30 November 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.

29 November 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.

28 November 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.  

27 November 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.

26 November 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.

23 November 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: sequeira Distant, 1885
Wingspan of Adult Butterfly: 31-35mm
Caterpillar Local Host Plants: Mangifera indica (Anacardiaceae, common name: Mango), Hibiscus tiliaceus (Malvaceae), Syzygium zeylanicum (Myrtaceae), Mallotus paniculatus (Euphorbiaceae, common name: Turn-in-the-wind) and Saraca thaipingensis (Fabaceae, common name: Yellow Saraca).

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.

21 November 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.

19 November 2013

Malayan Birdwing sighted again

Malayan Birdwing (Troides amphrysus ruficollis)
Another sighting of this giant birdwing!

Back in March 2011, I found the caterpillar of the Malayan Birdwing (Troides amphrysus ruficollis) at Alexandra Hospital. It was recorded as a re-discovery and species #301 in the Singapore Butterfly Checklist. After that, there appeared to be no reliable sightings of this gentle giant butterfly until now.

Last weekend, ButterflyCircle member Yong WH managed to encounter the Malayan Birdwing again! This time, a male was spotted perched on some leaves of the Fishtail Palm, taking a rest. It is hoped that with more schools and gardens cultivating one of its host plants, Aristolochia acuminata, this magnificent Birdwing will fly in our Singapore skies again.

16 November 2013

Butterfly of the Month - November 2013

Butterfly of the Month - November 2013
The Lime Butterfly (Papilio demoleus malayanus)

A two-in-one shot, showing the upper and under side of the Lime Butterfly

The month of November is upon us all too soon! The 2nd of November 2013 saw the 400,000-plus Indian community in Singapore celebrating Deepavali (or Diwali, which marks the beginning of the Hindu New Year according to the Lunar Calendar. Also known as the Festival of Lights, Deepavali celebrates the victory of Goodness over Evil and Light over Darkness - as it ushers in the new year.

Over in the Philippines, what is believed to be the strongest tropical cyclone ever recorded to make landfall struck the areas covering Biliran Island, Eastern Samar, Leyte, northern Cebu, Samar, Southern Leyte and Luzon. The city of Tacloban in Leyte was badly hit by the 310 km/hr winds, and the estimates of casualties numbered in the thousands. The category 5 "super typhoon" Haiyan has come and gone, leaving entire communities decimated in its wake and the survivors have just begun the potentially long and traumatic process of getting their lives back to normalcy again. Our sympathy and prayers go to all those affected.

One wonders if these extreme weather phenomenon that we experience today is attributed to the process of climate change and global warming? Even in Singapore the weather patterns that have changed over the past few years leaves one wondering if the designs of our infrastructure and buildings would be able to withstand the onslaught of heavy rains and strong winds. Already, unprecedented flash floods in some areas of Singapore have required the government departments to expedite the drainage works to accommodate the inundation of our little island with the intensity and volume of rainfall rarely encountered in the past.

And there will certainly be the debates on whether the extent of deforestation in many countries will continue to increase, leaving the cleared land even more vulnerable to extreme weather conditions. Singapore, our little 712 sq km island nation has been spared natural disasters like typhoons, tsunamis and earthquakes so far. But if we were to be affected one day, will we be ready?

Over to our Butterfly of the Month for November, we feature the humble and common urban butterfly, the Lime Butterfly (Papilio demoleus malayanus). Attractively coloured with black and pale yellow markings on the upperside forming an irregular band running from the forewings to the hindwings. The underside is pale yellow with black markings. Both sexes are mostly yellow with black streaks and irregularly-shaped spots. On the hindwing, several black spots are lined with blue striae. There is a series of orange post-discal bars on both hind- and forewings.

The sexes are very similar. The distinguishing characteristic can be found in space 1b on the hindwing. There is a red spot in both sexes. In the male, this spot is capped with a narrow blue lunule with a very narrow intervening black gap. In contrast, the red spot and the blue lunule in the female have a rather large black spot between them. Like in all Papilionidae, the Lime Butterfly has all six legs fully developed. The eyes are 'opaque' and jet black.

The Lime Butterfly is a fast flyer and its rapid and erratic flight makes it very challenging to shoot whilst in flight, although not impossible. There have been excellent shots taken by ButterflyCircle members where the Lime Butterfly was photographed in mid-flight whilst feeding on flowers. At times, the butterfly stops to rest amongst shrubbery, either with its wings folded upright, or opened flat to sunbathe.

A Lime Butterfly feeding on the flowers of Lantana

It is common in urban areas where its caterpillar host plants - mainly the Citrus spp., are cultivated. It has several alternative host plants, largely from the Rutaceae family. Even the Indian Curry Leaf plant (Murraya koenigii) is one of the Lime Butterfly's host plants. The complete life history of the Lime Butterfly has been recorded here.

We have had reports of caterpillars found on a potted Citrus plant on the 13th storey of a high rise apartment in Singapore. The owner was quite certain that the plant was over a year old (implying that the caterpillars were not stowaways on a new plant and brought up to that height) and placed along the common corridor of the apartment, suggesting that the visiting female Lime Butterfly flew up to that height (about 40m high) to oviposit on the host plant.

A male Lime Butterfly puddling on damp sand in the nature reserves

The Lime Butterfly can be found in parks and gardens, often seen feeding on Lantana and Ixora flowers, flying rapidly amongst the greenery. It is sometimes observed at the fringes of the forested nature reserves and even in the nature reserves. Males of the species have been observed to puddle at the sandbanks of forest streams, in the company of other Papilionidae, Pieridae and Lycaenidae butterflies.

Text by Khew SK : Photos by Sunny Chir, Khew SK, Henry Koh, Loke PF, Bobby Mun, Nelson Ong, Nona Ooi & Anthony Wong

14 November 2013

Butterflies Galore! : Metallic Caerulean

Butterflies Galore!
The Metallic Caerulean (Jamides alecto ageladas)

This Lycaenid was re-discovered by ButterflyCircle members in 2008 when a colony of the species was found at the now-gone Mandai Orchid Garden. As the caterpillar of this species feeds on the flower of the Torch Ginger, several other colonies of the Metallic Caerulean have been found since. A translocation attempt at the Zoo was also successful, and the species can also be found at the Zoo today.

Males have a black diffuse border on the forewing above whilst the females have the forewing border extending narrowly along the costa to the base. The upperside is a bright metallic light blue. The species has many lookalikes in the genus. This Metallic Caerulean was photographed by young ButterflyCircle member Jonathan Soong.

12 November 2013

Butterflies Galore! : Tree Yellow

Butterflies Galore!
The Tree Yellow (Gandaca harina distanti)

The Tree Yellow is the only representative of the genus Gandaca in Singapore and Malaysia. It is distinctive in that the underside is completely unmarked. On the upperside, except for a narrow black marginal border on the forewing, the colour of the butterfly is a plain lemon yellow throughout. When it flight, it could sometimes be mistaken for one of the several Grass Yellow (Eurema) species, but its lighter lemon yellow and generally larger size usually distinguishes it from the others.

This shot shows the Tree Yellow puddling (imbibing salts from damp sand) in the nature reserves. Although common, the species is usually associated with the forested areas in the nature reserves and is seldom seen in urban gardens and parks. At times, several individuals are observed puddling together.

09 November 2013

Life History of the Common Dartlet

Life History of the Common Dartlet (Oriens gola pseudolus)

Butterfly Biodata:
Genus: Oriens Evans, 1932
Species: gola Moore, 1877
Sub-species: pseudolus Mabille, 1883
Wingspan of Adult Butterfly: 22-27mm
Caterpillar Local Host Plants: Ottochloa nodosa (Poaceae), Axonopus compressus (Poaceae, common names: Wide-leaved Carpet Grass, Cow Grass), Centotheca lappacea (Poaceae, common name: Sefa).

Physical Description of Adult Butterfly:
On the upperside, both sexes are dark brown with yellowish orange post-discal bands on both fore- and hindwings. The forewing band stretches from the dorsum to almost touching the costa, and is deeply excavate at vein 5. On the underside, the wings are yellowish-orange with post-discal bands mirroring those on the upperside. These bands are roughly defined by varying degrees of black shading.

Field Observations of Butterfly Behaviour:
This small and fast flying skipper is common in Singapore and can be found in parks, gardens and the nature reserve. At these locations, the adults can be seen enjoying the sun in sunny condition, typically in grassy areas or low shrubs. They visit flowers for nectar and puddle on wet ground or even bird droppings for mineral intake.

07 November 2013

Butterflies Galore! : Common Rose

Butterflies Galore!
The Common Rose (Pachliopta aristolochiae asteris)

This pretty swallowtail is very local in distribution, and oftentimes found in the vicinity where its caterpillar host plant, Aristolochia acuminata can be found. It is widely distributed, and can be seen in urban parks like the Singapore Botanic Gardens and Hort Park, as well as in forested areas and offshore island like Pulau Ubin. The crimson red body and marginal spots on the hindwing is a display of aposematic colouration that warns predators that it is distasteful.

This shot, taken by ButterflyCircle member Nelson Ong, shows a Common Rose puddling - a rather rare phenomenon in Singapore, where the butterfly is more often seen fluttering and feeding at flowers, rather than puddling.

05 November 2013

Butterflies Galore! : Banded Swallowtail

Butterflies Galore! 
The Banded Swallowtail (Papilio demolion demolion)

This fast-flying swallowtail can be common at times. Last Sunday, I was out with young ButterflyCircle member Jonathan Soong, when we saw at least four individuals chasing each other at a flowering bush in the nature reserves. The Banded Swallowtail is usually fast-flying and skittish, but after a bout of vigorous activity and feeding, they are often observed to stop for a break with their wings open flat on the topside of leaves.

Jonathan was able to take a shot of this Banded Swallowtail when it stopped to take a breather. The pale green band on the wings are well-exposed in this shot. Usually, our shots tend to be overexposed due to the contrast between the black wings and this pale green band, giving the band an almost white appearance.

03 November 2013

Two More Nymphalidae Make it 308!

Two More Nymphalidae Make it 308!
Additions to the Singapore Butterfly Checklist

Horace Tan shot this mysterious orange butterfly in the nature reserves

Whilst out on a leaf-run to document the early stages of a Papilio species, ButterflyCircle member Horace Tan spotted a relatively large fast-flying orange butterfly fluttering around at the tree tops. Unable to get close for a better shot, Horace took an 'insurance' shot from afar.  For a moment, the orange butterfly may have been a male Cruiser (Vindula dejone erotella)

A zoomed in shot showing the mystery butterfly

Upon reaching home, Horace zoomed it on the orange butterfly and it didn't look anything like the Cruiser. The highly cropped shot shown above suggested that it was something that has not been seen for a long time in Singapore. Referring to Butterflies of the Malay Peninsula 4th Edition by Corbet & Pendlebury (C&P4), the butterfly looked very similar to the Malay Yeoman (Cirrochroa emalea emalea)

A shot of a Malay Yeoman taken in Malaysia for comparison

Scrutinising the details of the cropped shot, the underside of the butterfly matched the Malay Yeoman. The forewing discal band which is narrow at the dorsum and widens significantly at the costa can be clearly seen. The distinguishing constriction of the discal band on the hindwing in spaces 5 & 6 can also be seen in the shot, confirming that this species is indeed the Malay Yeoman!

Upperside of the Malay Yeoman (shot in Malaysia)

Further reference to C&P4 indicated that the Malay Yeoman was marked [S] designating it as a "species which, so far as known, have not been taken again in Singapore during the present century". (Note that the present century meaning the 20th century as the 4th Edition of the book was updated in 1992). This species is described as fulvous orange above, with a black distal margin. We now record is as species #307 in the Singapore Butterfly Checklist. As it is a common species in Malaysia, observers should continue to look out for it in the Central Catchment Nature Reserves in Singapore, where Horace Tan saw this species.

An Angled Castor with partially opened wings shot recently in the nature reserves in Singapore

Another species that surprised members of ButterflyCircle on our regular weekend outing on 12 Oct 2013 was the Angled Castor (Ariadne ariadne ariadne). The species has reddish brown upperside traversed by sinous black lines and having a prominent white subapical streak on the forewing. The Angled Castor is described as local and found in forest clearings.

Another shot of the same Angled Castor with wings folded upright

Indeed, ButterflyCircle members Simon Sng and Loke PF came across this species at a forest clearing where other species were present due to the mass fruiting of the Singapore Rhododendron (Melastoma malabathricum). Both photographers managed to take a few shots of the Angled Castor before it made its way to the treetops and disappeared.

A record upperside shot of the same individual showing the subapical white spot on the forewing

The shots shown here confirmed the existence of the Angled Castor beyond any doubt. The single black line just beyond the cell end and the white subapical spot on the upperside and underside of the forewing validates the identity of the Angled Castor. The other likely species that occurs in nearby Johor in Malaysia, is the Malay Castor (Ariadne isaeus isaeus). However, this species is described as having a narrow, zigzagged orange brown band just beyond the cell end of the forewing, and without a white apical spot.

A similar-looking species, the Malay Castor (Ariadne isaeus isaeus) taken in Panti Forest, Johor, Malaysia.  Note no subapical white spot, and the orange-brown band beyond the cell area

Again, a species that was encountered in the forested nature reserves of Singapore suggests that there may still be more surprises in our forests that have yet to be discovered. The Angled Castor is considered a re-discovery, as the C&P4 checklist indicates this species as extant in Singapore. The importance of our central catchment core cannot be overstated, as it is a critical sanctuary to a diverse range of floral and faunal biodiversity in Singapore.

An Angled Castor shot in Penang, Malaysia for comparison

The Angled Castor is added to the Singapore Butterfly Checklist as species #308. It is hoped that these two species will continue to be spotted in Singapore even though at the moment, they would be considered 'seasonal visitors'. However, given the period that both have been spotted in Singapore, the postulation that these species may have been carried over by the prevailing winds from Malaysia may be unfounded. This is because the prevailing winds in the months of mid-Aug to Oct 2013, are largely from the south-west!

The Singapore Butterfly Checklist is hence updated to 308 species as at end Oct 2013. There are a number of Hesperiidae and Lycaeninae which are currently under investigations and will be added to the Singapore Checklist by the end of this year when all the validations are complete.

Text by Khew SK : Photos by Khew SK, Loke PF, Simon Sng & Horace Tan

References :

  • [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society, 1992
  • Butterflies of West Malaysia & Singapore, WA Fleming, 2nd Edition, 1983
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012