Saturday, November 30, 2013

Silent Voices in the Wilderness

Silent Voices in the Wilderness
Butterflies in MacRitchie Forest 

A female Plane (Bindahara phocides phocides) a rare Lycaenid that is found only in our forested nature reserves

When the Land Transport Authority (LTA) announced in Jan this year, that a proposed new 50km MRT line that starts from Changi and ends in Jurong will be ready by 2030, it raised more than just eyebrows amongst the nature community.  The new east-west MRT line's alignment will bring it right across the MacRitchie Forest, which falls within the boundaries of what is traditionally known as Singapore's "nature reserves". Although the LTA clarified that the line will be well below ground, it did not manage to convince the nature community that in the process of constructing the line, there will be no impact to the environment and delicate habitats within the nature reserves.

The proposed alignment of the Cross Island MRT line cutting through a narrow 'neck' of the Central Catchment Nature Reserves

A lot of questions were raised, many of which were valid and technically relevant. How would the soil investigation activities, which some estimated at having a bore hole at intervals of at least 20m apart, affect the forested areas? Would there be utility structures and penetrations above ground that serve the tunnel beneath that would be located within the nature reserves? What would LTA do to mitigate impact to the flora and fauna during the tunnelling process? What kind of maintenance regime and access to the forests would be needed after the line is completed and in operation? And so on...

The proposed alignment of the CRL showing approximately where it will run under the MacRitchie Forest, including two patches of primary forest. (Source : Nature Society Singapore)

From the viewpoint of the engineers and the economists, the alignment of the Cross Island Line (CRL) will take the most technically efficient and economically pragmatic route, which will cut across the narrowest portion of the Central Catchment Nature Reserves (see map). As the line will be completely below ground, it was also assumed that the impact to the forest habitats above would be "minimal".

The Common Faun (Faunis canens arcesilas) a forest denizen that is not found outside of the nature reserves nor is seen in urban parks and gardens.

Much has been debated about the potentially damaging and irreversible impact to the flora and fauna that may be caused by the CRL, so I won't delve into the details of those arguments. We have been asked about how butterflies could be affected by habitat changes that may be caused by the CRL and the construction activities that are associated with the line. As butterflies are mobile and can fly to other areas, why would any changes in the MacRitchie Forest environment threaten them?

Arhopala trogon a rare Oakblue that is found in only a few locations in the nature reserves, one of which is in the MacRitchie Forest

The host plant specificity of the early stages of butterflies makes them particularly vulnerable to changes in plant diversity due to changes in land use and loss of their host plants. The information on the host plants of butterfly species in Singapore is largely incomplete.

The Malay Gem (Poritia philota philota) a rare forest butterfly of which the MacRitchie Forest is one of a couple of locations that this species can be found

As Koh et al. (2004a) pointed out, “the preservation of whole habitats is urgently needed if we are to avoid the possible cascading effects of species (co-)extinctions, especially in ecological communities, such as tropical rainforests, where different species are inextricably dependent on one another.”

The Dark Blue Jungle Glory (Thaumantis klugius lucipor) a large Morphinae that lurks in heavily shaded forested areas in the nature reserves

Although butterflies are able to fly from location to location in search of their caterpillar host plants, it is not known for certain why certain species have gone extinct. Some species may go extinct sooner than their host plants when the relative rarity, and not absolute disappearance, of certain host plants reduce butterflies to below their minimum viable populations. Coupled with predation, environmental factors and loss of habitats, some species of butterflies may have gone extinct long before their host plants actually disappear from our forests.

Cover of RMBR's Expose of Singapore's Rainforests showcasing the amazing diversity in our nature reserves and rainforests in Singapore

The unpredictability of the extent of damage that starts with the soil investigation works and how the plant diversity and the associated habitats will change and adapt through the construction period, tunnelling and eventual changes in water table will form the major part of the risk of undertaking the CRL. Whilst the tunnelling work is assumed to have minimal visible impact at the ground level within the nature reserves, very little is known about how the water table changes when an impervious concrete tube is built - spanning up to 20m across and running a few kilometres across the nature reserve, some 40m or more below the surface.

Two pages about forest butterflies from RMBR's Expose of Singapore's Rainforests

Many of the larger trees may suffer due to the changes in the water table, and if they die out, the drying out of the forest in that area will spread unpredictably, and may cause damage of untold proportions. Such changes in the forest may threaten some of the host plants and hence the related butterfly caterpillars that feed on them.

A male Archduke (Lexias pardalis dirteana) another forest-dependent butterfly

It is estimated that at least 60% of Singapore's butterfly fauna are forest-dependent. Whilst the increase of urban planting and landscaping strategies to attract butterflies in urban areas have begun to bear fruit, the same cannot be said for forest butterflies. Many of the forest-dependent species will not come out to the urban butterfly gardens. Most of the butterfly species featured in this article are rarely seen in urban parks and gardens.

The Harlequin (Taxila haquinus haquinus) that may now be extinct on Singapore island due to the destruction of its habitat in the north-western part of Singapore.  Attempts to translocate it to other sites have not been successful.

Even if their caterpillar host plants are available, these butterflies' preferred habitats have to be conducive to support a sustainable population. Not enough is known about why certain species prefer particular locations whilst other similar habitats elsewhere do not attract the same species. An earlier attempt by ButterflyCirle to translocate the Harlequin (Taxila haquinus haquinus) at a forested site that was threatened by development was unsuccessful. Whilst a few sites were chosen, that were similar in terms of habitats and availability of host plants, there were no signs that Harlequin survived in the new locations after a period of monitoring.

The Lesser Harlequin (Laxita thuisto thuisto) a relative rare Riodinid that survives only in our forested areas in Singapore

Around the MacRitchie Forest area, there are records of some rare species of butterflies that are found in the forested area and a few have only been observed in that area and nowhere else. If their habitats or host plants are affected, there is a high risk that these species may face extinction in Singapore.

The very rare Storey's Palmer (Zela storeyi) which is found in our forested nature reserves

It is encouraging that the LTA has confirmed that an Environmental Impact Assessment study will be carried out over the next two years, starting in early 2014 to assess the potential environmental impact caused by the CRL. Will the study recommend that the CRL be realigned outside the Nature Reserves? Or will it support the current alignment but with strict mitigation measures be put in to minimise damage to the MacRitchie Forest?

A 3D topographical map of the MacRitchie Forest area. (Source : Nature Society Singapore)

How deep should the tunnels be constructed, where it will not cause any changes or damage to the forest ecology? We have to acknowledge that we do not know. But a general rule of thumb in tree biology points out that the tap roots of large trees like Dipterocarps can reach as deep as the height of the tree itself. That would mean that a 30m tree would have roots reaching 30m or more below ground. Would a tunnel that runs below such trees affect the health of the forest? Has it been done elsewhere before? Should we even try?

The Five Bar Swordtail (Pathysa anthiphates itamputi) a forest-dependent butterfly that is found regularly in the nature reserves of Singapore

As to the fate of our forest butterflies, if the CRL were to proceed as planned, we cannot say for sure - we do not know enough. The CRL appears to be a rare project that has breached the previously-assumed impenetrable gazetted nature reserves in Singapore. True, there have been other structures like the military facilities or water treatment plants sited within the nature reserves, but none so recent nor extensive as to generate quite a bit of controversy and grab the attention of the nature community in Singapore like the CRL.

The Purple Duke (Eulaceura osteria kumana) - common but forest dependent.  Can such a butterfly be attracted to urban habitats like our parks and gardens with judicious planting of its host plants?  Apparently not.

Are there no other alternatives to the alignment that LTA has proposed? The NSS has come up with a position paper that says otherwise. Will the alternative route be still technically possible but will come at a great financial cost to the government? How would that expenditure stack up against the nature reserves which some consider as 'priceless' and it would be futile to even put a value to? Are there any compromises that can be made?  Both sides will have to keep an open mind to options.

The Central Catchment Nature Reserves - our "Green Heart" of Singapore

Are we courageous enough to gamble with a part of the 'green heart' of Singapore and stand to lose a part of our natural heritage and sacrifice a legacy to our future generations? We should know the recommendations of the EIA in early 2016, and the fate of MacRitchie Forest then. At that point in time, we hope that we will make a wise decision for the greater good of all Singaporeans and the flora and fauna that share our little island with us.

Text by Khew SK : Photos by Sunny Chir, Khew SK, Koh CH, Nelson Ong & Horace Tan

Further Reading

References :

  • Koh, L.P. & Sodhi, N.S. 2004. Importance of reserves, fragments and parks for butterfly conservation in a tropical urban landscape. Ecological Applications, 14, 1695–1708.
  • Koh, L.P., Sodhi, N.S. & Brook, B.W. 2004a. Co-extinctions of tropical butterflies and their hostplants. Biotropica, 36, 272–274.
You have read this article with the title November 2013. You can bookmark this page URL Thanks!
Thursday, November 28, 2013

Butterflies Galore! : Bamboo Tree Brown

Butterflies Galore!
The Bamboo Tree Brown (Lethe europa malaya)

This skittish Satyrinae often lurks in the shaded areas in the vicinity of bamboo clumps and remain well camouflaged until it is disturbed. In freshly eclosed individuals, the large violet submarginal ocelli on the underside of both wings are very attractive. The species is uncommon, but not rare. It is local in distribution and usually found in the vicinity of its caterpillar host plant - bamboos.

This Bamboo Tree Brown was photographed by young ButterflyCircle member Jonathan Soong at the Butterfly Hill on Pulau Ubin last Sunday. For this species, a butterfly photographer has to be very patient in stalking it, especially when the butterfly is extremely alert and skittish, and prefers to stop amongst dead leaves and forest litter at low levels.

You have read this article with the title November 2013. You can bookmark this page URL Thanks!
Wednesday, November 27, 2013

Butterflies Galore! : Great Mormon

Butterflies Galore!
The Great Mormon (Papilio memnon agenor)

Over here in Singapore, the large flower of the Hibiscus (Malaysia's national flower) does not appear to attract butterflies very often.  Is it because there are other more nectar-rich flowers around that makes a butterfly simply avoid the Hibiscus?  However, at the Butterfly Hill on Pulau Ubin last Sunday, we saw a number of large butterflies, like this Great Mormon, feeding on the Hibiscus flower.  Amongst the other species are the Common Birdwing, Common Mormon and Orange Emigrant.  

This male Great Mormon, shot by young ButterflyCircle member Brian Goh, is shown probing deep into the Hibiscus flower with its proboscis for nectar.  There were certainly other flowering plants around in full bloom that day, like the Ixora, Lantana, Bidens, Wedelia, Stachytarpheta and Cordia planted at Butterfly Hill.  So, why did the Hibiscus suddenly become so attractive to the butterflies?  Readers are invited to share their observations and experience here.  

You have read this article with the title November 2013. You can bookmark this page URL Thanks!
Tuesday, November 26, 2013

Butterflies Galore! : Great Eggfly

Butterflies Galore!
The Great Eggfly (Hypolimnas bolina bolina)

This "Eggfly" occurs as two different subspecies in Singapore - Hypolimnas bolina bolina (known as the Great Eggfly), and Hypolimnas bolina jacintha (known as the Jacintha Eggfly). Whilst the females of the two subspecies are relatively easier to distinguish, the males are almost indistinguishable and look very similar in appearance. It would be quite interesting to ascertain if the two subspecies can interbreed, and whether they are evolving into a single species or otherwise.

The submarginal white chevron markings on the underside of the hindwing were used to distinguish between ssp bolina and ssp jacintha. However, intermediates are beginning to show, and rendering this physical diagnostic attribute unreliable to separate the two. These two Eggfly subspecies should be observed closely to see whether they eventually separate more distinctly or merge into a single subspecies.

You have read this article with the title November 2013. You can bookmark this page URL Thanks!
Monday, November 25, 2013

Butterflies Galore! : Malay Lacewing

Butterflies Galore!
The Malay Lacewing (Cethosia hypsea hypsina)

The Malay Lacewing is one of three species of the genus Cethosia that occurs in Singapore. One of the species, the Plain Lacewing, was last seen in Singapore in the late 1990's and has not been seen since. The other, the Leopard Lacewing, a "foreign talent" species, is considered relatively common now, after being first spotted in Singapore some time in 2005. The Malay Lacewing is essentially a forest-dependent butterfly, although there have been sporadic sightings of it in urban parks, even at the Singapore Botanic Gardens.

The common name Lacewing was probably coined for the intricate patterns on the underside of the wings of this butterfly, which features pretty patterns on a ground colour of orange and red. The life history of the Malay Lacewing has been recorded on Adenia macrophylla var. singaporeana a member of the Passifloraceae family. This female, feeding on the flowers of Lantana, was shot last weekend at Pulau Ubin.

You have read this article with the title November 2013. You can bookmark this page URL Thanks!
Saturday, November 23, 2013

Life History of the Copper Flash

Life History of the Copper Flash (Rapala pheretima sequeira)

Butterfly Biodata:
Genus: Rapala Moore, 1881
Species: pheretima Hewitson, 1863
Subspecies: sequeiraDistant, 1885
Wingspan of Adult Butterfly: 31-35mm
Caterpillar Local Host Plants: Mangifera indica (Anacardiaceae, common name: Mango), Hibiscus tiliaceus (Malvaceae), Syzygium zeylanicum (Myrtaceae).

Physical Description of Adult Butterfly:
On the upperside, the male is mostly dark reddish brown, and the female is dull steely blue. On the underside, both sexes are pale brown. Both wings have a broad cell-end bar and a brown post-discal band which is whitened on the outer side. The forewing has a spot in the middle of the forewing cell (which could be absent in some females). The hindwing has a black marginal spot in space 2 and another on the tornal lobe. Between the two spots, the marginal area in space 1b is covered with bluish scaling. There is a white-tipped tail at the end of vein 2. The legs are white and black-banded.

Field Observations:
This species is moderately common in Singapore and can be found in serveral urban parks and nature reserves. The adults are fast flyers and make rapid sorties among foliage. Both sexes have been observed to visit flowers of various plants for nectar.

Early Stages:
The Copper Flash is polyphagous as its early stages feed on a number of host plants from different families. Locally three plants, Mangifera indica, Hibiscus tiliaceus and Syzygium zeylanicum, have so far been identified as the larval hosts. One other plant is still awaiting identification. The caterpillars of the Copper Flash feed on the young and tender leaves of the host plants. In the wild, the caterpillars are typically found in the company of the Weaver Ant (Oecophylla smaragdina).

Local host plant #1: Syzygium zeylanicum..

Local host plant #2: Mangifera indica.

The eggs are laid singly on leaves, stems or young shoots of the host plants. Each egg is about 0.6mm in diameter, green in colour. It is burger-shaped with a depressed micropylar at the pole and a surface covered in a reticulated pattern.

Two views of an egg of the Copper Flash.

It takes about 3 days for the egg to hatch. The newly hatched is pale yellowish with lateral brown bands running lengthwise. Its body has a length of about 1.1mm. Dark brown patches can be seen on the 1st, 7th-8th abdominal segments and on the anal plate. It also has a black prothoracic shield and a black head. The body also features moderately long setae dorso-laterally and laterally. After about 2 days of growth in the first instar, and reaching a length of about 2.3mm, the caterpillar moults to the next instar.

1st instar caterpillar, newly hatched, length: 1.1mm.

Two views of a 1st instar caterpillar, length: 2.3mm.

Two views of a late 1st instar caterpillar, dormant prior to its moult, length: 2.1mm.

In the 2nd instar, the prothoracic shield is changed to pale yellowish brown. There are numerous short fine setae emanating from rows of conical projections occurring dorso-laterally. Numerous short setae are also projected sub-spiracularly along the body fringe. The 2nd instar caterpillar reaches a length of about 4mm, and after about 1.5-2 days in this stage, it moults again.

Two views of a 2nd instar caterpillar, length: 3.7mm.

Two views of a late 2nd instar caterpillar, dormant prior to its moult, length: 2.1mm.

Compared to the 2nd instar caterpillar, the yellowish green 3rd instar caterpillar has a more striking appearance with oblique dorso-lateral patches outlined in white. There are conical projections occurring dorso-laterally and along the body fringe, each with a tuff of setae at its tip. The dorso-lateral conical projections on the 7th abdominal segment is reddish in contrast to the pale yellowish coloration for the rest of such projections. On the 7th abdominal segment, the dorsal nectary organ is now more readily observed. The 3rd instar takes about 1.5 to 2 days to complete with the body length reaching about 8.5mm.

Two views of a 3rd instar caterpillar, length: 6mm.

Two views of a late 3rd instar caterpillar, dormant prior to its moult, length: 8mm.

The 4th instar caterpillar has a more prominent appearance, featuring broad triangular to semi-circular dorsal patches in yellow or pink (giving rise to different colour forms), broad triangular lateral patches in lime green to pigment green. It seems that the colour form assumed by the caterpillar is closely associated with the colour of the host plant leaf the caterpillar is feeding on. The 4th instar takes about 2-2.5 days to complete with the body length reaching 15mm.

Two views of a 4th instar caterpillar, length: 10mm.

Two views of a late 4th instar caterpillar, dormant prior to its moult, length: 13mm.

The 5th instar caterpillar has similar markings as in the 4th instar. Conical projections along the body fringe on the 2nd-3rd thoracic segments, 1st, 2nd and 8th abdominal segments are coloured dark red to dark green with the rest are coloured yellow.

Two views of a 5th instar caterpillar, length: 19.5mm.

Two views of a 5th instar caterpillar, length: 24mm.

A 5th instar caterpillar found in the field on a leaf of the host plant yet to be identified.

After about 3.5-4 days of feeding and reaching a length of about 24mm, the caterpillar stops food intake and wanders around for a pupation site. During this time, its body gradually shortened. Typically the caterpillar chooses a concealed space in a leaf litter for its pupation site.

Weaver ants attending to a 5th instar caterpillar of the Copper Flash.

The pre-pupatory caterpillar prepares for pupation by spinning a silk girdle and a silk pad to which it attaches itself via anal claspers. After about 1 day as a pre-pupa, pupation takes place. The pupa is predominantly reddish brown and has numerous small dark speckles. Pupal length: 14-15mm. The pupa has a typical lycaenid shape with a short abdomen.

Two views of a pre-pupa of the Copper Flash.

Two views of a fresh pupa of the Copper Flash, moments after the pupation event.

Two views of a pupa of the Copper Flash.

Nine days later, the pupa turns black, first in the wing pad and thorax, then progressively in the abdomen. The presence and absence of the bluish patch in the wing pads gives an early indication of the gender of the soon-to-emerge adult. The next day, the pupal stage comes to an end with the emergence of the adult butterfly.

Two views of a mature pupa of a Copper Flash.

A newly eclosed Copper Flash.

  • [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society, 1992.
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012.
  • A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2010.
Text by Horace Tan, Photos by Benedict Tay, Bobby Mun, Loke PF, Nelson Ong, Simon Sng, Sunny Chir and Horace Tan
You have read this article with the title November 2013. You can bookmark this page URL Thanks!
Thursday, November 21, 2013

Butterflies Galore! : Common Three Ring

Butterflies Galore!
The Common Three Ring (Ypthima pandocus corticaria)

This "Cinderella" of butterflies is unlikely to raise the heart rate of butterfly photographers or create any sort of excitement when spotted. It is a relatively common and unremarkable species that is encountered at the fringes of the nature reserves amongst grassy patches. It flutters weakly at low levels and stops to perch, either with its wings folded upright as is shown here, or opened when sunbathing at certain hours of the day. However, it is alert and somewhat skittish and it would take a bit of persistence on the part of the photographer to get a shot of this butterfly on an ideal perch.

The Common Three Ring is the largest member of the genus Ypthima in Singapore. It is greyish brown above, with a large subapical black yellow-ringed ocellus on the forewing. There are two silvery spots in the black ocellus. On the hindwing, there is a similar but smaller subtornal ocellus, and another pair at the tornal area. The underside is greyish to pale buff brown, with the wings traversed by innumerable fine dark brown striations where the hindwing has three yellow-ringed black submarginal ocelli.

You have read this article with the title November 2013. You can bookmark this page URL Thanks!