Pulau Semakau Butterfly Survey

Pulau Semakau Butterfly Survey - Dec 08



ButterflyCircle was invited to participate in the biodiversity survey of Pulau Semakau as part of the Semakau Book Project, an initiative of the National Environment Agency. The book project is expected to document the various flora and fauna that exists and thrive on the 350Ha landfill for waste disposal.



On 20 Dec 2008, a group of ButterflyCircle members, together with 2 NParks staff and our energizer-bunny nature expert, Ria Tan, met at the West Coast Ferry Terminal for the boat to take us to Pulau Semakau. After a quick security check, we boarded the boat, and were on our way to Singapore's only landfill for waste disposal. The boat was fast, and we were told that a larger ferry would normally take slightly more than half an hour to reach Pulau Semakau. But our fast boat delivered us to the Semakau Jetty in 20 mins flat!


Filling up forms on the boat, and arrival at Semakau!

Upon arrival, we were briefed by Ria on the island and the friendly NEA staff was on hand to further tell us all about the operations of the facility. The group was also fortunate to have the bus on hand, and we were shown around the island from the comfort of an airconditioned bus. The landfill capacity was 63 million m3 and is expected to meet Singapore's need for landfill space beyond the year 2045.

Ria briefing the group on where we would be going, and what to expect on the island

More interesting anecdotes by Ria, and ButterflyCircle members' guns out and ready to go!

At the southernmost tip of the landfill, we stopped at a weather monitoring station and had a group photo taken to commemorate ButterflyCircle's first trip to Pulau Semakau. It was a hot, sunny and windy day!

From L to R : Mark , John , Ben Jin, Khew, Jacqueline, Ria, Benedict, Wong, Bobby, Chung Pheng, Keneric and Anthony

It was extremely windy, and we were surprised to encounter a few Blue Pansys, Lesser Grass Blues and Palm Darts.. It was a pleasant surprise to see butterflies on this little island, as I did not expect to see any butterflies on this little island so far south from Singapore. How did these butterflies end up here? Perhaps with the plants that were delivered to the island? We may never know for sure. But the Palm Darts which were zipping around, kept returning to the coconut palms, suggesting that this may be their host plant.


The wind was blowing strongly!

Shooting each other... but where's the butt??

After we were dropped off at the western part of the island where there was a patch of mangrove swamp, and vegetation, presumably from the original Pulau Semakau, before the rock bund was constructed to combine Semakau and Pulau Sakeng to form the current landfill island.


Coastal mangrove habitat

Over on the coastal side, there were two main habitats - the coastal mangrove environment, and shaded forested mangrove areas. Across from this patch of forest, were the landfill cells - one of which had been filled, and grasses and vegetation had begun to re-generate in this cell. This formed the third habitat, one of open grassland and secondary growth.


Forested back-mangroves - and mosquito-infested country!



Open grassland habitat

ButterflyCircle members then proceeded to cover the small area to look for butterflies. Surprisingly, at the end of the trip, we counted no less than 18 species of butterflies! This had far exceeded our expectations of the butterfly fauna of this island. Of particular interest, was the discovery of the Two Spotted Line Blue (Nacaduba biocellata) here! This species was a recent discovery in Singapore and reported in the Blog here, where the species, a common butterfly in Australia, was first found in Singapore. How it came to be on Semakau is a very interesting mystery. There may be more species than our very short survey had observed, and a second survey is on the cards soon.

All shacked out after a long hot day out looking for butterflies


Checklist of Butterflies Observed at Pulau Semakau on 20 Dec 2008.
  1. Common Grass Yellow (Eurema hecabe contubernalis)
  2. Common Tiger (Danaus genutia genutia)
  3. Black Veined Tiger (Danaus melanippus hegesippus)
  4. Blue Glassy Tiger (Ideopsis vulgaris macrina)
  5. Tawny Coster (Acraea violae)
  6. Perak Lascar (Pantoporia paraka paraka)
  7. Autumn Leaf (Doleschallia bisaltide bisaltide)
  8. Great Eggfly (Hypolimnas bolina bolina)
  9. Blue Pansy (Junonia orithya wallacei)
  10. Common Palmfly (Elymnias hypermestra agina)
  11. Centaur Oakblue (Arhopala centaurus nakula)
  12. (Hypolycaena thecloides thecloides)
  13. Long Banded Silverline (Spindasis lohita senama)
  14. Two Spotted Line Blue (Nacaduba biocellata)
  15. Tailless Line Blue (Prosotas dubiosa lumpura)
  16. Lesser Grass Blue (Zizina otis lampa)
  17. Palm Dart (Telicota augias augias)
  18. Palm Bob (Suastus gremius gremius)





Text by Khew SK ; Photos by Khew SK, Benedict Tay, Bobby Mun, Mark Wong, Wong CM and Jacqueline Lau.

Relevant Links :

Another Exotic Visitor Reaches Singapore's Shores

The Indian Red Admiral lands in Singapore


Around this time last year, Singapore had an American "Lady" visiting us. The Painted Lady (Vanessa cardui) was seen at three separate locations in Singapore and successfully photographed by ButterflyCircle members.


It was therefore without much surprise that again, another similar-looking butterfly was seen again near the same location where the Painted Lady was spotted last year. It was photographed on 23 Dec 08 by ButterflyCircle member James Chia, and then on a subsequent day by Sunny Chir and Federick Ho.




However, upon closer scrutiny, this was no American visitor! The species was confirmed to be the Indian Red Admiral (Vanessa indica indica Herbst, 1794), a close relative of the Painted Lady!



Described on Wikipedia as being "found in the higher altitude regions (above 2000 feet) of India including the Nilgiri hills in southern India. It also occurs on smaller hill ranges in Peninsular India such as the Nandi hills near Bangalore", it again poses another mystery of how it got this far south to Singapore! Another website records it as "East and South Asia, and also the Canary Islands and Madeira; migrates actively northwards and appears regularly in SE Siberia (up to Kamchatka)." It has also been reported from Thailand, Taiwan, Hong Kong and mainland China and as far east as Japan.




As the local butterfly parks are not known to feature this species as part of their live collections, it is unlikely to have been an escapee from these facilities. Whilst it could have been introduced by human agency or accidentally stowed away on a ship that was passing this way, the Indian Red Admiral belongs to a genus of butterflies that is known for their strong migratory tendencies with large flight ranges, and it would not be totally impossible that this species somehow flew all the way here from the Indian SubContinent! It could also have come from Thailand, the nearest neighbouring country where the species is known to exist. But whatever the case may be, Singapore records a new species in the Checklist with this single specimen of the Indian Red Admiral.




On the Butterflies of Sri Lanka website, the Indian Red Admiral is reported to be "... an active butterfly that may be seen day after day in the same location". This habit appears to have held true, as the same individual was seen over 3 days at an urban hill park in Singapore.

The Indian Red Admiral resembles the Painted Lady but the ground-colour is darker both on the upper and under sides, and the orange markings deeper and richer. A medium sized dark gray brown butterfly with reddish orange and white markings. The forewing has orange patches forming a post-discal band, and white apical and subapical spots. The hindwing above is mainly light brown with a series of black submarginal spots on an orange submarginal band. The underside has a blotched appearance with many shades and patterns of brown and gray.



It has a strong flight, and may be territorial, but often stops to feed. It is observed to be partial to human perspiration and has been noted to settle on humans to feed on sweat.



The caterpillars of this species are known to feed on nettles (Family : Urticaceae).


So Singapore welcomes the Indian Red Admiral and has species #285 recorded in its Checklist. It is not known where the individual has flown to, or whether it has ended up in the stomach of a hungry predator or it may have continued its journey southwards. But we hope that we will continue to get visits from these strong migratory visitors during the North-East Monsoon season, where the northern winds may carry unexpected butterflies to our little Red Dot of an island in the sun!



A fitting end to the butterfly biodiversity in Singapore for 2008!

Happy New Year! : )

Text by Khew SK ; Photos by James Chia, Sunny Chir and Federick Ho

References :

Life History of the Fulvous Pied Flat

Life History of the Fulvous Pied Flat (Pseudocoladenia dan dhyana)



Butterfly Biodata:
Genus: Pseudocoladenia Shirôzu Saigusa, 1962
Species: dan Fabricius, 1787
Sub species: dhyana Fruhstorfer, 1909
Wingspan of Adult Butterfly: 34mm
Caterpillar Host Plants:
Cyathula prostrata (Amaranthaceae)


A male Fulvous Pied Flat sunbathing in the late afternoon.


A male Fulvous Pied Flat visiting a flower of Asystasia gangetica in a forest clearing.


A newly eclosed female Fulvous Pied Flat.

Physical Description of Adult Butterfly:
Both sexes have reddish brown wings on both under- and uppersides. The forewing has a dark submarginal fascia, and the hindwing is traversed by irregular lines composed of dark, diffuse spots. The male has two large, yellow, hyaline spots at the end of the forewing cell, which are conjoined to form a single, outwardly deeply indented spot, and there is a small spot above it in space 11; in addition there are rather large spots in spaces 2 and 3, and small subapical spots in spaces 6, 7 and 8. The female has the same set of spots but most of these are smaller than those present in the male, and the lower cell spot may be absent.


A sequence of three shots of a male Fulvous Pied Flat with the main light source shifted
from front to back to show the hyalinity of the forewing spots.

Field Observations of Butterfly Behaviour:
This species is rarely encountered in Singapore. Sightings are restricted to sites in the Central Catchment Nature Reserves where the host plant can be found. The adults are fast-fliers and can only be observed when they stop to feed on flowers and bird dropping, or when the females are carrying out oviposition routines of leaf hopping. When resting, as with other "flat" skippers, adults have the habit of perching on leaf undersides.

Early Stages:
The host plant, Cyathula prostrata (common names: Hookweed, Nyarang, 倒扣草 , 杯苋), is a creeping and straggling to more or less erect herb. It has opposite, hairy leaves which are oblong or rhomboid in shape. Flowers occur in clusters of 1-3 on spikes. This plant has a wide distribution and can be found in Asia, Australia, Africa and tropical America. Parts of the plant are used as food and medicines for diarrhoea, dysentery, pain-relief etc. Locally, this plant can be found in waste places, forest margins and alongside trails in the northern and western catchment reserves. All early stages of the Fulvous Pied Flat feed on the leaf lamina of the host plant and retreat to their leaf shelters between feeds. Typically, they rest in a curled-up posture within the shelter.


Host plant : Cyathula prostrata. Left: side view of leaves. Right: top view, note one small leaf shelter.


Host plant : Cyathula prostrata; close-up on flowers in the right panel.

The eggs are laid singly on the upperside of a leaf. Each egg is red to pink when freshly laid, but decolorize to white as it matures. It is dome-shaped with vertical ridges, and has a diameter of 0.7mm. Eggs of the Fulvous Pied Flat are not concealed in a mess of fine hairs as is typical for a number of "flat" skippers such as the Chestnut Angle.



Two views of an egg of the Fluvous Pied Flat. Diameter: about 0.7mm


Left: mature egg with the caterpillar ready to emerge Right: empty egg shell.

It takes 4 days for the egg to hatch. The young caterpillar eats just enough of the shell to emerge, and has a length of about 1.8mm. Its cylindrical-shaped body is reddish orange, one red dorso-lateral line along each side of the body, and has a transverse black line right behind a black bilobed head.
After leaving the egg shell, the 1st instar caterpillar makes its way to the leaf edge to construct its first leaf shelter. It rests within the shelter and ventures out to eat the leaf surface nearby. The intake of this diet gives the caterpillar a greenish undertone.


1st instar caterpillar, newly hatched, length: 1.8mm

After 4 days in 1st instar and reaching a length of about 3mm, the caterpillar moults to the next instar within the shelter. It has a light yellowish body with a green undertone. The anal plate has a darker patch on it. The caterpillar reaches a length of about 4mm after 4 days of growth in this instar.


Leaf shelters for Fulvous Pied Flat in the field. Top: 1st instar; Bottom: 2nd instar.


2nd instar caterpillars. Top: 3.5mm. Bottom: late in this stage, 4mm

The 3rd instar caterpillar has a similar appearance as in the previous instar except for a faint dorsal line, and two thin white dorso-lateral lines running the sides of the body. The 3rd instar lasts about 5-6 days with the body length reaches 8mm.



3rd instar caterpillar, length: 6mm


3rd instar caterpillar, late in this stage, length: 8mm

The 4th instar caterpillar looks similar to the earlier instars with the only visible difference being the distinctive white speckles on its body and more distinctive dorso-lateral lines. The 4th instar takes about 6-7 days to complete with the body length reaching 12-14mm.


An early 4th instar caterpillar found feeding on the host plant in the nature reserves.


4th instar caterpillar, length:14mm.

The final and 5th instar caterpillar is similar to the 4th instar caterpillar. The head capsule is dark reddish brown, and its surface is rough and covered with a layer of short fine hairs. This final instar takes about 7 days to complete with the body length reaching about 18-20mm.


Two views of the head capsule of a 5th instar caterpillar.


5th instar caterpillar, length: 20mm

Towards the end of 5th instar, the body of the caterpillar gradually shrinks in length and decolorizes to a milky yellow color. Soon it becomes dormant in its leaf shelter and enters the prepupatory phase which lasts for one day.


Two views of a pre-pupatory larva of the Fluvous Pied Flat.

Pupation takes place within the leaf shelter. The pupa secures itself with its cremaster attached to a short transverse band on the leaf surface, and has a silk girdle. The lightly hairy pupa is mostly green in base colour but with abdominal segments mostly in white. It has a short thorax and a rather long abdomen.
There is also a pair of small dark brown projections on the anterior part of the mesothorax. Length of pupae: 14.5-16.5mm.


Top: a pre-pupa very close to the pupation event.
Middle and bottom: Two views of a fresh pupa of the Fluvous Pied Flat.

After 6-6.5 days, the pupa becomes mostly dark brown in color with the spots on the forewing somewhat distinguishable through the now transparent pupal skin. Eclosion takes place the next morning.


Two views of a mature pupa of a male Fluvous Pied Flat.


A newly eclosed male Fluvous Pied Flat drying its wings near its pupal case.


A newly eclosed female Fulvous Pied Flat

References
  • The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.

  • The Butterflies of Hong Kong, M. Bascombe, G. Johnston, F. Bascombe, Princeton University Pres 1999

Text and Photos by Horace Tan