Bukit Timah Nature Reserve

Singapore, lying within the tropical zone, and blessed with high temperature and high rainfall all year round, was once covered with tropical rainforests. It has been estimated that primary rainforest once covered about 82% of the land area of Singapore, approximately 442 km² or 44,200 hectares (ha).

However, ever since people have settled on the island, more and more of the original natural vegetation has been cleared, to make way for settlements and for agriculture and plantations. Today, only 192 ha or 0.43% of the original forest cover remains. Most of the surviving primary forest is restricted to the more pristine areas of the 163ha Bukit Timah Nature Reserve (BTNR), and in scattered patches throughout the 3,043 ha Central Catchment Nature Reserve (CCNR). The remainder of these two nature reserves is occupied mostly by secondary forest.

The Bukit Timah Nature Reserve contains the largest patch of primary rainforest left in Singapore. Bukit Timah Hill, at about 163.63 metres above sea level, is the highest point in Singapore.

A Treasure Trove of Species...

Bukit Timah has been the focus of attention for many scientists, not only because it is a rare example of a rainforest that has managed to survive while completely surrounded by urban development, but also because of the extremely rich diversity of flora and fauna that still exists within the nature reserve. This richness in plant and animal life has been noted ever since the 19th Century.

Back in 1854, the world-famous English naturalist Alfred Russel Wallace visited Singapore to collect beetles. He spent a lot of his time in the vicinity of Bukit Timah, which proved to be an extremely productive place for him:

"Insects were exceedingly abundant and very interesting, and every day furnished scores of new and curious forms. In about two months I obtained no less than 700 species of beetles, a large proportion of which were quite new, and among them were 130 distinct kinds of the elegant Longicorns (Cerambycidae), so much esteemed by collectors. Almost all of these were collected in one patch of jungle, not more than a square mile in extent, and in all my subsequent travels in the East I rarely if ever met with so productive a spot."

Wallace also mentioned some of the potential dangers he faced, among them the tigers which still prowled the forests in those days:

"There are always a few tigers roaming about Singapore, and they kill on an average a Chinaman every day, principally those who work on the gambir plantations, which are always made in newly-cleared jungle. We heard a tiger roar once or twice in the evening, and it was rather nervous work hunting for insects among the fallen trunks and old sawpits, when one of these savage animals might be lurking close by, waiting an opportunity to spring upon us."

Today however, Singapore's primary forests are very different from the pristine forests in the rest of Southeast Asia because many of the large animal species are now extinct in Singapore. Tigers disappeared from the Bukit Timah area during the 1920s; the last tiger in Singapore was shot in the mid-1930s. Other large animals, such as leopard, wild boar, sambar deer, and various birds such as hornbills and pheasants have also been wiped out from the forests of Bukit Timah and the Central Catchment Area. Habitat destruction and deliberate hunting and persecution led to these species becoming extinct locally.

Although we have lost a lot of our larger animal species, there is a lot that still survives within our remaining rainforests. Today, it is estimated that BTNR is home to more than 840 flowering plant species and more than 500 species of animals. Scientists are still discovering new species previously unknown to science, and it appears that many of the species living in the BTNR and CCNR are found only in Singapore, and nowhere else in the world!

BTNR: Biodiversity

Within the forest of BTNR, it is dark and cool as the trees form a continuous canopy; very little sunlight reaches the forest floor. On the forest floor, only plants that do not need a lot of sunlight can survive.

Among the various species of plants include hardwood trees such as seraya, keruing and meranti. Palms, rattans, fig trees, lianas, vines and epiphytes are a few other examples of the rich diversity of plant species that can be found within the forest.

The animal life is also extremely rich; most visitors to the reserve will be able to spot one of the most common forest creatures, the long-tailed macaque. Other animals commonly seen include the plantain squirrel, slender squirrel, and common tree shrew. The colugo, also mistakenly known as the flying lemur, is a shy and nocturnal creature, but is often spotted by the sharp-eyed visitor. The forest is also home to many rare and endangered species, such as the lesser mousedeer, Sunda pangolin, and slow loris.

A large proportion of our native bird species are found within the rainforests of BTNR and CCNR, and virtually nowhere else in Singapore. Similarly, the forest is the habitat for a large number of species of lizards, frogs, and snakes that depend heavily on pristine, undisturbed rainforest. The rainforest is also home to a great diversity of insects and spiders; it is impossible not to hear the incessant call of the cicadas, and it is common to spot the huge webs spun by the golden orb web spider. Small streams flowing through the nature reserves are the last refuge for many native fish and other aquatic lifeforms such as freshwater prawns and crabs. In fact, Singapore has three endemic species of freshwater crab found only within streams in BTNR and CCNR. These species are found exclusively in pristine and undisturbed streams that flow through these nature reserves, and are found nowhere else in the world.

Importance of Tropical Rainforests in Singapore

Even though we do not possess very large areas of tropical rainforests, as compared to other countries like Malaysia, Indonesia, Congo and Brazil, our few remaining rainforests are still very important, for various reasons.

• Tropical rainforests have taken hundreds of years to develop and once cleared, they are almost impossible to replace. There are many species of plant and animal in the rainforests, most of which are found nowhere else in the world. And when they are destroyed, some species may become extinct and be lost forever. These include plants with medicinal value which have not even been identified and tested. So, rainforests in Singapore now perform the very important role of providing a place for many species to thrive and grow.
• Rainforests in Singapore also provide us with an idea of what Singapore was like at the beginning of the nineteenth century. Singapore was once covered by tropical rainforests. Hence, by looking at the rainforests now, we get a glimpse of what Singapore might have been like then.
• The rainforests form our water catchment areas. When rain falls, the rainwater is trapped by some of the leaves on the trees. The rainwater then drains slowly into the ground and may be collected in the nearby reservoirs. In this way rainforests help us 'catch' the rain and add to our water supply.
• As Singapore becomes increasingly built up, rainforests act as giant 'lungs' by absorbing large amounts of carbon dioxide and producing oxygen in exhange.
• The rainforests are beautiful and scenic, with fresh air and natural surroundings. They provide us with a peaceful alternative to the busy city, and these last bastions of wilderness are places of peace and quiet where Singaporeans can go to enjoy and appreciate nature at its best. They can also be a tourist attraction.
• The rainforests are a legacy of our natural heritage, and it is important to protect and conserve them, keeping them intact for the country's future generations to learn and appreciate the richness of our country's heritage.

Links:

National Parks Board: Bukit Timah Nature Reserve
wildsingapore: Bukit Timah Nature Reserve
Ecology Asia: Bukit Timah Nature Reserve - a precious remnant of primary rainforest
Singapore's vest-pocket park: a rainforest survives within sight of skyscrapers
An Inordinate Fondness for Beetles
The Prowling Naturalist: Bukit Timah I: Alfred Russel Wallace in the Malay Archipelago
The Prowling Naturalist: Bukit Timah II: Visiting the Reserve

Tropical Savanna: Migration of the herbivores

As all of you should be aware of by now, the tropical grasslands of the world are home to an extremely rich variety of large mammals. Nowhere else is this diversity more apparent than in tropical Africa, where close to 50 different species of antelope, of all shapes, sizes and habits, along with numerous other large herbivores, inhabit various parts of the savannas that span the continent. And this diversity of herbivores feeds a wide variety of carnivores.









Note that not all of the creatures one can find in the savanna are 'true' savanna species; many of them actually prefer forest, but can be found in mixed habitats, such as in areas where the tropical rainforest slowly makes way for woodland, and subsequently turns into savanna. Many of these forest-dwelling animals are also occasionally found in savanna habitat adjacent to the forests where they would normally live. And some of these actually live within the savanna, wherever there is sufficient dense vegetation, bush, or thickets to hide in, such as in gallery forest, which refers to forests that grow along the banks of rivers in areas where it would otherwise be too dry for forest to grow.

By and large, however, the majority of large antelope are savanna inhabitants. Many are adapted to grazing on the grasses, herbs, and other low-growing plants. Others are browsers, choosing to nibble on tender young leaves and shoots from bushes, shrubs and trees. This way, competition between species is minimised, as each species has its own particular preference where it comes to food and habitat. The savanna may seem like a broad, homogeneous space to us, but there is a wide variety of microhabitats and ecological niches available for herbivores to exploit.

One thing that most of the larger savanna-dwelling herbivores have in common is a tendency to live in large herds. Living in large herds has its advantages, and it mostly has to do with avoiding predators. First of all, if you live in a herd, there are so many more pairs of eyes and ears on the alert for any sign of danger. Secondly, if a predator attacks, the fact that there are so many potential targets to choose from means that the likelihood of you becoming the main course for the resident lions or hyenas is so much lesser.

Due to the seasonal nature of the savanna, there are very distinct dry and wet seasons in most tropical grasslands. This has implications for the large numbers of herbivores which depend on an adequate supply of water and grazing. Many of these antelope are tough, and adapted to survive with little water and poor-quality food. These tend to stay put during the dry season. However, there are many other species which depend on having frequent access to water, and depend on tender young grass. When the dry season comes, these herbivores will migrate in huge herds, abandoning their former haunts for new pastures, travelling wherever the rain brings water and fresh green grass.

Migration is such an important part of these animals' lives that in many species, calves must learn to stand up and run with the herd within days or even hours of their birth. For wildebeest, mothers even synchronise their births as well; all will drop their calves within a short span of 2 to 3 weeks. Birth is timed to coincide with the rainy season, as well as to completely overwhelm the local predators so that overall survival rate of newborn calves is higher.

These herds may number in the thousands or even millions, all engaged in the tireless quest for food and water. Migration takes its toll, and many will perish; predators will bring down a few, whereas for others, the exhaustion and strain will be too much to bear. Where migration routes bring the herds across rivers, the death toll can be even higher, and it's not just due to the hungry Nile crocodiles that lie in wait in the water. Many of these rivers have only a few entry and exit points along the steep riverbanks, and for the thousands of hungry and thirsty herbivores, these few spots along the river banks become chokepoints. In the ensuing stampedes, many will be trampled, or drown in the waters from sheer exhaustion.

Wildebeest Migration

All over the tropical savannas of Africa, this beautiful yet harsh drama of life and death has played out for eons, with mighty herds perpetually on the move, chasing the rainclouds in a never-ending quest for fresh grass and water. Today however, many of these migrations are no more; hunting and development has decimated many of the great herds, whereas in some areas, the herds find their old migration routes blocked off with fences and development.

One of the last places where you can still see a surviving example of the great herbivore migrations is in East Africa. Here, more than a million wildebeest, and thousands of zebra and antelope make an annual journey, travelling from the Masai Mara Game Reserve in Kenya to the Serengeti National Park in neighbouring Tanzania, and back again later in the year.

Wildebeest Migration Made Simple
Serengeti Wildebeest Migration route map

This phenomenon attracts countless tourists, who pay to witness first-hand the migration of nearly 1.4 million wildebeest, 360,000 Thomson's gazelle, and nearly 200,000 zebra.

Here's a few more videos that capture the essence of life on the tropical savanna, and show us a slice of the awe-inspiring wildlife spectacle that is the Masai Mara-Serengeti migration: