We love exploring biodiversity hot spots, scouting for exotic flora and fauna and sharing photos and travel stories with our friends while encouraging nature conservation.
One of our favourite destinations is the island of Borneo, a 1 1/2-hour flight from Singapore.
Borneo is the third-largest island in the world, 1,000 times the size of Singapore. Less than 1 per cent is occupied by Brunei, 27 per cent by East Malaysia under the states of Sabah and Sarawak, and 73 per cent of it is Indonesia's five Kalimantan provinces.
Borneo's species-rich lowland rainforests, complex mangrove coastal forests, mature riverine forests and even the relatively infertile peat swamp forests boast a high degree of endemism.
It is biologically diverse and deeply threatened. As an avid birdwatcher and wildlife spectator, there is an urgency to capture the best moment of the world's oldest rainforest before someone empties this treasure trove.
In the past two decades, despite visiting the island a few dozen times, Borneo never fails to mesmerise us with her charismatic Big-Three - the Bornean orang utans, proboscis monkeys and pygmy elephants, plus countless interesting animals and plants.
Whether you are a first-timer looking for an easy jungle walk or a seasoned explorer looking for new frontiers, Borneo has something for everyone.
Our eight essential items for expeditions always include a hat, sunscreen, mosquito repellent, light-weight and quick-drying long pants and long-sleeved shirts (to protect from the sun, insects and splashy mud), poncho, water bottle and anti-leech socks.
Our journey begins at the most accessible Kinabatangan Wildlife Sanctuary in Sabah. After an easy flight to Sandakan and a two-hour drive, we arrive at our rustic lodge near Sukau Village, preparing energetically for our river cruise.
There are plenty of eco-lodges and homestays in the area, all providing local guides, clean and spacious rooms and delicious home-cooked meals.
The award-winning Sukau Rainforest Lodge (www.sukau.com/about-us/our-lodge) offers all-in, full-board packages for three days and two nights from about RM1,500 (S$502) a person, including airport pick-up in Sandakan and boat safaris.
It can be difficult to settle down in your lodge nestled on the bank of the Kinabatangan River, when you are bewildered by the cacophony of its inhabitants.
A few species of hornbills are squawking in the fruiting fig trees and others are whooshing their wings in flight high overhead, while the proboscis monkeys join them to show off their funny noses.
It was awesome to watch these big birds foraging in pairs. We boarded our small boat to cruise along the banks of the Kinabatangan, Sabah's longest river.
We love photographing wildlife on boat trips -a royal treatment compared with carrying a clumsy tripod and camera equipment weighing more than 15kg, trekking up and down in the humid tropical rainforest and chasing the ever-moving animals.
On the first afternoon, we see six out of the eight species of hornbills in Borneo, including the rare and critically endangered helmeted hornbill, with a wingspan of 2m.
This species is facing the plague of illegal hunting, as its solid horn or casque is worth more than ivory.
Over the years, we have optimised our wildlife-watching schedule for the day: bird-watching before sunrise. It is the most active feeding time for birds after a long night. After breakfast, we go mammal and primate "hunting" till lunch. It is also a good time to photograph insects and butterflies.
It is siesta time after lunch, when the sun is biting hot and most animals are in hiding.
We resume at about 3pm until dinner time. Diurnal (active during the day) animals are looking for a safe place to roost, while crepuscular (active during twilight) animals are foraging.
•Fanny Lai is a conservationist and former group chief executive of Wildlife Reserves Singapore. Bjorn Olesen is a wildlife photographer.
See more of their images of Borneo's biodiversity and natural wonders in A Visual Celebration Of Borneo's Wildlife, a 468-page coffee-table book on sale at leading bookstores for $67.41. Authors' royalties from this publication will be donated to Fauna & Flora International in aid of its conservation projects in South-east Asia.
After dinner, energy and weather permitting, we continue with a walk in search of nocturnal creatures.
One morning, after a successful bird-watching session, we hear the soft trumpet of a herd of Bornean pygmy elephants on the waterfront.
The family of a bull, some cows and juveniles are foraging for grass and palm leaves, while the matriarch demonstrates to her calf how to enjoy wild bananas.
We switch off our boat engine and stay quietly at a distance, whispering among ourselves while photographing and observing the family having fun.
Then, the herd starts to cross the narrow tributary in twos and threes at a time.
We stop counting when 10 of them have crossed, as we see the mother elephant and her calf entering the water. It is obvious that the calf is reluctantly making his maiden voyage.
At the halfway point, he starts to panic, wanting to go back. However, with the encouragement and guidance of his experienced mother, he swims ashore safely.
How could you top the breakfast experience of savouring creamy Sabah curry-laksa after an inspirational session with a herd of wild and wise elephants?
From Kinabatangan, we drive to Kinabalu National Park, dominated by Mount Kinabalu - the highest summit in South-east Asia - at 4,095m above sea level.
The goal is to explore this Unesco World Heritage Site's wide range of habitats - from tropical lowland to sub-alpine forest.
It is one of the most important biological sites in the world, with more than 4,500 species of fauna and flora.
At the foothill, we find the iconic Rafflesia, a parasitic flowering plant named after Sir Stamford Raffles in 1818.
There are many species of Rafflesia and it has the largest flower of any plant, at least in terms of weight.
The flower of the Rafflesia arnoldii tips the scale at 10kg, and is 100cm in diameter across the lobes.
It is the state flower of Sabah and one of the three national flowers of Indonesia, chosen mostly because of its formidable size.
As we are engrossed by the great variety of bromeliads, lianas, mosses, fungi and ferns, we find the world's largest pitcher plant - the Rajah Brooke's Pitcher Plant - behind the bushes.
The lower pitcher of this "king of the pitcher plants" can grow up to 41cm and hold more than two litres of water.
It is also the largest carnivorous plant in the world, known to trap insects and small rodents.
In the late morning, despite trekking in the rainforest, we can feel the fiery ball in the sky.
We always drink as much water as possible when we receive the "rainforest sauna" treatment, to allow every pore on our skin to perspire and detox.
As we climb onto a steep slope, we are completely speechless when we accidentally stumble upon the rarest and, possibly, the most expensive flower in the world, the Rothschild Slipper orchid.
This special bloom is endemic to Kinabalu Park and it is estimated that fewer than 50 are left in the wild, as many are taken to be sold on the international black market. The flower takes about 15 years to grow and bloom.
The large flower holding its petals almost horizontally is spectacularly stunning, like a beautiful dancer extending her arms to embrace her suitor.
No wonder it is critically endangered. We watch in awe, admiring The Gold of Kinabalu.
What a privileged day it is, rubbing shoulders with the mighty, the royalty and the beauty.
We move on to Sabah's largest protected lowland rainforest in the upper catchment area of the Danum and Segama rivers - the Danum Valley.
Before it became a conservation area, there were no human settlements in this territory, making it pristine and unique for wildlife observation. The nearest town is about a two-hour drive on mainly logging roads.
Halfway through our journey, we discover a few orang utan nests on the laran trees' horizontal branches - a positive sign of a healthy population.
A few minutes later, we spot a large male Bornean orang utan resting on a branch, enjoying his mid-afternoon break with a bunch of wild figs.
We take photos of him from a distance. When we want to leave, we have to walk under the big tree he is perched at.
At this point, he starts urinating, possibly to express his displeasure with us for invading his personal space. We cover our heads and leave promptly.
The Borneo Rainforest Lodge at Danum Valley offers many action-packed programmes - from cultural adventures and nature treks to bird-watching and river rafting.
From the main lodge, there is an extensive network of well-laid-out trails, where you can observe some of the six species of colourful pittas, a kind of bird.
The lodge offers all-in, full-board packages for three days and two nights, including airport transfers, guided walks and night drives, from RM3,159.
The Valley is an excellent location for bird-watching in the morning, and night walks to enjoy the company of the Horsfield's Tarsier, Sunda Colugo, Greater Mouse Deer and various species of owls and amphibians.
In Sarawak, the most exciting adventure is exploring the Gunung Mulu National Park, another Unesco World Heritage Site.
The mysterious Mulu Cave with magnificent limestone karsts formed over millions of years is far superior to any contemporary and abstract sculpture display.
One of the natural chambers is so large that it can accommodate 40 Boeing 747 planes.
Deep in the dark and cool cave, with dampness in the air, we step carefully on slippery guano-rich ground, avoiding touching the wall while manoeuvring the narrow and undulating path.
While pausing to enjoy the calming effect of water dripping and tinkling with echoes, we spot a 2m Cave Racer scaling the limestone walls nonchalantly and feeding on a roosting swiftlet.
Be prepared to strain your neck when observing three million or so wrinkle-lipped bats leave the Deer Cave before dusk.
They form a circle to gain altitude before flying off at a height of 3,000m. Occasionally, the odd Bat Hawk comes after them. This hypnotising process goes on for a few hours every evening.
For adventure buffs, take the challenge of cave-diving or climbing the pinnacles to witness the world's most breathtaking limestone landscape.
Due to the relative accessibility of Sabah and Sarawak, fewer naturalists have ventured into the more sparsely populated Kalimantan in Indonesia.
Nevertheless, we like the popular Tanjung Puting National Park in Central Kalimantan, well-known for its orang utan research and conservation projects at Camp Leakey, with the largest wild Bornean orang utan population in the world.
This 415,000ha park houses the largest protected tropical forests and peat swamp forests in South-east Asia.
However, like the other protected areas, the park faces encroachment, fire damage and degradation.
Besides orang utans, the park is also home to Malayan Sun Bears, porcupines, banteng (wild cattle), giant butterflies and nine species of primates including the proboscis monkey, the red leaf-eating monkey, the Bornean Agile Gibbon and the Silvery Langur.
Bird-watching on the klotok (small boat) is convenient and rewarding.
Rhinoceros, Oriental Pied and Black Hornbills are comparatively easy to spot, in addition to the endangered Storm's Stork. Not to mention countless interesting species of fish, amphibians and reptiles inhabiting this land.
After two decades of visiting this beautiful island, we have witnessed how economic development has taken its toll on biodiversity.
The rainforest that cleans and filters the air supply, protects and conserves water and soil, regulates temperature, reduces landslides and flooding as well as provides food and shelter for wildlife, plants and people, is fast disappearing.
The swamp forest that reserves water supply, prevents saltwater intrusion into groundwater and rivers as well as provides a source of energy and natural resources for fauna and flora, has been burned and removed to produce goods for supermarkets.
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