following a trail not much wider than a machete blade, we crossed patches of shoe-sucking mud and kicked up finger-size leeches, which slowed our pace as we kept stopping to shake them off. We also stopped often to look at macaques, a well-named slow loris (a lemurlike primate that, we were told, has a toxic bite), small deer known as muntjacs, and blue-banded kingfishers. Some of the trees were rare tropical hardwoods highly valued by loggers. Overhead, we heard monkeys and birds calling. As we'd been warned, despite the machete man at our backs, there were no traces of any tigers, the very thing we most hoped to see.

"Perhaps the tiger cams are the best way to see the tigers," our guide, Hari, said once we were back at the ranger station, offering the thought as a sort of consolation prize. Removing leeches from our clothes, hats and shoes as the machete man grilled fresh fish on an open fire, we were inclined to agree.

After lunch, we tried a different route into the park. The five of us set off in a small boat that cruised slowly along the Way Kambas River, on glassy water the color of milky tea. Our wake barely roused a mostly submerged freshwater crocodile. There were no muddy tiger footprints along the bank, but gibbons and long-tailed macaques spotted us and moved higher up into the trees.

With the help of a small laser pointer, Hari showed us a gray python tucked into the hollow of a tree branch. Farther along, he spotted two black-and-yellow mangrove snakes well hidden in dark undergrowth. The machete man, who was running the motor, maneuvered the boat so close branches whacked us in the face.

"Very bad, very poisonous," Hari said of the snakes, again highlighting them with the laser pointer. We didn't need much convincing. Wishing we had machetes of our own, we headed back to the lodge, agreeing it's best to let sleeping snakes lie.

In the morning, Hari picked us up and promised we'd have better luck seeing Sumatran rhinos and elephants. We followed a bumpy dirt road into the park, driving past more muntjacs, monkeys, and crested fireback pheasants on our way to the Sumatran Rhino Sanctuary.

The sanctuary aids Sumatra's endangered rhinos, considered among the most threatened large mammals in the world. They are the smallest rhinoceros species - and considered the most vocal - and are also known as hairy rhinos because of the hair on their bodies. Less fortunately, Sumatra's rhinos are the only species in Asia with two horns, making them particularly attractive to poachers. They're hunted for their horns, which are ground into a power that's used in traditional medicines and that some believe to be an aphrodisiac. Once found across Southeast Asia, Sumatran rhinos today number about 100, with only 25 to 35 at Way Kambas.

We were fortunate enough to see one, a young 1,500-pound female that had gone to the sanctuary for breakfast. Like other rhinos there, she's being reintroduced into the wild after a period in captivity. Mostly solitary creatures, the sanctuary's rhinos each receive a large wedge of rain forest to roam in, with the wedges radiating from a large circle, at the center of which is the sanctuary. This rhino was particularly prized as a young female that can produce offspring. Efforts to breed Sumatran rhinos in captivity have failed.

The rhino had returned from a night in the forest to eat mounds of leafy branches. She chewed slowly while a sanctuary staff member told a German documentary film crew (and us) that rhinos eat 10 percent of their weight each day, which is certainly food for thought. Curious about the crowd, the rhino ambled over closer to us. Up close, her leathery skin was marked by patches of dark hair. Her eyes were lively, and she was surprisingly light on her feet. She cautiously investigated our small group and, fortunately for us, decided not to mark her territory with excrement (another Sumatran rhino characteristic). Instead, a sanctuary staffer briefly misted her with water. Her curiosity satisfied, she laid down for a nap.

In the sweltering heat, the mist looked inviting, but we had elephants to see, and still held out hope for tigers.

A teeth-rattling ride in the SUV landed us at the Elephant Conservation Center. Along the way, we encountered a few motor scooters nearly obscured by piles of branches, presumably to feed the rhinos, heaped behind the drivers. We also passed lush forest and small patches of land cleared for farming, some marked by tall wooden platforms.

Hari told us farmers use the platforms to watch over the fields at night to make sure elephants don't trample their crops. Like the rhinos and tigers, Sumatran elephants have had their troubles. They are critically endangered, with fewer than 3,000 remaining, about 200 of them in the Way Kambas park.

The clearing of forests for palm oil, illegal coffee cultivation, and timber has dramatically shrunk the amount of open space available to the elephants, making them more likely to run into people who see them as a threat, particularly to crops. Poachers in search of elephant tusks, valued in the ivory trade, also use the crude roads cut into the forest to support the illicit farming and logging.

The elephant center aims to mitigate some of these issues and help elephants injured by run-ins with humans. This year, it expects to open Indonesia's first elephant hospital. Heather and I toured the center's low-slung bungalows and let a baby elephant reach into our backpacks and pockets with its long trunk to consume our stash of bananas.

Then we climbed aboard two resident elephants to explore farther afield. Our elephant drivers, or mahouts, guided us along a red dirt track, across swampy water, and onto a grassy plain. In the distance, we could see pockets of grazing wild elephants.

"Any tigers here?" I asked the elephant driver, our elephants' ears flapping as we pushed through high bushes.

"Maybe in the past you'd see droppings," he said, pointing to the ground, "but now not too much."

After an hour, somewhat saddle-sore from the ride, we headed back to the elephant center, where the call to prayer from the mosque filled the air.

That night at the eco-lodge, my sister and I drank warm beer and toasted our good fortune at seeing the elephants, rhino, and other rare wildlife. A small cat wandered from table to table hustling scraps, and we agreed it would have to do for our tiger of Sumatra.

I headed to the kitchen for more beer and stopped in front of two white boards in the dining room. A long list of local wildlife covered one. On the other was a rough map of the area on which visitors had written in the animals they'd spotted. Some I wished I had seen, such as the colorful sun bear; others, such as the spitting cobra, I was glad to have avoided. And then I saw it.

Near the eco-lodge, someone had written: "At 6 p.m., a tiger crossed the road 3m in front of motor bike."

Finally, there it was. A Sumatran tiger sighting, one small sign of an all-but-gone ghost cat, tellingly written in not-so-permanent marker.