05 April 2020

Lepidoptera exotica - Part 2

Lepidoptera exotica Pt 2 : The Vagrants
Exotic butterfly species in Singapore

The Indian Red Admiral, a medium elevation species, was spotted in Singapore at Mt Faber Park in 2008

In this 2nd part of exotic (or non-native) butterflies spotted in Singapore, we investigate a handful of species that has mysteriously appeared in Singapore, and then were not seen again, with long intervals between sightings. For some of these species, they were spotted only once and have not appeared since. Although they were added to the list of butterflies found in Singapore, they are considered "vagrants" or "strays" and will not be assessed under the IUCN guidelines in the forthcoming Singapore Red Data Book 3rd Edition.

The Red Helen is a common species in Malaysia, but has been reliably recorded only once in recent years in Singapore

In the animal world, a vagrant is described as "a migratory animal that is off course" or "an animal occurring beyond its normal range; an accidental or nomadic organism." This applies to butterflies that are found straying into an environment where they are normally not found, or beyond their normal known geographical range. They are classified as non-natives or exotics.

A solitary Red Spot Sawtooth was observed in the Central Catchment Nature Reserves in 2014

Vagrancy is characterised by these species' random and unpredictable appearance without any particular explanation or reason. This is opposed to what we refer to as "migrants" or "seasonal migrants" which appear from time to time during certain seasons, and repeatedly appear over a period of several years. Some even have colonies or extend their stay over several generations, before disappearing, and then re-appearing again.

The Great Jay was recorded puddling in the Central Catchment Nature Reserves in 2014

We take a look at some of these "vagrant" or "stray" species that have appeared and reliably recorded by observers over the years.

1) The Red Helen (Papilio helenus helenus)

The Red Helen is a common species in Malaysia, and at times, relatively large congregations can be found at their favourite puddling spots on moist sandy streambanks. Although it is usually associated with forested habitats, it has sometimes also been spotted in some urban parks and gardens in Malaysia.

Some time in 2014, a single Red Helen was photographed at the National University of Singapore area in Kent Ridge. It was feeding at the flowers of Ixora and there was no doubt about the identity of the Red Helen shot that day. How it came to be at that location remains a mystery, as this species has not be recorded in the early authors' checklists before.

A large Swallowtail, the Red Helen superficially resemble the two extant species in Singapore - the Great Helen and Blue Helen. However, the complete series of red ocelli on the marginal area of the underside of the hindwing instantly sets it apart from the other two species.

2) The Great Jay (Graphium eurypylus mecisteus)

Also spotted and photographed in 2014, a solitary Great Jay was spotted within the Central Catchment Nature Reserves. A relatively battered individual was observed puddling at a sandy streambank. This suggests that this wayward species could have made its way into Singapore on its own steam, as the Graphiums are known to be powerful flyers and are likely to travel long distances.

The Great Jay is relatively rarer than many of its related cousins, so it was a surprise that a stray ended up in Singapore. From all our contemporary records, it appears to be the only time this species has been found in Singapore. Fortunately, the photograph of this species was good enough to identify it without a doubt.

The Great Jay is almost indistinguishable from the closely related species. The distinguishing marking on the underside of the hindwing is the red-centred costal bar with is conjoined with the basal band. It is fast-flying and hard to identify if it had not stopped to puddle during the chance encounter back in 2014. Again it is considered another vagrant to Singapore.

3) The Red Spot Sawtooth (Prioneris philonome themana)

Another vagrant that visited Singapore, also in 2014, was the Red Spot Sawtooth. A powerful flyer and skittish butterfly, a Red Spot Sawtooth was spotted feeding at a flowering tree in the nature reserves in Singapore. Again, it stopped long enough for a photo to be taken and identified.

This vagrant species was observed only once in 2014 in Singapore

It was the only encounter of this species on record, and this vagrant has not been reliably seen or photographed again since then. The Red Spot Sawtooth is not uncommon in Malaysia, and I have encountered it many times in several parts of Malaysia, usually puddling along sandy streambanks with many other species of butterflies.

4) The Lesser Albatross (Appias paulina distanti)

Two records of the Lesser Albatross was documented in Singapore.  Both were females and probably strays

Two females of this species, the Lesser Albatross, were spotted. First in 2005 and then again in 2014. The 2nd record was of a dead individual found in the north eastern part of Singapore in an urban residential development. Species of the Pieridae are fast flyers, some of which are known to display migratory tendencies.

However, the chance or opportunistic encounters of this species have fortunately been able to definitively identify that these vagrants visited Singapore. In flight, it may be difficult to separate the Lesser Albatross from many of the local species and unlikely to be identified with great confidence.

A trio of male Lesser Albatrosses puddling in Malaysia

It is a relatively common species in Malaysia, often puddling at sandy streambanks with many other species of Papilionidae and Pieridae. Males tend to congregate in numbers and are locally common. They are often difficult to separate from many of the white and yellow species from the family and not easy to identify when in flight.

5) The Indian Red Admiral (Vanessa indica indica)

A single Indian Red Admiral appeared for 3 days at Mount Faber Park in 2008, and has never been seen again in Singapore since then

In 2008, an individual of the Indian Red Admiral was spotted at Mount Faber Park. This vagrant would have travelled for thousands of miles for it to appear here in Singapore! It has not been recorded in Malaysia and this is the first record of its appearance in Singapore. The nearest known location of this species is in northern Thailand.

A native of India and Indo-China, the Indian Red Admiral is described as a montane species, preferring elevations of above 1,000m ASL. The individual that was observed in Singapore stayed at the same location for 3 days, and sighted by different photographers.

Again, how it ended up in Singapore remains a mystery. The species has not been observed since then. Such is the mystery of nature, and many of our encounters with these vagrants and strays often bewilder us butterfly enthusiasts when we suddenly see a species that is totally new to Singapore.

Text by Khew SK : Photos by Sunny Chir, Khew SK, Loke PF and Mark Wong

29 March 2020

A Tale of Two Kings

A Tale of Two Kings
Featuring : The King Crow and Palm King

Two Kings amongst the Singapore butterfly fauna

Whenever the title of "King" is conferred to a person, a thing or an animal, it bestows on the holder a large measure of high regard or an expectation of being preeminent in its class. A King in the human world describes a ruler of people and territory - a leader, a sovereign or a monarch, inherited by birthright or by conquest. Used as an adjective, it suggests superiority over the normal, due to sheer size, influence or magnificence.

Various poses of the King Crow

In the butterfly world, there are a number of species that have been given the common name of "King" by the early collectors and authors. Of these, two can be found amongst the butterfly fauna in Singapore. Whether these species deserve this majestic name or not, is subject to debate, but over the years, they have been regularly called by their respective names that have remained in common use by butterfly enthusiasts.

Palm Kings are more likely to be spotted perched in the well shaded forests in Singapore

Both these species are notable for their larger size in relation to other related species in their sub-families. Although they are rather drab butterflies, their presence in the environment is very obvious as they fly around in their respective habitats. Both these species are not uncommon, and generally observed in localised areas where they frequent - usually in the vicinity of their caterpillar host plants and preferred habitats.

The King Crow (Euploea phaenareta castelnaui)

A King Crow feeding on the flower of Lantana camara

The first of our "Kings" is the King Crow (Euploea phaenareta castelnaui). Also called the Great Crow in certain regions, this species is the largest in its genus Euploea, of which 8 species have been recorded in Singapore. The King Crow frequents mainly mangrove and back-mangrove environments where its caterpillar host plant, the Pong-Pong Tree (Cerbera odollam) can usually be found. It is a resilient butterfly and has a large mobility index where it can fly long distances to other habitats in search of food.

There was a time when the Pong-Pong Tree was cultivated along roadsides and in urban parks and gardens as a shade tree. However, the damage caused by its large round fruits dropping onto parked cars and also the fact that this lactiferous tree has a poisonous sap that may be harmful to humans and pets has made it less desirable as a roadside tree in recent years. However, it still grows commonly in mangrove areas like Pasir Ris Park mangroves and Pulau Ubin.

A female King Crow feeding on the flower of the Buas-Buas

The King Crow is a slow flyer, making its presence felt by its sheer size as it glides by unhurriedly at treetop level. It is one of the distasteful Crow species that predators, like birds and reptiles, usually avoid. Its typical colour combination of black wings with white spots of the Danainae is a form of aposematic colouration that predators recognise.

A King Crow feeding on the flowers of a String Bush

The King Crow has large violet-tinged forewing apical spots sets it apart from the lookalike Malayan Crow. On the male, there is a raised scent patch on the hindwing cell and tornal area. The tornal area has a purplish sheen when viewed in a sidelight. The dorsum of the forewing of males are bowed, whilst it is straight in the females.

The Palm King (Amathusia phidippus phidippus)

The 2nd "King" that lords over Singapore's butterfly scene is the Palm King (Amathusia phidippus phidippus). The genus comprises a number of similar-looking species that are not easy to identify. All the species are large, usually shy and most are rare. The only common species that is most likely to be encountered by the butterfly enthusiast is the Palm King.

A Palm King perched on the leaves of a Coconut Palm, its caterpillar host plant

The Palm King is usually found in heavily shaded areas in the vicinity of its caterpillar host plant, the Coconut Palm (Cocos nucifera). It is attracted by overripe fruits and is sometimes encountered puddling on decomposing matter on the forest floor. It is a large butterfly, and is very conspicuous when it takes off in the habitats where it can be found.

A visiting Palm King perched on the wall of a HDB residential apartment block

The species is crepuscular in habit, and is attracted to lights of houses, and sometimes in urban Singapore, to the well-lit corridors of our HDB high rise apartments. There have been observations of pristine individuals perched on the walls of high rise residential areas, especially in the late evening hours of the day.

A Palm King perched on a twig

The Palm King is a medium brown on the upperside and usually unmarked. The underside is patterned with broad reddish-brown bands and narrower whitish bands across both wings. The hindwing features two large white-centred ocelli. The tornal area is blunt and has a pair of false "eyes".

A potential 3rd King in Singapore?

Recently, a possible 3rd "King" appeared in the form of a related species, the Bicolor-Haired Palm King (Amathusia friedrici holmanhunti). The key identifying attribute of this species are the abdominal hair tufts which are bicoloured, as compared to the Palm King's unicolourous hair tufts. It is hoped that a voucher specimen that will settle the doubt can be acquired soon. Until then, we have, for certain, two "Kings" in the butterfly world in Singapore.

Text by Khew SK : Photos by Alan Ang, David Chan, Khew SK, Huang CJ, Lim CA, Loh MY and Jonathan Soong

21 March 2020

Lepidoptera exotica

Lepidoptera exotica : The Non-Natives
Exotic butterfly species in Singapore

An "exotic" species in Singapore, the Great Orange Tip 

Recently, I attended a workshop conducted by NParks to discuss the definitions and clarify questions about various categories that are defined in the IUCN guidelines on threatened species. The workshop was held for the team leads and assessors of the forthcoming 3rd Edition of the Singapore Red Data Book. The Singapore Red Data Book conforms to the IUCN Red List of Threatened Species but is focused specifically on Singapore's biodiversity.

The IUCN status categories in the Red List

A group of over 60 experts and taxonomic leads/assessors from academia, government organisations and the public, specialising in various terrestrial and marine groups were there to share experiences and views on the Red Data Book.  The workshop session was to help standardise how we were going to assign categories and status of the various species in our respective taxonomic areas of interest.

Some controversial categories that were debated at the Workshop

Amongst the different classifications and categories discussed, was how to consider indigenous (native) species vs exotic (non-native) species. In many cases, some of our exotic butterfly species have been "naturalised" and have established viable and sustainable colonies in Singapore. In our human world, perhaps it could somewhat be comparable to a foreigner who has lived here for many years, became a permanent resident and then took up Singapore citizenship - what is often referred to as a "naturalised Singaporean".

Another non-native species found in Singapore, the Malayan Jester

Hence do we consider "naturalised" species as native? And how long should they be "naturalised" before we take them as native? Eventually, it was decided that only native species will be assessed (irrespective of whether they are naturalised or not) while non-native species will be excluded unless they are of conservation concern, but they will be placed in a separate holding section. For the butterfly group, the question that remained was, so which species is native and which is non-native?

The Pale Grass Blue can be considered a "naturalised" exotic in Singapore, having been continuously seen in urban parks and gardens since it was first discovered in the early 2000's

Native (indigenous) is described as "naturally existing in a place or country rather than arriving from another place" or "produced, growing, living, or occurring naturally in a particular region or environment. On the other hand, a non-native (exotic) species is one that "relates to a plant or animal that is not indigenous to a region" or "an organism that living or growing in a place that is not the location of its natural occurrence."

A mating pair of Tawny Costers, an exotic that was first discovered here in 2006

Whilst the definition of native and non-native is easy to understand, the challenge is the reference baseline information. For butterflies, we have often turned to the checklists that were produced by the authors of "Butterflies of the Malay Peninsula" and "Butterflies of West Malaysia and Singapore". These checklists made reference to data from collections that dated back to the late 19th century and are used as the baseline for the definition of what species is "native' or occurred naturally in Singapore.

The Yellow Palm Dart was discovered around 2009 and is now considered common in Singapore

Let us take a look at some of these "exotic" species in Singapore, and their status based on the IUCN guidelines, if they were to be assessed. These species are deemed as non-native as they were never recorded in Singapore before, based on our reference baseline checklists.  Other than Riodinidae, all the other five families of butterflies have examples of what is non-native in Singapore.

1) The Common Jay (Graphium doson evemonides) - IUCN : Vulnerable

The non-native Common Jay was discovered in 2004, and there is a resident population on Pulau Ubin

The Common Jay was not listed in the reference checklists of the early authors and thus far, we have had no evidence of its having been captured in Singapore in the reference collections that correspond to the checklists. It was hence a "new discovery" for Singapore when it was first spotted on the offshore island of Pulau Ubin in 2004. Over the years, however, there is a sustainable colony of the species on Pulau Ubin, and continues to be seen to this day.

Given its continued presence in Singapore, the Common Jay may be assumed to be a naturalised exotic to Singapore. As it has been bred on a variety of caterpillar host plants, amongst which are Desmos chinensis, Michelia alba and Polyathia longifolia, the species has a higher chance of sustaining its existence as part of Singapore's butterfly biodiversity. However, being a non-native species, it would be excluded from being assessed for the Singapore Red Data Book 3rd Edition.

2) The Great Orange Tip (Hebomoia glaucippe arturus) - IUCN : Endangered

The Great Orange Tip is a relatively large butterfly and has a strong flight. It was recorded from Singapore near one of our reservoir parks in the early 2000's. Several reported sightings were made on the island of Pulau Ubin in subsequent years. The sightings of this non-native species were probably of vagrant individuals that made it south to Singapore carried over by prevailing winds.

The Great Orange Tip is also a feature species in butterfly parks and individuals seen in Singapore could also have been escapees from these aviaries. This non-native is rarely seen in recent years, and will not be assessed for the Red Data Book 3rd Edition.

3) The Tawny Coster (Acraea terpsicore) - IUCN : Least Concern

First recorded as a new discovery to Singapore in 2006, the Tawny Coster is common here today, and continues to be seen regularly in urban and suburban areas. It has several alternative caterpillar host plants, and is hence able to maintain a sustainable population in Singapore for the past 14 years. It is also considered naturalised and is part of our urban biodiversity in Singapore.

The exotic Tawny Coster is now a naturalised species in Singapore, where it is common in urban areas

This slow-flying species is known to be distasteful to predators and that adds to its tenacity to survive and thrive in Singapore. Another naturalised species, the non-native Tawny Coster is likely to stay for the long term and has even widened its range to as far south as Australia in recent years.

4) The Malayan Jester (Symbrenthia hippoclus selangorana) - IUCN : Endangered

A small colony of the Malayan Jester survived at the Dairy Farm Nature Park for some time.

An individual of the Malayan Jester was first recorded as a new discovery for Singapore when it was spotted in 2012. The species was considered a possible vagrant until in the past 3-4 years when a colony established itself at the Dairy Farm Nature Park area. Whether the population can be sustained to qualify this species as a naturalised species remains to be seen.

Unlike other non-native species that have become common in Singapore, the appearance of this species has been erratic. However, where it occurs in Malaysia, the species is not uncommon. However, its appearance in Singapore would classify it as a non-native species and will not be assessed for the Singapore Red Data Book 3rd Edition.

5) The Pale Grass Blue (Zizeeria maha serica) - IUCN : Least Concern

This small butterfly was discovered here in the early 2000's, and was validated by the late Col John Eliot. The species was included in his Malayan Nature Journal : Update to C&P4 paper. The species has been considered extant in Singapore since the early 2000's and continues to be found here as a relatively common species. An individual was photographed at the Bt Panjang Butterfly Garden as recently as last weekend.

This naturalised species is relatively common, and in areas where they fly, there can be as many as 6-12 individuals fluttering around the grasses and wild flowers. Its caterpillar host plant, the Yellow Sorrel (Oxalis corniculata) is a common "weed". The Pale Grass Blue would be considered as "Least Concern" under the IUCN guidelines, but is still classified as a non-native species in Singapore and will not be assessed in the Singapore Red Data Book 3rd Edition.

6) The Yellow Palm Dart (Cephrenes trichopepla) - IUCN : Least Concern

A species that is more associated with the Australian region than Southeast Asia, this species first appeared in 2009 in Singapore. Since then, it has also moved northwards and has been spotted in West Malaysia. The fact that the common coconut palm (Cocos nucifera) is its caterpillar host plant may explain its rapid spread across the region.

This exotic species has now become common and is regularly seen at urban parks and gardens where the coconut palm can be found. It was even recorded from the offshore island of Pulau Semakau during our surveys conducted for the National Environment Agency on the island.

Participants at the Red Data Book 3rd Edition Workshop organised by NParks

And so, here we see a small sample of the exotics or non-native butterflies of Singapore. Some have become naturalised and common, whilst others continue to be elusive or probably vagrants. There are many other species that are exotic to Singapore, and they will not be assessed and featured in the main section on butterflies in the Singapore Red Data Book 3rd Edition.

Text by Khew SK : Photos by Khew SK, Loh MY, Jonathan Soong and Anthony Wong