Help save our critically endangered straw-headed bulbuls and their natural habitats

As dead as a dodo? Not our bulbuls, please.

Have you heard of the idiom “as dead as a dodo”?

The dodo is an unusual bird that used to live only on the remote island of Mauritius.

It is also one of the most well-known examples of human-induced extinction.

When the sailors arrived in Mauritus in the 16th century, dodos had no natural enemies.

However, due to sheer human carelessness, the dodos became extinct by 1681.

Over here in Singapore, we are blessed to have the critically endangered straw-headed bulbuls in our few remaining forests.

According to a research paper by Cambridge University Press (16 Nov 2020):

“The Straw-headed Bulbul Pycnonotus zeylanicus is one of South-East Asia’s most threatened songbirds due to relentless demand for the regional cage-bird trade”

The last strongholds of these endangered songbirds include Batok Batok and Batok Gombak.

On 16 Nov 2020, Dr Chee, Naresh and the Young Democrat team and I were fortunate to hear the melodious sounds of a straw-headed bulbul during our survey at Bukit Batok Hillside Park area.

Alas, this bird wasn’t recorded during the 9-day wildlife survey conducted by the EIA team at Bukit Batok Hillside Park area in April 2018.

It is therefore paramount that we spare no effort in preserving the remaining natural habitats of this rare bird species, in order to maximise its chances of survival.

In view of how it has been poached to the brink of extinction, the critically endangered bird species could easily go the way of the dodo.

“the Straw-headed Bulbul had an original range across a number of countries. Now, due mostly to widespread poaching for the caged song-bird trade, its population is so drastically reduced elsewhere that Singapore has become of key importance to prevent its global extinction. Can Singaporeans rise to the challenge of preserving and increasing its numbers? Would the eloquent eyes of the last Tiger in Singapore, recorded in the well-known photo, or those of the unrecorded last Black Panther, speak less tragically if the bubbling song of the Straw-headed Bulbul were guaranteed to sing forever in their native land?”

(Nature Watch, Jul-Sep 2019 issue)

Let’s join our forces to save the entire Bukit Batok Hillside Park area and our native Straw-headed Bulbuls today.

Sign the petition here.


Environmental Impact Study for Proposed Housing Development at Bukit Batok Hillside Park Area: EIS Report for Bukit Batok Hillside Park Area

The following is an excerpt about the terrestrial fauna survey from the EIS report for Bukit Batok Hillside Park area (HDB BB EIS Report Final_rev13), dated 1 June 2020, prepared for Housing and Development Board (HDB) of Singapore.

“Many of the species recorded during these surveys are considered to be widespread and common in secondary vegetation and parkland across Singapore. However, the presence of some forest-dependent species, such as the Malay Tailed Judy (Abisara savitri savitri), Copper-cheeked Frog (Chalcorana labialis), Common Treeshrew (Tupaia glis), and Slender Squirrel (Sundasciurus tenuis) shows that the survey area may serve as a refugium for some of these species.

Due to the ongoing construction work taking place at the edges of the survey area, patches of grassland and small pools have been created. All of the damselfly and dragonfly species are typical of open areas, as are quite a number of butterflies. Among the amphibians, the Field Frog (Fejervarya limnocharis) was only found at the periphery of the construction sites, and was absent at the pond at the forest edge.

The number of Wild Boar (Sus scrofa) present in Bukit Batok Hillside Park area is unknown. The two camera traps that documented the presence of Wild Boar were placed at different areas of the site; one was located along the stream, while the other was near the top of the ridge, in close proximity to an old wallow. Each camera captured a single individual, a lone adult male. Based on the general scarcity of signs of Wild Boar activity during the surveys, and the territorial behaviour of the adult male Wild Boar, it is likely that there is only one resident individual in this forest patch, although the possibility of more individuals wandering from other nearby forest patches cannot be ruled out.

Other species that have been recorded from similar secondary forest habitats such as Bukit Batok Nature Park, may be present within the survey area but were not documented during the surveys. These include the more uncommon animals such as the Sunda Colugo (Galeopterus variegatus), Sunda Pangolin (Manis javanica), Horsfield’s Flying Squirrel (Iomys horsfieldii), and Lowland Freshwater Crab (Parathelphusa maculata). These species are rarely observed outside of Singapore’s central nature reserves and Bukit Batok Nature Park, but are often difficult to detect, with some being nocturnal or arboreal. Therefore, while they were not observed during the surveys, we cannot discount the possibility that some of these species may still be present at Bukit Batok Hillside Park. The non-native East Asian Ornate Chorus Frog (Microhyla fissipes) was not previously recorded in Bukit Batok; this may represent a new locality record for this species in Singapore.

It is also important to note that these surveys took place outside of the migratory season for birds; surveys conducted when various passage migrants and winter visitors may be found in Singapore would likely yield very different results.

Although the survey area is a small, isolated patch of secondary forest with relatively few species of conservation importance, its potential role in maintaining connectivity for birds and other animal species cannot be discounted. With the ongoing development of the Tengah area as a new housing estate, it is likely that some animals may move to the Bukit Batok Hillside Park area, and then disperse to other forest patches in Bukit Batok, possibly reaching Bukit Timah Nature Reserve via Bukit Batok Nature Park.”

Why Bukit Batok Hillside Park should be spared from housing development

The dense secondary rainforest in Bukit Batok Hillside Park serves as a natural habitat and safe haven for our dwindling numbers of wildlife residents and plants (of which 10 species have been identified in the EIA report to be of conservation concern).

The Housing and Development Board (HDB) has engaged an environmental consultancy firm to conduct an Environmental Impact Assessment (EIA) on Bukit Batok Hillside Park in the western region of Singapore.

Aerial view of new BTO flats in Bukit Batok West from Bukit Batok Hillside Park

Ground view of Bukit Batok Hillside Park, which is sandwiched between the new BTO flats in Bukit Batok West and the existing HDB flats in Bukit Gombak.

According to HDB’s website, they “carefully consider the findings from the studies so that (they) can sensitively plan the land use and make adjustments to the Master Plan if needed to mitigate the potential impact, and establish urban design strategies to provide a quality living environment.”
While I commend HDB for initiating the environmental study in their proposal to build more housing units, I have several concerns about the potential impacts of deforestation in Bukit Batok Hillside Park:

  1. Loss of biodiversity and natural heritage
  2. Risk of soil erosion and landslides
  3. Loss of natural cooling effect and increase in urban heat effect
  4. Loss of cultural and historical heritage
  5. Loss of connection to Nature and increase in stress and anxiety associated with urban claustrophobia
  6. Increase in dengue fever cases due to conditions favouring increased reproduction of disease-carrying mosquitoes
1) Loss of our biodiversity and natural heritage in the western region of Singapore

Oriental Whip Snake in Bukit Batok Hillside Park, which is endemic in Asia

During a short hike in and around the forest of Bukit Batok Hillside Park on 5 July 2020, I spotted several animal species, such as oriental whip snake, greater racket-tailed drongo, white-crested laughing thrushes, black-naped orioles, yellow-vented bulbuls, and insect species such as dragonflies and butterflies.

These are merely a fraction of the 81 fauna species recorded in the EIA (and there may be more species that have yet to be discovered during the 9-day wildlife survey). The presence of predators such as snakes suggests a fairly complex food web in this fragile secondary forest ecosystem, which is still recovering from past human disturbance.

Bukit Batok Hillside Park faces the disappearing Tengah forest opposite Bukit Batok Road.

Since Tengah forest nearby is currently being cleared to make way for new homes, most of the wildlife there will have nowhere else to escape to, since it is bounded by expressways in the north and west, and by roads along Choa Chu Kang housing estate in the east and along Bukit Batok and Bukit Gombak housing estates in the south.

Some birds may be able to fly across Bukit Batok Road from the disappearing Tengah forest to take refuge in Bukit Batok Hillside Park. However, if the forest in Bukit Batok Hillside Park were to be destroyed too, then there would be a huge loss of the existing biodiversity in this region. This is because Bukit Batok Hillside Park serves as the last remaining node of connectivity between Tengah forest and the forested areas in Bukit Batok town park (Little Guilin), Bukit Batok nature park and Bukit Timah nature reserve.

With Tengah Forest looking set to disappear in about 10-20 years’ time due to housing development, Bukit Batok Hillside Park is the last remaining refuge for the wildlife in this region. (Source: Google Maps)

Although the upcoming Tengah town is designed to have “forest corridors“, they will be closely intersected by roads, pavements and cycling tracks. These do not allow the animal residents to move freely, unlike in a real forest setting such as in Bukit Batok Hillside Park, where they can go about their daily lives – eating, mating, reproducing, sleeping, etc – undisturbed by human presence.

Bukit Batok Road and the new BTO flat construction site pose a challenge for the native ground-moving animals, such as the critically endangered Sunda pangolins, to cross safely from the diminishing Tengah forest to Bukit Batok Hillside Park.

Like Dr Ho Hua Chew, vice-president of Nature Society (Singapore), said, “some species of birds, such as parakeets, eagles and others that can fly longer distances, will be able to use the fragmented patches of forests as stepping stones from the Tengah forest to Bukit Batok Nature Park or the nature reserve and vice versa”. On the other hand, he is also concerned that “wiping out the vegetation (in the Bukit Batok area) further disrupts the route that wildlife can use to move from forest to forest”.

2) Steep slopes prone to soil erosion and landslides in Bukit Batok

The steep slopes of Bukit Batok Hillside Park are prone to soil erosion and landslides, especially if the protective tree cover is removed.

Fragile topsoil exposed in a gully in the forest of Bukit Batok Hillside Park

Bukit Batok is blessed with several small forested hills and ridges, which thankfully have helped the town retain its overall green appearance for the most part, compared to most other towns in Singapore. Thanks to their steep slopes, some of these forested hills, such as Bukit Batok neighborhood park along Bukit Batok Street 21 and the hills surrounding Bukit Batok MRT station, have escaped urban development so far.

Hence, I find it inconceivable that Bukit Batok Hillside Park is being considered for housing development, since the steep slopes, especially those adjacent to Bukit Batok West Avenue 2, are prone to soil erosion and landslides if the vegetation cover is removed. The seasonal monsoon rains and late afternoon thunderstorms, which are common in Singapore, add to the risk of natural hazards such as landslides. It is also dangerous and expensive to construct buildings on steep slopes, hence Bukit Batok Hillside Park is not ideal for housing development.

3) Loss of natural cooling effect of forest and increased urban heat effect in the western region of Singapore

The tropical rainforests in the western region of Singapore help to lower the temperatures in towns such as Bukit Batok, whereas the highly built-up areas in the central and eastern regions of Singapore, such as Toa Payoh, experience significantly higher temperatures. (Source:

According to HDB’s website, “greenery is present in every HDB estate. It helps to reduce temperatures and mitigate heat while improving air quality and biodiversity, besides being pleasing and attractive.”

I agree with that. I would like to add that sizeable forested areas, such as Bukit Batok Hillside Park, help to reduce temperatures in housing estates much more effectively than roadside trees and fragments of ornamental vegetation in town parks in highly built-up areas, such as Toa Payoh.

For example, when I was staying in Toa Payoh in central Singapore, where I grew up in from 1973 to 2014, I could feel the warm humid air on most nights. This is because Toa Payoh is located in a highly built-up environment with fragmented vegetation and lack of a dense forest. After moving to Bukit Batok in the western region of Singapore in 2014, I could feel the difference in temperatures, as the air is cooler on most nights. This is because of the presence of dense forests in and around Bukit Batok.

In fact, the above map shows that on average, the night-time temperature in Bukit Batok is about 1.5 degrees Celsius cooler than that in Toa Payoh. Now that Tengah forest is disappearing and becoming more and more fragmented due to deforestation for housing development, it is likely that the surface temperatures around the neighbourhood of Bukit Batok will rise gradually.

A loss of the dense forest in Bukit Batok Hillside Park will lead to a loss of natural cooling effect and a rise in urban heat effect in the neighbourhoods of Bukit Batok West and Bukit Gombak.

If the forest in Bukit Batok Hillside Park is removed too, then the temperature in the neighbourhood will rise further due to the loss of cooling effect of the dense tree growth. With an increase in urban heat effect, there will likely be an increase in electricity consumption, due to higher usage of air conditioning in homes, especially on warm, stuffy nights. The increased heat will be exacerbated by the ongoing global warming climate, which will inevitably result in more physical discomfort and stress for the residents in the coming years.

In addition, the quality of air is likely to deteriorate if Bukit Batok Hillside Park is sacrificed for housing development, due to increased motor traffic around the vicinity and less natural vegetation to filter air impurities or toxic chemicals and reduce air pollution.

4) Loss of cultural and historical heritage in Bukit Batok

An abandoned well in Bukit Batok Hillside Park, which has historical and cultural significance

Relics of a former settlement and plantation, such as ceramic ware, in Bukit Batok Hillside Park have historical and cultural values.

As Singapore becomes more and more modernised, our younger generations face the danger of losing touch with our history, cultures and traditions. According to the EIA report, Bukit Batok Hillside Park comprises a former rubber plantation, with natural freshwater streams, which are rarely seen in Singapore today.

Hence, not only is the forested area worthy to be conserved for natural heritage, it is also worthy to be preserved for having historical and cultural significance. For example, the abandoned well and other relics in Bukit Batok Hillside Park can serve as useful tools for educating the public about Singapore’s history in an authentic setting (like how the abandoned kampong houses in the former Hainan Village are now preserved for public education in Thomson Nature Park).

5) Loss of connection with Nature and increased stress and anxiety associated with urban claustrophobia felt by people

The intriguing remains of a rocky trail in Bukit Batok Hillside Park are worth preserving, not only for their aesthetic value, but also for enabling visitors to explore and experience the forest as part of nature therapy.

An article by NParks noted that forest therapy helped people to relax and destress, and often enabled them to feel happier and more positive.

“A mental and emotional boost, you may say. And scientific research backs this up.”

– “Urban Forest Therapy in Singapore” by NParks

Moreover, a scientific study “reported that individuals’ positive moods increased significantly inside a forest than outside it or at its periphery, whereas their negative moods increased outside the forest.”

Hence, if the forest in Bukit Batok Hillside Park is destroyed for housing development, it will increase the likelihood of the residents losing connection with Nature, which in turn can be detrimental to their physical, mental and emotional health and well-being in the long run.

6) Deforestation can lead to an increase in dengue fever cases

Dengue cluster map
In July 2020, the dengue clusters are mainly concentrated in highly built-up areas in central and east Singapore, where people live around fragmented vegetation spots in deforested areas. (Source: NEA)

The above map shows that dengue fever cases are fewer in the western region of Singapore, including Bukit Batok, where there are dense forested areas nearby, such as Bukit Batok Hillside Park, Bukit Batok nature park and Bukit Timah nature reserve, which are relatively undisturbed by humans.

Notably, an academic research paper reported in 2016 that “a growing body of scientific evidence shows that the felling of tropical forests creates optimal conditions for the spread of mosquito-borne scourges, including malaria and dengue.”

Similarly, a Straits Times article reported in 2019 that the ecological history of deforestation in the Philippines – followed by urbanisation, the further degradation of our forests and climate change – continues to explain the tenacity of dengue in the country.

Hence, it is imperative that the authorities take drastic steps to stop or minimise deforestation as much as possible, in order to curb the current dengue outbreak in Singapore, which has become the worst outbreak in recent history.

My Proposed Alternatives
In view of my concerns described above, may I propose the following alternatives?

First, we can consider reinstating Bukit Batok Hillside Park as an enhanced nature park with educational trails and conservation zones.

Second, we can choose to focus on recycling or redeveloping brownfield sites (such as old or disused developed areas) instead of clearing greenfield sites (such as Bukit Batok Hillside Park) for future housing development, as also suggested by HDB CEO Dr Cheong Koon Hean in her IPS-Nathan lecture in 2018.

“Similar to many mature cities, as we become built up over time we will be left with more brownfield rather than greenfield sites. This requires us to shift progressively into an ‘urban redevelopment/regeneration’ mode.

For an island city-state limited by our territorial waters, available land for new development will come mainly from ‘recycling’ existing land and properties.”

– Dr Cheong Koon Hean, HDB CEO (IPS-Nathan lecture, 2018)

Last but not least, we should definitely review our national development master plan, since The Straits Times reported on 3 July 2020 that “recent trends ensure that Singapore’s population will be significantly below 6.9 million in 2030″. Surely we don’t really need to keep destroying our few remaining valuable forests for housing development, given that our population is not expected to increase as quickly as we had once thought?


In summary, by sparing Bukit Batok Hillside Park (and other greenfield sites) from deforestation for housing development and by choosing to develop brownfield sites instead, we can achieve the following benefits:

The residents of the new and existing flats in Bukit Batok West and Bukit Gombak will appreciate having Bukit Batok Hillside Park for recreation and outdoor education on nature conservation.
“We recommend the conservation of these secondary regrowth forest patches as they are, as refuges for nationally threatened native species, which make up about 20% of the species we recorded in each forest patch (namely, Bukit Batok Hillside Park, Bukit Batok Town Park, Bukit Batok Nature Park and Bukit Batok East Forest).”
(Source: The Vascular Plant Flora in Bukit Batok, Singapore by National University of Singapore, 2013)

P.S. To help support the conservation of Bukit Batok Hillside Park area, please click here to sign the petition.