Author: admin

by Angela Hijjas

A small group of Oriental Pied Hornbills (Anthracoceros albirostris convexus) has recently been seen around Rimbun Dahan. Like all hornbills, they have large bills topped with a hollow casque. This species is resident up to 150m, where it frequents forests, the forest edge, plantations and beach scrub. Although it feeds mainly on insects and other small vertebrates, it gathers in groups to feed in fruiting trees, as it did at Rimbun Dahan to feed on the fruits of Kelompang jari (Sterculia foetida).

Oriental Pied Hornbills are a noisy species, whose flight consists of rapid flaps followed by short glides. It is also remarkably tame — large groups can often be observed by vacationers gathering in beach-side trees on Pulau Pangkor.

In other bird news, Rimbun Dahan usually hosts a group of Ashy Minivets (Pericrocotus divaricatus) during the northern winter. The first two arrived on 3rd November 08, and more the next day. I have been observing them easing because the tree they favour was struck by lightning a few months previously, and has little vegetation. Fortunately there are three other trees close by of the same species, Terminalia bellirica, so the group of winter migrants had alternatives.

On the morning of 29th January, I saw an unusually large number, at least 25, in the same tree, with others flitting around and feeding on insects in the other trees. Then a second flock of possibly 40 birds (from the corner of my eye, I initially I took them to be mynas) flew past. Most of those in my tree took off and followed them, heading northwest. I suspect I witnessed the departure for the north – what a moment!

Our snake of the month is the Copperhead Ratsnake (Elaphe radiata Boie 1827), otherwise known as the Radiated Ratsnake. A fine specimen of this large non-venomous snake, over a meter long, was found this week in one of the artists’ studios.

Copperhead Ratsnake

According to Klaus Dieter-Schulz, who has published a monograph on the Elaphe genus, many snakes of this type are associated with water and swim very well, which has been confirmed with findings of the Copperhead Ratsnake far out to sea. It is thought that this helps them colonise offshore islands, and the snake is well distributed across Asia. Other typical ratsnake habitats include fallow land and scrub edges, interspersed with rubble and larger rocks, like abandoned quarries and refuse disposal sites. Many species of the genus also favour man-made environments, where they prey on newborn and subadult rodents. The Copperhead is sometimes encountered in piles of coconut shells, leading to its local name in Thailand of ‘Coconut Snake’.

When agitated the Copperhead Ratsnake assumes an interesting defence mechanism. It inflates the front half of its body, not width-wise like the cobra, but in height, meanwhile rearing up in an s-shape, in order to appear much bigger than it really is. “They literally dive towards the apparent aggressor with their mouth agape,” Dieter-Schulz writes, “The inflation of the neck causes the often differently coloured interstitial skin to become visible between the scales and the snake immediately assumes a different appearance.” However, if this attack is ineffective, the snake will also play dead, laying limp and motionless on the ground for some time.

Reference:
A monograph of the colubrid snakes of the genus Elaphe Fitzinger, by Klaus-Dieter Schulz, André Entzeroth. Published by Koeltz Sceintific Books, 1996.

November has been wet. Last night we had 35 mm of rain in an hour, and over the month a total of 437 mm, and still one day to go. Since we started recording rainfall in 2005, the wettest month ever was in November 2006 with 446 mm, and November 2008 may yet be more. A pity we can’t export to Australia…

A snake was found this morning on the road, apparently washed out of a tree and drowned in the deluge (picture below). It has been identified as a White-Spotted Slug Snake, Pareas margaritophorus, another new addition to the snake population at Rimbun Dahan. Lauren Black, whose room is in the guest house, had a tiny Paradise Tree Snake, Chrysopelea paradisi, on her balcony the other day, poking its head up through the floor slats (see images at right).

The population of macaques is thriving, but causing some damage to new plantings, although like the birds they feasted on buah salam, Eugenia pseudosubtilis (see image below left) . The newly planted Dipterocarpus crinitus, keruing mempalas, have had to be caged as the monkeys constantly pull off the new pink shoots thinking it is something to eat. Other Dipterocarps, like the Shorea gratissima, left, are establishing well. A new addition to the Dipterocarp collection is Shorea henryana, pictured at right.

It has been hard to find any colour in the garden with the constant rain, but the flowering ginger Hedychium coronarium (below right) is fruiting, and the Ixora schortechinii (below middle) is flowering; one must search the whole 14 acres for these small flashes of colour.

The birds, though, make up for this. The birding has been excellent this last month, made even better with the perch provided by a dead tree in front of the house. ‘Lifers’ in the last week were a Ruddy Kingfisher, Halcyon coromanda, and a Red-bearded Bee-eater, Nyctyornis amictus (right) and there was much excitement among the staff when four Oriental Pied-Hornbills, Anthracoceros albirostris, (left) perched on said dead tree for a few minutes.

BY ANGELA HIJJAS

The main objective in the planting programme at Rimbun Dahan is to develop the highest canopy possible, not always easy when trees tend to branch out as soon as they reach clear light. To encourage monopodial structure for as long as possible, we prune side branches and force the trees up by dense planting. Inevitably this has made them the tallest structures in the neighbourhood, apart from the DiGi tower on an adjacent block, and they are vulnerable to lightening. Two trees were lost on different occasions, a durian on the right-hand side and a Sterculia (fortunately not an indigenous species). We lose four or five trees a year, but then we have an open space where we can plant something else, in a ready-made ‘tube’ for rapid vertical growth.

The notes on Shorea sumatrana last month generated an interesting response on its rapid growth, spurring me on to measure more of Rimbun Dahan’s dipterocarps, although not all of them have a definite planting date. The following species have been measured this month, and the dates of planting noted where they are known. Measurements are in inches GBH, or girth at breast height.

1992, Shorea materialis, balau pasir, 10 saplings were planted in a sandy area of the garden and now measure between 18″ and 58″. There is no apparent reason why some have done better than others, but it seems where there is under planting and the trees are perhaps less disturbed they do better, but this is not always the case… the biggest of them all is out in the open.

Sizes of the ten trees are: 18″, 20″, 30″, 38″, 43.5″, 44″, 46″, 46″, 50.5″ and 58.5″.

A Terminalia foetida planted in the same vicinity at the same time measures 55″.

Three Hopea nutans, also planted at that time, or earlier, measure 30″, 21″ and 25″. Another four planted a few years later, measure 17″, 17″, 17″ and 15.5″. Planting dates are uncertain.

Beside the dance studio there are three Dipterocarpus dyeri trees, planting dates unknown, and they now measure 46″, 51″ and 52.5″. There is one 44″ Hopea nutans in the same area.

Three Dipterocarpus baudii planted in 1990, now measure 34″, 36.5″ and 28″. The last fell over at some point and was tied up to other trees for support, so that must have affected growth.

The row of Hopea odorata planted along the front drive in 1990 vary in size, the biggest being a princely 68″, but the others vary leading me to think that some seedlings are less successful than others.

Five Shorea roxburghii were planted in 1996 and they now measure between 31″ and 50″ (31, 33, 38.5,48.5, 50).

The following are not dipterocarps, but have done well:

A row of ten jelutong, Dyera costulata, was planted in 1999, but only six survive. Their dimensions range between 24″ and 50″ (24, 37, 42, 44, 47, 50).

Five ipoh trees, Antiaris toxicaria, were planted in 1989, and they measure between 53″ and 85″ (53, 59, 62, 62, 85). The 59er was struck by lightening about 5 years ago but recovered.

Just when you thought we couldn’t have more pictures of snakes eating things — here’s another scaly individual, possibly a rat snake or a bronzeback, gorging on a lizard, right near our front door! Photos by resident artist Oceu Apristawijaya.

We are also raising a new clutch of chickens… just 15, hopefully for our own consumption, hopefully not for snake food.

A critically endangered species, Shorea sumatrana was one of the first Dipterocarps planted at Rimbun Dahan, probably in 1992. It is now flowering for the first time, and although we have had Dipterocarps flower before, they have always been more common species like Hopea odorata or Shorea roxburgii, species that cope better in our drying weather. Earlier this year, our one specimen of Shorea sumatrana was measured to have a GBH (girth at breast height) of 90cm, so it has grown well, despite not being in a more favourable wet position.

The flowers are tiny, perhaps half a centimeter, but the flush on the branches gives a pinky hue. We look forward to posting news of fruit setting, but so far no pollinators have been observed.

This species is being painted by Rimbun Dahan resident botanical artist, Lauren Black, whose subjects are rare species; rare either because they do not occur often in their natural habitat, or because of habitat loss and logging.

Shorea sumatrana or sengkawang is endemic to Sumatra and the Malay Peninsula, generally on the East Coast, where it is frequently found in low-lying swampy habitats along the banks of rivers. It is now critically endangered by population fragmentation and habitat destruction.