Sunday, February 20, 2011

Plenty to see at Chek Jawa

The Naked Hermit Crabs had a wonderful outing to Chek Jawa Boardwalk on February 12. It was our regular monthly trip out to our favourite place. There were 12 visitors and so we split into 2 groups, one led by PY and Daniel, and the other by LK.

At the start of the walk, an observant visitor, Karen, spotted an Oriental Pied Hornbill (Anthracoceros albirostris) perched on a high branch right above our heads. The hornbills were really quiet that morning, but fortunately we managed to catch a glimpse of this large beautiful bird. It is reported that there are approximately 100 hornbills in the wild in Singapore. It was definitely a good start to the trip! A joy!

Oriental Pied Hornbill in Chek Jawa

Our next checkpoint was the Jejawi Tower. On our way up, we were able to see lots of nests formed by the Weaver Ants (Oecophylla smaragdina) on the tree next to the tower. These ants are able to glue leaves together until they form a large ball with a cavity inside. The nests are considered some of the most complex of ants' nests. This is because the process of building the nests involves complex co-ordination by the ants to pull and stick the edges of the leaves together. It is also observed that a large colony would build several satellite nests on a tree. When the leaves forming the nests dry up, the ants would move away and form new nests with fresh green leaves. The process of building new nests is never done! Fascinating nature facts!

A new nest being built by Weaver Ants

Two old nests
At the inner mangroves area, we were able to observe many tree-climbing crabs. These crabs are usually seen in the mud mounds formed by the Mud Lobsters. The crabs have another common name, Vinegar Crabs. It is a Teochew delicacy to pickle these crabs in black vinegar. The food culture of eating vinegar crabs in Singapore seems to be lost already. However, a few years ago, one of our visitors who was originally from Bangkok told me that we can still find this delicacy in the Chinatown area (Yaowarat Road) of Bangkok. Another visitor, an elderly Teochew gentleman, told me that he had eaten vinegared crabs when he was a young man. He thinks too that no one prepares them in this way any more.

Surprisingly, we did not see any giant mudskippers in the inner mangrove area today.

Further down the path, we came up close to a large web formed by the Golden Orb Web Spider (Nephila maculata). You can recognise this spider by looking for the gold colour on the joints on the legs. The female is very large relative to the tiny inconspicuos male spider.

Ah....! It is low tide at the mangroves! We were excited by the prospect of observing more animal activity on the exposed inter-tidal area.

That's right! We saw 3 large (about a metre tall) shore birds feeding in the shallow waters on the outer sand bank area. A zoom-in of our photographs revealed that it was the Grey Heron (Ardea cinerea). There are many heronries on Pulau Ubin. So, on your next visit to Pulau Ubin, do look out for the nests usually set high up on trees found next to bodies of water. One of the Crabs' favourite spots to observe the Grey Herons and their nests is at Pekan Quarry.

Grey heron feeding on the mudflat at low tide

We also stopped for a long time at the silty area where a stream empties into the shore. Lots of mudskippers here! And there are several different species too. In particular, we were fascinated by the dancing mudskippers! These are the Bearded Mudskippers (Scartelaos histophorus). In recent months, we have observed that they have become a regular sighting at Chek Jawa at low tide. The Bearded mudskipper has a long slender body and, in my opinion, it is a very expressive fish, if there were such a thing as an expressive fish! It was very active, constantly moving around, and sometimes, it leapt up into the air in an almost vertical position.

Bearded mudskipper

On this particular trip, we noticed that the Bearded Mudskipper actually digs a burrow in the silt! Here is a picture of the mudskipper returning, head first, into its little burrow.

A Bearded Mudskipper going into its burrow

No visit to Chek Jawa is complete without spending some time to observe the beautiful fiddler crabs (Uca sp.). There were large numbers of fiddler crabs on the shore, especially the males with their uneven claws; one large and one small claw. Fiddler crabs are common on the natural undisturbed shores of Singapore. The fiddler crabs (male) have bright orange claws, and the shells of some of them are multi-coloured (mostly blue) and some even have markings.

We had a leisurely walk on the coastal boardwalk. At low tide, it is possible to see the beautiful seagrass meadows, oysters and barnacles on the rocks, large shells such as the Noble Volute, and a couple of carpet anemones scattered on the lagoon.

Chek Jawa coastal boardwalk at low tide

Seagrass meadow in Chek Jawa
Near the coral rubble area, we were lucky to spot a pair of very colourful male Red Junglefowl (Gallus gallus) sunning themselves at the edge of the coastal forest. We were able to see the characteristic white patch behind the ear, as well as the white patch on the rump. According to PY and Daniel who led the other group, they saw about 4 of these birds including the young. We were delighted with this relatively rare sighting.

Sighting of Red Junglefowl at Chek Jawa
It was definitely a good trip for everyone. The weather was kind to us and we had a lot of interesting sightings of the fauna of Chek Jawa. Everyone, guides and visitors alike, left the place pleased with a Saturday morning that was well spent. Hope you guys had fun at the nature walk!

And what our visitors are saying....

1) Here is a link to more lovely photos of flora and fauna of Pulau Ubin taken by a visitor, Wei Neng.
In particular, look out for great shots of the jumping mudskippers!

2) Karen, one of our visitors on this trip, wrote to tell us that her group stayed on to explore after the walk and came across many other birds and creatures including a pair of Brahminy kites, a Common Flameback woodpecker, a White-rumped Shama,a collared kingfisher, and yet another hornbill amongst other things. Thank you for sharing your sightings!

A pair of Brahminy Kites (photo by Karen)

Female Common Flameback (photo by Karen)
Members of the public can sign up for our free walks whch are held every second Saturday of the month. Register by writing to Our next trip is on 12th March.

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