Sunday, 17 June 2012

Fascinating behaviour of Green Metalwing (Neurobasis chinensis)

I wrote about my recent trip to Endau Rompin in my previous blog (posted on 10 June 2012). During the trip I recorded on video interesting behaviour of a few nice species of forest stream. Let me talk about that of a Neurobasis species today.

Species of Neurobasis are known as 'Metalwings', on account of the brilliant iridescence of their coloured wings. They are damselflies and engage in elaborate territorial fight and courtship during which the male displays brilliatly coloured wings, a performance which always leaves the observer breathless with admiration. The late M.A. Lieftinck spoke for many when he called Metalwings the "Birds of Paradise among Odonata."

In Singapore, only one species of metalwings had ever existed - Neurobasis chinensis (Green Metalwing). The last individual of Neurobasis chinensis was seen in a stream in the Upper MacRitchie Basin in 1970. Now, this species is considered to be nationally extinct. All suitable habitats for this species (clear, moderately flowing streams) have been destroyed in Singapore.

The footage of Neurobasis chinensis below was recorded in Malaysia in June 2012. It shows the patrol flight of a male, followed by vigorous territorial fight between two males. A female then came to the scene and the winning male copulated with her. I couldn't follow the mating pair with my camera as they flew to a concealed position in the vegetation. When they returned, they flew separately, with the male flying very low, just above water. The tips of his hindwings occassionally touched the fast flowing water, as if to test the flow rate. His abdomen was uplifted, apparently displaying the small white spot beneath. The female followed him closely behind, occasionally touching the flowing water with the tips of her legs, as if to test the flow rate too. The male eventually landed, perched on an oviposition substrate with his abdomen tip still turned upward. The female landed behind him and soon started to oviposit by curling her abdomen into a semi-circle and dipping the tip into water. Her male guarded her responsibly. At times, the male flew further from his mate and perch on a leaf nearby.

The other male (the one who lost the battle to the winning male earlier) came back and challenged the winning male again. The winning male took on the challenge and the two males flew in a tight circle just above the ovipositing female. The loser lost again and flew away. The female continued to oviposit without being harassed by the intruder.

It is amazing how such a delicate insect can stand against the swift current while ovipositing. A few times I thought she would be washed away by the strong current, but she could almost always hold onto the water plants. When she did lose grasp, she simply flew up and landed again.

For a more detailed account of the behaviour of Neurobasis chinensis, please refer to this book:

The Metalwing Demoiselles of the Eastern Tropics by Albert G. Orr and Matti Hämäläinen.

Sunday, 10 June 2012

Endau Rompin Trip (June 2012)

Four of us spent four days in Endau Rompin National Park last week. We were there exploring the rivers and streams for dragonflies. Due to the pristine habitats, we were able to see many nice forest species. I observed and video-recorded interesting behaviour of Neurobasis chinensis (Green Metalwing) and Libellago aurantiaca (Fiery Gem). I will post about them in the coming few weeks.

On day 2 we were exploring a stream just outside the park. We saw two animal tracks, left behind by two large animals, probably strolling along side by side.

We were excited to see the tracks but were unfamiliar with animal footprints. We know there are Sumatran Rhinoceros, deer, black leopards, tigers, tapirs and elephants living in the park. We were hoping that those were tiger tracks, but I knew they probably were not, as tigers are solitary animals. The chance of two adult tigers walking side by side is almost non-existent.

This is a wing of a beautiful insect. Do you know what insect it is?

In Malaysia, and some other countries too, oil palm plantations are rapidly replacing the rainforest habitat. It is very sad. On our way to Endau Rompin National Park, we saw oil palm plantations all along the way. Just 10 km before the park entrance, we saw a large area of rainforest just cleared for yet another oil palm plantation.

30 or 40 years ago, we hardly used any palm oil. Now our demand for palm oil is so huge and is still growing fast.

There are many alternatives to palm oil, such as canola oil, peanut oil, sunflower oil and coconut oil, but unfortunately none as cheap or efficient, which is why companies are reluctant to switch.

But what is the real cost of palm oil?

Saturday, 2 June 2012

Libellago lineata (Golden Gem)

I gave a talk on the Dragonflies of Singapore on 26 May 2012 during the inaugural Festival of Biodiversity organized by the National Parks Board. During the talk, I showed a video of two male Libellago lineata engaged in territorial fight and the audience liked it very much. The footage shows two male Libellago lineata engaged in territorial fight.

Libellago lineata males may fight for over an hour, taking short breaks occasionally. During the fight, they do not have bodily contact at all, and therefore none of them would get hurt. When a third male joins in the fight, they would chase one another in a circle.

In fact, Libellago is my favourite genus of damselflies. This ia an Asian genus under the family Chlorocyphidae. It has only about 30 species and many of them are brilliantly coloured and exhibit territorial behaviour, and require pristine habitats such as clear flowing streams in the forest. 

In Singapore, four Libellago species have been recorded. Sadly, one of them has become nationally extinct.

The Singapore Libellagos:

Libellago aurantiaca (Fiery Gem)
Libellago hyalina (Clearwing Gem)
Libellago lineata (Golden Gem)
Libellago stigmatizans (Orange-faced Gem), nationally extinct

Two male Libellago aurantiaca (Fiery Gem) in combat. 
They fight very similarly to Libellago lineata (Golden Gem).