Wednesday, December 21, 2011

Track 16: Libellago lineata (Golden Gem)

Recently at Track 16 while doing a survey (on a sunny day) we observed a flash of yellow and black, and upon tracking it down discovered that it was a Libellago lineata. We hadn't seen this species at this location before for the survey.

As we transected along the stream we kept seeing individuals and we wondered if it was the same one following us, but after a while we confirmed that there were multiple individuals. As we walked on we realized there were really a lot of Libellago lineata in the area - which was a delightful surprise, as we later found the female individuals.

In total we counted about 10 males and 5 females. The colour of the Libellago genus is always very amazing to me: L. aurantiaca (Fiery Gem) is the brilliant red and yellow, L. hyalina (Clearwing Gem) is a yellow and purple, and L. lineata is a beautiful yellow and black. The last one ever recorded in Singapore is L. stigmatizans (Orange-Faced Gem) which is suspected to be extinct locally.

The males of the Libellago genus have interesting territorial displays - the males hover before each other, as in Mr Tang's video:

We observed that behaviour several times at Track 16, however noted that the lineata display is very fast, settling the 'fight' much faster than that of the aurantiaca species.

For courtship, the males extend their white legs forward before the female, and the females reject the males by lifting their tail end up. We observed the rejected male moving on to the next female and the next, until a female consented. The entire process was extremely fast - they formed the heartshaped position, and a while later the female was ovipositing, with the male guarding her on the same twig floating on the water. And a while later, the male was with another female.

There was only one male in the area with around 4 females - probably the big winner of the day's territorial competitions.

Thursday, December 1, 2011

Chestnut Marsh

Site: Chestnut Marsh
Species list: 

  • Crocothemis cervilia
  • Diplacodes trivialis
  • Ictinogomphus decoratus
  • Indothemis limbata
  • Nanophyea pygmea
  • Orthetrum Sabina
  • Orthetrum testaceum
  • Pantala flavescens
  • Rhyothemis phyllis phyllis
  • Ceriagrion cerinorubellum
  • Pseudagrion microcephallum

Weather: Perfect! Sun - 100%; Cloud - 0%
Time: 0845 - 0945

Chestnut Marsh is a shallow and open water body. Clear water with a muddy substrate - some vegetation growing within the marsh in the form of large patches of reeds in the middle of the area, and the banks that we accessed the area by were covered with ferns and pitcher plants.

Upon bashing into the growth on the bank we found hordes of Nanophyea pygmea (Scarlet Dwarf). These little guys are really amazingly good-looking! I never tire of observing them. Its probably something about the size - they seem too miniature to be quite real. Yet real they are, there were little red specks every few centimeters and also some tiny yellows (the females). I've gone for too long without seeing these little guys and it was good to see them again in such abundance. Rarely do we find them congregating in such numbers though! It felt quite as though we'd walked into Lilliputia.

Some interesting marsh species here! A pity we couldn't access the area from the other parts of the perimeter as the opposite banks had much denser growth; and the substrate of the marsh was too soft to be walked on..