27 January 2019

Return of the Angled Castor

Return of the Angled Castor
Angled Castor Colonises Ubin!

An Angled Castor perches on a blade of grass with its wings opened flat to sunbathe

Some time back in mid-Oct 2013, a solitary individual of the Angled Castor (Ariadne ariadne ariadne) was spotted in the Mandai forests in the northern part of the Central Catchment Area. Recorded as a re-discovery over 5 years ago, there were no further sightings of this species thereafter. Until recently, that is. Late last year, the Angled Castor was observed on Pulau Ubin.

A skittish Angled Castor beats a hasty retreat from its perch on a leaf of its caterpillar host plant, Castor Oil Plant (Ricinus communis)

Then there were more sightings of this species and the pristine condition of the individuals spotted suggested that they were not chance observations of seasonal migrants. This led to the theory that the Angled Castor had somehow managed to sustain a breeding population and that a colony of the species has established itself on Pulau Ubin.

A large grove of the Castor Oil Plant can be found on Pulau Ubin

Locating this colony was not too difficult, as the Angled Castor is not a rare species in Malaysia and Thailand, where the species can be locally common where it occurs. The key is to look for its preferred caterpillar host plant called the Castor Oil Plant (Ricinus communis). There is a site on Pulau Ubin where after clearance, the Castor Oil Plant grows in abundance.

An Angled Castor perched on a blade of grass in the early morning hours

When we visited this area on Pulau Ubin over the weekend, we found that a small colony of the Angled Castor had established itself in the vicinity of the host plants. A rough estimate of at least 30 adults and caterpillars were counted. Two adult female Angled Castors were even observed ovipositing on its host plant.

The leaves of the caterpillar host plant, Castor Oil Plant, reminds us of tapioca leaves

Firstly, let us consider the caterpillar host plant, the Castor Oil Plant. It has been described as an invasive species that colonises wastelands and cleared areas that have been neglected. It tends to form monospecific stands at the expense of other species of native plants and can displace other species due to its aggressive growth and the way the seeds can be distributed. In terms of plant biodiversity, it is considered an unwelcome "weed" that needs to be managed or eradicated.

Flowers, fruits and seed pods of the Castor Oil Plant

The Castor Oil Plant has a reputation of being a noxious weed and its seeds, if chewed and ingested, can have potentially fatal consequences to humans and animals. One deadly toxin, the notorious ricin is extracted from its seeds. Having been used as a terrorism weapon will not help its case! Furthermore, its commercial value of having the seed oil extracted for a variety of uses from cosmetics to lubricating oil and biodiesel does not exist in Singapore. Hence the plant faces the risk of being managed out of the eco-system in favour of other more useful plants.

A female Angled Castor ovipositing on the underside of a leaf of the Castor Oil Plant

Let us come back to the butterfly that depends on this plant of "ill-repute" for its survival, the Angled Castor. It is likely that a female of the species flew over from nearby Johor where it exists, and managed to oviposit on the host plants that grows on Ubin. That chance moment then started the next generations of individuals that now populate this area of Pulau Ubin.

An Angled Castor sunbathing on the top of a leaf

Besides the potential eradication of its caterpillar host plants, what are the other risks to the continued sustainability of the colony of this species in Singapore? Firstly, genetics should be considered. Will this very localised colony suffer from in-breeding and wipe itself out after a few generations? It is known that some species of butterflies are more vulnerable to in-breeding than others. If there are no new genetic material coming into Singapore from up north, can this colony survive?

Different instars of the Angled Castor's caterpillars found on the Castor Oil Plant on Pulau Ubin

What about predation? Given that the caterpillars and butterflies of this species are not known to be distasteful to birds and other predators, the delicate existence of this colony may also be wiped out by predation. The caterpillars are also in full view of areas with human activity and may be deemed as pests and eradicated.

Angled Castors appear to favour the flowers of this grass species for its nectaring source

Whilst observing the adult butterflies, they appear to be depending on their sustenance from the flowers of a particular species of wild grass. Several adults were seen feeding on the grass flowers. Other individuals were puddling on the damp muddy areas at the site. Whilst there are areas nearby with nectaring flowers, the Angled Castor has not been seen beyond the confines of this small area, nor to feed on other flowering plants so far.

The Angled Castor is the sole representative of the subfamily Biblidinae of the family Nymphalidae in Singapore. The butterfly is dark reddish brown with thin black squiggly lines on the upperside of its wings. There is a prominent white sub-apical spot on the upperside and underside of the forewing. The underside is a duller brown and similarly streaked with black lines but having a more 'banded' appearance in the darker areas between the lines.

The butterfly superficially appears like the Chocolate Pansy (Junonia hedonia ida) and is equally as skittish. Males of the Angled Castor have been observed to engage in 'dogfights', probably in their quest for territorial space. From our observations, the butterflies can fly for long periods of time with occasional stops to rest with their wings opened flat.

A newly-eclosed Angled Castor still hanging on to its pupal case

A puddling Angled Castor feeding on moisture along a footpath

At the Ubin site, several instars of caterpillars were found on a single host plant, suggesting that the eggs have been laid at different times over the past month or so. A newly-eclosed female was chanced upon, still hanging onto its pupal case. From the number of individuals observed this weekend - both pristine and tattered/weathered adults, it is obvious that the colony has been thriving at this location for the past few weeks, if not months.

An Angled Castor perched with wings folded upright, showing its undersides

For a species that is considered a "very rare" seasonal migrant to Singapore, it is now "very common" at this localised area on Pulau Ubin and from the breeding population, it can be now be assumed to be an extant species here. The status of various species can change from time to time, depending on circumstances and ecological and environmental changes that affect their existence in a country. It remains to be seen for how long this re-discovered species can continue to survive in Singapore, and whether natural or human-initiated threats affect this colony in the longer term.

Text by Khew SK : Photos by Khew SK, Loh Mei Yee and Tea Yi Kai.

20 January 2019

Blue Skies Above!

Blue Skies Above!
Butterflies Against a Blue Canvas

A Common Mime feeds on the pink hybrid of Lantana camara against a clear blue sky

The storm has passed. Dark clouds dissipate quickly, as the sun peeks through. The blue sky reappears as the foreboding darkness gives way to rejuvenating light and the world is bright and cheery again. The sight of a pretty butterfly against a clear blue sky is often uplifting and brings delight to our hearts.

A female Striped Blue Crow feeding on the flowers of Syzygium zeylanicum

The ominous darkness that brings sadness, grief, sorrow and pain to many aspects of our lives does not last forever. Whether at work or at home, such times of torment and trouble will come to pass, and the sunshine and blue skies will breathe healing, revival and positivity into our lives once again.

A Blue Glassy Tiger feeding on the flower of Syzygium zeylanicum

For us butterfly watchers and photographers, the sight of sunshine and a bright blue sky brings joy to our souls. For this is the type of weather that wakes up our beloved butterflies and where we will enjoy their fluttering activity and Mother Nature's beauty and works of art.

A Plain Tiger perches on a high twig

A male Plain Tiger (right) harassing a feeding female Plain Tiger

This weekends blogpost is about butterflies photographed against a blue sky - a canvas of blue that is a refreshing difference from the typical natural backgrounds and green environments that we normally see butterflies in.

Painted Jezebels feeding on high flowering plants against a clear blue sky

Ever so often, a tree blooms and the flowers attract a myriad of butterflies to feed on the delectable nectar within. In many cases, the flowers are way above eye-level, and the feeding butterflies are isolated against a bright blue sky on a clear day. This gives an opportunity to photograph the butterfly in a unique setting against a backdrop of the blue sky.

A Common Bluebottle high up at the flowers of Syzygium zelanicum

Somehow, a butterfly feeding against a blue background elicits a feeling of lightness and uplifts the spirit. The complementary colours of a butterfly's wings against the cool blue background bring the beauty of the butterfly to life.

A Common Rose feeding on the flowers of Buas-Buas (Premna serratifolia)

Never pass up an opportunity to photograph a butterfly against the backdrop of a clear blue sky whenever the situations arises. From a photographer's perspective, it is an ideal lighting situation as the brightness of the open skies usually allows you to use a low ISO that reduces 'noise' in your shots.

A Copper Flash on the flower of Syzygium zeylanicum

Remember that due to the bright background, your subject (the butterfly) will be in shadow if you are using a matrix (or average) metering mode. This will darken the subject and you may end up with a lack of detail on the butterfly although the background is correctly exposed.

A female Common Birdwing flies high up after feeding on the flowers of the Javan Ixora

For such photography situations, a fill-flash is almost always necessary to provide illumination to the wings of the butterfly against a bright background. In many cases, you may have to increase the power (compensate +EV) on the flash to adequately illuminate the butterfly. Alternatively, you may choose to use spot metering to correctly expose for the butterfly but this often ends up with an overexposed sky that is either washed out and even appear white!

A Dark Glassy Tiger feeding on the flower of the Water Jasmine (Wrightia religiosa) against a blue sky canvas

I find that using smaller apertures like f/10 or f/11 helps to increase the saturation of the blue sky when shooting upwards. Other than the fact that you will have good depth of field and will be able to get the subject in sharp tip-to-tip focus, the blue of the sky is also deeper and more saturated. In shooting situations like this, you will not have to worry about the background being cluttered as the sky is obviously very far away from your subject butterfly.

A King Crow feeding on the flower of Syzygium zeylanicum

Shooting a butterfly against a clear blue sky also frequently shows up 'dust bunnies' on your camera's sensor, especially if you have not been cleaning the sensor for some time. This does not pose a big problem that a little post-processing cannot solve. But it is a good reminder for your next trip to the camera servicing agent to do some sensor maintenance!

A Common Tree Nymph soars high amongst the treetops with the blue sky in the background

So when the opportunities present themselves when you are out in the field, look for situations where you can pose your butterfly subject against the blue sky and fire away! Let your butterfly spirit soar and enjoy the exhilaration of capturing the beauty of nature's flying jewels against a crystal clear blue backdrop.  And to all our fellow butterfly watchers and photographers, may you always have sunshine, blue skies and beautiful butterflies all year round! 

Text by Khew SK : Photos by Bob Cheong, James Chia, Khew SK, Loke PF, Mei Hwang and Neo TP

12 January 2019

Butterfly of the Month - January 2019

Butterfly of the Month - January 2019
The Coconut Skipper (Hidari irava)

A pristine Coconut Skipper perches on a leaf in a shaded spot

The new year slipped quietly by as we bade farewell and good riddance (as far as some of us are concerned!) to 2018. New Year resolutions are made and book-marked; some filed away whilst others are pursued with enthusiasm and determination. Another year starts and we look ahead for brighter days - for our families, work, and especially our butterflies.

Strangely, it has been a similar situation for butterflies globally - a consistent comment from enthusiasts and butterfly-watchers that the numbers of butterflies seem to be dwindling all over the world. Or at least not as many as in previous years. Just last week, a report from the Xerces Society highlighted that the overwintering Monarch butterfly population in California plunged by 86% !

Let's hope that the butterfly populations recover naturally. But with intensive development and thoughtless destruction of habitats, the prognosis is pretty bleak. Conservation efforts are few and far between, even though there are individuals who are still working hard behind the scenes to make a difference to stem the downward trends of butterfly diversity and numbers.

In Singapore, there are small groups of enthusiasts who are helping to post butterfly photos on social media in an attempt to showcase these beautiful insects to the world. Every small attempt to educate and get more people to appreciate butterflies would be a step forward in helping to conserve them.

When taken without a flash in natural lighting, the wings of the Coconut Skipper appear a drab brown

Those of us who are working with the communities to set up butterfly gardens, and with the National Parks Board to create butterfly-friendly habitats are doing our bit to try to conserve butterflies for future generations to enjoy. But it is a constant battle with infrastructural development on our little land-scarce city state and the ever-mounting pressures for competing land use.

Our first Butterfly of the Month for 2019 is the humble and low-key Hesperiidae, the Coconut Skipper (Hidari irava). Even the common English name is simple and straightforward, that it is a Skipper and the fact that its caterpillars feed on the leaves of the Coconut palm (Cocos nucifera). It is one of the species of butterflies that is consistent wherever it occurs and the scientific name stops at the species level.

The Coconut Skipper occurs in urban parks and gardens, as well as in forested areas, particularly where its host plant, the Coconut Palm can be found. The species is a fast flyer but can often be observed perched on the tops of leaves or branches with its wings folded upright. The species is crepuscular, and when seen in the daytime, it is usually found at rest amongst the shrubbery in deep shade.

An opportunistic shot showing the upperside of a Coconut Skipper

The upperside of the Coconut Skipper is a rich dark brown with pale yellow hyaline spots on the forewing. The upperside of the hindwing is usually unmarked. The underside is predominantly pale buff brown with a faint purple wash in a sidelight. In pristine individuals, the purple sheen can appear quite prominent when photographed with a flash. The hindwing has a few post-discal spots and a white spot just above the cell. The forewing below has a series of dark sub-apical spots.

In a side light or with flash, the purplish sheen of the wings of the Coconut Skipper is obvious

The Coconut Skipper has deep red eyes and the apiculus and part of the club of the antennae is yellow. The cilia on fresh individuals is pale yellow on both wings.  All the six legs are developed, although when some individuals are perched, their forelegs are held tightly against its thorax, appearing that it is only standing on four legs. 

Text by Khew SK  : Photos by David Chan, Khew SK, Koh CH, Loke PF, Nelson Ong and Jonathan Soong

06 January 2019

Interesting Ubin Butterflies

Interesting Ubin Butterflies
Featuring 10 Butterflies on Pulau Ubin

Our first weekend blogpost for 2019 showcases 10 species of butterflies that are more often spotted on Pulau Ubin than any other location in Singapore. Some are not uncommon when they make a seasonal appearance, whilst others are rare and seen only once or twice on the island. Quite a few of the species featured in this article include newly discovered/re-discovered species for Singapore.

The male Malayan Birdwing (left) was spotted on Pulau Ubin, whilst the female was bred from a caterpillar found at Alexandra Hospital Butterfly Trail

Amongst the Papilionidae, two species are noteworthy. The first is the Malayan Birdwing (Troides amphrysus ruficollis). A re-discovered species that was first documented in 2011, a free-ranging male was photographed in late Nov 2013 on Pulau Ubin. Recorded as extant in the early authors' checklists, the Malayan Birdwing has not been seen in Singapore for a long time. The species is known for its wide flight range and the male spotted in Nov 2013 could have been aided by the North-easterly winds during the monsoon months of the year in this region.

A Common Jay feeding on the flower of the Buas-Buas bush at Pulau Ubin

A puddling Common Jay shot at Pulau Ubin in 2004

The second Papilionidae is the Common Jay (Graphium doson evemonides). A new discovery when it was first spotted in 2004, the species is regularly seen on Pulau Ubin. Given that its caterpillars can feed on a number of relatively common host plants on the island, the colony of Common Jay that currently still exists on the island is probably quite sustainable. Even as recent as in Jan 2019, a Common Jay was spotted feeding on the flowers of Lantana at Butterfly Hill.

A recent addition to the Singapore Checklist in 2018, the Orange Gull was spotted puddling at Pulau Ubin

A recent re-discovery amongst the Pieridae, is the Orange Gull (Cepora iudith malaya), that was spotted puddling on the island. Listed on the checklists of the early authors, this species has not been seen in the past three decades at least, until Dec 2018. Again, the theory that some of these strong-flying species were aided by the tail-winds of the North east prevailing winds could be true.

This female Wanderer was found near the Sensory Trail in 2011

Back in March 2011, a female Wanderer (Pareronia valeria lutescens) was photographed on Pulau Ubin. Although reports of the fast-flying males were made some time earlier, no reliable evidence of this species was available until this female was spotted perched on a leaf in the shady undergrowth. Again, considering the month that this species was found in Singapore, there could be a correlation with the North-easterly winds that are prevailing from around Dec to early March annually as defined by the Meteorological Services of Singapore website.

The Grey Glassy Tiger was observed at Butterfly Hill at Pulau Ubin

Amongst the Danainae, the Grey Glassy Tiger (Ideopsis juventa sitah) was discovered in Oct 2014. The robust Danainae, known for their toughness and migratory characteristics, are able to fly long distances and perhaps this individual made it to Pulau Ubin from up north. However, what is curious is that another individual was photographed at the Singapore Botanic Gardens in Jul/Aug 2015 that debunks any theory that these are wind-aided individuals that reached Singapore.

The Dwarf Crow is common and is regularly seen at Butterfly Hill on Pulau Ubin

The Dwarf Crow (Euploea tulliolus ledereri), first spotted on Pulau Ubin in 2002, continues to be regularly seen on the island and makes seasonal appearances where it can be considered common. Then it disappears altogether for several months and then re-appears again where up to five or six individuals can be observed together at nectaring plants on the island. Recorded as a re-discovery, the colony of Dwarf Crow is probably a sustainable population as it has been seen almost annually on the island.

The very rare Mangrove Tree Nymph made an appearance at Butterfly Hill at Pulau Ubin in 2013

One of our largest butterflies in terms of wing surface area, is the Mangrove Tree Nymph (Idea leuconoe chersonesia). This subspecies, which is mainly found in mangrove swamps in Malaysia, Singapore and Indonesia, is very rare and local. First observed during a survey of the butterfly fauna of Pulau Tekong, a Mangrove Tree Nymph was photographed on Butterfly Hill at Pulau Ubin in Jul 2013.

Spotted a number of times at Pulau Ubin, the Malayan Nawab was a re-discovered species for Singapore

The Malayan Nawab (Polyura moori moori) another re-discovery, has been spotted at least half a dozen times on Pulau Ubin. Given its similarity to the Plain Nawab (Polyura hebe plautus), it is likely that this species may have been missed earlier or misidentified as its commoner cousin. As recent as in Oct 2018, another individual was photographed again on Pulau Ubin. Thus far, the species has not been reliably seen on the main island of Singapore yet.

The White Banded Flat is a species regularly seen on Pulau Ubin but not elsewhere in Singapore

Amongst the Hesperiidae, another Ubin "resident" species is the White Banded Flat (Celaenorrhinus asmara asmara) which was first spotted in 2011. Unlike the vagrants or seasonal migrants, this species is extant on Pulau Ubin and a viable colony has existed till now. As recently as Jan 2019, the White Banded Flat has been spotted on the island.

The very rare Yellow Streak Darter was first discovered on Pulau Ubin in 2011.  Thus far, it has not been seen anywhere else in Singapore

The final species of the top 10 interesting Ubin butterflies is the Yellow Streak Darter (Salanoemia tavoyana). First discovered in 2011, this very rare species occurs on the island in a small localised colony. The caterpillars were found on the Mangrove Fan Palm (Licuala spinosa) and successfully bred to adulthood. However, the adult is rarely seen and prefers to lurk in heavily shaded vegetation.

There are likely to be several more species to be added to the Ubin list of unique and interesting butterflies, but that will be for another time.  Ubin is probably a convenient 'pit-stop' for migratory or stray butterflies coming from Malaysia, and more should be looked out for in future. 

Text by Khew SK : Photos by Bob Cheong, Federick Ho, Mei Hwang, Khew SK, Loh MY, Loke PF, Michael Soh, Horace Tan and Yong WH