ON a clear December day about 12 years ago, I ventured into a southern Thailand forest of the sort I thought no longer existed.
Deep in the heart of Khao Sok National Park lay Ao Din Daeng, a roundish valley surrounded by towering limestone peaks and covered by dense jungle.
Under the peaks there was a cave system used by the Communists as a base camp during the 1970s and ’80s insurgency.
Rainwater percolated down through the limestone into the middle of the valley where a series of pools held water year-round, attracting a variety of wildlife.
Civets, barking deer, mouse deer, and porcupines all came to drink there, and that day, their tracks were all over the muddy edges of the pools.
Khao Sok (650 square kilometres) was declared a national park in 1980, then in 1987, more than 200 square kilometres of pristine rainforest were cut down to make way for the Chiew Larn Dam, hydro-electric project.
Thousands of animals fled the area.
At the same time, forests around the edge of the park were felled for a quasi-legal timber trade.
Poachers could now reach rich forests full of wildlife by boat across the artificial lake, or along logging tracks from the outside.
But pockets of forest such as Ao Din Daeng remained too remote for poachers, and animals such as tigers and leopards still roamed the forest.
I came here to find out how many big cats there were in Khao Sok.
Any useful estimate must take into account how much food is available to support them, how much forest exists, its connections to other forests, and the level of human disturbance.
Twenty years ago, rainforests stretched for thousands kilometres from Khao Sok, in the south, to the border with Myanmar (formerly Burma), and northwards up the Tennaserim Range.
There were no roads in the area, and people got around on foot, hunting wild pigs and deer, fishing and growing fruit to survive.
The place was truly wild, and there would have been plenty of food and enough good breeding habitat to support hundreds of big cats.
During the 1990s, some poachers gave up their traps and guns to help with conservation projects, relieving some of the pressure on big cats and other wildlife.
In the last five years, Khao Sok has increasingly attracted foreign and Thai visitors looking for adventure and the ultimate nature experience.
This has led to more poachers joining nature travel operations and leading treks to see the live wildlife instead of killing it.
In the past, conservationists based tiger counts on number of tracks they found.
Leopard tracks are, on average, just a little smaller than tiger tracks (90mm in length compared to 120mm), so the two can be confused.
One alternative is to count tigers and leopards by their coat patterns.
The stripes on a tiger or the spots on a leopard are unique to that individual, much like walking barcodes.
Camera traps were set up along wildlife trails, where the movements of animals trip infrared sensors, to count the big cats.
Counting leopards isn’t always easy because there are two kinds of coat patterns, spotted and black. Black leopards are also known as panthers and, while it’s possible to distinguish different spotted leopards, the same isn’t true for panthers.
At Khao Sok, I set camera-traps with master guide Anisak ‘Nit’ Chanyoo, and on one occasion, we photographed a beautiful panther as it visited the still pools at Ao Din Daeng.
The big cats play an important role as top predators in the tropical forest ecosystem.
They control the populations of animals lower down the food chain, thus ensuring that balance is maintained. The cats are also an indicator of a healthy forest.