10 February 2018

Birdwing Season in Singapore

Birdwing Season in Singapore
Featuring the Common Birdwing (Troides helena cerberus)

The Common Birdwing is one of Singapore's largest butterfly species by wingspan. A large female of this species can have a wingspan measured from tip to tip up to 180mm. The species can be seen from time to time throughout the year, but is sometimes uncommon in certain months. From records of sightings of this species over the years, it appears to be quite seasonal.

The Common Birdwing is more often spotted in the months of November to February each year. Towards the end of 2017 and over the first two months of 2018, the species has been spotted more often in urban parks and gardens and also at the fringes of our nature reserves. Where its caterpillar host plant, Aristolochia acuminata grows, observations of the species' caterpillars are more prevalent in these months of the year.

The Common Birdwing has rich golden yellow hindwings with black margins and black forewings, often with suffused white along the forewing veins. The female has a full range of large black submarginal spots which are not conjoined. The male has only one or occasionally more submarginal spots - usually at the tornal area. The thorax area is usually reddened from the base of the wings to the collar just behind the head of the butterfly.

A male Common Birdwing courting a female at the Singapore Botanic Gardens

The Common Birdwing is a spectacular butterfly in flight. Its large size allows it to be spotted easily as it swoops overhead, almost bird-like. The butterfly is capable of flying long distances and at great heights. As it flutters and glides at tree top level, the Common Birdwing is a sight to behold.

Male Common Birdwings feeding on Ixora (top) and Buas-Buas (bottom)

Males are usually smaller than the females. However, unlike the usual Papilionidae behaviour, the males are rarely seen to puddle at damp sandy spots along streambanks. Both sexes are more often seen feeding at flowering plants like Ixora, Pagoda Flower, Hibiscus, Peacock Flower, Prickly Lantana and even Buas Buas (Premna serratifolia).

In late 2017 and early 2018, sightings of the Common Birdwing became more and more frequent. The Common Birdwing was spotted in locations like Jurong Eco Green, Pulau Ubin, Singapore Botanic Gardens, Hort Park and Upper Seletar Reservoir Park. Invariably, all these locations where the butterfly was observed are usually where the Common Birdwing was feeding at flowering plants, or flying around looking for flowers to feed on.

Common Birdwing caterpillars

Both the males and females were equally common. Caterpillars of the species were found at various areas where the host plant was cultivated - Hort Park, Jurong Eco Green and Pulau Ubin. Over at Seletar Country Club's Butterfly Garden, where the host plant was cultivated some time ago in the hope of attracting the Common Birdwing and Common Rose, the caterpillars of the Common Birdwing suddenly appeared.

Newly eclosed Common Birdwing released at Seletar Country Club

The caterpillars were reared until successful eclosion and the adult butterflies released in the hope that they will spawn the next generation of Common Birdwings at Seletar Country Club, or appear at nearby locations where the butterfly can sustain future generations. Sadly, the unsustainable feeding habit of the caterpillars of this species is such that they tend to kill off the Aristolochia vine unnecessarily, and in the process, deprive themselves of their critical food source.

The Common Birdwing displays the usual Papilionidae flight characteristic when feeding at flowers. The hindwings are held relatively still to balance the butterfly, whilst its forewings flutter rapidly to keep it aloft. Like most species in the family, the Common Birdwing has six long and fully-developed legs which it extends and holds on to the perch or flower that it is feeding on.

Male (top) and Female (bottom) Common Birdwing feeding on Hibiscus flower

So whilst the Common Birdwing season is in full swing, do seek out the favourite locations where it is often seen and get your fill of the beauty of this butterfly before it becomes uncommon again!

Text by Khew SK : Photos by David Chan, May Chan, Bob Cheong, Foo JL, Khew SK and Ros Qian